diff mbox

[5/5] arc: Add prologue analysis

Message ID 20170214100130.29194-5-Anton.Kolesov@synopsys.com
State New
Headers show

Commit Message

Anton Kolesov Feb. 14, 2017, 10:01 a.m. UTC
Add a prologue analysis that recognizes all instructions that may happen in
compiler-generated prologue, including various stores, core register moves,
subtraction and ENTER_S instruction that does a lot of prologue actions through
microcode.

Testcases cover various prologue scenarios, including instructions that are
spread across multiple 16-bit encodings (for example there are 7 encodings of
store instruction).

gdb/ChangeLog:

yyyy-mm-dd  Anton Kolesov  <anton.kolesov@synopsys.com>

	* arc-tdep.c (arc_frame_cache): Add support for prologue analysis.
	(arc_skip_prologue): Likewise.
	(arc_make_frame_cache): Likewise.
	(arc_pv_get_operand): New function.
	(arc_is_in_prologue): Likewise.
	(arc_fprintf_disasm): Likewise.
	(arc_disassemble_info): Likewise.
	(arc_analyze_prologue): Likewise.
	(arc_print_frame_cache): Likewise.
	(MAX_PROLOGUE_LENGTH): New constant.

gdb/doc/ChangeLog:

yyyy-mm-dd  Anton Kolesov  <anton.kolesov@synopsys.com>

	* gdb.texinfo (Synopsys ARC): Document "set debug arc 2".

gdb/testsuite/ChangeLog:
yyyy-mm-dd  Anton Kolesov  <anton.kolesov@synopsys.com>

	* gdb.arch/arc-analyze-prologue.S: New file.
	* gdb.arch/arc-analyze-prologue.exp: Likewise.
---
 gdb/arc-tdep.c                                  | 526 +++++++++++++-
 gdb/arc-tdep.h                                  |   2 +
 gdb/doc/gdb.texinfo                             |   3 +-
 gdb/testsuite/gdb.arch/arc-analyze-prologue.S   | 903 ++++++++++++++++++++++++
 gdb/testsuite/gdb.arch/arc-analyze-prologue.exp | 206 ++++++
 5 files changed, 1622 insertions(+), 18 deletions(-)
 create mode 100644 gdb/testsuite/gdb.arch/arc-analyze-prologue.S
 create mode 100644 gdb/testsuite/gdb.arch/arc-analyze-prologue.exp

Comments

Eli Zaretskii Feb. 14, 2017, 3:51 p.m. UTC | #1
> From: Anton Kolesov <Anton.Kolesov@synopsys.com>
> Cc: Anton Kolesov <Anton.Kolesov@synopsys.com>,	Francois Bedard <Francois.Bedard@synopsys.com>
> Date: Tue, 14 Feb 2017 13:01:30 +0300
> 
> Add a prologue analysis that recognizes all instructions that may happen in
> compiler-generated prologue, including various stores, core register moves,
> subtraction and ENTER_S instruction that does a lot of prologue actions through
> microcode.
> 
> Testcases cover various prologue scenarios, including instructions that are
> spread across multiple 16-bit encodings (for example there are 7 encodings of
> store instruction).
> 
> gdb/ChangeLog:
> 
> yyyy-mm-dd  Anton Kolesov  <anton.kolesov@synopsys.com>
> 
> 	* arc-tdep.c (arc_frame_cache): Add support for prologue analysis.
> 	(arc_skip_prologue): Likewise.
> 	(arc_make_frame_cache): Likewise.
> 	(arc_pv_get_operand): New function.
> 	(arc_is_in_prologue): Likewise.
> 	(arc_fprintf_disasm): Likewise.
> 	(arc_disassemble_info): Likewise.
> 	(arc_analyze_prologue): Likewise.
> 	(arc_print_frame_cache): Likewise.
> 	(MAX_PROLOGUE_LENGTH): New constant.
> 
> gdb/doc/ChangeLog:
> 
> yyyy-mm-dd  Anton Kolesov  <anton.kolesov@synopsys.com>
> 
> 	* gdb.texinfo (Synopsys ARC): Document "set debug arc 2".
> 
> gdb/testsuite/ChangeLog:
> yyyy-mm-dd  Anton Kolesov  <anton.kolesov@synopsys.com>
> 
> 	* gdb.arch/arc-analyze-prologue.S: New file.
> 	* gdb.arch/arc-analyze-prologue.exp: Likewise.

OK for the documentation part.

Thanks.
Pedro Alves Feb. 17, 2017, 1:25 p.m. UTC | #2
On 02/14/2017 10:01 AM, Anton Kolesov wrote:
> +
> +/* Copy of fprintf_disasm from disasm.c.  */
> +
> +static int ATTRIBUTE_PRINTF (2, 3)
> +arc_fprintf_disasm (void *stream, const char *format, ...)
> +{
> +  va_list args;
> +
> +  va_start (args, format);
> +  vfprintf_filtered ((struct ui_file *) stream, format, args);
> +  va_end (args);
> +  /* Something non -ve.  */

This is always the null stream AFAICS,
so why waste time with calling vfprintf_filtered?
See disasm.c:gdb_buffered_insn_length_fprintf, for example.

> +  return 0;
> +}
> +
> +/* Return properly initialized disassemble_info.  */
> +
> +struct disassemble_info
> +arc_disassemble_info (struct gdbarch *gdbarch)

Also, something's odd with the patch split, since this function
was used by an earlier patch.

> +# Test more levels of backtrace.
> +gdb_breakpoint nested_prologue_inner temporary
> +gdb_continue_to_breakpoint nested_prologue_inner
> +gdb_test "backtrace 10" \
> +    "#0\[ \t\]*$hex in nested_prologue_inner .*\r\n#1\[ \t\]*$hex in nested_prologue_outer .*\r\n#2\[ \t\]*$hex in main.*" \
> +    "backtrace in nested_prologue_inner"
> +    set regs [saved_regs_to_str {r13 r18}]
> +    gdb_test "info frame" ".*Saved registers:$regs" \
> +	"saved registers in nested_prologue_inner"
> +    set regs [saved_regs_to_str {r14 r15 blink}]
> +    gdb_test "info frame 1" ".*Saved registers:$regs" \
> +	"saved registers in nested_prologue_outer"
> +

Something's odd with indentation here.

This is missing a NEWS entry for the command.

But otherwise, this looks very good to me.

Thanks,
Pedro Alves
diff mbox

Patch

diff --git a/gdb/arc-tdep.c b/gdb/arc-tdep.c
index a18f16a..9076c98 100644
--- a/gdb/arc-tdep.c
+++ b/gdb/arc-tdep.c
@@ -28,6 +28,7 @@ 
 #include "gdbcore.h"
 #include "gdbcmd.h"
 #include "objfiles.h"
+#include "prologue-value.h"
 #include "trad-frame.h"
 
 /* ARC header files.  */
@@ -42,8 +43,7 @@ 
 #include "features/arc-v2.c"
 #include "features/arc-arcompact.c"
 
-/* The frame unwind cache for the ARC.  Current structure is a stub, because
-   it should be filled in during the prologue analysis.  */
+/* The frame unwind cache for ARC.  */
 
 struct arc_frame_cache
 {
@@ -52,7 +52,35 @@  struct arc_frame_cache
      frame.  */
   CORE_ADDR prev_sp;
 
-  /* Store addresses for registers saved in prologue.  */
+  /* Register that is a base for this frame - FP for normal frame, SP for
+     non-FP frames.  */
+  int frame_base_reg;
+
+  /* Offset from the previous SP to the current frame base.  If GCC uses
+     `SUB SP,SP,offset` to allocate space for local variables, then it will be
+     done after setting up a frame pointer, but it still will be considered
+     part of prologue, therefore SP will be lesser than FP at the end of the
+     prologue analysis.  In this case that would be an offset from old SP to a
+     new FP.  But in case of non-FP frames, frame base is an SP and thus that
+     would be an offset from old SP to new SP.  What is important is that this
+     is an offset from old SP to a known register, so it can be used to find
+     old SP.
+
+     Using FP is preferable, when possible, because SP can change in function
+     body after prologue due to alloca, variadic arguments or other shenanigans.
+     If that is the case in the caller frame, then PREV_SP will point to SP at
+     the moment of function call, but it will be different from SP value at the
+     end of the caller prologue.  As a result it will not be possible to
+     reconstruct caller's frame and go past it in the backtrace.  Those things
+     are unlikely to happen to FP - FP value at the moment of function call (as
+     stored on stack in callee prologue) is also an FP value at the end of the
+     caller's prologue.  */
+
+  LONGEST frame_base_offset;
+
+  /* Store addresses for registers saved in prologue.  During prologue analysis
+     GDB stores offsets relatively to "old SP", then after old SP is evaluated,
+     offsets are replaced with absolute addresses.  */
   struct trad_frame_saved_reg *saved_regs;
 };
 
@@ -117,6 +145,10 @@  static const char *const core_arcompact_register_names[] = {
   "lp_count", "reserved", "limm", "pcl",
 };
 
+/* Functions are sorted in the order as they are used in the
+   _initialize_arc_tdep (), which uses the same order as gdbarch.h.  Static
+   functions are defined before the first invocation.  */
+
 /* Implement the "write_pc" gdbarch method.
 
    In ARC PC register is a normal register so in most cases setting PC value
@@ -650,6 +682,419 @@  arc_frame_base_address (struct frame_info *this_frame, void **prologue_cache)
   return (CORE_ADDR) get_frame_register_unsigned (this_frame, ARC_FP_REGNUM);
 }
 
+/* Helper function that returns valid pv_t for an instruction operand:
+   either a register or a constant.  */
+
+static pv_t
+arc_pv_get_operand (pv_t *regs, const struct arc_instruction &insn, int operand)
+{
+  if (insn.operands[operand].kind == ARC_OPERAND_KIND_REG)
+    return regs[insn.operands[operand].value];
+  else
+    return pv_constant (arc_insn_get_operand_value (insn, operand));
+}
+
+/* Determine whether the given disassembled instruction may be part of a
+   function prologue.  If it is, the information in the frame unwind cache will
+   be updated.  */
+
+static bool
+arc_is_in_prologue (struct gdbarch *gdbarch, const struct arc_instruction &insn,
+		    pv_t *regs, struct pv_area *stack)
+{
+  /* It might be that currently analyzed address doesn't contain an
+     instruction, hence INSN is not valid.  It likely means that address points
+     to a data, non-initialized memory, or middle of a 32-bit instruction.  In
+     practice this may happen if GDB connects to a remote target that has
+     non-zeroed memory.  GDB would read PC value and would try to analyze
+     prologue, but there is no guarantee that memory contents at the address
+     specified in PC is address is a valid instruction.  There is not much that
+     that can be done about that.  */
+  if (!insn.valid)
+    return false;
+
+  /* Branch/jump or a predicated instruction.  */
+  if (insn.is_control_flow || insn.condition_code != ARC_CC_AL)
+    return false;
+
+  /* Store of some register.  May or may not update base address register.  */
+  if (insn.insn_class == STORE || insn.insn_class == PUSH)
+    {
+      /* There is definetely at least one operand - register/value being
+	 stored.  */
+      gdb_assert (insn.operands_count > 0);
+
+      /* Store at some constant address.  */
+      if (insn.operands_count > 1
+	  && insn.operands[1].kind != ARC_OPERAND_KIND_REG)
+	return false;
+
+      /* Writeback modes:
+	 Mode	Address used		    Writeback value
+	 --------------------------------------------------
+	 No	reg + offset		    no
+	 A/AW	reg + offset		    reg + offset
+	 AB	reg			    reg + offset
+	 AS	reg + (offset << scaling)   no
+
+	 "PUSH reg" is an alias to "ST.AW reg, [SP, -4]" encoding.  However
+	 16-bit PUSH_S is a distinct instruction encoding, where offset and
+	 base register are implied through opcode.  */
+
+      /* Register with base memory address.  */
+      int base_reg = arc_insn_get_memory_base_reg (insn);
+
+      /* Address where to write.  arc_insn_get_memory_offset returns scaled
+	 value for ARC_WRITEBACK_AS.  */
+      pv_t addr;
+      if (insn.writeback_mode == ARC_WRITEBACK_AB)
+	addr = regs[base_reg];
+      else
+	addr = pv_add_constant (regs[base_reg],
+				arc_insn_get_memory_offset (insn));
+
+      if (pv_area_store_would_trash (stack, addr))
+	return false;
+
+      if (insn.data_size_mode != ARC_SCALING_D)
+	{
+	  /* Find the value being stored.  */
+	  pv_t store_value = arc_pv_get_operand (regs, insn, 0);
+
+	  /* What is the size of a the stored value?  */
+	  CORE_ADDR size;
+	  if (insn.data_size_mode == ARC_SCALING_B)
+	    size = 1;
+	  else if (insn.data_size_mode == ARC_SCALING_H)
+	    size = 2;
+	  else
+	    size = ARC_REGISTER_SIZE;
+
+	  pv_area_store (stack, addr, size, store_value);
+	}
+      else
+	{
+	  if (insn.operands[0].kind == ARC_OPERAND_KIND_REG)
+	    {
+	      /* If this is a double store, than write N+1 register as well.  */
+	      pv_t store_value1 = regs[insn.operands[0].value];
+	      pv_t store_value2 = regs[insn.operands[0].value + 1];
+	      pv_area_store (stack, addr, ARC_REGISTER_SIZE, store_value1);
+	      pv_area_store (stack,
+			     pv_add_constant (addr, ARC_REGISTER_SIZE),
+			     ARC_REGISTER_SIZE, store_value2);
+	    }
+	  else
+	    {
+	      pv_t store_value
+		= pv_constant (arc_insn_get_operand_value (insn, 0));
+	      pv_area_store (stack, addr, ARC_REGISTER_SIZE * 2, store_value);
+	    }
+	}
+
+      /* Is base register updated?  */
+      if (insn.writeback_mode == ARC_WRITEBACK_A
+	  || insn.writeback_mode == ARC_WRITEBACK_AB)
+	regs[base_reg] = pv_add_constant (regs[base_reg],
+					  arc_insn_get_memory_offset (insn));
+
+      return true;
+    }
+  else if (insn.insn_class == MOVE)
+    {
+      gdb_assert (insn.operands_count == 2);
+
+      /* Destination argument can be "0", so nothing will happen.  */
+      if (insn.operands[0].kind == ARC_OPERAND_KIND_REG)
+	{
+	  int dst_regnum = insn.operands[0].value;
+	  regs[dst_regnum] = arc_pv_get_operand (regs, insn, 1);
+	}
+      return true;
+    }
+  else if (insn.insn_class == SUB)
+    {
+      gdb_assert (insn.operands_count == 3);
+
+      /* SUB 0,b,c.  */
+      if (insn.operands[0].kind != ARC_OPERAND_KIND_REG)
+	return true;
+
+      int dst_regnum = insn.operands[0].value;
+      regs[dst_regnum] = pv_subtract (arc_pv_get_operand (regs, insn, 1),
+				      arc_pv_get_operand (regs, insn, 2));
+      return true;
+    }
+  else if (insn.insn_class == ENTER)
+    {
+      /* ENTER_S is a prologue-in-instruction - it saves all callee-saved
+	 registers according to given arguments thus greatly reducing code
+	 size.  Which registers will be actually saved depends on arguments.
+
+	 ENTER_S {R13-...,FP,BLINK} stores registers in following order:
+
+	 new SP ->
+		   BLINK
+		   R13
+		   R14
+		   R15
+		   ...
+		   FP
+	 old SP ->
+
+	 There are up to three arguments for this opcode, as presented by ARC
+	 disassembler:
+	 1) amount of general-purpose registers to be saved - this argument is
+	    always present even when it is 0;
+	 2) FP register number (27) if FP has to be stored, otherwise argument
+	    is not present;
+	 3) BLINK register number (31) if BLINK has to be stored, otherwise
+	    argument is not present.  If both FP and BLINK are stored, then FP
+	    is present before BLINK in argument list.  */
+      gdb_assert (insn.operands_count > 0);
+
+      int regs_saved = arc_insn_get_operand_value (insn, 0);
+
+      bool is_fp_saved;
+      if (insn.operands_count > 1)
+	is_fp_saved = (insn.operands[1].value  == ARC_FP_REGNUM);
+      else
+	is_fp_saved = false;
+
+      bool is_blink_saved;
+      if (insn.operands_count > 1)
+	is_blink_saved = (insn.operands[insn.operands_count - 1].value
+			  == ARC_BLINK_REGNUM);
+      else
+	is_blink_saved = false;
+
+      /* Amount of bytes to be allocated to store specified registers.  */
+      CORE_ADDR st_size = ((regs_saved + is_fp_saved + is_blink_saved)
+			   * ARC_REGISTER_SIZE);
+      pv_t new_sp = pv_add_constant (regs[ARC_SP_REGNUM], -st_size);
+
+      /* Assume that if the last register (closest to new SP) can be written,
+	 then it is possible to write all of them.  */
+      if (pv_area_store_would_trash (stack, new_sp))
+	return false;
+
+      /* Current store address.  */
+      pv_t addr = regs[ARC_SP_REGNUM];
+
+      if (is_fp_saved)
+	{
+	  addr = pv_add_constant (addr, -ARC_REGISTER_SIZE);
+	  pv_area_store (stack, addr, ARC_REGISTER_SIZE, regs[ARC_FP_REGNUM]);
+	}
+
+      /* Registers are stored in backward order: from GP (R26) to R13.  */
+      for (int i = ARC_R13_REGNUM + regs_saved - 1; i >= ARC_R13_REGNUM; i--)
+	{
+	  addr = pv_add_constant (addr, -ARC_REGISTER_SIZE);
+	  pv_area_store (stack, addr, ARC_REGISTER_SIZE, regs[i]);
+	}
+
+      if (is_blink_saved)
+	{
+	  addr = pv_add_constant (addr, -ARC_REGISTER_SIZE);
+	  pv_area_store (stack, addr, ARC_REGISTER_SIZE,
+			 regs[ARC_BLINK_REGNUM]);
+	}
+
+      gdb_assert (pv_is_identical (addr, new_sp));
+
+      regs[ARC_SP_REGNUM] = new_sp;
+
+      if (is_fp_saved)
+	regs[ARC_FP_REGNUM] = regs[ARC_SP_REGNUM];
+
+      return true;
+    }
+
+  /* Some other architectures, like nds32 or arm, try to continue as far as
+     possible when building a prologue cache (as opposed to when skipping
+     prologue), so that cache will be as full as possible.  However current
+     code for ARC doesn't recognize some instructions that may modify SP, like
+     ADD, AND, OR, etc, hence there is no way to guarantee that SP wasn't
+     clobbered by the skipped instruction.  Potential existence of extension
+     instruction, which may do anything they want makes this even more complex,
+     so it is just better to halt on a first unrecognized instruction.  */
+
+  return false;
+}
+
+/* Copy of fprintf_disasm from disasm.c.  */
+
+static int ATTRIBUTE_PRINTF (2, 3)
+arc_fprintf_disasm (void *stream, const char *format, ...)
+{
+  va_list args;
+
+  va_start (args, format);
+  vfprintf_filtered ((struct ui_file *) stream, format, args);
+  va_end (args);
+  /* Something non -ve.  */
+  return 0;
+}
+
+/* Return properly initialized disassemble_info.  */
+
+struct disassemble_info
+arc_disassemble_info (struct gdbarch *gdbarch)
+{
+  struct disassemble_info di;
+  init_disassemble_info (&di, &null_stream, arc_fprintf_disasm);
+  di.arch = gdbarch_bfd_arch_info (gdbarch)->arch;
+  di.mach = gdbarch_bfd_arch_info (gdbarch)->mach;
+  di.endian = gdbarch_byte_order (gdbarch);
+  di.read_memory_func = [](bfd_vma memaddr, gdb_byte *myaddr,
+			   unsigned int len, struct disassemble_info *info)
+    {
+      return target_read_code (memaddr, myaddr, len);
+    };
+  return di;
+}
+
+/* Analyze the prologue and update the corresponding frame cache for the frame
+   unwinder for unwinding frames that doesn't have debug info.  In such
+   situation GDB attempts to parse instructions in the prologue to understand
+   where each register is saved.
+
+   If CACHE is not NULL, then it will be filled with information about saved
+   registers.
+
+   There are several variations of prologue which GDB may encouter.  "Full"
+   prologue looks like this:
+
+	sub	sp,sp,<imm>   ; Space for variadic arguments.
+	push	blink	      ; Store return address.
+	push	r13	      ; Store callee saved registers (up to R26/GP).
+	push	r14
+	push	fp	      ; Store frame pointer.
+	mov	fp,sp	      ; Update frame pointer.
+	sub	sp,sp,<imm>   ; Create space for local vars on the stack.
+
+   Depending on compiler options lots of things may change:
+
+    1) BLINK is not saved in leaf functions.
+    2) Frame pointer is not saved and updated if -fomit-frame-pointer is used.
+    3) 16-bit versions of those instructions may be used.
+    4) Instead of a sequence of several push'es, compiler may instead prefer to
+    do one subtract on stack pointer and then store registers using normal
+    store, that doesn't update SP.  Like this:
+
+
+	sub	sp,sp,8		; Create space for calee-saved registers.
+	st	r13,[sp,4]      ; Store callee saved registers (up to R26/GP).
+	st	r14,[sp,0]
+
+    5) ENTER_S instruction can encode most of prologue sequence in one
+    instruction (except for those subtracts for variadic arguments and local
+    variables).
+    6) GCC may use "millicode" functions from libgcc to store callee-saved
+    registers with minimal code-size requirements.  This function currently
+    doesn't support this.
+
+   ENTRYPOINT is a function entry point where prologue starts.
+
+   LIMIT_PC is a maximum possible end address of prologue (meaning address
+   of first instruction after the prologue).  It might also point to the middle
+   of prologue if execution has been stopped by the breakpoint at this address
+   - in this case debugger should analyze prologue only up to this address,
+   because further instructions haven't been executed yet.
+
+   Returns address of the first instruction after the prologue.  */
+
+static CORE_ADDR
+arc_analyze_prologue (struct gdbarch *gdbarch, const CORE_ADDR entrypoint,
+		      const CORE_ADDR limit_pc, struct arc_frame_cache *cache)
+{
+  if (arc_debug)
+    debug_printf ("arc: analyze_prologue (entrypoint=%s, limit_pc=%s)\n",
+		  paddress (gdbarch, entrypoint),
+		  paddress (gdbarch, limit_pc));
+
+  /* Prologue values.  Only core registers can be stored.  */
+  pv_t regs[ARC_LAST_CORE_REGNUM + 1];
+  for (int i = 0; i <= ARC_LAST_CORE_REGNUM; i++)
+    regs[i] = pv_register (i, 0);
+  struct pv_area *stack = make_pv_area (ARC_SP_REGNUM,
+					gdbarch_addr_bit (gdbarch));
+  struct cleanup *back_to = make_cleanup_free_pv_area (stack);
+
+  CORE_ADDR current_prologue_end = entrypoint;
+
+  /* Look at each instruction in the prologue.  */
+  while (current_prologue_end < limit_pc)
+    {
+      struct arc_instruction insn;
+      struct disassemble_info di = arc_disassemble_info (gdbarch);
+      arc_insn_decode (current_prologue_end, &di, arc_delayed_print_insn,
+		       &insn);
+
+      if (arc_debug >= 2)
+	arc_insn_dump (insn);
+
+      /* If this instruction is in the prologue, fields in the cache will be
+	 updated, and the saved registers mask may be updated.  */
+      if (!arc_is_in_prologue (gdbarch, insn, regs, stack))
+	{
+	  /* Found an instruction that is not in the prologue.  */
+	  if (arc_debug)
+	    debug_printf ("arc: End of prologue reached at address %s\n",
+			  paddress (gdbarch, insn.address));
+	  break;
+	}
+
+      current_prologue_end = arc_insn_get_linear_next_pc (insn);
+    }
+
+  if (cache != NULL)
+    {
+      /* Figure out if it is a frame pointer or just a stack pointer.  */
+      if (pv_is_register (regs[ARC_FP_REGNUM], ARC_SP_REGNUM))
+	{
+	  cache->frame_base_reg = ARC_FP_REGNUM;
+	  cache->frame_base_offset = -regs[ARC_FP_REGNUM].k;
+	}
+      else
+	{
+	  cache->frame_base_reg = ARC_SP_REGNUM;
+	  cache->frame_base_offset = -regs[ARC_SP_REGNUM].k;
+	}
+
+      /* Assign offset from old SP to all saved registers.  */
+      for (int i = 0; i <= ARC_LAST_CORE_REGNUM; i++)
+	{
+	  CORE_ADDR offset;
+	  if (pv_area_find_reg (stack, gdbarch, i, &offset))
+	    cache->saved_regs[i].addr = offset;
+	}
+    }
+
+  do_cleanups (back_to);
+  return current_prologue_end;
+}
+
+/* Estimated maximum prologue length in bytes.  This should include:
+   1) Store instruction for each callee-saved register (R25 - R13 + 1)
+   2) Two instructions for FP
+   3) One for BLINK
+   4) Three substract instructions for SP (for variadic args, for
+   callee saved regs and for local vars) and assuming that those SUB use
+   long-immediate (hence double length).
+   5) Stores of arguments registers are considered part of prologue too
+      (R7 - R1 + 1).
+   This is quite an extreme case, because even with -O0 GCC will collapse first
+   two SUBs into one and long immediate values are quite unlikely to appear in
+   this case, but still better to overshoot a bit - prologue analysis will
+   anyway stop at the first instruction that doesn't fit prologue, so this
+   limit will be rarely reached.  */
+
+const static int MAX_PROLOGUE_LENGTH
+  = 4 * (ARC_R25_REGNUM - ARC_R13_REGNUM + 1 + 2 + 1 + 6
+	 + ARC_LAST_ARG_REGNUM - ARC_FIRST_ARG_REGNUM + 1);
+
 /* Implement the "skip_prologue" gdbarch method.
 
    Skip the prologue for the function at PC.  This is done by checking from
@@ -679,15 +1124,19 @@  arc_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
   /* No prologue info in symbol table, have to analyze prologue.  */
 
   /* Find an upper limit on the function prologue using the debug
-     information.  If the debug information could not be used to provide that
-     bound, then pass 0 and arc_scan_prologue will estimate value itself.  */
+     information.  If there is no debug information about prologue end, then
+     skip_prologue_using_sal will return 0.  */
   CORE_ADDR limit_pc = skip_prologue_using_sal (gdbarch, pc);
-  /* We don't have a proper analyze_prologue function yet, but its result
-     should be returned here.  Currently GDB will just stop at the first
-     instruction of function if debug information doesn't have prologue info;
-     and if there is a debug info about prologue - this code path will not be
-     taken at all.  */
-  return (limit_pc == 0 ? pc : limit_pc);
+
+  /* If there is no debug information at all, it is required to give some
+     semi-arbitrary hard limit on amount of bytes to scan during prologue
+     analysis.  */
+  if (limit_pc == 0)
+    limit_pc = pc + MAX_PROLOGUE_LENGTH;
+
+  /* Find the address of the first instruction after the prologue by scanning
+     through it - no other information is needed, so pass NULL as a cache.  */
+  return arc_analyze_prologue (gdbarch, pc, limit_pc, NULL);
 }
 
 /* Implement the "print_insn" gdbarch method.
@@ -837,6 +1286,28 @@  arc_frame_align (struct gdbarch *gdbarch, CORE_ADDR sp)
   return align_down (sp, 4);
 }
 
+/* Dump the frame info.  Used for internal debugging only.  */
+
+static void
+arc_print_frame_cache (struct gdbarch *gdbarch, char *message,
+		       struct arc_frame_cache *cache, int addresses_known)
+{
+  debug_printf ("arc: frame_info %s\n", message);
+  debug_printf ("arc: prev_sp = %s\n", paddress (gdbarch, cache->prev_sp));
+  debug_printf ("arc: frame_base_reg = %i\n", cache->frame_base_reg);
+  debug_printf ("arc: frame_base_offset = %s\n",
+		plongest (cache->frame_base_offset));
+
+  for (int i = 0; i <= ARC_BLINK_REGNUM; i++)
+    {
+      if (trad_frame_addr_p (cache->saved_regs, i))
+	debug_printf ("arc: saved register %s at %s %s\n",
+		      gdbarch_register_name (gdbarch, i),
+		      (addresses_known) ? "address" : "offset",
+		      paddress (gdbarch, cache->saved_regs[i].addr));
+    }
+}
+
 /* Frame unwinder for normal frames.  */
 
 static struct arc_frame_cache *
@@ -848,12 +1319,11 @@  arc_make_frame_cache (struct frame_info *this_frame)
   struct gdbarch *gdbarch = get_frame_arch (this_frame);
 
   CORE_ADDR block_addr = get_frame_address_in_block (this_frame);
-  CORE_ADDR prev_pc = get_frame_pc (this_frame);
-
   CORE_ADDR entrypoint, prologue_end;
   if (find_pc_partial_function (block_addr, NULL, &entrypoint, &prologue_end))
     {
       struct symtab_and_line sal = find_pc_line (entrypoint, 0);
+      CORE_ADDR prev_pc = get_frame_pc (this_frame);
       if (sal.line == 0)
 	/* No line info so use current PC.  */
 	prologue_end = prev_pc;
@@ -865,18 +1335,42 @@  arc_make_frame_cache (struct frame_info *this_frame)
     }
   else
     {
+      /* If find_pc_partial_function returned nothing then there is no symbol
+	 information at all for this PC.  Currently it is assumed in this case
+	 that current PC is entrypoint to function and try to construct the
+	 frame from that.  This is, probably, suboptimal, for example ARM
+	 assumes in this case that program is inside the normal frame (with
+	 frame pointer).  ARC, perhaps, should try to do the same.  */
       entrypoint = get_frame_register_unsigned (this_frame,
 						gdbarch_pc_regnum (gdbarch));
-      prologue_end = 0;
+      prologue_end = entrypoint + MAX_PROLOGUE_LENGTH;
     }
 
   /* Allocate new frame cache instance and space for saved register info.
-   * FRAME_OBSTACK_ZALLOC will initialize fields to zeroes.  */
+     FRAME_OBSTACK_ZALLOC will initialize fields to zeroes.  */
   struct arc_frame_cache *cache
     = FRAME_OBSTACK_ZALLOC (struct arc_frame_cache);
   cache->saved_regs = trad_frame_alloc_saved_regs (this_frame);
 
-  /* Should call analyze_prologue here, when it will be implemented.  */
+  arc_analyze_prologue (gdbarch, entrypoint, prologue_end, cache);
+
+  if (arc_debug)
+    arc_print_frame_cache (gdbarch, "after prologue", cache, false);
+
+  CORE_ADDR unwound_fb = get_frame_register_unsigned (this_frame,
+						      cache->frame_base_reg);
+  if (unwound_fb == 0)
+    return cache;
+  cache->prev_sp = unwound_fb + cache->frame_base_offset;
+
+  for (int i = 0; i <= ARC_LAST_CORE_REGNUM; i++)
+    {
+      if (trad_frame_addr_p (cache->saved_regs, i))
+	cache->saved_regs[i].addr += cache->prev_sp;
+    }
+
+  if (arc_debug)
+    arc_print_frame_cache (gdbarch, "after previous SP found", cache, true);
 
   return cache;
 }
diff --git a/gdb/arc-tdep.h b/gdb/arc-tdep.h
index db7647d..ff21f51 100644
--- a/gdb/arc-tdep.h
+++ b/gdb/arc-tdep.h
@@ -123,6 +123,8 @@  arc_mach_is_arcv2 (struct gdbarch *gdbarch)
   return gdbarch_bfd_arch_info (gdbarch)->mach == bfd_mach_arc_arcv2;
 }
 
+struct disassemble_info arc_disassemble_info (struct gdbarch *gdbarch);
+
 /* Function to access ARC disassembler.  Underlying opcodes disassembler will
    print an instruction into stream specified in the INFO, so if it is
    undesired, then this stream should be set to some invisible stream, but it
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 8cb656a..92759ae 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -22077,8 +22077,7 @@  acceptable commands.
 @item set debug arc
 @kindex set debug arc
 Control the level of ARC specific debug messages.  Use 0 for no messages (the
-default) and 1 for debug messages.  At present higher values offer no further
-messages.
+default), 1 for debug messages, and 2 for even more debug messages.
 
 @item show debug arc
 @kindex show debug arc
diff --git a/gdb/testsuite/gdb.arch/arc-analyze-prologue.S b/gdb/testsuite/gdb.arch/arc-analyze-prologue.S
new file mode 100644
index 0000000..90e1035
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/arc-analyze-prologue.S
@@ -0,0 +1,903 @@ 
+; This testcase is part of GDB, the GNU debugger.
+
+; Copyright 2017 Synopsys Inc.
+
+; This program is free software; you can redistribute it and/or modify
+; it under the terms of the GNU General Public License as published by
+; the Free Software Foundation; either version 3 of the License, or
+; (at your option) any later version.
+;
+; This program is distributed in the hope that it will be useful,
+; but WITHOUT ANY WARRANTY; without even the implied warranty of
+; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+; GNU General Public License for more details.
+;
+; You should have received a copy of the GNU General Public License
+; along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+.section .data
+some_variable:
+.long	0xdeadbeef
+
+.section .text
+.global	main
+.type	main, @function
+
+; Standard prologue.
+
+.align 4
+standard_prologue:
+	push	blink
+	sub	sp,sp,12
+	st	r13, [sp, 0]
+	st	r14, [sp, 4]
+	st	r18, [sp, 8]
+	add	r0, r1, r2
+	ld	r18, [sp, 8]
+	ld	r14, [sp, 4]
+	ld	r13, [sp, 0]
+	add	sp,sp,12
+	pop	blink
+	j	[blink]
+
+; Standard prologue using short instructions.
+
+.align 4
+mini_prologue:
+	push_s	blink
+	sub_s	sp,sp,12
+	; ST_S can store only some of the core registers.
+	st_s	r13, [sp, 0]
+	st_s	r15, [sp, 4]
+	st_s	r14, [sp, 8]
+	add	r0, r1, r2
+	add	sp,sp,16
+	j	[blink]
+
+; Standard prologue without `sub sp,sp,INTEGER`.
+
+.align 4
+no_subsp_prologue:
+	push	blink
+	push	r13
+	push	r20
+	push	r25
+	add	r0, r1, r2
+	pop	r25
+	pop	r20
+	pop	r13
+	pop	blink
+	j	[blink]
+
+; Standard prologue of leaf function.
+
+.align 4
+leaf_prologue:
+	sub	sp,sp,8
+	st	r13, [sp, 0]
+	st	r15, [sp, 4]
+	add	r0, r1, r2
+	ld	r13, [sp, 0]
+	ld	r15, [sp, 4]
+	j.d	[blink]
+	add	sp,sp,8
+
+; Prologue with `push fp`.
+
+.align 4
+pushfp_prologue:
+	push	r13
+	push	r14
+	push	fp
+	; mov fp,sp is part of prologue, but this test will not verify that.
+	; It will be checked later in the "arg_regs_fp" test.
+	mov	fp, sp
+	add	r0, r1, r2
+	pop	fp
+	pop	r14
+	pop	r13
+	j	[blink]
+
+; Prologue with frame pointer and store relative to FP.
+
+.align 4
+fp_prologue_with_store:
+	push	r13
+	push	r14
+	push	fp
+	mov	fp, sp
+	sub_s	sp,sp,4
+	st	r15,[fp,-4]
+	add	r0, r1, r2
+	pop	r15
+	pop	fp
+	pop	r14
+	pop	r13
+	j	[blink]
+
+; Verify that store of the non-callee saved registers is not part of prologue.
+; Repeat this test for multiple registers, to check boundaries. Also check
+; with both ST and PUSH (aka ST.AW). We have to use multiple functions for
+; this, because GDB would stop analisys at the first instruction that is not
+; part of prologue.
+
+.align 4
+noncallee_saved_regs_r12_st:
+	sub	sp,sp,8
+	st	r13, [sp, 4]
+	st	r12, [sp, 0]
+	add	r0, r1, r2
+	j.d	[blink]
+	add	sp,sp,8
+
+.align 4
+noncallee_saved_regs_r12_push:
+	push	r13
+	push	r12
+	add	r0, r1, r2
+	j.d	[blink]
+	add	sp,sp,8
+
+.align 4
+noncallee_saved_regs_r2_push:
+	push	r13
+	push	r2
+	add	r0, r1, r2
+	j.d	[blink]
+	add	sp,sp,8
+
+.align 4
+noncallee_saved_regs_gp_push:
+	push	r25
+	push	gp
+	add	r0, r1, r2
+	j.d	[blink]
+	add	sp,sp,8
+
+; LP_COUNT is treated like a normal register.
+
+.align 4
+noncallee_saved_regs_lp_count:
+	push	r25
+	push	lp_count
+	add	r0, r1, r2
+	j.d	[blink]
+	add	sp,sp,8
+
+; BLINK is saved, but after an instruction that is not part of prologue.
+; Currently arc_analyze_prologue stops analisys at the first intstruction
+; that is not a part of prologue. This might be not the best way, but it is
+; what it is right now, so this test confirms this.
+
+.align 4
+noncallee_saved_regs_blink_out_of_prologue:
+	push	r25
+	push	gp
+	push	blink
+	add	r0, r1, r2
+	j.d	[blink]
+	add	sp,sp,12
+
+; Saving arguments register via FP.
+
+.align 4
+arg_regs_fp:
+	push	fp
+	mov	fp, sp
+	sub	sp, sp, 16
+	st	r0, [fp, -4]
+	st	r1, [fp, -8]
+	st	r7, [fp, -12]
+	st	r8, [fp, -16]
+	add	r0, r1, r2
+	add	sp,sp,16
+	pop	fp
+	j	[blink]
+
+; Like the previous, but with mov_s.
+
+.align 4
+arg_regs_fp_mov_s:
+	push	fp
+	mov_s	fp, sp
+	sub	sp, sp, 8
+	st	r0, [fp, -4]
+	; Not part of the prologue.
+	st	r8, [fp, -8]
+	add	r0, r1, r2
+	add	sp,sp,8
+	pop	fp
+	j	[blink]
+
+; Saving arguments register without FP.
+
+.align 4
+arg_regs_sp:
+	sub	sp, sp, 24
+	st	r0, [sp, 0]
+	st	r1, [sp, 4]
+	st	r7, [sp, 8]
+	; Normally that would be done before saving args, but it is used as a
+	; marker that saving arguments relatively to SP is considered part of
+	; prologue.
+	st	r13, [sp, 16]
+	; Not part of the prologue.
+	st	r8, [sp, 12]
+	st	r14, [sp, 20]
+	add	r0, r1, r2
+	j.d	[blink]
+	add	sp,sp,24
+
+; ENTER_S that does nothing.
+
+.align 4
+enter_s_nop:
+	; Effectively a nop.
+	enter_s	0
+	add	r0,r1,r2
+	j	[blink]
+
+; ENTER_S that stores BLINK.
+
+.align 4
+enter_s_blink:
+	enter_s	32
+	add	r0,r1,r2
+	j.d	[blink]
+	add	sp,sp,4
+
+; ENTER_S that stores FP.
+
+.align 4
+enter_s_fp:
+	enter_s	16
+	add	r0,r1,r2
+	j.d	[blink]
+	add	sp,sp,4
+
+; ENTER_S that stores R13, FP and BLINK.
+
+.align 4
+enter_s_r13:
+	enter_s	(32 + 16 + 1)
+	add	r0,r1,r2
+	j.d	[blink]
+	add	sp,sp,12
+
+; ENTER_S that stores R13-R15
+
+.align 4
+enter_s_r15:
+	enter_s	3
+	add	r0,r1,r2
+	j.d	[blink]
+	add	sp,sp,12
+
+; ENTER_S that stores everything it could.
+
+.align 4
+enter_s_all:
+	enter_s	(32 + 16 + 14)
+	add	r0,r1,r2
+	j.d	[blink]
+	add	sp,sp,64
+
+; Deeper nesting.
+
+.align 4
+nested_prologue_inner:
+	sub	sp,sp,8
+	st	r18, [sp, 4]
+	st	r13, [sp, 0]
+	add	r0, r1, r2
+	ld	r18, [sp, 4]
+	ld	r13, [sp, 0]
+	j.d	[blink]
+	add	sp,sp,8
+
+.align 4
+nested_prologue_outer:
+	push	blink
+	sub	sp,sp,8
+	st	r14, [sp, 0]
+	st	r15, [sp, 4]
+	bl	@nested_prologue_inner
+	add	r0, r1, r2
+	ld	r14, [sp, 0]
+	ld	r15, [sp, 4]
+	add	sp,sp,8
+	pop	blink
+	j	[blink]
+
+; Prologue with maximum length.
+; Expressions like (0xFFFFFFFF + 25) force assembler to use long immediate
+; even for values that don't need it, thus letting us test maksimum prologue
+; length without having huge frames.
+.align 4
+max_length_prologue:
+	; Variadic args
+	sub	sp,sp,(0xFFFFFFFF + 25) ; 24 bytes
+	push	blink
+	; Allocate space for 13 callee-saved and 8 arg regs.
+	sub	sp,sp,(0xFFFFFFFF + 1 + 21 * 4)
+	st	r13, [sp, 0]
+	st	r14, [sp, 4]
+	st	r15, [sp, 8]
+	st	r16, [sp, 12]
+	st	r17, [sp, 16]
+	st	r18, [sp, 20]
+	st	r19, [sp, 24]
+	st	r20, [sp, 28]
+	st	r21, [sp, 32]
+	st	r22, [sp, 36]
+	st	r23, [sp, 40]
+	st	r24, [sp, 44]
+	st	r25, [sp, 48]
+	st	r0,  [sp, 52]
+	st	r1,  [sp, 56]
+	st	r2,  [sp, 60]
+	st	r3,  [sp, 64]
+	st	r4,  [sp, 68]
+	st	r5,  [sp, 72]
+	st	r6,  [sp, 76]
+	st	r7,  [sp, 80]
+	push	fp
+	mov	fp,sp
+	sub	sp,sp,(0xFFFFFFFF + 1 + 16) ; Space for local variables.
+	; End of prologue.
+	add	sp,sp,24 + 21 * 4 + 16
+	j	[blink]
+
+; Few tests that test that prologue analysis stops at branch. There are four
+; types of "branches": conditional and non-conditional, relative branches and
+; absolute jumps.
+
+.align 4
+branch_in_prologue:
+	push	r13
+	b	@.L1
+	; This store on stack is not a prologue.
+	push	r14
+.L1:
+	add	r0,r1,r2
+	j.d	[blink]
+	add	sp,sp,4
+
+.align 4
+cond_branch_in_prologue:
+	sub_s	sp,sp,8
+	st_s	r13,[sp,4]
+	; Doesn't matter if branch is taken or not.
+	breq	r0,r1,@.L2
+	; This store on stack is not a prologue.
+	st_s	r14,[sp,0]
+.L2:
+	add	r0,r1,r2
+	pop	fp
+	j.d	[blink]
+	add	sp,sp,8
+
+.align 4
+jump_in_prologue:
+	push	r13
+	j	@.L3
+	; This store on stack is not a prologue.
+	push	r14
+.L3:
+	add	r0,r1,r2
+	j.d	[blink]
+	add	sp,sp,4
+
+.align 4
+cond_jump_in_prologue:
+	sub_s	sp,sp,8
+	st_s	r13,[sp,4]
+	; It doesn't matter if jump is taken or not - prologue analysis has to
+	; stop before `jeq` in any case.
+	jeq	@.L4
+	; This store on stack is not a prologue.
+	st_s	r14,[sp,0]
+.L4:
+	add	r0,r1,r2
+	j.d	[blink]
+	add	sp,sp,8
+
+.align 4
+predicated_insn:
+	sub_s	sp,sp,12
+	st_s	r13,[sp,8]
+	st_s	r15,[sp,0]
+	; Use SUB SP,SP,0 because it is otherwise a valid instruction for
+	; prologue, so it will halt analysis purely because of its predicate.
+	sub.eq	sp,sp,0 ; This is not a prologue anymore.
+	st_s	r14,[sp,4]
+	add	sp,sp,12
+	j	[blink]
+
+; Loops should halt prologue analysis.
+
+.align 4
+loop_in_prologue:
+	push r25
+	push lp_count
+	mov lp_count, 4
+	lp @.Lloop_end1
+	push r26 ; Not part of prologue.
+	add	r0, r1, r2
+.Lloop_end1:
+	add	r1, r1, r2
+	pop r26
+	add sp,sp,8
+	pop r25
+	j   [blink]
+
+; Store of a constant value (not a register).
+
+.align 4
+store_constant:
+	sub_s	sp,sp,12
+	st_s	r13,[sp,8]
+	st	0xdeadbeef,[sp,0]
+	st_s	r14,[sp,4]
+	add	sp,sp,12
+	j	[blink]
+
+; Test that store to immediate address halts prologue analysis.
+.align 4
+st_c_limm:
+	push	r15
+	st	r14,[@some_variable]
+	push	r13
+	add	sp,sp,8
+	j	[blink]
+
+; Store with AB writeback mode.
+
+.align 4
+st_ab_writeback:
+	sub	sp,sp,8
+	st	r13,[sp,4]
+	st.ab	r14,[sp,-4]
+	st	r15,[sp,0]
+	add	sp,sp,12
+	j	[blink]
+
+; Store of a word with AS writeback mode.
+
+.align 4
+st_as_writeback:
+	sub	sp,sp,12
+	st	r13,[sp,8]
+	st.as	r14,[sp,1] ; ST.AS, hence address is (offset << 2).
+	st	r15,[sp,0]
+	add	sp,sp,12
+	j	[blink]
+
+; Store of a halfword with AS writeback mode.
+
+.align 4
+sth_as_writeback:
+	sub	sp,sp,12
+	st	r13,[sp,8]
+	sth.as	r14,[sp,2] ; STH.AS, hence address is (offset << 1).
+	st	r15,[sp,0]
+	add	sp,sp,12
+	j	[blink]
+
+; Store of a double word with AS writeback mode. Shift is still 2, like ST!
+
+.align 4
+std_as_writeback:
+	sub	sp,sp,16
+	st	r13,[sp,12]
+#ifdef __ARC_LL64__
+	std.as	r14,[sp,1] ; STD.AS, hence address is (offset << 2).
+#else
+	st.as	r14,[sp,1] ; STD.AS, hence address is (offset << 2).
+	st.as	r15,[sp,2] ; STD.AS, hence address is (offset << 2).
+#endif
+	st	r16,[sp,0]
+	add	sp,sp,12
+	j	[blink]
+
+; Store of the halfword. R14 will not be reported as "saved".
+
+.align 4
+st_halfword:
+	sub	sp,sp,12
+	st	r13,[sp,8]
+	sth	r14,[sp,4]
+	st	r15,[sp,0]
+	add	sp,sp,12
+	j	[blink]
+
+; Store of the halfword. R14 will not be reported as "saved".
+
+.align 4
+sts_halfword:
+	sub	sp,sp,12
+	st	r13,[sp,8]
+	mov	r13,sp
+	sth_s	r14,[r13,4]
+	st	r15,[sp,0]
+	add	sp,sp,12
+	j	[blink]
+
+; Store of the byte. R14 will not be reported as "saved".
+
+.align 4
+st_byte:
+	sub	sp,sp,12
+	st	r13,[sp,8]
+	stb	r14,[sp,4]
+	st	r15,[sp,0]
+	add	sp,sp,12
+	j	[blink]
+
+; Store of the byte. R14 will not be reported as "saved".
+
+.align 4
+sts_byte:
+	sub	sp,sp,12
+	st	r13,[sp,8]
+	mov	r13,sp
+	stb_s	r14,[r13,4]
+	st	r15,[sp,0]
+	add	sp,sp,12
+	j	[blink]
+
+; Store of the byte. R14 will not be reported as "saved".
+
+.align 4
+sts_byte_sp:
+	sub	sp,sp,12
+	st	r13,[sp,8]
+	stb_s	r14,[sp,4]
+	st	r15,[sp,0]
+	add	sp,sp,12
+	j	[blink]
+
+; Double word store, optionally available for ARC HS.
+
+.align 4
+st_double:
+	sub	sp,sp,8
+#ifdef __ARC_LL64__
+	std	r14,[sp,0]
+	std.aw	r18,[sp,-8]
+	std.aw	0xdeadbeef,[sp,-8]
+#else
+	st	r14,[sp,0]
+	st	r15,[sp,4]
+	st.aw	r19,[sp,-4]
+	st.aw	r18,[sp,-4]
+	sub	sp,sp,8
+#endif
+	add	sp,sp,24
+	j	[blink]
+
+; Store relative to some register with a known value.
+
+.align 4
+r_relative_store:
+	sub_s	sp,sp,12
+	st_s	r13,[sp,8]
+	mov	r13,sp
+	; Check for both mov and mov_s in one testcase.
+	mov_s	r12,r13
+	st	r15,[r12,0]
+	st_s	r14,[sp,4]
+	add	sp,sp,12
+	j	[blink]
+
+; Store relative to some register with a known value using sub.
+; Like a previous test, but register is assigned via sub, instead of mov.
+
+.align 4
+r_relative_sub_store:
+	; Following is a complicated way to construct frame like this:
+	; sub_s	sp,sp,12
+	; st_s	r13,[sp,8]
+	; st_s	r14,[sp,4]
+	; st_s	r15,[sp,0]
+	sub_s	sp,sp,12
+	st_s	r13,[sp,8]
+	sub	r13,sp,4
+	st	r14,[r13,8]
+	st_s	r15,[sp,0]
+	add	sp,sp,12
+	j	[blink]
+
+; Like r_relative_store, but using st_s c,[b,u7] which has different opcode.
+
+.align 4
+r_relative_store_st_s:
+	sub_s	sp,sp,12
+	st_s	r13,[sp,8]
+	mov	r13,sp
+	st_s	r15,[r13,4]
+	st_s	r14,[sp,0]
+	add	sp,sp,12
+	j	[blink]
+
+; Store relative to some register with a unknown value.
+
+.align 4
+r_relative_store_unknown:
+	sub_s	sp,sp,12
+	st_s	r13,[sp,8]
+	st	r15,[gp,0] ; GP value is not relative to SP.
+	st_s	r14,[sp,4]
+	add	sp,sp,12
+	j	[blink]
+
+; Store relative to some register with a unknown value, using st_s r0,[gp,s11].
+
+.align 4
+st_s_r0gp:
+	sub_s	sp,sp,12
+	st_s	r13,[sp,8]
+	st_s	r0,[gp,0] ; GP value is not relative to SP.
+	st_s	r14,[sp,4]
+	add	sp,sp,12
+	j	[blink]
+
+; Check prologue that uses `push_s RR` instructions. `push_s b` and `push_s
+; blink` use slightly different subopcodes.
+
+.align 4
+push_s_prologue:
+	push_s	r12
+	push_s	r0
+	push_s	r3
+	push_s	r13
+	push_s	r1
+	push_s	r14
+	push_s	r15
+	push_s	r2
+	push_s	blink ; Also tested in mini_prologue ().
+	add	sp,sp,(4 * 9)
+	j	[blink]
+
+; Check for SUB_S c,b,u3 presence - it doesn't affect prologue.
+
+.align 4
+sub_s_cbu3:
+	push_s	r13
+	sub_s	r0,r1,3
+	push_s	r14
+	add	sp,sp,8
+	j	[blink]
+
+; Check for SUB_S b,b,c presence - it doesn't affect prologue.
+
+.align 4
+sub_s_bbc:
+	push_s	r13
+	sub_s	r0,r0,r1
+	push_s	r0
+	push_s	r1
+	push_s	r14
+	add	sp,sp,16
+	j	[blink]
+
+; Check for SUB_S b,b,u5.
+
+.align 4
+sub_s_bbu5:
+	push_s	r13
+	sub_s	r2,r2,14
+	push_s	r2
+	push_s	r14
+	add	sp,sp,12
+	j	[blink]
+
+; Check for SUB 0,b,c, which is effectively a noop (but it can set status
+; flags).  It shouldn't stop prologue analysis.
+
+.align 4
+sub_0bc:
+	push_s	r13
+	sub	0,r1,r2
+	sub.f	0,r3,r4
+	push_s	r14
+	add	sp,sp,8
+	j	[blink]
+
+; Check for SUB a,limm,c.
+
+.align 4
+sub_alimmb:
+	push_s	r13
+	sub	r13,0xdeadbeef,r14
+	push_s	r14
+	add	sp,sp,8
+	j	[blink]
+
+; Check for sub_s.ne b,b,b.  Has a condition code, hence should halt prologue.
+
+.align 4
+sub_s_ne_bbb:
+	push_s	r13
+	sub_s.ne  r13,r13,r13
+	push_s	r14
+	add	sp,sp,8
+	j	[blink]
+
+; Check MOV that uses LIMM values.
+
+.align 4
+mov_limm:
+	push_s	r13
+	mov	r13,0xdeadbeef
+	push_s	r14
+	add	sp,sp,4
+	pop_s	r13
+	j	[blink]
+
+; Check MOV 0,c.
+
+.align 4
+mov0c_limm:
+	push_s	r13
+	mov	0,r13
+	push_s	r14
+	add	sp,sp,4
+	pop_s	r13
+	j	[blink]
+
+; Check that MOV_S h,s3 doesn't prevent prologue analysis.
+
+.align 4
+mov_s_hs3:
+	push_s	r13
+	mov_s	r5,1
+	push_s	r14
+	add	sp,sp,8
+	j	[blink]
+
+; Check that MOV_S b,u8 doesn't prevent prologue analysis.
+
+.align 4
+mov_s_bu8:
+	push_s	r13
+	mov_s	r12,250
+	push_s	r14
+	add	sp,sp,8
+	j	[blink]
+
+; Check that `mov_s.ne b,h` halts prologue analysis.
+
+.align 4
+mov_s_ne_bh:
+	push_s	r13
+	mov_s.ne r13,r5
+	push_s	r14
+	add	sp,sp,8
+	j	[blink]
+
+; Check that register R12 which original value is not stored will not pop-up in
+; the "Saved registers" list.
+
+.align 4
+unstored_reg:
+	sub_s	sp,sp,12
+	st_s	r13,[sp,0]
+	st_s	r14,[sp,4]
+	mov	r12,0x42
+	st_s	r12,[sp,8]
+	add	sp,sp,12
+	j	[blink]
+
+; Two stores at the same adddress. GDB should report only the R14.
+
+.align 4
+double_store:
+	sub_s	sp,sp,4
+	st_s	r13,[sp,0]
+	st_s	r14,[sp,0]
+	add	sp,sp,4
+	j	[blink]
+
+; Test for a case where callee has an alloca or anything else that might
+; modify stack dynamically in the function body - after the prologue.
+; This assumes that FP is set properly, so that GDB can use it - this holds
+; true for frames generated by GCC.
+
+.align 4
+alloca_outer:
+	sub	sp,sp,8
+	st	blink,[sp,4]
+	st	fp,[sp,0]
+	mov	fp,sp
+	add	r0,r1,r2 ; Not a prologue anymore.
+	sub	sp,sp,8
+	bl	@alloca_inner
+	add	sp,sp,8
+	ld	fp,[sp,0]
+	ld	blink,[sp,4]
+	j.d	[blink]
+	add	sp,sp,8
+
+.align 4
+alloca_inner:
+	push	r13
+	push	r14
+	add	sp,sp,8
+	j	[blink]
+
+
+.align 4
+main:
+	push	blink
+	# Create small section for GP-relative accesses.
+	push	gp
+	sub	sp,sp,16
+	add	gp,sp,8
+	bl	@standard_prologue
+	bl	@mini_prologue
+	bl	@no_subsp_prologue
+	bl	@leaf_prologue
+	bl	@pushfp_prologue
+	bl	@fp_prologue_with_store
+	bl	@noncallee_saved_regs_r12_st
+	bl	@noncallee_saved_regs_r12_push
+	bl	@noncallee_saved_regs_r2_push
+	bl	@noncallee_saved_regs_gp_push
+	bl	@noncallee_saved_regs_lp_count
+	bl	@noncallee_saved_regs_blink_out_of_prologue
+	bl	@arg_regs_fp
+	bl	@arg_regs_fp_mov_s
+	bl	@arg_regs_sp
+	bl	@enter_s_nop
+	bl	@enter_s_blink
+	bl	@enter_s_fp
+	bl	@enter_s_r13
+	bl	@enter_s_r15
+	bl	@enter_s_all
+	bl	@nested_prologue_outer
+	bl	@max_length_prologue
+	bl	@branch_in_prologue
+	bl	@cond_branch_in_prologue
+	bl	@jump_in_prologue
+	bl	@cond_jump_in_prologue
+	bl	@predicated_insn
+	bl	@loop_in_prologue
+	bl	@store_constant
+	bl	@st_c_limm
+	bl	@st_ab_writeback
+	bl	@st_as_writeback
+	bl	@sth_as_writeback
+	bl	@std_as_writeback
+	bl	@st_halfword
+	bl	@sts_halfword
+	bl	@st_byte
+	bl	@sts_byte
+	bl	@sts_byte_sp
+	bl	@st_double
+	bl	@r_relative_store
+	bl	@r_relative_sub_store
+	bl	@r_relative_store_st_s
+	bl	@r_relative_store_unknown
+	bl	@st_s_r0gp
+	bl	@push_s_prologue
+	bl	@sub_s_cbu3
+	bl	@sub_s_bbc
+	bl	@sub_s_bbu5
+	bl	@sub_0bc
+	bl	@sub_alimmb
+	bl	@sub_s_ne_bbb
+	bl	@mov_limm
+	bl	@mov0c_limm
+	bl	@mov_s_hs3
+	bl	@mov_s_bu8
+	bl	@mov_s_ne_bh
+	bl	@unstored_reg
+	bl	@double_store
+	bl	@alloca_outer
+	add	sp,sp,16
+	pop	gp
+	pop	blink
+	j_s     [blink]
+
+.align 4
diff --git a/gdb/testsuite/gdb.arch/arc-analyze-prologue.exp b/gdb/testsuite/gdb.arch/arc-analyze-prologue.exp
new file mode 100644
index 0000000..f126604
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/arc-analyze-prologue.exp
@@ -0,0 +1,206 @@ 
+# This testcase is part of GDB, the GNU debugger.
+
+# Copyright 2017 Synopsys Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+if {![istarget "arc*-*-*"]} then {
+    verbose "Skipping ARC prologue test."
+    return
+}
+
+standard_testfile .S
+
+if { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable "" ] != "" } {
+    untested arc-analyze-prologue.exp
+    return -1
+}
+
+# Initialization routine.
+gdb_exit
+gdb_start
+gdb_reinitialize_dir $srcdir/$subdir
+gdb_load ${binfile}
+
+if ![runto_main] {
+    fail "Can't run to main"
+    return 0
+}
+
+# Convert list of saved registers and their offsets to a GDB string.
+proc saved_regs_to_str { savedregs } {
+    set str ""
+    # If blink is stored, that it is present twice in saved regs - as blink and
+    # as pc.
+    set has_blink 0
+    set blink_addr 0
+    foreach r $savedregs {
+	if { [llength $r] == 1 } {
+	    append str ".*$r at.*"
+	} else {
+	    set name [lindex $r 0]
+	    set offset [lindex $r 1]
+	    set addr [get_hexadecimal_valueof "\$sp+$offset" 0]
+	    append str "\\s*$name at $addr,?"
+	    if { $name == "blink" } {
+		set has_blink 1
+		set blink_addr $addr
+	    }
+	}
+    }
+    if { $has_blink == 1 } {
+	append str "\\s*pc at $blink_addr"
+    }
+    return $str
+}
+
+# Arguments:
+# funcname -	name of function to test
+# savedregs -	list of register saved in the frame. Each entry can be either
+#		a string, where it is a register name, or it is a list of two
+#		items - name of register and it's offset relatively to SP in
+#		the memory. SP value is at the moment of prologue end.
+# fp_offset -	if not an empty string, then proc will test that FP register
+#		has a value that is (SP + offset).
+
+proc prologue_test {funcname {savedregs ""} {fp_offset ""} } {
+    global hex
+    gdb_breakpoint $funcname temporary
+    gdb_continue_to_breakpoint $funcname
+    gdb_test "backtrace 10" \
+	"#0\[ \t\]*$hex in $funcname .*\r\n#1\[ \t\]*$hex in main.*" \
+	"backtrace in $funcname"
+    if { $savedregs != "" } {
+	set str [saved_regs_to_str $savedregs]
+	gdb_test "info frame" \
+	    ".*Saved registers:[saved_regs_to_str $savedregs]" \
+	    "saved registers in $funcname"
+    }
+    if { $fp_offset != "" } {
+	set sp [get_integer_valueof \$sp -1]
+	set fp_val [expr $sp + $fp_offset]
+	set fp_real_val [get_integer_valueof \$fp 0]
+	if { $fp_real_val != $fp_val } {
+	    fail "check FP value in $funcname"
+	} else {
+	    pass "check FP value in $funcname"
+	}
+    }
+}
+
+
+prologue_test "standard_prologue" { {r13 0} {r14 4} {r18 8} {blink 12} }
+prologue_test "mini_prologue" { {r13 0} {r14 8} {r15 4} {blink 12} }
+prologue_test "no_subsp_prologue" { {r13 8} {r20 4} {r25 0} {blink 12} }
+prologue_test "leaf_prologue" { {r13 0} {r15 4} }
+prologue_test "pushfp_prologue" { {r13 8} {r14 4} {fp 0} } 0
+prologue_test "fp_prologue_with_store" { {r13 12} {r14 8} {r15 0} {fp 4} } 4
+prologue_test "noncallee_saved_regs_r12_st" { {r12 0} {r13 4} }
+# Register offset is specified relatively to SP at the prologue end, so
+# "push r12" hasn't been executed at this moment.
+prologue_test "noncallee_saved_regs_r12_push" { {r12 0} {r13 4} }
+prologue_test "noncallee_saved_regs_r2_push" { {r2 0} {r13 4} }
+prologue_test "noncallee_saved_regs_gp_push" { {r25 4} {gp 0} }
+prologue_test "noncallee_saved_regs_lp_count" { {r25 4} {lp_count 0} }
+prologue_test "noncallee_saved_regs_blink_out_of_prologue" { {r25 8} {gp 4} \
+    {blink 0}}
+# Argument registers are not reported as "saved" regs.
+prologue_test "arg_regs_fp" { {r0 12} {r1 8} {r7 4} {r8 0} {fp 16} } 16
+prologue_test "arg_regs_fp_mov_s" { {r0 4} {r8 0} {fp 8} } 8
+prologue_test "arg_regs_sp" { {r0 0} {r1 4} {r7 8} {r8 12} {r13 16} {r14 20} }
+prologue_test "enter_s_nop"
+prologue_test "enter_s_blink" { {blink 0} }
+prologue_test "enter_s_fp" { {fp 0} } 0
+# Layout of registers as stored by enter_s doesn't conform to ARC ABI.
+prologue_test "enter_s_r13" { {r13 4} {fp 8} {blink 0} } 0
+prologue_test "enter_s_r15" { {r13 0} {r14 4} {r15 8} } 0
+# This enter_s saves GP, however because it is not a "calle-saved register",
+# GDB will not report it as "saved register" (but maybe it should). GP is at
+# offset 56.
+prologue_test "enter_s_all" { {r13 4} {r14 8} {r15 12} {r16 16} {r17 20} \
+    {r18 24} {r19 28} {r20 32} {r21 36} {r22 40} {r23 44} {r24 48} {r25 52} \
+    {gp 56} {fp 60} {blink 0} } 0
+
+# Test more levels of backtrace.
+gdb_breakpoint nested_prologue_inner temporary
+gdb_continue_to_breakpoint nested_prologue_inner
+gdb_test "backtrace 10" \
+    "#0\[ \t\]*$hex in nested_prologue_inner .*\r\n#1\[ \t\]*$hex in nested_prologue_outer .*\r\n#2\[ \t\]*$hex in main.*" \
+    "backtrace in nested_prologue_inner"
+    set regs [saved_regs_to_str {r13 r18}]
+    gdb_test "info frame" ".*Saved registers:$regs" \
+	"saved registers in nested_prologue_inner"
+    set regs [saved_regs_to_str {r14 r15 blink}]
+    gdb_test "info frame 1" ".*Saved registers:$regs" \
+	"saved registers in nested_prologue_outer"
+
+# sub sp,sp for local variables is part of prologue, hence should be added to
+# all of those offsets.
+prologue_test "max_length_prologue" { {r0 72} {r1 76} {r2 80} {r3 84} {r4 88} \
+    {r5 92} {r6 96} {r7 100} {r13 20} {r14 24} {r15 28} {r16 32} \
+    {r17 36} {r18 40} {r19 44} {r20 48} {r21 52} {r22 56} {r23 60} {r24 64} \
+    {r25 68} {fp 16} {blink 104} }
+
+prologue_test "branch_in_prologue" { {r13 0} }
+prologue_test "cond_branch_in_prologue" { {r13 4} }
+prologue_test "jump_in_prologue" { {r13 0} }
+prologue_test "cond_jump_in_prologue" { {r13 4} }
+prologue_test "predicated_insn" { {r13 8} {r15 0} }
+prologue_test "loop_in_prologue" { {r25 4} {lp_count 0} }
+prologue_test "store_constant" { {r13 8} {r14 4} }
+prologue_test "st_c_limm" { {r15 0} }
+prologue_test "st_ab_writeback" { {r13 8} {r14 4} {r15 0} }
+prologue_test "st_as_writeback" { {r13 8} {r14 4} {r15 0} }
+prologue_test "sth_as_writeback" { {r13 8} {r15 0} }
+prologue_test "std_as_writeback" { {r13 12} {r14 4} {r15 8} {r16 0} }
+prologue_test "st_halfword" { {r13 8} {r15 0} }
+prologue_test "sts_halfword" { {r13 8} {r15 0} }
+prologue_test "st_byte" { {r13 8} {r15 0} }
+prologue_test "sts_byte" { {r13 8} {r15 0} }
+prologue_test "sts_byte_sp" { {r13 8} {r15 0} }
+prologue_test "st_double" { {r14 16} {r15 20} {r18 8} {r19 12}}
+prologue_test "r_relative_store" { {r13 8} {r14 4} {r15 0} }
+prologue_test "r_relative_sub_store" { {r13 8} {r14 4} {r15 0} }
+prologue_test "r_relative_store_st_s" { {r13 8} {r14 0} {r15 4} }
+prologue_test "r_relative_store_unknown" { {r13 8} }
+prologue_test "st_s_r0gp" { {r13 8} }
+prologue_test "push_s_prologue" { {r0 28} {r1 16} {r2 4} {r3 24} {r12 32} \
+    {r13 20} {r14 12} {r15 8} {blink 0}}
+prologue_test "sub_s_cbu3" { {r13 4} {r14 0} }
+prologue_test "sub_s_bbc" { {r1 4} {r13 12} {r14 0} }
+prologue_test "sub_s_bbu5" { {r13 8} {r14 0} }
+prologue_test "sub_0bc" { {r13 4} {r14 0} }
+prologue_test "sub_alimmb" { {r13 4} {r14 0} }
+prologue_test "sub_s_ne_bbb" { {r13 0} }
+prologue_test "mov_limm" { {r13 4} {r14 0} }
+prologue_test "mov0c_limm" { {r13 4} {r14 0} }
+prologue_test "mov_s_hs3" { {r13 4} {r14 0} }
+prologue_test "mov_s_bu8" { {r13 4} {r14 0} }
+prologue_test "mov_s_ne_bh" { {r13 0} }
+prologue_test "unstored_reg" { {r13 0} {r14 4} }
+prologue_test "double_store" { {r14 0} }
+
+# alloca() tests
+gdb_breakpoint alloca_inner temporary
+gdb_continue_to_breakpoint alloca_inner
+gdb_test "backtrace 3" \
+    "#0\[ \t\]*$hex in alloca_inner .*\r\n#1\[ \t\]*$hex in alloca_outer .*\r\n#2\[ \t\]*$hex in main.*" \
+    "backtrace in alloca_inner"
+    set regs [saved_regs_to_str {r13 r14}]
+    gdb_test "info frame 0" ".*Saved registers:$regs" \
+	"saved registers in nested_prologue_inner"
+    set regs [saved_regs_to_str {fp blink}]
+    gdb_test "info frame 1" ".*Saved registers:$regs" \
+	"saved registers in nested_prologue_outer"
+