Find tailcall frames before inline frames

diff --git a/gdb/dwarf2/frame.c b/gdb/dwarf2/frame.c
index b240a25e2d8..74488f9a8aa 100644
--- a/gdb/dwarf2/frame.c
+++ b/gdb/dwarf2/frame.c
@@ -959,22 +959,12 @@  struct dwarf2_frame_cache
   /* The .text offset.  */
   CORE_ADDR text_offset;
 
-  /* True if we already checked whether this frame is the bottom frame
-     of a virtual tail call frame chain.  */
-  int checked_tailcall_bottom;
-
   /* If not NULL then this frame is the bottom frame of a TAILCALL_FRAME
      sequence.  If NULL then it is a normal case with no TAILCALL_FRAME
      involved.  Non-bottom frames of a virtual tail call frames chain use
      dwarf2_tailcall_frame_unwind unwinder so this field does not apply for
      them.  */
   void *tailcall_cache;
-
-  /* The number of bytes to subtract from TAILCALL_FRAME frames frame
-     base to get the SP, to simulate the return address pushed on the
-     stack.  */
-  LONGEST entry_cfa_sp_offset;
-  int entry_cfa_sp_offset_p;
 };
 
 static struct dwarf2_frame_cache *
@@ -1037,6 +1027,8 @@  dwarf2_frame_cache (struct frame_info *this_frame, void **this_cache)
      in an address that's within the range of FDE locations.  This
      is due to the possibility of the function occupying non-contiguous
      ranges.  */
+  LONGEST entry_cfa_sp_offset;
+  int entry_cfa_sp_offset_p = 0;
   if (get_frame_func_if_available (this_frame, &entry_pc)
       && fde->initial_location <= entry_pc
       && entry_pc < fde->initial_location + fde->address_range)
@@ -1049,8 +1041,8 @@  dwarf2_frame_cache (struct frame_info *this_frame, void **this_cache)
 	  && (dwarf_reg_to_regnum (gdbarch, fs.regs.cfa_reg)
 	      == gdbarch_sp_regnum (gdbarch)))
 	{
-	  cache->entry_cfa_sp_offset = fs.regs.cfa_offset;
-	  cache->entry_cfa_sp_offset_p = 1;
+	  entry_cfa_sp_offset = fs.regs.cfa_offset;
+	  entry_cfa_sp_offset_p = 1;
 	}
     }
   else
@@ -1195,6 +1187,10 @@  incomplete CFI data; unspecified registers (e.g., %s) at %s"),
       && fs.regs.reg[fs.retaddr_column].how == DWARF2_FRAME_REG_UNDEFINED)
     cache->undefined_retaddr = 1;
 
+  dwarf2_tailcall_sniffer_first (this_frame, &cache->tailcall_cache,
+				 (entry_cfa_sp_offset_p
+				  ? &entry_cfa_sp_offset : NULL));
+
   return cache;
 }
 
@@ -1239,16 +1235,6 @@  dwarf2_frame_prev_register (struct frame_info *this_frame, void **this_cache,
   CORE_ADDR addr;
   int realnum;
 
-  /* Check whether THIS_FRAME is the bottom frame of a virtual tail
-     call frame chain.  */
-  if (!cache->checked_tailcall_bottom)
-    {
-      cache->checked_tailcall_bottom = 1;
-      dwarf2_tailcall_sniffer_first (this_frame, &cache->tailcall_cache,
-				     (cache->entry_cfa_sp_offset_p
-				      ? &cache->entry_cfa_sp_offset : NULL));
-    }
-
   /* Non-bottom frames of a virtual tail call frames chain use
      dwarf2_tailcall_frame_unwind unwinder so this code does not apply for
      them.  If dwarf2_tailcall_prev_register_first does not have specific value
@@ -1410,10 +1396,6 @@  static const struct frame_unwind dwarf2_signal_frame_unwind =
 void
 dwarf2_append_unwinders (struct gdbarch *gdbarch)
 {
-  /* TAILCALL_FRAME must be first to find the record by
-     dwarf2_tailcall_sniffer_first.  */
-  frame_unwind_append_unwinder (gdbarch, &dwarf2_tailcall_frame_unwind);
-
   frame_unwind_append_unwinder (gdbarch, &dwarf2_frame_unwind);
   frame_unwind_append_unwinder (gdbarch, &dwarf2_signal_frame_unwind);
 }
diff --git a/gdb/frame-unwind.c b/gdb/frame-unwind.c
index 35f2e82c57d..3334c472d02 100644
--- a/gdb/frame-unwind.c
+++ b/gdb/frame-unwind.c
@@ -27,6 +27,7 @@ 
 #include "gdb_obstack.h"
 #include "target.h"
 #include "gdbarch.h"
+#include "dwarf2/frame-tailcall.h"
 
 static struct gdbarch_data *frame_unwind_data;
 
@@ -43,6 +44,18 @@  struct frame_unwind_table
   struct frame_unwind_table_entry **osabi_head;
 };
 
+/* A helper function to add an unwinder to a list.  LINK says where to
+   install the new unwinder.  The new link is returned.  */
+
+static struct frame_unwind_table_entry **
+add_unwinder (struct obstack *obstack, const struct frame_unwind *unwinder,
+	      struct frame_unwind_table_entry **link)
+{
+  *link = OBSTACK_ZALLOC (obstack, struct frame_unwind_table_entry);
+  (*link)->unwinder = unwinder;
+  return &(*link)->next;
+}
+
 static void *
 frame_unwind_init (struct obstack *obstack)
 {
@@ -51,13 +64,21 @@  frame_unwind_init (struct obstack *obstack)
 
   /* Start the table out with a few default sniffers.  OSABI code
      can't override this.  */
-  table->list = OBSTACK_ZALLOC (obstack, struct frame_unwind_table_entry);
-  table->list->unwinder = &dummy_frame_unwind;
-  table->list->next = OBSTACK_ZALLOC (obstack,
-				      struct frame_unwind_table_entry);
-  table->list->next->unwinder = &inline_frame_unwind;
+  struct frame_unwind_table_entry **link = &table->list;
+
+  link = add_unwinder (obstack, &dummy_frame_unwind, link);
+  /* The DWARF tailcall sniffer must come before the inline sniffer.
+     Otherwise, we can end up in a situation where a DWARF frame finds
+     tailcall information, but then the inline sniffer claims a frame
+     before the tailcall sniffer, resulting in confusion.  This is
+     safe to do always because the tailcall sniffer can only ever be
+     activated if the newer frame was created using the DWARF
+     unwinder, and it also found tailcall information.  */
+  link = add_unwinder (obstack, &dwarf2_tailcall_frame_unwind, link);
+  link = add_unwinder (obstack, &inline_frame_unwind, link);
+
   /* The insertion point for OSABI sniffers.  */
-  table->osabi_head = &table->list->next->next;
+  table->osabi_head = link;
   return table;
 }