[v7,01/34] Add and restructure function declaration macros
Commit Message
Most of these changes support subsequent patches in this series.
Particularly, the FUNC_START macro becomes part of a new macro chain:
* FUNC_ENTRY Common global symbol directives
* FUNC_START_SECTION FUNC_ENTRY to start a new <section>
* FUNC_START FUNC_START_SECTION <".text">
The effective definition of FUNC_START is unchanged from the previous
version of lib1funcs. See code comments for detailed usage.
The new names FUNC_ENTRY and FUNC_START_SECTION were chosen specifically
to complement the existing FUNC_START name. Alternate name patterns are
possible (such as {FUNC_SYMBOL, FUNC_START_SECTION, FUNC_START_TEXT}),
but any change to FUNC_START would require refactoring much of libgcc.
Additionally, a parallel chain of new macros supports weak functions:
* WEAK_ENTRY
* WEAK_START_SECTION
* WEAK_START
* WEAK_ALIAS
Moving the CFI_* macros earlier in the file scope will increase their
scope for use in additional functions.
gcc/libgcc/ChangeLog:
2022-10-09 Daniel Engel <gnu@danielengel.com>
* config/arm/lib1funcs.S:
(LLSYM): New macro prefix ".L" for strippable local symbols.
(CFI_START_FUNCTION, CFI_END_FUNCTION): Moved earlier in the file.
(FUNC_ENTRY): New macro for symbols with no ".section" directive.
(WEAK_ENTRY): New macro FUNC_ENTRY + ".weak".
(FUNC_START_SECTION): New macro FUNC_ENTRY with <section> argument.
(WEAK_START_SECTION): New macro FUNC_START_SECTION + ".weak".
(FUNC_START): Redefined in terms of FUNC_START_SECTION <".text">.
(WEAK_START): New macro FUNC_START + ".weak".
(WEAK_ALIAS): New macro FUNC_ALIAS + ".weak".
(FUNC_END): Moved after FUNC_START macro group.
(THUMB_FUNC_START): Moved near the other *FUNC* macros.
(THUMB_SYNTAX, ARM_SYM_START, SYM_END): Deleted unused macros.
---
libgcc/config/arm/lib1funcs.S | 109 +++++++++++++++++++++-------------
1 file changed, 69 insertions(+), 40 deletions(-)
@@ -69,11 +69,13 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
#define TYPE(x) .type SYM(x),function
#define SIZE(x) .size SYM(x), . - SYM(x)
#define LSYM(x) .x
+#define LLSYM(x) .L##x
#else
#define __PLT__
#define TYPE(x)
#define SIZE(x)
#define LSYM(x) x
+#define LLSYM(x) x
#endif
/* Function end macros. Variants for interworking. */
@@ -182,6 +184,16 @@ LSYM(Lend_fde):
#endif
.endm
+.macro CFI_START_FUNCTION
+ .cfi_startproc
+ .cfi_remember_state
+.endm
+
+.macro CFI_END_FUNCTION
+ .cfi_restore_state
+ .cfi_endproc
+.endm
+
/* Don't pass dirn, it's there just to get token pasting right. */
.macro RETLDM regs=, cond=, unwind=, dirn=ia
@@ -324,10 +336,6 @@ LSYM(Lend_fde):
.endm
#endif
-.macro FUNC_END name
- SIZE (__\name)
-.endm
-
.macro DIV_FUNC_END name signed
cfi_start __\name, LSYM(Lend_div0)
LSYM(Ldiv0):
@@ -340,48 +348,76 @@ LSYM(Ldiv0):
FUNC_END \name
.endm
-.macro THUMB_FUNC_START name
- .globl SYM (\name)
- TYPE (\name)
- .thumb_func
-SYM (\name):
-.endm
-
/* Function start macros. Variants for ARM and Thumb. */
#ifdef __thumb__
#define THUMB_FUNC .thumb_func
#define THUMB_CODE .force_thumb
-# if defined(__thumb2__)
-#define THUMB_SYNTAX
-# else
-#define THUMB_SYNTAX
-# endif
#else
#define THUMB_FUNC
#define THUMB_CODE
-#define THUMB_SYNTAX
#endif
+.macro THUMB_FUNC_START name
+ .globl SYM (\name)
+ TYPE (\name)
+ .thumb_func
+SYM (\name):
+.endm
+
+/* Strong global symbol, ".text" section.
+ The default macro for function declarations. */
.macro FUNC_START name
- .text
+ FUNC_START_SECTION \name .text
+.endm
+
+/* Weak global symbol, ".text" section.
+ Use WEAK_* macros to declare a function/object that may be discarded in by
+ the linker when another library or object exports the same name.
+ Typically, functions declared with WEAK_* macros implement a subset of
+ functionality provided by the overriding definition, and are discarded
+ when the full functionality is required. */
+.macro WEAK_START name
+ .weak SYM(__\name)
+ FUNC_START_SECTION \name .text
+.endm
+
+/* Strong global symbol, alternate section.
+ Use the *_START_SECTION macros for declarations that the linker should
+ place in a non-defailt section (e.g. ".rodata", ".text.subsection"). */
+.macro FUNC_START_SECTION name section
+ .section \section,"x"
+ .align 0
+ FUNC_ENTRY \name
+.endm
+
+/* Weak global symbol, alternate section. */
+.macro WEAK_START_SECTION name section
+ .weak SYM(__\name)
+ FUNC_START_SECTION \name \section
+.endm
+
+/* Strong global symbol.
+ Use *_ENTRY macros internal to a function/object body to declare a second
+ or subsequent entry point without changing the assembler state.
+ Because there is no alignment specification, these macros should never
+ replace the *_START_* macros as the first declaration in any object. */
+.macro FUNC_ENTRY name
.globl SYM (__\name)
TYPE (__\name)
- .align 0
THUMB_CODE
THUMB_FUNC
- THUMB_SYNTAX
SYM (__\name):
.endm
-.macro ARM_SYM_START name
- TYPE (\name)
- .align 0
-SYM (\name):
+/* Weak global symbol. */
+.macro WEAK_ENTRY name
+ .weak SYM(__\name)
+ FUNC_ENTRY \name
.endm
-.macro SYM_END name
- SIZE (\name)
+.macro FUNC_END name
+ SIZE (__\name)
.endm
/* Special function that will always be coded in ARM assembly, even if
@@ -447,6 +483,11 @@ SYM (__\name):
#endif
.endm
+.macro WEAK_ALIAS new old
+ .weak SYM(__\new)
+ FUNC_ALIAS \new \old
+.endm
+
#ifndef NOT_ISA_TARGET_32BIT
.macro ARM_FUNC_ALIAS new old
.globl SYM (__\new)
@@ -1459,10 +1500,8 @@ LSYM(Lover12):
#ifdef L_dvmd_tls
#ifdef __ARM_EABI__
- WEAK aeabi_idiv0
- WEAK aeabi_ldiv0
- FUNC_START aeabi_idiv0
- FUNC_START aeabi_ldiv0
+ WEAK_START aeabi_idiv0
+ WEAK_START aeabi_ldiv0
RET
FUNC_END aeabi_ldiv0
FUNC_END aeabi_idiv0
@@ -2170,16 +2209,6 @@ LSYM(Lchange_\register):
#endif /* Arch supports thumb. */
-.macro CFI_START_FUNCTION
- .cfi_startproc
- .cfi_remember_state
-.endm
-
-.macro CFI_END_FUNCTION
- .cfi_restore_state
- .cfi_endproc
-.endm
-
#ifndef __symbian__
/* The condition here must match the one in gcc/config/arm/elf.h and
libgcc/config/arm/t-elf. */