Breaking ARM's mcount implementations into a separate file

[Thomas Schwinge <thomas at codesourcery dot com>]

Hello!

ARM currently implements the mcount functions as inline assembly in
__attribute__ (__naked__) functions.  This interferes with my ongoing
work to add CFI statements to ARM's assembly code, as I can't be sure
whether .cfi_startproc has already been issued (-g with recent GCC) or
not (and I'd have to do it manually in the inline assembly code then, but
only in this latter case).  Also, this patch simplifies the code by
undoing the wrapping of macro definitions containing C functions
containing (only) inline assembly code, and aligns to what the mainline
code is using.


2009-12-15  Thomas Schwinge  <thomas@codesourcery.com>

	* sysdeps/arm/eabi/Makefile [gmon] (sysdep_routines): Add arm-mcount.
	* sysdeps/arm/eabi/machine-gmon.h (mcount_internal): Define to
	`__mcount_internal'.
	(MCOUNT (__gnu_mcount_nc), OLD_MCOUNT (_mcount), mcount): Move to...
	* sysdeps/arm/eabi/arm-mcount.S: ... this new file as __gnu_mcount_nc,
	_mcount, and mcount, respectively.

diff --git a/glibc-ports-mainline/sysdeps/arm/eabi/Makefile b/glibc-ports-mainline/sysdeps/arm/eabi/Makefile
index 36ddb8e..73185cb 100644
--- a/glibc-ports-mainline/sysdeps/arm/eabi/Makefile
+++ b/glibc-ports-mainline/sysdeps/arm/eabi/Makefile
@@ -15,6 +15,10 @@ static-only-routines += $(aeabi_constants)
 gen-as-const-headers += rtld-global-offsets.sym
 endif
 
+ifeq ($(subdir),gmon)
+sysdep_routines += arm-mcount
+endif
+
 ifeq ($(subdir),debug)
 CFLAGS-backtrace.c += -funwind-tables
 CFLAGS-tst-backtrace2.c += -funwind-tables
diff --git a/glibc-ports-mainline/sysdeps/arm/eabi/arm-mcount.S b/glibc-ports-mainline/sysdeps/arm/eabi/arm-mcount.S
new file mode 100644
index 0000000..82ef02b
--- /dev/null
+++ b/glibc-ports-mainline/sysdeps/arm/eabi/arm-mcount.S
@@ -0,0 +1,78 @@
+/* Implementation of profiling support.  ARM EABI version.
+   Copyright (C) 2008, 2009 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <sysdep.h>
+
+#undef CALL_MCOUNT
+#define CALL_MCOUNT /* Don't call mcount when calling mcount...  */
+	
+/* Use an assembly stub with a special ABI.  The calling lr has been
+   pushed to the stack (which will be misaligned).  We should preserve
+   all registers except ip and pop a word off the stack.
+
+   NOTE: This assumes mcount_internal does not clobber any non-core
+   (coprocessor) registers.  Currently this is true, but may require
+   additional attention in the future.
+
+   The calling sequence looks something like:
+func:
+   push {lr}
+   bl __gnu_mount_nc
+   <function body>
+*/
+
+ENTRY(__gnu_mcount_nc)
+	push {r0, r1, r2, r3, lr}
+	bic r1, lr, #1
+	ldr r0, [sp, #20]
+	bl __mcount_internal
+	pop {r0, r1, r2, r3, ip, lr}
+	bx ip
+END(__gnu_mcount_nc)
+
+
+/* Provide old mcount for backwards compatibility.  This requires
+   code be compiled with APCS frame pointers.  */
+
+#ifdef __thumb2__
+ENTRY(_mcount)
+	push {r0, r1, r2, r3, fp, lr}
+	movs r0, fp
+	ittt ne
+	ldrne r0, [r0, #-4]
+	movsne r1, lr
+	blne __mcount_internal
+	pop {r0, r1, r2, r3, fp, pc}
+END(_mcount)
+#else
+ENTRY(_mcount)
+	stmdb sp!, {r0, r1, r2, r3, fp, lr}
+	movs fp, fp
+	ldrne r0, [fp, #-4]
+	movnes r1, lr
+	blne __mcount_internal
+	ldmia sp!, {r0, r1, r2, r3, fp, lr}
+	bx lr
+END(_mcount)
+#endif
+
+/* The canonical name for the function is `_mcount' in both C and asm,
+   but some old asm code might assume it's `mcount'.  */
+#undef mcount
+weak_alias (_mcount, mcount)
diff --git a/glibc-ports-mainline/sysdeps/arm/eabi/machine-gmon.h b/glibc-ports-mainline/sysdeps/arm/eabi/machine-gmon.h
index 189a9a3..aca23c9 100644
--- a/glibc-ports-mainline/sysdeps/arm/eabi/machine-gmon.h
+++ b/glibc-ports-mainline/sysdeps/arm/eabi/machine-gmon.h
@@ -1,5 +1,5 @@
 /* Machine-dependent definitions for profiling support.  ARM EABI version.
-   Copyright (C) 2008 Free Software Foundation, Inc.
+   Copyright (C) 2008, 2009 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -17,83 +17,18 @@
    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
    02111-1307 USA.  */
 
+#include <sysdep.h>
+
 /* GCC for the ARM cannot compile __builtin_return_address(N) for N != 0, 
    so we must use an assembly stub.  */
 
-#include <sysdep.h>
-static void mcount_internal (u_long frompc, u_long selfpc) __attribute_used__;
+/* We must not pollute the global namespace.  */
+#define mcount_internal __mcount_internal
 
+extern void mcount_internal (u_long frompc, u_long selfpc) internal_function;
 #define _MCOUNT_DECL(frompc, selfpc) \
-static void mcount_internal (u_long frompc, u_long selfpc)
-
-/* Use an assembly stub with a special ABI.  The calling lr has been
-   pushed to the stack (which will be misaligned).  We should preserve
-   all registers except ip and pop a word off the stack.
-
-   NOTE: This assumes mcount_internal does not clobber any non-core
-   (coprocessor) registers.  Currently this is true, but may require
-   additional attention in the future.
-
-   The calling sequence looks something like:
-func:
-   push {lr}
-   bl __gnu_mount_nc
-   <function body>
- */
-
-
-#define MCOUNT								\
-void __attribute__((__naked__)) __gnu_mcount_nc(void)			\
-{									\
-    asm ("push {r0, r1, r2, r3, lr}\n\t"				\
-	 "bic r1, lr, #1\n\t"						\
-	 "ldr r0, [sp, #20]\n\t"					\
-	 "bl mcount_internal\n\t"					\
-	 "pop {r0, r1, r2, r3, ip, lr}\n\t"				\
-	 "bx ip");							\
-}									\
-OLD_MCOUNT
-
-/* Provide old mcount for backwards compatibility.  This requires
-   code be compiled with APCS frame pointers.  */
-
-#ifndef NO_UNDERSCORES
-/* The asm symbols for C functions are `_function'.
-   The canonical name for the counter function is `mcount', no _.  */
-void _mcount (void) asm ("mcount");
-#else
-/* The canonical name for the function is `_mcount' in both C and asm,
-   but some old asm code might assume it's `mcount'.  */
-void _mcount (void);
-weak_alias (_mcount, mcount)
-#endif
-
-#ifdef __thumb2__
-
-#define OLD_MCOUNT							\
-void __attribute__((__naked__)) _mcount (void)				\
-{									\
-  __asm__("push		{r0, r1, r2, r3, fp, lr};"			\
-	  "movs		r0, fp;"					\
-	  "ittt		ne;"						\
-	  "ldrne	r0, [r0, #-4];"					\
-	  "movsne	r1, lr;"					\
-	  "blne		mcount_internal;"				\
-	  "pop		{r0, r1, r2, r3, fp, pc}");			\
-}
-
-#else
+  void internal_function mcount_internal (u_long frompc, u_long selfpc)
 
-#define OLD_MCOUNT							\
-void __attribute__((__naked__)) _mcount (void)				\
-{									\
-  __asm__("stmdb	sp!, {r0, r1, r2, r3, fp, lr};"			\
-	  "movs		fp, fp;"					\
-	  "ldrne	r0, [fp, #-4];"					\
-	  "movnes	r1, lr;"					\
-	  "blne		mcount_internal;"				\
-	  "ldmia	sp!, {r0, r1, r2, r3, fp, lr};"			\
-	  "bx		lr");						\
-}
 
-#endif
+/* Define MCOUNT as empty since we have the implementation in another file.  */
+#define MCOUNT


I inspected the pre / post libraries (symbols, disassembly), and did test
runs to confirm that profiling still works in the ``normal'' and -mthumb
cases.


Regards,
 Thomas

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