[m-dev.] partial fix for gcc 4.{123}.

[Paul Bone]

Here's the patch for the GCC problems.

I havn't been able to test it on gcc 4.4, I don't have that on my system (yet).

It will only work for x86_64 at the moment.

It works for the trivial tests I've tried, but won't bootstrap.

Thanks.

Index: runtime/mercury_goto.h
===================================================================
RCS file: /home/mercury1/repository/mercury/runtime/mercury_goto.h,v
retrieving revision 1.50
diff -u -p -b -r1.50 mercury_goto.h
--- runtime/mercury_goto.h	12 Jun 2007 06:06:33 -0000	1.50
+++ runtime/mercury_goto.h	30 Sep 2009 04:10:29 -0000
@@ -321,6 +321,7 @@
   ** instruction on entry to the procedure to set up the right gp value.
   */
   #define MR_ASM_JUMP(address)				\
+	MR_PRETEND_FAKE_REGISTERS_INPUT;		\
 	__asm__("bis %0, %0, $27\n\t" 			\
 		: : "r"(address) : "$27");		\
 	goto *(address)
@@ -371,16 +372,19 @@
   */
   #if defined(__i386__)
     #define MR_ASM_JUMP(label)				\
+	MR_PRETEND_FAKE_REGISTERS_INPUT;		\
   	{ register int stack_pointer __asm__("esp");	\
   	__asm__("" : : "g"(stack_pointer)); }		\
   	goto *(label)
   #elif defined(__x86_64__)
     #define MR_ASM_JUMP(label)				\
+	MR_PRETEND_FAKE_REGISTERS_INPUT;		\
 	{ register int stack_pointer __asm__("rsp");	\
 	__asm__("" : : "g"(stack_pointer)); }		\
 	goto *(label)
   #elif defined(__mc68000__)
     #define MR_ASM_JUMP(label)				\
+	MR_PRETEND_FAKE_REGISTERS_INPUT;		\
   	{ register int stack_pointer __asm__("sp");	\
   	__asm__("" : : "g"(stack_pointer)); }		\
   	goto *(label)
@@ -670,7 +674,9 @@
 ** MR_ASM_ENTRY, MR_ASM_STATIC_ENTRY, or MR_ASM_LOCAL_ENTRY.
 */
 #ifndef MR_ASM_JUMP
-#define MR_ASM_JUMP(address)	goto *(address)
+#define MR_ASM_JUMP(address) \
+	MR_PRETEND_FAKE_REGISTERS_INPUT; \
+	goto *(address)
 #endif
 
 /*---------------------------------------------------------------------------*/
@@ -778,7 +784,7 @@
   ** with versions of gcc before version 4.
   */
   #define MR_PRETEND_REGS_ARE_USED \
-	__asm__ __volatile("":::"memory")
+	__asm__ __volatile__("": : : MR_callee_saved_register_clobbers, "memory")
   /*
   Explanation:
   	__asm__
@@ -794,6 +800,42 @@
 	)
    */
 
+  #if MR_NUM_REAL_REGS > 0 
+	#define MR_PRETEND_FAKE_REGISTERS_OUTPUT \
+	  __asm__ __volatile__("": MR_fake_register_outputs :)
+  #else
+	#define MR_PRETEND_FAKE_REGSITERS_OUTPUT
+  #endif
+  /*
+  Explanation:
+  	__asm__
+	__volatile__		 			Don't optimize this asm away.
+	(
+		""			                Empty assembler code.
+        : MR_fake_register_outputs  A list of real Mercury abstract machine
+                                    register outputs.
+		:			                No inputs.
+	)
+  */
+
+  #if MR_NUM_REAL_REGS > 0 
+	#define MR_PRETEND_FAKE_REGISTERS_INPUT \
+      __asm__ __volatile__("": : MR_fake_register_inputs)
+  #else
+	#define MR_PRETEND_FAKE_REGISTERS_INPUT
+  #endif
+  /*
+  Explanation:
+  	__asm__
+	__volatile__		 			Don't optimize this asm away.
+	(
+		""			                Empty assembler code.
+		:
+        : MR_fake_register_inputs	A list of real Mercury abstract machine
+                                    register inputs.
+	)
+  */
+
   /*
   ** Since we're jumping into and out of the middle of functions,
   ** we need to make sure that gcc thinks that (1) the function's address
@@ -851,18 +893,20 @@
     #define MR_define_extern_entry(label)	MR_declare_entry(label)
     #define MR_define_entry(label)		\
 		MR_ASM_ENTRY(label)		\
+		MR_PRETEND_FAKE_REGISTERS_OUTPUT; \
+		MR_PRETEND_REGS_ARE_USED; \
 	}					\
 	label:					\
 	MR_PRETEND_ADDRESS_IS_USED(&&MR_entry(label));	\
-	{ \
-	MR_PRETEND_REGS_ARE_USED;
+	{
     #define MR_define_static(label)		\
 		MR_ASM_STATIC_ENTRY(label) 	\
+		MR_PRETEND_FAKE_REGISTERS_OUTPUT; \
+		MR_PRETEND_REGS_ARE_USED; \
 	}					\
 	label:					\
 	MR_PRETEND_ADDRESS_IS_USED(&&MR_entry(label));	\
-	{ \
-	MR_PRETEND_REGS_ARE_USED;
+	{
     /*
     ** The MR_PRETEND_ADDRESS_IS_USED macro is necessary to
     ** prevent an over-zealous gcc from optimizing away `label'
@@ -902,11 +946,13 @@
     #define MR_define_entry(label)	\
 	}	\
 	MR_entry(label): \
+	MR_PRETEND_FAKE_REGISTERS_OUTPUT; \
 	label:	\
 	{
     #define MR_define_static(label)	\
 	}	\
 	MR_entry(label): \
+	MR_PRETEND_FAKE_REGISTERS_OUTPUT; \
 	label:	\
 	{
     #define MR_init_entry(label)	\
@@ -964,6 +1010,7 @@
   #define MR_GOTO_LOCAL(label) 	MR_GOTO_LABEL(label)
   #define MR_GOTO_LABEL(label) 	do {					\
   					MR_debuggoto(MR_LABEL(label));	\
+  					MR_PRETEND_FAKE_REGISTERS_INPUT;	\
 					goto label;			\
 				} while(0)
 
Index: runtime/machdeps/x86_64_regs.h
===================================================================
RCS file: /home/mercury1/repository/mercury/runtime/machdeps/x86_64_regs.h,v
retrieving revision 1.2
diff -u -p -b -r1.2 x86_64_regs.h
--- runtime/machdeps/x86_64_regs.h	2 Aug 2006 06:48:56 -0000	1.2
+++ runtime/machdeps/x86_64_regs.h	26 Sep 2009 09:37:27 -0000
@@ -42,6 +42,24 @@ register	MR_Word	MR_mr3 __asm__("r15");	
 #define MR_real_reg_number_mr2	r14
 #define MR_real_reg_number_mr3	r15
 
+/*
+** A list of outputs suitable for GCC's inline assembler syntax.  This is used
+** when we want to ensure that GCC doesn't schedule instructions that read
+** these registers too early.
+*/
+#define MR_fake_register_outputs \
+   "=g"(MR_mr0), "=g"(MR_mr1), "=g"(MR_mr2), "=g"(MR_mr3) 
+#define MR_fake_register_inputs \
+   "g"(MR_mr0), "g"(MR_mr1), "g"(MR_mr2), "g"(MR_mr3)
+
+/*
+** We also mark registers not mapped to abstract machine registers as
+** clobbered, this prevents GCC 4.{234} from scheduling moves into these
+** registers in the prelude of the function.
+*/
+#define MR_callee_saved_register_clobbers \
+    "rax", "rbx", "rcx", "rdx", "rsi", "rdi", "r8", "r9", "r10", "r11"
+
 #define MR_save_regs_to_mem(save_area) (	\
 	save_area[0] = MR_mr0,			\
 	save_area[1] = MR_mr1,			\

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