re PR rtl-optimization/5878 (gcc 3.1 breaks on C code generated by the Mercury compiler)

	PR 5878
	* config/arc/arc.h, config/cris/cris.h, config/i386/i386.h,
	config/m68k/m68k.h, config/s390/s390.h, config/sparc/sparc.h
	(PIC_OFFSET_TABLE_REGNUM): Conditionalize on flag_pic.

	* config/arm/arm.h config/i386/i386.h, config/m68k/m68k.h,
	config/sparc/sparc.h (CONDITIONAL_REGISTER_USAGE): Set
	PIC_OFFSET_TABLE_REGNUM based on INVALID_REGNUM not flag_pic.

	* config/arc/arc.h (CONDITIONAL_REGISTER_USAGE): New.
	* config/arm/arm.c (arm_pic_register): Init to INVALID_REGNUM.
	(arm_override_options): Set arm_pic_register if TARGET_APCS_STACK
	also.  Don't set it if not flag_pic.
	* config/i386/i386.c (ix86_save_reg): Trust PIC_OFFSET_TABLE_REGNUM
	to be INVALID_REGNUM when not used.

	* gcc.dg/20020312-2.c: New.

From-SVN: r50713

9 files changed, 68 insertions, 62 deletions

diff --git a/gcc/config/arc/arc.h b/gcc/config/arc/arc.h
index 4ba19f1..651d81e 100644
--- a/gcc/config/arc/arc.h
+++ b/gcc/config/arc/arc.h
@@ -355,6 +355,16 @@ if (GET_MODE_CLASS (MODE) == MODE_INT		\
   48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,		\
   27, 28, 29, 30 }
 
+/* Macro to conditionally modify fixed_regs/call_used_regs.  */
+#define CONDITIONAL_REGISTER_USAGE			\
+do {							\
+  if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM)	\
+    {							\
+      fixed_regs[PIC_OFFSET_TABLE_REGNUM] = 1;		\
+      call_used_regs[PIC_OFFSET_TABLE_REGNUM] = 1;	\
+    }							\
+} while (0)
+
 /* Return number of consecutive hard regs needed starting at reg REGNO
    to hold something of mode MODE.
    This is ordinarily the length in words of a value of mode MODE
@@ -1152,7 +1162,7 @@ do {							\
    pointer and frame pointer registers.  If this macro is not defined, it
    is up to the machine-dependent files to allocate such a register (if
    necessary).  */
-#define PIC_OFFSET_TABLE_REGNUM 26
+#define PIC_OFFSET_TABLE_REGNUM  (flag_pic ? 26 : INVALID_REGNUM)
 
 /* Define this macro if the register defined by PIC_OFFSET_TABLE_REGNUM is
    clobbered by calls.  Do not define this macro if PIC_OFFSET_TABLE_REGNUM
diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index 4a0e851..8e85957 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -268,7 +268,7 @@ enum machine_mode output_memory_reference_mode;
 
 /* The register number to be used for the PIC offset register.  */
 const char * arm_pic_register_string = NULL;
-int arm_pic_register = 9;
+int arm_pic_register = INVALID_REGNUM;
 
 /* Set to 1 when a return insn is output, this means that the epilogue
    is not needed.  */
@@ -651,8 +651,8 @@ arm_override_options ()
   
   /* If stack checking is disabled, we can use r10 as the PIC register,
      which keeps r9 available.  */
-  if (flag_pic && !TARGET_APCS_STACK)
-    arm_pic_register = 10;
+  if (flag_pic)
+    arm_pic_register = TARGET_APCS_STACK ? 9 : 10;
   
   if (TARGET_APCS_FLOAT)
     warning ("passing floating point arguments in fp regs not yet supported");
@@ -713,18 +713,16 @@ arm_override_options ()
 
   if (arm_pic_register_string != NULL)
     {
-      int pic_register;
-
+      int pic_register = decode_reg_name (arm_pic_register_string);
+      
       if (!flag_pic)
 	warning ("-mpic-register= is useless without -fpic");
 
-      pic_register = decode_reg_name (arm_pic_register_string);
-      
       /* Prevent the user from choosing an obviously stupid PIC register.  */
-      if (pic_register < 0 || call_used_regs[pic_register]
-	  || pic_register == HARD_FRAME_POINTER_REGNUM
-	  || pic_register == STACK_POINTER_REGNUM
-	  || pic_register >= PC_REGNUM)
+      else if (pic_register < 0 || call_used_regs[pic_register]
+	       || pic_register == HARD_FRAME_POINTER_REGNUM
+	       || pic_register == STACK_POINTER_REGNUM
+	       || pic_register >= PC_REGNUM)
 	error ("unable to use '%s' for PIC register", arm_pic_register_string);
       else
 	arm_pic_register = pic_register;
diff --git a/gcc/config/arm/arm.h b/gcc/config/arm/arm.h
index c180e26..240595e 100644
--- a/gcc/config/arm/arm.h
+++ b/gcc/config/arm/arm.h
@@ -838,7 +838,7 @@ extern const char * structure_size_string;
 	   regno <= LAST_ARM_FP_REGNUM; ++regno)		\
 	fixed_regs[regno] = call_used_regs[regno] = 1;		\
     }								\
-  if (flag_pic)							\
+  if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM)		\
     {								\
       fixed_regs[PIC_OFFSET_TABLE_REGNUM] = 1;			\
       call_used_regs[PIC_OFFSET_TABLE_REGNUM] = 1;		\
diff --git a/gcc/config/cris/cris.h b/gcc/config/cris/cris.h
index 235777d..21065a9 100644
--- a/gcc/config/cris/cris.h
+++ b/gcc/config/cris/cris.h
@@ -1468,7 +1468,7 @@ call_ ## FUNC (void)						\
 
 /* Node: PIC */
 
-#define PIC_OFFSET_TABLE_REGNUM 0
+#define PIC_OFFSET_TABLE_REGNUM (flag_pic ? 0 : INVALID_REGNUM)
 
 #define LEGITIMATE_PIC_OPERAND_P(X) cris_legitimate_pic_operand (X)
 
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 56fdf90..2d06499 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -3880,9 +3880,7 @@ ix86_save_reg (regno, maybe_eh_return)
      int regno;
      int maybe_eh_return;
 {
-  if (flag_pic
-      && ! TARGET_64BIT
-      && regno == PIC_OFFSET_TABLE_REGNUM
+  if (regno == PIC_OFFSET_TABLE_REGNUM
       && (current_function_uses_pic_offset_table
 	  || current_function_uses_const_pool
 	  || current_function_calls_eh_return))
diff --git a/gcc/config/i386/i386.h b/gcc/config/i386/i386.h
index 50e8dd5..9435913 100644
--- a/gcc/config/i386/i386.h
+++ b/gcc/config/i386/i386.h
@@ -937,7 +937,7 @@ do {									\
         call_used_regs[i] = (call_used_regs[i]				\
 			     & (TARGET_64BIT ? 2 : 1)) != 0;		\
       }									\
-    if (flag_pic && PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM)		\
+    if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM)			\
       {									\
 	fixed_regs[PIC_OFFSET_TABLE_REGNUM] = 1;			\
 	call_used_regs[PIC_OFFSET_TABLE_REGNUM] = 1;			\
@@ -1113,11 +1113,11 @@ do {									\
 #define STATIC_CHAIN_REGNUM (TARGET_64BIT ? FIRST_REX_INT_REG + 10 - 8 : 2)
 
 /* Register to hold the addressing base for position independent
-   code access to data items.
-   We don't use PIC pointer for 64bit mode.  Define the regnum to
-   dummy value to prevent gcc from pessimizing code dealing with EBX.
- */
-#define PIC_OFFSET_TABLE_REGNUM (TARGET_64BIT ? INVALID_REGNUM : 3)
+   code access to data items.  We don't use PIC pointer for 64bit
+   mode.  Define the regnum to dummy value to prevent gcc from
+   pessimizing code dealing with EBX.  */
+#define PIC_OFFSET_TABLE_REGNUM \
+  (TARGET_64BIT || !flag_pic ? INVALID_REGNUM : 3)
 
 /* Register in which address to store a structure value
    arrives in the function.  On the 386, the prologue
diff --git a/gcc/config/m68k/m68k.h b/gcc/config/m68k/m68k.h
index 9a20494..55f5fd1 100644
--- a/gcc/config/m68k/m68k.h
+++ b/gcc/config/m68k/m68k.h
@@ -387,7 +387,7 @@ extern int target_flags;
 #endif
 
 /* This defines the register which is used to hold the offset table for PIC.  */
-#define PIC_OFFSET_TABLE_REGNUM 13
+#define PIC_OFFSET_TABLE_REGNUM (flag_pic ? 13 : INVALID_REGNUM)
 
 #ifndef SUPPORT_SUN_FPA
 
@@ -469,43 +469,43 @@ extern int target_flags;
 
 #ifdef SUPPORT_SUN_FPA
 
-#define CONDITIONAL_REGISTER_USAGE \
-{ 						\
-  int i; 					\
-  HARD_REG_SET x; 				\
-  if (! TARGET_FPA)				\
-    { 						\
-      COPY_HARD_REG_SET (x, reg_class_contents[(int)FPA_REGS]); \
-      for (i = 0; i < FIRST_PSEUDO_REGISTER; i++ ) \
-       if (TEST_HARD_REG_BIT (x, i)) 		\
-	fixed_regs[i] = call_used_regs[i] = 1; 	\
-    } 						\
-  if (! TARGET_68881)				\
-    { 						\
-      COPY_HARD_REG_SET (x, reg_class_contents[(int)FP_REGS]); \
-      for (i = 0; i < FIRST_PSEUDO_REGISTER; i++ ) \
-       if (TEST_HARD_REG_BIT (x, i)) 		\
-	fixed_regs[i] = call_used_regs[i] = 1; 	\
-    } 						\
-  if (flag_pic)					\
-    fixed_regs[PIC_OFFSET_TABLE_REGNUM]		\
-      = call_used_regs[PIC_OFFSET_TABLE_REGNUM] = 1;\
+#define CONDITIONAL_REGISTER_USAGE				\
+{ 								\
+  int i; 							\
+  HARD_REG_SET x; 						\
+  if (! TARGET_FPA)						\
+    { 								\
+      COPY_HARD_REG_SET (x, reg_class_contents[(int)FPA_REGS]);	\
+      for (i = 0; i < FIRST_PSEUDO_REGISTER; i++ )		\
+       if (TEST_HARD_REG_BIT (x, i)) 				\
+	fixed_regs[i] = call_used_regs[i] = 1; 			\
+    } 								\
+  if (! TARGET_68881)						\
+    { 								\
+      COPY_HARD_REG_SET (x, reg_class_contents[(int)FP_REGS]);	\
+      for (i = 0; i < FIRST_PSEUDO_REGISTER; i++ )		\
+       if (TEST_HARD_REG_BIT (x, i)) 				\
+	fixed_regs[i] = call_used_regs[i] = 1; 			\
+    } 								\
+  if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM)		\
+    fixed_regs[PIC_OFFSET_TABLE_REGNUM]				\
+      = call_used_regs[PIC_OFFSET_TABLE_REGNUM] = 1;		\
 }
 #else
-#define CONDITIONAL_REGISTER_USAGE \
-{ 						\
-  int i; 					\
-  HARD_REG_SET x; 				\
-  if (! TARGET_68881)				\
-    { 						\
-      COPY_HARD_REG_SET (x, reg_class_contents[(int)FP_REGS]); \
-      for (i = 0; i < FIRST_PSEUDO_REGISTER; i++ ) \
-       if (TEST_HARD_REG_BIT (x, i)) 		\
-	fixed_regs[i] = call_used_regs[i] = 1; 	\
-    } 						\
-  if (flag_pic)					\
-    fixed_regs[PIC_OFFSET_TABLE_REGNUM]		\
-      = call_used_regs[PIC_OFFSET_TABLE_REGNUM] = 1;\
+#define CONDITIONAL_REGISTER_USAGE				\
+{ 								\
+  int i; 							\
+  HARD_REG_SET x; 						\
+  if (! TARGET_68881)						\
+    { 								\
+      COPY_HARD_REG_SET (x, reg_class_contents[(int)FP_REGS]);	\
+      for (i = 0; i < FIRST_PSEUDO_REGISTER; i++ )		\
+       if (TEST_HARD_REG_BIT (x, i)) 				\
+	fixed_regs[i] = call_used_regs[i] = 1; 			\
+    } 								\
+  if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM)		\
+    fixed_regs[PIC_OFFSET_TABLE_REGNUM]				\
+      = call_used_regs[PIC_OFFSET_TABLE_REGNUM] = 1;		\
 }
 
 #endif /* defined SUPPORT_SUN_FPA */
diff --git a/gcc/config/s390/s390.h b/gcc/config/s390/s390.h
index 8ab287b..93b355c 100644
--- a/gcc/config/s390/s390.h
+++ b/gcc/config/s390/s390.h
@@ -249,7 +249,7 @@ if (INTEGRAL_MODE_P (MODE) &&	        	    	\
    GPR 14: Return registers holds the return address
    GPR 15: Stack pointer */
 
-#define PIC_OFFSET_TABLE_REGNUM 12
+#define PIC_OFFSET_TABLE_REGNUM (flag_pic ? 12 : INVALID_REGNUM)
 #define BASE_REGISTER 13
 #define RETURN_REGNUM 14
 #define STACK_POINTER_REGNUM 15
diff --git a/gcc/config/sparc/sparc.h b/gcc/config/sparc/sparc.h
index aeb1078..92c8ace 100644
--- a/gcc/config/sparc/sparc.h
+++ b/gcc/config/sparc/sparc.h
@@ -984,7 +984,7 @@ if (TARGET_ARCH64				\
 #define CONDITIONAL_REGISTER_USAGE				\
 do								\
   {								\
-    if (flag_pic)						\
+    if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM)		\
       {								\
 	fixed_regs[PIC_OFFSET_TABLE_REGNUM] = 1;		\
 	call_used_regs[PIC_OFFSET_TABLE_REGNUM] = 1;		\
@@ -1159,7 +1159,7 @@ extern int sparc_mode_class[];
 /* Register which holds offset table for position-independent
    data references.  */
 
-#define PIC_OFFSET_TABLE_REGNUM 23
+#define PIC_OFFSET_TABLE_REGNUM (flag_pic ? 23 : INVALID_REGNUM)
 
 /* Pick a default value we can notice from override_options:
    !v9: Default is on.