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[PATCH, i386]: Commited: Disable x87 register passing for now.

Hello!

There is a problem exposed by the testcase from PR target/30120, where unused registers were not handled properly in reg-stack.c

The solution for this problem is, that all registers that currently hold values should be marked live at function entry.
However, there is a strange bug in reg-stack.c; for some reason stack handling code segfaults on this change.

As I consider this bug to be very dangerous, I have comitted the patch that (for now) disables x87 register passing functionality by setting X87_REGPARM_MAX to 0. Patch was bootstrapped on i686-pc-linux-gnu and regression tested for c, c++ and fortran.

2006-12-08 Uros Bizjak <ubizjak@gmail.com>

       PR target/30120
       * reg-stack.c (convert_regs_entry): Mark current argument passing
       registers as live.

       * config/i386/i386.h (X87_REGPARM_MAX): Set to 0 to disable passing
       of float arguments in x87 registers.


testsuite/ChangeLog:

2006-12-08 Uros Bizjak <ubizjak@gmail.com>

       * gcc.target/i386/x87regparm-1.c: XFAIL.
       * gcc.target/i386/x87regparm-2.c: XFAIL.
       * gcc.target/i386/x87regparm-3.c: XFAIL.
       * gcc.target/i386/x87regparm-4.c: XFAIL.

Uros. 
Index: testsuite/gcc.target/i386/x87regparm-2.c
===================================================================
--- testsuite/gcc.target/i386/x87regparm-2.c	(revision 119661)
+++ testsuite/gcc.target/i386/x87regparm-2.c	(working copy)
@@ -19,4 +19,4 @@
 
 /* Check that no memory is used to pass arguments.  */
 
-/* { dg-final { scan-assembler-not "\\(%esp\\)" } } */
+/* { dg-final { scan-assembler-not "\\(%esp\\)" { xfail *-*-* } } } */
Index: testsuite/gcc.target/i386/x87regparm-3.c
===================================================================
--- testsuite/gcc.target/i386/x87regparm-3.c	(revision 119661)
+++ testsuite/gcc.target/i386/x87regparm-3.c	(working copy)
@@ -19,4 +19,4 @@
 
 /* Check that float and double arguments are passed through memory.  */
 
-/* { dg-final { scan-assembler-times "\\(%esp\\)" 4 } } */
+/* { dg-final { scan-assembler-times "\\(%esp\\)" 4 { xfail *-*-* } } } */
Index: testsuite/gcc.target/i386/x87regparm-4.c
===================================================================
--- testsuite/gcc.target/i386/x87regparm-4.c	(revision 119661)
+++ testsuite/gcc.target/i386/x87regparm-4.c	(working copy)
@@ -19,4 +19,4 @@
 
 /* Check that no memory is used to pass arguments.  */
 
-/* { dg-final { scan-assembler-not "\\(%esp\\)" } } */
+/* { dg-final { scan-assembler-not "\\(%esp\\)" { xfail *-*-* } } } */
Index: testsuite/gcc.target/i386/x87regparm-1.c
===================================================================
--- testsuite/gcc.target/i386/x87regparm-1.c	(revision 119661)
+++ testsuite/gcc.target/i386/x87regparm-1.c	(working copy)
@@ -19,4 +19,4 @@
 
 /* Check that no memory is used to pass arguments.  */
 
-/* { dg-final { scan-assembler-not "\\(%esp\\)" } } */
+/* { dg-final { scan-assembler-not "\\(%esp\\)" { xfail *-*-* } } } */
Index: reg-stack.c
===================================================================
--- reg-stack.c	(revision 119661)
+++ reg-stack.c	(working copy)
@@ -2595,7 +2595,8 @@
       int reg, top = -1;
 
       for (reg = LAST_STACK_REG; reg >= FIRST_STACK_REG; --reg)
-	if (TEST_HARD_REG_BIT (bi->stack_in.reg_set, reg))
+	if (TEST_HARD_REG_BIT (bi->stack_in.reg_set, reg)
+	    || TEST_HARD_REG_BIT (incoming_regs, reg))
 	  {
 	    rtx init;
 
Index: config/i386/i386.h
===================================================================
--- config/i386/i386.h	(revision 119661)
+++ config/i386/i386.h	(working copy)
@@ -1778,7 +1778,9 @@
 
 #define REGPARM_MAX (TARGET_64BIT ? 6 : 3)
 
-#define X87_REGPARM_MAX 3
+/* ??? Currently disabled, as reg-stack.c does not know how to
+   rearrange input registers if some arguments are left unused.  */
+#define X87_REGPARM_MAX 0
 
 #define SSE_REGPARM_MAX (TARGET_64BIT ? 8 : (TARGET_SSE ? 3 : 0))
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