[backport gcc-4.8/trunk r196612, adjusted for cleanup_auto_inc_dec being
 in combine.c not valtrack.c <mikpe@it.uu.se>]

Date: Mon, 11 Mar 2013 19:06:13 +0100
From: Jan Hubicka <hubicka at ucw dot cz>
Subject: Fix sharing of clobbers
List-Archive: <http://gcc.gnu.org/ml/gcc-patches/>

Hi,
in the testcase we die in post-reload cprop because updating one insn clobber
actually affect other insn clobber.  I actually introduced clobber sharing back
in 2005 to save memory for (clobber cc0).  This broke with introduction of post-reload
code copying that is now done by shrink wrapping.

Fixed by unsharing those clobbers that originate from pseudos.
Bootstrapped/regtested x86_64-linux, OK?

gcc/

2013-03-11  Jan Hubicka  <jh@suse.cz>

	PR middle-end/56571
	* valtrack.c (cleanup_auto_inc_dec): Unshare clobbers originating
	from pseudos.
	* emit-rtl.c (verify_rtx_sharing): Likewise.
	(copy_insn_1): Likewise.
	* rtl.c (copy_rtx): Likewise.

gcc/testsuite/

2013-03-11  Jan Hubicka  <jh@suse.cz>

	PR middle-end/56571
	* gcc.c-torture/compile/pr56571.c: New testcase.

--- gcc-4.7.2/gcc/combine.c.~1~	2012-08-09 17:33:28.000000000 +0200
+++ gcc-4.7.2/gcc/combine.c	2013-03-15 08:53:38.519178243 +0100
@@ -2387,7 +2387,11 @@ cleanup_auto_inc_dec (rtx src, enum mach
       /* SCRATCH must be shared because they represent distinct values.  */
       return x;
     case CLOBBER:
-      if (REG_P (XEXP (x, 0)) && REGNO (XEXP (x, 0)) < FIRST_PSEUDO_REGISTER)
+      /* Share clobbers of hard registers (like cc0), but do not share pseudo reg
+         clobbers or clobbers of hard registers that originated as pseudos.
+         This is needed to allow safe register renaming.  */
+      if (REG_P (XEXP (x, 0)) && REGNO (XEXP (x, 0)) < FIRST_PSEUDO_REGISTER
+	  && ORIGINAL_REGNO (XEXP (x, 0)) == REGNO (XEXP (x, 0)))
 	return x;
       break;
 
--- gcc-4.7.2/gcc/emit-rtl.c.~1~	2012-02-22 11:37:03.000000000 +0100
+++ gcc-4.7.2/gcc/emit-rtl.c	2013-03-15 08:53:38.529178204 +0100
@@ -2524,10 +2524,14 @@ verify_rtx_sharing (rtx orig, rtx insn)
     case RETURN:
     case SIMPLE_RETURN:
     case SCRATCH:
-      return;
       /* SCRATCH must be shared because they represent distinct values.  */
+      return;
     case CLOBBER:
-      if (REG_P (XEXP (x, 0)) && REGNO (XEXP (x, 0)) < FIRST_PSEUDO_REGISTER)
+      /* Share clobbers of hard registers (like cc0), but do not share pseudo reg
+         clobbers or clobbers of hard registers that originated as pseudos.
+         This is needed to allow safe register renaming.  */
+      if (REG_P (XEXP (x, 0)) && REGNO (XEXP (x, 0)) < FIRST_PSEUDO_REGISTER
+	  && ORIGINAL_REGNO (XEXP (x, 0)) == REGNO (XEXP (x, 0)))
 	return;
       break;
 
@@ -2744,7 +2748,11 @@ repeat:
       /* SCRATCH must be shared because they represent distinct values.  */
       return;
     case CLOBBER:
-      if (REG_P (XEXP (x, 0)) && REGNO (XEXP (x, 0)) < FIRST_PSEUDO_REGISTER)
+      /* Share clobbers of hard registers (like cc0), but do not share pseudo reg
+         clobbers or clobbers of hard registers that originated as pseudos.
+         This is needed to allow safe register renaming.  */
+      if (REG_P (XEXP (x, 0)) && REGNO (XEXP (x, 0)) < FIRST_PSEUDO_REGISTER
+	  && ORIGINAL_REGNO (XEXP (x, 0)) == REGNO (XEXP (x, 0)))
 	return;
       break;
 
@@ -5281,7 +5289,11 @@ copy_insn_1 (rtx orig)
     case SIMPLE_RETURN:
       return orig;
     case CLOBBER:
-      if (REG_P (XEXP (orig, 0)) && REGNO (XEXP (orig, 0)) < FIRST_PSEUDO_REGISTER)
+      /* Share clobbers of hard registers (like cc0), but do not share pseudo reg
+         clobbers or clobbers of hard registers that originated as pseudos.
+         This is needed to allow safe register renaming.  */
+      if (REG_P (XEXP (orig, 0)) && REGNO (XEXP (orig, 0)) < FIRST_PSEUDO_REGISTER
+	  && ORIGINAL_REGNO (XEXP (orig, 0)) == REGNO (XEXP (orig, 0)))
 	return orig;
       break;
 
--- gcc-4.7.2/gcc/rtl.c.~1~	2011-09-13 01:38:21.000000000 +0200
+++ gcc-4.7.2/gcc/rtl.c	2013-03-15 08:53:38.529178204 +0100
@@ -261,7 +261,11 @@ copy_rtx (rtx orig)
       /* SCRATCH must be shared because they represent distinct values.  */
       return orig;
     case CLOBBER:
-      if (REG_P (XEXP (orig, 0)) && REGNO (XEXP (orig, 0)) < FIRST_PSEUDO_REGISTER)
+      /* Share clobbers of hard registers (like cc0), but do not share pseudo reg
+         clobbers or clobbers of hard registers that originated as pseudos.
+         This is needed to allow safe register renaming.  */
+      if (REG_P (XEXP (orig, 0)) && REGNO (XEXP (orig, 0)) < FIRST_PSEUDO_REGISTER
+	  && ORIGINAL_REGNO (XEXP (orig, 0)) == REGNO (XEXP (orig, 0)))
 	return orig;
       break;
 
--- gcc-4.7.2/gcc/testsuite/gcc.c-torture/compile/pr56571.c.~1~	1970-01-01 01:00:00.000000000 +0100
+++ gcc-4.7.2/gcc/testsuite/gcc.c-torture/compile/pr56571.c	2013-03-15 08:53:38.519178243 +0100
@@ -0,0 +1,8 @@
+/* { dg-options "-funroll-loops -ftracer" } */
+int a, b;
+
+int f(void)
+{
+    (a % b) && f();
+    a = (0 || a | (a ? : 1));
+}