From: Segher Boessenkool <segher@kernel.crashing.org>
Date: Thu, 2 Oct 2014 02:18:01 +0000 (+0200)
Subject: re PR rtl-optimization/62151 (wrong code at -O2 and -O3 on x86_64-linux-gnu)
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=fef32cf89f7fe0c8864443dca942c6e34a204976;p=gcc.git

re PR rtl-optimization/62151 (wrong code at -O2 and -O3 on x86_64-linux-gnu)

2014-10-01  Segher Boessenkool  <segher@kernel.crashing.org>

gcc/
	PR rtl-optimization/62151
	* combine.c (can_combine_p): Allow the destination register of INSN
	to be clobbered in I3.
	(subst): Do not substitute into clobbers of registers.

gcc/testsuite/
	* gcc.dg/combine-clobber.c: New.

From-SVN: r215789
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 6a59825c064..aafbd2e0486 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2014-10-01  Segher Boessenkool  <segher@kernel.crashing.org>
+
+	PR rtl-optimization/62151
+	* combine.c (can_combine_p): Allow the destination register of INSN
+	to be clobbered in I3.
+	(subst): Do not substitute into clobbers of registers.
+
 2014-10-01  Jakub Jelinek  <jakub@redhat.com>
 
 	PR debug/63342
diff --git a/gcc/combine.c b/gcc/combine.c
index 1457eabadf9..ff5f0dbd509 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -1950,11 +1950,7 @@ can_combine_p (rtx_insn *insn, rtx_insn *i3, rtx_insn *pred ATTRIBUTE_UNUSED,
     for (i = XVECLEN (PATTERN (i3), 0) - 1; i >= 0; i--)
       if (GET_CODE (XVECEXP (PATTERN (i3), 0, i)) == CLOBBER)
 	{
-	  /* Don't substitute for a register intended as a clobberable
-	     operand.  */
 	  rtx reg = XEXP (XVECEXP (PATTERN (i3), 0, i), 0);
-	  if (rtx_equal_p (reg, dest))
-	    return 0;
 
 	  /* If the clobber represents an earlyclobber operand, we must not
 	     substitute an expression containing the clobbered register.
@@ -4963,6 +4959,11 @@ subst (rtx x, rtx from, rtx to, int in_dest, int in_cond, int unique_copy)
    || (REG_P (X) && REG_P (Y)	\
        && REGNO (X) == REGNO (Y) && GET_MODE (X) == GET_MODE (Y)))
 
+  /* Do not substitute into clobbers of regs -- this will never result in
+     valid RTL.  */
+  if (GET_CODE (x) == CLOBBER && REG_P (XEXP (x, 0)))
+    return x;
+
   if (! in_dest && COMBINE_RTX_EQUAL_P (x, from))
     {
       n_occurrences++;
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 9936e6192ec..0cf36a08329 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2014-10-01  Segher Boessenkool  <segher@kernel.crashing.org>
+
+	* gcc.dg/combine-clobber.c: New.
+
 2014-10-01  Jakub Jelinek  <jakub@redhat.com>
 
 	PR debug/63342