reload1.c (emit_reload_insns): Pass the reload register for a non-spill output reload through forget_old_reloads_1.

gcc/
	* reload1.c (emit_reload_insns): Pass the reload register
	for a non-spill output reload through forget_old_reloads_1.

From-SVN: r121105

2 files changed, 22 insertions, 0 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index abd821f..b1946e8 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2007-01-24  Richard Sandiford  <richard@codesourcery.com>
+
+	* reload1.c (emit_reload_insns): Pass the reload register
+	for a non-spill output reload through forget_old_reloads_1.
+
 2007-01-23  Joseph Myers  <joseph@codesourcery.com>
 
 	* config/rs6000/rs6000-c.c (rs6000_cpu_cpp_builtins): Define
diff --git a/gcc/reload1.c b/gcc/reload1.c
index efa1a39..8f7c703 100644
--- a/gcc/reload1.c
+++ b/gcc/reload1.c
@@ -7561,6 +7561,23 @@ emit_reload_insns (struct insn_chain *chain)
 	  rtx out = ((rld[r].out && REG_P (rld[r].out))
 		     ? rld[r].out : rld[r].out_reg);
 	  int nregno = REGNO (out);
+
+	  /* REG_RTX is now set or clobbered by the main instruction.
+	     As the comment above explains, forget_old_reloads_1 only
+	     sees the original instruction, and there is no guarantee
+	     that the original instruction also clobbered REG_RTX.
+	     For example, if find_reloads sees that the input side of
+	     a matched operand pair dies in this instruction, it may
+	     use the input register as the reload register.
+
+	     Calling forget_old_reloads_1 is a waste of effort if
+	     REG_RTX is also the output register.
+
+	     If we know that REG_RTX holds the value of a pseudo
+	     register, the code after the call will record that fact.  */
+	  if (rld[r].reg_rtx && rld[r].reg_rtx != out)
+	    forget_old_reloads_1 (rld[r].reg_rtx, NULL_RTX, NULL);
+
 	  if (nregno >= FIRST_PSEUDO_REGISTER)
 	    {
 	      rtx src_reg, store_insn = NULL_RTX;