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re PR rtl-optimization/34773 (miscompilation of vfprintf_r)

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PR rtl-optimization/34773
	* reg-notes.def (EQUAL): Mention significance of combination of
	REG_EQUAL and REG_RETVAL.
	* fwprop.c (try_fwprop_subst): Don't add REG_EQUAL to an
	insn that has a REG_RETVAL.

From-SVN: r132053
This commit is contained in:
Hans-Peter Nilsson 2008-02-01 21:28:46 +00:00 • committed by Hans-Peter Nilsson
parent 2449e8e5cd
commit 3e836a310d
3 changed files with 17 additions and 4 deletions
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8
gcc/ChangeLog
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@ -1,3 +1,11 @@
2008-02-01 Hans-Peter Nilsson <hp@axis.com>
PR rtl-optimization/34773
* reg-notes.def (EQUAL): Mention significance of combination of
REG_EQUAL and REG_RETVAL.
* fwprop.c (try_fwprop_subst): Don't add REG_EQUAL to an
insn that has a REG_RETVAL.
2008-02-01 Roger Sayle <roger@eyesopen.com>
PR bootstrap/33781

9
gcc/fwprop.c
View file

@ -729,9 +729,12 @@ try_fwprop_subst (struct df_ref *use, rtx *loc, rtx new, rtx def_insn, bool set_
{
cancel_changes (0);
/* Can also record a simplified value in a REG_EQUAL note, making a
new one if one does not already exist. */
if (set_reg_equal)
/* Can also record a simplified value in a REG_EQUAL note,
making a new one if one does not already exist.
Don't do this if the insn has a REG_RETVAL note, because the
combined presence means that the REG_EQUAL note refers to the
(full) contents of the libcall value. */
if (set_reg_equal && !find_reg_note (insn, REG_RETVAL, NULL_RTX))
{
if (dump_file)
fprintf (dump_file, " Setting REG_EQUAL note\n");

4
gcc/reg-notes.def
View file

@ -52,7 +52,9 @@ REG_NOTE (EQUIV)
/* Like REG_EQUIV except that the destination is only momentarily
equal to the specified rtx. Therefore, it cannot be used for
substitution; but it can be used for cse. */
substitution; but it can be used for cse. Together with a
REG_RETVAL note, it means that the insn sets the full contents of
the libcall value. */
REG_NOTE (EQUAL)
/* This insn copies the return-value of a library call out of the hard