From: segher <segher@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Tue, 24 Nov 2015 06:43:20 +0000 (+0000)
Subject: combine: Handle aborts in is_parallel_of_n_reg_sets (PR68381)
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=af7e839751f225946ccf763122868852656ea7e3;p=thirdparty%2Fgcc.git

combine: Handle aborts in is_parallel_of_n_reg_sets (PR68381)

Some users of is_parallel_of_n_reg_sets disregard the clobbers in a
parallel after it has returned "yes, this is a parallel of N sets and
maybe some clobbers".  But combine uses a clobber of const0_rtx to
indicate substitution failure, so this leads to disaster.

Fix this by checking for such special clobbers in is_parallel_of_n_reg_sets.


	PR rtl-optimization/68381
	* combine.c (is_parallel_of_n_reg_sets): Return false if the pattern
	is poisoned.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@230786 138bc75d-0d04-0410-961f-82ee72b054a4
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index e770638354df..b3538c487351 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2015-11-24  Segher Boessenkool  <segher@kernel.crashing.org>
+
+	PR rtl-optimization/68381
+	* combine.c (is_parallel_of_n_reg_sets): Return false if the pattern
+	is poisoned.
+
 2015-11-23  Nick Clifton  <nickc@redhat.com>
 	    Jeff Law  <law@redhat.com>
 
diff --git a/gcc/combine.c b/gcc/combine.c
index 2a66fd5c8bdf..4958d3bfc636 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -2512,7 +2512,8 @@ is_parallel_of_n_reg_sets (rtx pat, int n)
 	|| !REG_P (SET_DEST (XVECEXP (pat, 0, i))))
       return false;
   for ( ; i < len; i++)
-    if (GET_CODE (XVECEXP (pat, 0, i)) != CLOBBER)
+    if (GET_CODE (XVECEXP (pat, 0, i)) != CLOBBER
+	|| XEXP (XVECEXP (pat, 0, i), 0) == const0_rtx)
       return false;
 
   return true;