From: rguenth <rguenth@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Thu, 3 Aug 2017 14:08:15 +0000 (+0000)
Subject: 2017-08-03  Richard Biener  <rguenther@suse.de>
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=29a45e9306232eae17a79a9acf8d3867c4788d3a;p=thirdparty%2Fgcc.git

2017-08-03  Richard Biener  <rguenther@suse.de>

	* tree-ssa-reassoc.c (should_break_up_subtract): Also break
	up if the use is in USE - X.

	* gcc.dg/tree-ssa/reassoc-23.c: Adjust to fool early folding
	and CSE.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@250855 138bc75d-0d04-0410-961f-82ee72b054a4
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 9e3a8aac28d1..3febddcc051e 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2017-08-03  Richard Biener  <rguenther@suse.de>
+
+	* tree-ssa-reassoc.c (should_break_up_subtract): Also break
+	up if the use is in USE - X.
+
 2017-08-03 Alexander Monakov  <amonakov@ispras.ru>
 
 	* toplev.c (dumpfile.h): New include.
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 3613d165232a..03b66265855f 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2017-08-03  Richard Biener  <rguenther@suse.de>
+
+	* gcc.dg/tree-ssa/reassoc-23.c: Adjust to fool early folding
+	and CSE.
+
 2017-08-03 Richard Biener  <rguenther@suse.de>
 
 	PR middle-end/81148
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/reassoc-23.c b/gcc/testsuite/gcc.dg/tree-ssa/reassoc-23.c
index 0ab967d20abe..a5451ade6ef3 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/reassoc-23.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/reassoc-23.c
@@ -6,9 +6,10 @@ foo(unsigned int a, unsigned int b, unsigned int c, unsigned int d,
     unsigned int e, unsigned int f, unsigned int g, unsigned int h)
 {
   /* Should be transformed into e = 20 */
-  unsigned int i = (a + 9) + (c + 8);
-  unsigned int j = (-c + 1) + (-a + 2);
-
+  unsigned int i = (a + 9);
+  unsigned int j = (-c + 1);
+  i += (c + 8);
+  j += (-a + 2);
   e = i + j;
   return e;
 }
diff --git a/gcc/tree-ssa-reassoc.c b/gcc/tree-ssa-reassoc.c
index 6ecba809199c..561acea4dcc1 100644
--- a/gcc/tree-ssa-reassoc.c
+++ b/gcc/tree-ssa-reassoc.c
@@ -4729,7 +4729,9 @@ should_break_up_subtract (gimple *stmt)
       && (immusestmt = get_single_immediate_use (lhs))
       && is_gimple_assign (immusestmt)
       && (gimple_assign_rhs_code (immusestmt) == PLUS_EXPR
-	  ||  gimple_assign_rhs_code (immusestmt) == MULT_EXPR))
+	  || (gimple_assign_rhs_code (immusestmt) == MINUS_EXPR
+	      && gimple_assign_rhs1 (immusestmt) == lhs)
+	  || gimple_assign_rhs_code (immusestmt) == MULT_EXPR))
     return true;
   return false;
 }