From: Richard Biener <rguenther@suse.de>
Date: Fri, 20 Apr 2018 10:31:23 +0000 (+0000)
Subject: re PR tree-optimization/85475 (Compile time hog w/ -O1 -fpeel-loops)
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=b46ebc6c45d7a74ec18a0644f8b4e3c66ea84fb8;p=gcc.git

re PR tree-optimization/85475 (Compile time hog w/ -O1 -fpeel-loops)

2018-04-20  Richard Biener <rguenther@suse.de>

	PR middle-end/85475
	* match.pd ((X * CST) * Y -> (X * Y) * CST): Avoid exponential
	complexity by forcing a single use of the multiply operand.

	* gcc.dg/torture/pr85475.c: New testcase.

From-SVN: r259519
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index e06c6bc76cd..6309170f0b9 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2018-04-20  Richard Biener <rguenther@suse.de>
+
+	PR middle-end/85475
+	* match.pd ((X * CST) * Y -> (X * Y) * CST): Avoid exponential
+	complexity by forcing a single use of the multiply operand.
+
 2018-04-20  Martin Jambor  <mjambor@suse.cz>
 
 	ipa/85449
diff --git a/gcc/match.pd b/gcc/match.pd
index 442aad15e2c..0de4432d925 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -2578,8 +2578,9 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
 /* Reassociate (X * CST) * Y to (X * Y) * CST.  This does not introduce
    signed overflow for CST != 0 && CST != -1.  */
 (simplify
- (mult:c (mult:s @0 INTEGER_CST@1) @2)
+ (mult:c (mult:s@3 @0 INTEGER_CST@1) @2)
  (if (TREE_CODE (@2) != INTEGER_CST
+      && single_use (@3)
       && !integer_zerop (@1) && !integer_minus_onep (@1))
   (mult (mult @0 @2) @1)))
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 4e66877a9b1..dc5f7e766a5 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2018-04-20  Richard Biener <rguenther@suse.de>
+
+	PR middle-end/85475
+	* gcc.dg/torture/pr85475.c: New testcase.
+
 2018-04-20  Martin Jambor  <mjambor@suse.cz>
 
 	ipa/85449
diff --git a/gcc/testsuite/gcc.dg/torture/pr85475.c b/gcc/testsuite/gcc.dg/torture/pr85475.c
new file mode 100644
index 00000000000..0d475df3bc6
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr85475.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-fpeel-loops" } */
+
+int
+nj (int le)
+{
+  int zb;
+
+  for (zb = 0; zb < 16; ++zb)
+    le += le;
+
+  return le * le;
+}