From: Richard Biener <rguenther@suse.de>
Date: Mon, 1 Dec 2014 13:13:28 +0000 (+0000)
Subject: re PR tree-optimization/15346 ([tree-ssa] combine two successive divisions)
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=c306cfafefeb6e7b224cff163222c02f8def25f1;p=gcc.git

re PR tree-optimization/15346 ([tree-ssa] combine two successive divisions)

2014-12-01  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/15346
	* Makefile.in (gimple-match.o-warn): Remove -Wno-unused-parameter,
	add -Wno-unused-but-set-variable.
	* match.pd: Combine two successive divisions.

	* gcc.dg/tree-ssa/forwprop-32.c: New testcase.

From-SVN: r218211
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index d6968653f4d..ae3b3c37bbd 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2014-12-01  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/15346
+	* Makefile.in (gimple-match.o-warn): Remove -Wno-unused-parameter,
+	add -Wno-unused-but-set-variable.
+	* match.pd: Combine two successive divisions.
+
 2014-12-01  Richard Biener  <rguenther@suse.de>
 
 	PR middle-end/64126
diff --git a/gcc/Makefile.in b/gcc/Makefile.in
index 49f94e751b3..d36b2f04fbc 100644
--- a/gcc/Makefile.in
+++ b/gcc/Makefile.in
@@ -209,8 +209,8 @@ gengtype-lex.o-warn = -Wno-error
 libgcov-util.o-warn = -Wno-error
 libgcov-driver-tool.o-warn = -Wno-error
 libgcov-merge-tool.o-warn = -Wno-error
-gimple-match.o-warn = -Wno-unused-variable -Wno-unused-parameter
-generic-match.o-warn = -Wno-unused-variable -Wno-unused-parameter
+gimple-match.o-warn = -Wno-unused-variable -Wno-unused-but-set-variable
+generic-match.o-warn = -Wno-unused-variable -Wno-unused-but-set-variable
 
 # All warnings have to be shut off in stage1 if the compiler used then
 # isn't gcc; configure determines that.  WARN_CFLAGS will be either
diff --git a/gcc/match.pd b/gcc/match.pd
index 42e7c62cc79..ee9bbc65faf 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -129,6 +129,19 @@ along with GCC; see the file COPYING3.  If not see
       && TYPE_UNSIGNED (type))
   (trunc_div @0 @1)))
 
+/* Combine two successive divisions.  */
+(for div (trunc_div ceil_div floor_div round_div exact_div)
+ (simplify
+  (div (div @0 INTEGER_CST@1) INTEGER_CST@2)
+  (with {
+    bool overflow_p;
+    wide_int mul = wi::mul (@1, @2, TYPE_SIGN (type), &overflow_p);
+   }
+   (if (!overflow_p)
+    (div @0 { wide_int_to_tree (type, mul); }))
+   (if (overflow_p)
+    { build_zero_cst (type); }))))
+
 /* Optimize A / A to 1.0 if we don't care about
    NaNs or Infinities.  */
 (simplify
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index cb8bef7d901..e56f3d9bc4c 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2014-12-01  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/15346
+	* gcc.dg/tree-ssa/forwprop-32.c: New testcase.
+
 2014-12-01  Yuri Rumyantsev  <ysrumyan@gmail.com>
 
 	PR tree-optimization/63941
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/forwprop-32.c b/gcc/testsuite/gcc.dg/tree-ssa/forwprop-32.c
new file mode 100644
index 00000000000..93851a1e152
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/forwprop-32.c
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-forwprop1 -fdump-tree-ccp1" } */
+
+int foo (int x)
+{
+  int tem = x / 3;
+  return tem / 5;
+}
+int bar (int x)
+{
+  int tem = x / 3;
+  return tem / (__INT_MAX__ / 2);
+}
+
+/* { dg-final { scan-tree-dump "x_.\\(D\\) / 15" "forwprop1" } } */
+/* { dg-final { scan-tree-dump "return 0;" "ccp1" } } */
+/* { dg-final { cleanup-tree-dump "forwprop1" } } */
+/* { dg-final { cleanup-tree-dump "ccp1" } } */