match.pd: reassociate multiplications

	* match.pd ((X * CST) * Y): Reassociate to (X * Y) * CST.
testsuite/
	* gcc.dg/tree-ssa/assoc-2.c: New testcase.

From-SVN: r250523

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 242d89dfd4ff83700e984c702b49a2fce27e282b..654227cd55ddcc6ba4610500b1b2da4d82f2fbb5 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,4 +1,8 @@
-2017-07-07  Torsten Duwe  <duwe@suse.de>
+2017-07-25  Alexander Monakov  <amonakov@ispras.ru>
+
+       * match.pd ((X * CST) * Y): Reassociate to (X * Y) * CST.
+
+2017-07-25  Torsten Duwe  <duwe@suse.de>
 
        * common.opt: Introduce -fpatchable-function-entry
        command line option, and its variables function_entry_patch_area_size

diff --git a/gcc/match.pd b/gcc/match.pd
index 7f5807ce2f197d257cff515c3f783993b68eb143..39e1e5c8384f32e515064dbd4ec963d4d765e44f 100644 (file)
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -2213,6 +2213,14 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
  (mult @0 integer_minus_onep)
  (negate @0))
 
+/* 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)
+ (if (TREE_CODE (@2) != INTEGER_CST
+      && !integer_zerop (@1) && !integer_minus_onep (@1))
+  (mult (mult @0 @2) @1)))
+
 /* True if we can easily extract the real and imaginary parts of a complex
    number.  */
 (match compositional_complex

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index d8515ed3ed4b4e905e056e6791ee623aa832b104..a5c00b4e25ba068a8d5d635a3159f5d1dbfe1d54 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,4 +1,8 @@
-2017-07-07  Torsten Duwe  <duwe@suse.de>
+2017-07-25  Alexander Monakov  <amonakov@ispras.ru>
+
+       * gcc.dg/tree-ssa/assoc-2.c: New testcase.
+
+2017-07-25  Torsten Duwe  <duwe@suse.de>
 
        * c-c++-common/patchable_function_entry-default.c: New test.
        * c-c++-common/patchable_function_entry-decl.c: Likewise.

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/assoc-2.c b/gcc/testsuite/gcc.dg/tree-ssa/assoc-2.c
new file mode 100644 (file)
index 0000000..a92c882
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/assoc-2.c
@@ -0,0 +1,8 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-gimple-raw -fdump-tree-optimized-raw" } */
+
+int f0(int a, int b){
+  return a * 33 * b * 55;
+}
+
+/* { dg-final { scan-tree-dump-times "mult_expr" 2 "gimple" } } */