From 1447bf0556ad0cb300aabd1b883fedee314b6fca Mon Sep 17 00:00:00 2001
From: Richard Guenther <rguenther@suse.de>
Date: Tue, 29 Apr 2008 15:59:43 +0000
Subject: [PATCH] re PR tree-optimization/15255 ([tree-ssa] a * 2 + a * 2 is
not converted to a * 4)
2008-04-29 Richard Guenther <rguenther@suse.de>
PR middle-end/15255
* fold-const.c (fold_binary): Fold (A + A) * C to A * 2*C.
* gcc.dg/fold-plusmult.c: New testcase.
From-SVN: r134798
---
gcc/ChangeLog | 5 +++++
gcc/fold-const.c | 11 +++++++++++
gcc/testsuite/ChangeLog | 5 +++++
gcc/testsuite/gcc.dg/fold-plusmult.c | 15 +++++++++++++++
4 files changed, 36 insertions(+)
create mode 100644 gcc/testsuite/gcc.dg/fold-plusmult.c
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index e261305f13f6..b5ae15e141bc 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2008-04-29 Richard Guenther <rguenther@suse.de>
+
+ PR middle-end/15255
+ * fold-const.c (fold_binary): Fold (A + A) * C to A * 2*C.
+
2008-04-29 Richard Guenther <rguenther@suse.de>
* tree-ssa-alias.c (finalize_ref_all_pointers): Remove.
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index aae203777289..b4645ca256e8 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -10154,6 +10154,17 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1)
return fold_build2 (LSHIFT_EXPR, type, op1,
TREE_OPERAND (arg0, 1));
+ /* (A + A) * C -> A * 2 * C */
+ if (TREE_CODE (arg0) == PLUS_EXPR
+ && TREE_CODE (arg1) == INTEGER_CST
+ && operand_equal_p (TREE_OPERAND (arg0, 0),
+ TREE_OPERAND (arg0, 1), 0))
+ return fold_build2 (MULT_EXPR, type,
+ omit_one_operand (type, TREE_OPERAND (arg0, 0),
+ TREE_OPERAND (arg0, 1)),
+ fold_build2 (MULT_EXPR, type,
+ build_int_cst (type, 2) , arg1));
+
strict_overflow_p = false;
if (TREE_CODE (arg1) == INTEGER_CST
&& 0 != (tem = extract_muldiv (op0, arg1, code, NULL_TREE,
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index f2b69e90afca..dd8b3aee01c2 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2008-04-29 Richard Guenther <rguenther@suse.de>
+
+ PR middle-end/15255
+ * gcc.dg/fold-plusmult.c: New testcase.
+
2008-04-29 Richard Guenther <rguenther@suse.de>
PR middle-end/36077
diff --git a/gcc/testsuite/gcc.dg/fold-plusmult.c b/gcc/testsuite/gcc.dg/fold-plusmult.c
new file mode 100644
index 000000000000..d584b9588746
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/fold-plusmult.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-fdump-tree-original" } */
+
+int test1 (int a)
+{
+ return 2*a + 2*a;
+}
+
+int test2 (int a)
+{
+ return (a + a)*2;
+}
+
+/* { dg-final { scan-tree-dump-times "<a> \\\* 4" 2 "original" } } */
+/* { dg-final { cleanup-tree-dump "original" } } */
--
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