From 04b63ffef6183790951984b4899379ac76e890b1 Mon Sep 17 00:00:00 2001 From: rguenth Date: Wed, 1 Apr 2009 13:59:53 +0000 Subject: [PATCH] 2009-04-01 Richard Guenther * fold-const.c (fold_plusminus_mult_expr): Do not fold i * 4 + 2 to (i * 2 + 1) * 2. * gcc.dg/fold-plusmult-2.c: New testcase. git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@145403 138bc75d-0d04-0410-961f-82ee72b054a4 --- gcc/ChangeLog | 5 +++++ gcc/fold-const.c | 6 +++++- gcc/testsuite/ChangeLog | 4 ++++ gcc/testsuite/gcc.dg/fold-plusmult-2.c | 20 ++++++++++++++++++++ 4 files changed, 34 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/gcc.dg/fold-plusmult-2.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 54cad4cddc0e..f4b1e568f5a0 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +2009-04-01 Richard Guenther + + * fold-const.c (fold_plusminus_mult_expr): Do not fold + i * 4 + 2 to (i * 2 + 1) * 2. + 2009-04-01 Jakub Jelinek PR c/37772 diff --git a/gcc/fold-const.c b/gcc/fold-const.c index ec0695414124..9c1a46322b08 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -7466,7 +7466,11 @@ fold_plusminus_mult_expr (enum tree_code code, tree type, tree arg0, tree arg1) else maybe_same = arg11; - if (exact_log2 (abs (int11)) > 0 && int01 % int11 == 0) + if (exact_log2 (abs (int11)) > 0 && int01 % int11 == 0 + /* The remainder should not be a constant, otherwise we + end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has + increased the number of multiplications necessary. */ + && TREE_CODE (arg10) != INTEGER_CST) { alt0 = fold_build2 (MULT_EXPR, TREE_TYPE (arg00), arg00, build_int_cst (TREE_TYPE (arg00), diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 5aef381d4573..5462bead4bd3 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,7 @@ +2009-04-01 Richard Guenther + + * gcc.dg/fold-plusmult-2.c: New testcase. + 2009-04-01 Jakub Jelinek PR c/37772 diff --git a/gcc/testsuite/gcc.dg/fold-plusmult-2.c b/gcc/testsuite/gcc.dg/fold-plusmult-2.c new file mode 100644 index 000000000000..fd5376220a5e --- /dev/null +++ b/gcc/testsuite/gcc.dg/fold-plusmult-2.c @@ -0,0 +1,20 @@ +/* { dg-do compile } */ +/* { dg-options "-fdump-tree-original" } */ + +int foo (int i) +{ + return 2 + i * 4; +} + +/* We do _not_ want the above to be canonicalized to (i * 2 + 1) * 2. */ + +int bar (int i) +{ + return 4 + i * 2; +} + +/* But eventually this to be canonicalized to (i + 2) * 2. */ + +/* { dg-final { scan-tree-dump "i \\\* 4 \\\+ 2" "original" } } */ +/* { dg-final { scan-tree-dump "\\\(i \\\+ 2\\\) \\\* 2" "original" } } */ +/* { dg-final { cleanup-tree-dump "original" } } */ -- 2.47.2