From 4e62a0175be3a34d66a8b395589897f0d2f53f46 Mon Sep 17 00:00:00 2001 From: Richard Guenther Date: Thu, 21 Jan 2010 12:15:40 +0000 Subject: [PATCH] re PR middle-end/19988 (pessimizes fp multiply-add/subtract combo) 2010-01-21 Richard Guenther PR middle-end/19988 * fold-const.c (negate_expr_p): Pretend only negative real constants are easily negatable. * gcc.dg/pr19988.c: New testcase. From-SVN: r156152 --- gcc/ChangeLog | 6 ++++++ gcc/fold-const.c | 6 +++++- gcc/testsuite/ChangeLog | 5 +++++ gcc/testsuite/gcc.dg/pr19988.c | 14 ++++++++++++++ 4 files changed, 30 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/gcc.dg/pr19988.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 90061ec7f5a..207d68088d3 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2010-01-21 Richard Guenther + + PR middle-end/19988 + * fold-const.c (negate_expr_p): Pretend only negative + real constants are easily negatable. + 2010-01-20 Janis Johnson Jason Merrill diff --git a/gcc/fold-const.c b/gcc/fold-const.c index 9d249cc3b2f..e7a4b8c8f49 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -1129,10 +1129,14 @@ negate_expr_p (tree t) && TYPE_OVERFLOW_WRAPS (type)); case FIXED_CST: - case REAL_CST: case NEGATE_EXPR: return true; + case REAL_CST: + /* We want to canonicalize to positive real constants. Pretend + that only negative ones can be easily negated. */ + return REAL_VALUE_NEGATIVE (TREE_REAL_CST (t)); + case COMPLEX_CST: return negate_expr_p (TREE_REALPART (t)) && negate_expr_p (TREE_IMAGPART (t)); diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 9c89203d503..2bfa419d803 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2010-01-21 Richard Guenther + + PR middle-end/19988 + * gcc.dg/pr19988.c: New testcase. + 2010-01-20 Janis Johnson * g++.dg/compat/decimal/compat-common.h: New file. diff --git a/gcc/testsuite/gcc.dg/pr19988.c b/gcc/testsuite/gcc.dg/pr19988.c new file mode 100644 index 00000000000..aa2fed13961 --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr19988.c @@ -0,0 +1,14 @@ +/* { dg-do compile } */ +/* { dg-options "-O -fdump-tree-optimized -fdump-tree-original" } */ + +double foo(double x, double y) +{ + return ((x + 0.1234 * y) * (x - 0.1234 * y)); +} + +/* Keep positive constants during folding. */ +/* { dg-final { scan-tree-dump-times " 1.23" 2 "original" } } */ +/* CSE one multiplication. */ +/* { dg-final { scan-tree-dump-times " \\\* " 2 "optimized" } } */ +/* { dg-final { cleanup-tree-dump "original" } } */ +/* { dg-final { cleanup-tree-dump "optimized" } } */ -- 2.30.2