diff options
| -rw-r--r-- | gcc/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/fold-const.c | 6 | ||||
| -rw-r--r-- | gcc/testsuite/ChangeLog | 4 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.dg/fold-plusmult-2.c | 20 |
4 files changed, 34 insertions, 1 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 54cad4cd..f4b1e56 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +2009-04-01 Richard Guenther <rguenther@suse.de> + + * fold-const.c (fold_plusminus_mult_expr): Do not fold + i * 4 + 2 to (i * 2 + 1) * 2. + 2009-04-01 Jakub Jelinek <jakub@redhat.com> PR c/37772 diff --git a/gcc/fold-const.c b/gcc/fold-const.c index ec06954..9c1a463 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 5aef381..5462bea 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,7 @@ +2009-04-01 Richard Guenther <rguenther@suse.de> + + * gcc.dg/fold-plusmult-2.c: New testcase. + 2009-04-01 Jakub Jelinek <jakub@redhat.com> 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 0000000..fd53762 --- /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" } } */ |