From 146b8692e33b78872476435d084d5062a243a200 Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Thu, 11 Apr 2013 09:30:20 +0200 Subject: [PATCH] re PR tree-optimization/56899 (Wrong constant folding) PR tree-optimization/56899 * fold-const.c (extract_muldiv_1): Apply distributive law only if TYPE_OVERFLOW_WRAPS (ctype). * gcc.c-torture/execute/pr56899.c: New test. From-SVN: r197692 --- gcc/ChangeLog | 6 +++ gcc/fold-const.c | 6 ++- gcc/testsuite/ChangeLog | 5 ++ gcc/testsuite/gcc.c-torture/execute/pr56899.c | 47 +++++++++++++++++++ 4 files changed, 62 insertions(+), 2 deletions(-) create mode 100644 gcc/testsuite/gcc.c-torture/execute/pr56899.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 7e1cc32176c..bab67ab7b01 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2013-04-11 Jakub Jelinek + + PR tree-optimization/56899 + * fold-const.c (extract_muldiv_1): Apply distributive law + only if TYPE_OVERFLOW_WRAPS (ctype). + 2013-04-11 Bin Cheng PR target/56124 diff --git a/gcc/fold-const.c b/gcc/fold-const.c index dcf7aa0d6a5..467b6d65619 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -5850,8 +5850,10 @@ extract_muldiv_1 (tree t, tree c, enum tree_code code, tree wide_type, /* The last case is if we are a multiply. In that case, we can apply the distributive law to commute the multiply and addition - if the multiplication of the constants doesn't overflow. */ - if (code == MULT_EXPR) + if the multiplication of the constants doesn't overflow + and overflow is defined. With undefined overflow + op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */ + if (code == MULT_EXPR && TYPE_OVERFLOW_WRAPS (ctype)) return fold_build2 (tcode, ctype, fold_build2 (code, ctype, fold_convert (ctype, op0), diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index ef84fe1a495..62557021bba 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2013-04-11 Jakub Jelinek + + PR tree-optimization/56899 + * gcc.c-torture/execute/pr56899.c: New test. + 2013-04-10 David S. Miller * gcc.target/sparc/setcc-4.c: New test. diff --git a/gcc/testsuite/gcc.c-torture/execute/pr56899.c b/gcc/testsuite/gcc.c-torture/execute/pr56899.c new file mode 100644 index 00000000000..9adf9af00ff --- /dev/null +++ b/gcc/testsuite/gcc.c-torture/execute/pr56899.c @@ -0,0 +1,47 @@ +/* PR tree-optimization/56899 */ + +#if __SIZEOF_INT__ == 4 && __CHAR_BIT__ == 8 +__attribute__((noinline, noclone)) void +f1 (int v) +{ + int x = -214748365 * (v - 1); + if (x != -1932735285) + __builtin_abort (); +} + +__attribute__((noinline, noclone)) void +f2 (int v) +{ + int x = 214748365 * (v + 1); + if (x != -1932735285) + __builtin_abort (); +} + +__attribute__((noinline, noclone)) void +f3 (unsigned int v) +{ + unsigned int x = -214748365U * (v - 1); + if (x != -1932735285U) + __builtin_abort (); +} + +__attribute__((noinline, noclone)) void +f4 (unsigned int v) +{ + unsigned int x = 214748365U * (v + 1); + if (x != -1932735285U) + __builtin_abort (); +} +#endif + +int +main () +{ +#if __SIZEOF_INT__ == 4 && __CHAR_BIT__ == 8 + f1 (10); + f2 (-10); + f3 (10); + f4 (-10U); +#endif + return 0; +} -- 2.30.2