From 32894793ff96f4c56b90e0f0e1d961e526a6edc7 Mon Sep 17 00:00:00 2001 From: Richard Biener Date: Mon, 7 Nov 2016 12:25:09 +0000 Subject: [PATCH] re PR middle-end/78228 (fstrict-overflow breaks code without overflow?) 2016-11-07 Richard Biener PR tree-optimization/78228 * tree-ssa-phiopt.c (abs_replacement): Avoid introducing undefined behavior. * gcc.dg/tree-ssa/phi-opt-15.c: New testcase. From-SVN: r241899 --- gcc/ChangeLog | 6 ++++++ gcc/testsuite/ChangeLog | 5 +++++ gcc/testsuite/gcc.dg/tree-ssa/phi-opt-15.c | 12 ++++++++++++ gcc/tree-ssa-phiopt.c | 8 ++++++++ 4 files changed, 31 insertions(+) create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/phi-opt-15.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 1bc2934e5c0..262f0068b48 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2016-11-07 Richard Biener + + PR tree-optimization/78228 + * tree-ssa-phiopt.c (abs_replacement): Avoid introducing + undefined behavior. + 2016-11-07 Kyrylo Tkachov PR target/77822 diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 7094c885ab4..0dff659bda4 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2016-11-07 Richard Biener + + PR tree-optimization/78228 + * gcc.dg/tree-ssa/phi-opt-15.c: New testcase. + 2016-11-07 Kyrylo Tkachov PR target/77822 diff --git a/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-15.c b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-15.c new file mode 100644 index 00000000000..ac3018ef533 --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-15.c @@ -0,0 +1,12 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-optimized" } */ + +int +foo (int i) +{ + if (i > 0) + i = -i; + return i; +} + +/* { dg-final { scan-tree-dump-not "ABS" "optimized" } } */ diff --git a/gcc/tree-ssa-phiopt.c b/gcc/tree-ssa-phiopt.c index 3f3b88cfc61..63738d07e2e 100644 --- a/gcc/tree-ssa-phiopt.c +++ b/gcc/tree-ssa-phiopt.c @@ -1474,6 +1474,14 @@ abs_replacement (basic_block cond_bb, basic_block middle_bb, else negate = false; + /* If the code negates only iff positive then make sure to not + introduce undefined behavior when negating or computing the absolute. + ??? We could use range info if present to check for arg1 == INT_MIN. */ + if (negate + && (ANY_INTEGRAL_TYPE_P (TREE_TYPE (arg1)) + && ! TYPE_OVERFLOW_WRAPS (TREE_TYPE (arg1)))) + return false; + result = duplicate_ssa_name (result, NULL); if (negate) -- 2.30.2