From 684f84dea9cb2acf6c61bf461a9d50f6b7c03eca Mon Sep 17 00:00:00 2001 From: Marek Polacek Date: Tue, 9 May 2017 11:21:14 +0000 Subject: [PATCH] re PR c/80525 (-Wlogical-op confused by undefined integer overflow) PR c/80525 * c-warn.c (unwrap_c_maybe_const): New. (warn_logical_operator): Call it. * c-c++-common/Wlogical-op-1.c: Don't use -fwrapv anymore. * c-c++-common/Wlogical-op-2.c: New test. From-SVN: r247786 --- gcc/c-family/ChangeLog | 6 ++++++ gcc/c-family/c-warn.c | 24 ++++++++++++++++++---- gcc/testsuite/ChangeLog | 6 ++++++ gcc/testsuite/c-c++-common/Wlogical-op-1.c | 4 +--- gcc/testsuite/c-c++-common/Wlogical-op-2.c | 12 +++++++++++ 5 files changed, 45 insertions(+), 7 deletions(-) create mode 100644 gcc/testsuite/c-c++-common/Wlogical-op-2.c diff --git a/gcc/c-family/ChangeLog b/gcc/c-family/ChangeLog index 6409442060b..e76a6289cc4 100644 --- a/gcc/c-family/ChangeLog +++ b/gcc/c-family/ChangeLog @@ -1,3 +1,9 @@ +2017-05-09 Marek Polacek + + PR c/80525 + * c-warn.c (unwrap_c_maybe_const): New. + (warn_logical_operator): Call it. + 2017-05-09 Nathan Sidwell * c-common.c (c_register_builtin_type): Use pushdecl lang_hook. diff --git a/gcc/c-family/c-warn.c b/gcc/c-family/c-warn.c index 45dd583111e..aa0cfa97b04 100644 --- a/gcc/c-family/c-warn.c +++ b/gcc/c-family/c-warn.c @@ -30,6 +30,7 @@ along with GCC; see the file COPYING3. If not see #include "intl.h" #include "asan.h" #include "gcc-rich-location.h" +#include "gimplify.h" /* Print a warning if a constant expression had overflow in folding. Invoke this function on every expression that the language @@ -112,6 +113,21 @@ overflow_warning (location_t loc, tree value) } } +/* Helper function for walk_tree. Unwrap C_MAYBE_CONST_EXPRs in an expression + pointed to by TP. */ + +static tree +unwrap_c_maybe_const (tree *tp, int *walk_subtrees, void *) +{ + if (TREE_CODE (*tp) == C_MAYBE_CONST_EXPR) + { + *tp = C_MAYBE_CONST_EXPR_EXPR (*tp); + /* C_MAYBE_CONST_EXPRs don't nest. */ + *walk_subtrees = false; + } + return NULL_TREE; +} + /* Warn about uses of logical || / && operator in a context where it is likely that the bitwise equivalent was intended by the programmer. We have seen an expression in which CODE is a binary @@ -189,11 +205,11 @@ warn_logical_operator (location_t location, enum tree_code code, tree type, (with OR) or trivially false (with AND). If so, do not warn. This is a common idiom for testing ranges of data types in portable code. */ + op_left = unshare_expr (op_left); + walk_tree_without_duplicates (&op_left, unwrap_c_maybe_const, NULL); lhs = make_range (op_left, &in0_p, &low0, &high0, &strict_overflow_p); if (!lhs) return; - if (TREE_CODE (lhs) == C_MAYBE_CONST_EXPR) - lhs = C_MAYBE_CONST_EXPR_EXPR (lhs); /* If this is an OR operation, invert both sides; now, the result should be always false to get a warning. */ @@ -204,11 +220,11 @@ warn_logical_operator (location_t location, enum tree_code code, tree type, if (tem && integer_zerop (tem)) return; + op_right = unshare_expr (op_right); + walk_tree_without_duplicates (&op_right, unwrap_c_maybe_const, NULL); rhs = make_range (op_right, &in1_p, &low1, &high1, &strict_overflow_p); if (!rhs) return; - if (TREE_CODE (rhs) == C_MAYBE_CONST_EXPR) - rhs = C_MAYBE_CONST_EXPR_EXPR (rhs); /* If this is an OR operation, invert both sides; now, the result should be always false to get a warning. */ diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index af1e6deb648..98552a87fcd 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,9 @@ +2017-05-09 Marek Polacek + + PR c/80525 + * c-c++-common/Wlogical-op-1.c: Don't use -fwrapv anymore. + * c-c++-common/Wlogical-op-2.c: New test. + 2017-05-09 Senthil Kumar Selvaraj * gcc.dg/tree-ssa/cunroll-13.c: Use __INT32_TYPE__ for diff --git a/gcc/testsuite/c-c++-common/Wlogical-op-1.c b/gcc/testsuite/c-c++-common/Wlogical-op-1.c index e89a35a5e8f..c5f992a4007 100644 --- a/gcc/testsuite/c-c++-common/Wlogical-op-1.c +++ b/gcc/testsuite/c-c++-common/Wlogical-op-1.c @@ -1,8 +1,6 @@ /* PR c/63357 */ /* { dg-do compile } */ -/* For -fwrapv see PR80525, xfailing the subtest isn't possible as it passes - with the C++ FE which doesn't have maybe_const_expr. */ -/* { dg-options "-fwrapv -Wlogical-op" } */ +/* { dg-options "-Wlogical-op" } */ #ifndef __cplusplus # define bool _Bool diff --git a/gcc/testsuite/c-c++-common/Wlogical-op-2.c b/gcc/testsuite/c-c++-common/Wlogical-op-2.c new file mode 100644 index 00000000000..6360ef98090 --- /dev/null +++ b/gcc/testsuite/c-c++-common/Wlogical-op-2.c @@ -0,0 +1,12 @@ +/* PR c/80525 */ +/* { dg-do compile } */ +/* { dg-options "-Wlogical-op" } */ + +int +fn (int a, int b) +{ + if ((a + 1) && (a + 1)) /* { dg-warning "logical .and. of equal expressions" } */ + return a; + if ((a + 1) || (a + 1)) /* { dg-warning "logical .or. of equal expressions" } */ + return b; +} -- 2.30.2