From 4a88caf21a0a85129f6c985ca13ba3eb54ff5366 Mon Sep 17 00:00:00 2001 From: Richard Biener Date: Tue, 19 May 2020 07:58:33 +0200 Subject: [PATCH] c/95141 - fix bogus integer overflow warning This fixes an integer overflow warning that ultimatively happens because of TREE_OVERFLOW propagating through transforms and the existing guard against this, 375 if (TREE_OVERFLOW_P (ret) 376 && !TREE_OVERFLOW_P (op0) 377 && !TREE_OVERFLOW_P (op1)) 378 overflow_warning (EXPR_LOC_OR_LOC (expr, input_location, being insufficient. Rather than trying to use sth like walk_tree to exhaustively walk operands (with the possibility of introducing quadraticness when folding larger expressions recursively) the following amends the above with an ad-hoc test for a binary op0 with a possibly constant op1. 2020-05-30 Richard Biener PR c/95141 gcc/c * c-fold.c (c_fully_fold_internal): Enhance guard on overflow_warning. gcc/testsuite * gcc.dg/pr95141.c: New testcase. --- gcc/ChangeLog | 6 ++++++ gcc/c/c-fold.c | 1 + gcc/testsuite/ChangeLog | 5 +++++ gcc/testsuite/gcc.dg/pr95141.c | 8 ++++++++ 4 files changed, 20 insertions(+) create mode 100644 gcc/testsuite/gcc.dg/pr95141.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index fdaa94ae8b9..3133b3c4ef1 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2020-05-30 Richard Biener + + PR c/95141 + * c-fold.c (c_fully_fold_internal): Enhance guard on + overflow_warning. + 2020-05-20 Kito Cheng PR target/90811 diff --git a/gcc/c/c-fold.c b/gcc/c/c-fold.c index 63becfeaf2c..bd21d247051 100644 --- a/gcc/c/c-fold.c +++ b/gcc/c/c-fold.c @@ -374,6 +374,7 @@ c_fully_fold_internal (tree expr, bool in_init, bool *maybe_const_operands, ret = fold (expr); if (TREE_OVERFLOW_P (ret) && !TREE_OVERFLOW_P (op0) + && !(BINARY_CLASS_P (op0) && TREE_OVERFLOW_P (TREE_OPERAND (op0, 1))) && !TREE_OVERFLOW_P (op1)) overflow_warning (EXPR_LOC_OR_LOC (expr, input_location), ret, expr); if (code == LSHIFT_EXPR diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 48671f1105a..401025718ee 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2020-05-30 Richard Biener + + PR c/95141 + * gcc.dg/pr95141.c: New testcase. + 2020-05-19 Alex Coplan PR target/94591 diff --git a/gcc/testsuite/gcc.dg/pr95141.c b/gcc/testsuite/gcc.dg/pr95141.c new file mode 100644 index 00000000000..b6cbba2f908 --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr95141.c @@ -0,0 +1,8 @@ +/* { dg-do compile } */ + +#include + +uint64_t test(uint8_t IA1) +{ + return (uint8_t)(IA1 & 158) & 1UL; /* { dg-bogus "integer overflow" } */ +} -- 2.30.2