From: Richard Biener Date: Tue, 19 May 2020 05:58:33 +0000 (+0200) Subject: c/95141 - fix bogus integer overflow warning X-Git-Tag: releases/gcc-10.2.0~163 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cc08609b62ed37d279c986ebb9cb8294eb4e0e3b;p=thirdparty%2Fgcc.git 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. --- diff --git a/gcc/c/c-fold.c b/gcc/c/c-fold.c index 63becfeaf2c1..bd21d2470511 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/gcc.dg/pr95141.c b/gcc/testsuite/gcc.dg/pr95141.c new file mode 100644 index 000000000000..b6cbba2f9087 --- /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" } */ +}