On Tue, 19 May 2020, Joseph Myers wrote: > On Tue, 19 May 2020, Richard Biener wrote: > > > 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. > > > > Bootstrapped and tested on x86_64-unknown-linux-gnu, OK? > > OK. > > The test in bug 32643 looks vaguely similar, but that's an older > regression, do I take it this patch doesn't help with that one?
Yes, it doesn't help with that older bug. That is, it does not change in any way where we set TREE_OVERFLOW, it just avoids emitting an overflow warning in the above spot when overflow was already present on original operands and thus likely(!) propagated to the result. Pushed. Richard.
