On 9/29/26 4:24 AM, Richard Biener wrote:
From: Gemini Reviewer <gemini@localhost>
When combining conditions ifcombine_ifandif passes inner_cond_code as the
first comparison and outer_cond_code as the second to
maybe_fold_and_comparisons and maybe_fold_and_comparisons calls
and_comparisons_1 with both comparison orders. Both defeats preserving
IEEE exceptions of trapping outer comparisons which combine_comparisons
handles, but only when the order of the comparisons is preserved correctly.
This disables some optimization in and_comparisons_1 which only looks
through SSA defs for the first comparison. This requires larger
refactoring and the overall design seems dubious with recursions
going in ways that with the swapping look exponential.
Bootstrapped and tested on x86_64-unknown-linux-gnu.
OK?
Thanks,
Richard.
PR tree-optimization/53805
* tree-ssa-ifcombine.cc (ifcombine_ifandif): Pass comparisons
in the correct order.
* gimple-fold.cc (and_comparisons_1): Add FIXME comment.
(maybe_fold_and_comparisons): Do not call and_comparisons_1 with
swapped comparisons.
* gcc.dg/tree-ssa/fp-trapping-cmp-6.c: New testcase
* gcc.dg/tree-ssa/fp-trapping-cmp-7.c: Likewise.
I kind of expected some fallout for the potential missed optimization
case, but I guess it never got covered.
OK for the trunk.
jeff
