From 661c02e54ea72fb55205df0a717951ff28bb739e Mon Sep 17 00:00:00 2001 From: Andrew MacLeod Date: Tue, 23 Nov 2021 14:12:29 -0500 Subject: Check for equivalences between PHI argument and def. If a PHI argument on an edge is equivalent with the DEF, then it doesn't provide any new information, defer processing it unless they are all equivalences. PR tree-optimization/103359 gcc/ * gimple-range-fold.cc (fold_using_range::range_of_phi): If arg is equivalent to def, don't initially include it's range. gcc/testsuite/ * gcc.dg/pr103359.c: New. --- gcc/gimple-range-fold.cc | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'gcc/gimple-range-fold.cc') diff --git a/gcc/gimple-range-fold.cc b/gcc/gimple-range-fold.cc index ec9690b..d66ada5 100644 --- a/gcc/gimple-range-fold.cc +++ b/gcc/gimple-range-fold.cc @@ -771,6 +771,7 @@ fold_using_range::range_of_phi (irange &r, gphi *phi, fur_source &src) tree phi_def = gimple_phi_result (phi); tree type = gimple_range_type (phi); int_range_max arg_range; + int_range_max equiv_range; unsigned x; if (!type) @@ -794,6 +795,16 @@ fold_using_range::range_of_phi (irange &r, gphi *phi, fur_source &src) // Get the range of the argument on its edge. src.get_phi_operand (arg_range, arg, e); + // Likewise, if the incoming PHI argument is equivalent to this + // PHI definition, it provides no new info. Accumulate these ranges + // in case all arguments are equivalences. + if (src.query ()->query_relation (e, arg, phi_def, false) == EQ_EXPR) + { + single_arg = arg; + equiv_range.union_(arg_range); + continue; + } + if (!arg_range.undefined_p ()) { // Register potential dependencies for stale value tracking. @@ -816,6 +827,11 @@ fold_using_range::range_of_phi (irange &r, gphi *phi, fur_source &src) break; } + // If all arguments were equivalences, use the equivalence ranges as no + // arguments were processed. + if (!seen_arg) + r = equiv_range; + // If the PHI boils down to a single effective argument, look at it. if (single_arg) { -- cgit v1.1