https://gcc.gnu.org/g:992012439d28c56424189110e00321f257a31533
commit r16-9121-g992012439d28c56424189110e00321f257a31533 Author: Andrew Pinski <[email protected]> Date: Sat Jun 13 09:38:08 2026 -0700 phiopt: Fix is_factor_profitable for debug stmts [PR125776] This is a latent bug in is_factor_profitable where we would consider a debug statement as an use for lifetime usage afterwards. So you would get a compare debug failure in some cases. pr125776-2.c fails since r15-4503-g8d6d6d537fdc75. Pushed as obvious after a bootstrap/test. Note this is slightly modifed from the trunk version since the loop is slightly different. PR tree-optimization/125776 gcc/ChangeLog: * tree-ssa-phiopt.cc (is_factor_profitable): An usage in a debug stmt should be ignored. gcc/testsuite/ChangeLog: * gcc.dg/torture/pr125776-1.c: New test. * gcc.dg/torture/pr125776-2.c: New test. Signed-off-by: Andrew Pinski <[email protected]> (cherry picked from commit a4afea80fce5f1aafdd1174e48e9ebfc9ec8155d) Diff: --- gcc/testsuite/gcc.dg/torture/pr125776-1.c | 21 +++++++++++++++++++++ gcc/testsuite/gcc.dg/torture/pr125776-2.c | 21 +++++++++++++++++++++ gcc/tree-ssa-phiopt.cc | 2 ++ 3 files changed, 44 insertions(+) diff --git a/gcc/testsuite/gcc.dg/torture/pr125776-1.c b/gcc/testsuite/gcc.dg/torture/pr125776-1.c new file mode 100644 index 000000000000..58f143d203f5 --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/pr125776-1.c @@ -0,0 +1,21 @@ +/* { dg-do compile } */ +/* { dg-additional-options "-fcompare-debug" } */ +/* PR tree-optimization/125776 */ + +int a, b, d, e, f; +long c; +void g(); +void h() { + unsigned i; + for (;;) { + unsigned j = a ? a : d; + i += j; + f = b & 40 | b > 4; + e = a ? a : b; + if (e) + break; + if (j) + g(); + } + c = i; +} diff --git a/gcc/testsuite/gcc.dg/torture/pr125776-2.c b/gcc/testsuite/gcc.dg/torture/pr125776-2.c new file mode 100644 index 000000000000..6f89a5242ff7 --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/pr125776-2.c @@ -0,0 +1,21 @@ +/* { dg-do compile } */ +/* { dg-additional-options "-fcompare-debug" } */ +/* PR tree-optimization/125776 */ +int a, b, d, e, f; +long c; +void g(); +void h(int i) { + for (;;) { + i++; + int j = a ? a : d; + i = i > 0 ? i : -i; + f = b & 40 | b > 4; + e = a ? a : b; + if (e) + break; + if (j) + g(); + } + c = i; +} + diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc index 0bf7e58b8f03..ebbb5e2f1d8b 100644 --- a/gcc/tree-ssa-phiopt.cc +++ b/gcc/tree-ssa-phiopt.cc @@ -267,6 +267,8 @@ is_factor_profitable (gimple *def_stmt, basic_block merge, tree arg) FOR_EACH_IMM_USE_FAST (use_p, iter, arg) { gimple *use_stmt = USE_STMT (use_p); + if (is_gimple_debug (use_stmt)) + continue; basic_block use_bb = gimple_bb (use_stmt); if (dominated_by_p (CDI_DOMINATORS, merge, use_bb)) return true;
