https://gcc.gnu.org/g:c4d53bc3c96770438d63a0d35a638beabad67c65
commit r16-7323-gc4d53bc3c96770438d63a0d35a638beabad67c65 Author: Richard Earnshaw <[email protected]> Date: Wed Feb 4 14:14:37 2026 +0000 compare-elim: arm: enable compare-elimination on Arm [PR123604] The Arm port has never had the compare elimination pass enabled by adding a definition of TARGET_FLAGS_REGNUM. But just adding this is insufficient because the target uses COND_EXEC and compare-elim is not yet set up to handle this. This seems to be quite simple, since we just need to recognize COND_EXEC in insns when scanning for uses of the condition code register. This is a partial mitigation for the code quality regression reported in PR target/123604. gcc/ChangeLog: PR target/123604 * compare-elim.cc (find_flags_uses_in_insn): Handle COND_EXEC. * config/arm/arm.cc (TARGET_FLAGS_REGNUM): Define. Diff: --- gcc/compare-elim.cc | 2 ++ gcc/config/arm/arm.cc | 3 +++ 2 files changed, 5 insertions(+) diff --git a/gcc/compare-elim.cc b/gcc/compare-elim.cc index 006d4e35efcd..723f9e31c791 100644 --- a/gcc/compare-elim.cc +++ b/gcc/compare-elim.cc @@ -258,6 +258,8 @@ find_flags_uses_in_insn (struct comparison *cmp, rtx_insn *insn) x = SET_SRC (x); if (GET_CODE (x) == IF_THEN_ELSE) x = XEXP (x, 0); + if (GET_CODE (x) == COND_EXEC) + x = COND_EXEC_TEST (x); if (COMPARISON_P (x) && loc == &XEXP (x, 0) && XEXP (x, 1) == const0_rtx) diff --git a/gcc/config/arm/arm.cc b/gcc/config/arm/arm.cc index 0a1f6612d07f..ff3400ae0353 100644 --- a/gcc/config/arm/arm.cc +++ b/gcc/config/arm/arm.cc @@ -839,6 +839,9 @@ static const scoped_attribute_specs *const arm_attribute_table[] = #undef TARGET_VECTORIZE_GET_MASK_MODE #define TARGET_VECTORIZE_GET_MASK_MODE arm_get_mask_mode + +#undef TARGET_FLAGS_REGNUM +#define TARGET_FLAGS_REGNUM CC_REGNUM /* Obstack for minipool constant handling. */ static struct obstack minipool_obstack;
