[PATCH v1 0/1] arm: avoid unmatched insn in movhfcc [PR118460]

[Richard Earnshaw via Sourceware Forge]

Hi gcc-patches mailing list,
Richard Earnshaw <rearnsha@gcc.gnu.org> has requested that the following forgejo pull request
be published on the mailing list.

Created on: 2025-10-14 16:12:24+00:00
Latest update: 2025-10-14 16:17:40+00:00
Changes: 3 changed files, 22 additions, 3 deletions
Head revision: rearnsha/gcc-TEST ref hf-vsel-bug commit 714c43c62453f444d295ad3424ad48070dedb265
Base revision: gcc/gcc-TEST ref trunk commit 599d2902b0afd56485b56752a75b0f7a3b090c76 r16-4418-g599d2902b0afd5
Merge base: 599d2902b0afd56485b56752a75b0f7a3b090c76
Full diff url: https://forge.sourceware.org/gcc/gcc-TEST/pulls/100.diff
Discussion:  https://forge.sourceware.org/gcc/gcc-TEST/pulls/100
Requested Reviewers:

When compiling for m-profile with the floating-point extension we have
a vsel instruction that takes a limited set of comparisons.  In most
cases we can use this with careful selection of the operand order, but
we need to expand things in the right way.  This patch is in two parts:

1) We validate that the expansion will produce correct RTL;
2) We canonicalize the comparison to increase the chances that the
above check will pass.

gcc:

	PR target/118460
	* config/arm/arm.cc (arm_canonicalize_comparison): For floating-
	point comparisons, swap the operand order if that will be more
	likely to produce a comparison that can be used with VSEL.
	(arm_validize_comparison): Make sure that HFmode comparisons
	are compatible with VSEL.

gcc/testsuite:

	PR target/118460
	* gcc.target/arm/armv8_2-fp16-move-1.c: Adjust expected output.
	* gcc.target/arm/armv8_2-fp16-move-2.c: Likewise.

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Changed files:
- M: gcc/config/arm/arm.cc
- M: gcc/testsuite/gcc.target/arm/armv8_2-fp16-move-1.c
- M: gcc/testsuite/gcc.target/arm/armv8_2-fp16-move-2.c


Richard Earnshaw (1):
  arm: avoid unmatched insn in movhfcc [PR118460]

 gcc/config/arm/arm.cc                         | 19 +++++++++++++++++++
 .../gcc.target/arm/armv8_2-fp16-move-1.c      |  4 ++--
 .../gcc.target/arm/armv8_2-fp16-move-2.c      |  2 +-
 3 files changed, 22 insertions(+), 3 deletions(-)

-- 
2.50.1