[PATCH 0/2] x86: speedup local_irq_save() for clang

[Eric Dumazet <edumazet@google.com>]

clang generates poor code for local_irq_save() callers,
because of asm "=rm" output constraint being mishandled.

Frst patch adds ASM_OUTPUT_RM macro, extending ASM_INPUT_RM
that Linus added in linux-6.10. Suggested by Uros Bizjak.

Second patch uses it in local_irq_save(), to not penalize gcc
while forcing clang to generate better code especially
when CONFIG_STACKPROTECTOR_STRONG=y.

smap_save() could also use it, but is not in any fast path.

Eric Dumazet (2):
  clang: work around asm output constraint problems
  x86/irqflags: Use ASM_OUTPUT_RM in native_save_fl()

 arch/x86/include/asm/irqflags.h | 2 +-
 include/linux/compiler-clang.h  | 7 +++++++
 include/linux/compiler_types.h  | 6 +++++-
 3 files changed, 13 insertions(+), 2 deletions(-)

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2.52.0.322.g1dd061c0dc-goog