On Wed, Jun 18, 2025 at 6:38 PM H.J. Lu <hjl.to...@gmail.com> wrote:
>
> commit ef26c151c14a87177d46fd3d725e7f82e040e89f
> Author: Roger Sayle <ro...@nextmovesoftware.com>
> Date: Thu Dec 23 12:33:07 2021 +0000
>
> x86: PR target/103773: Fix wrong-code with -Oz from pop to memory.
>
> added "*mov<mode>_and" and extended "*mov<mode>_or" to transform
> "mov $0,mem" to the shorter "and $0,mem" and "mov $-1,mem" to the shorter
> "or $-1,mem" for -Oz. But the new pattern:
>
> (define_insn "*mov<mode>_and"
> [(set (match_operand:SWI248 0 "memory_operand" "=m")
> (match_operand:SWI248 1 "const0_operand"))
> (clobber (reg:CC FLAGS_REG))]
> "reload_completed"
> "and{<imodesuffix>}\t{%1, %0|%0, %1}"
> [(set_attr "type" "alu1")
> (set_attr "mode" "<MODE>")
> (set_attr "length_immediate" "1")])
>
> and the extended pattern:
>
> (define_insn "*mov<mode>_or"
> [(set (match_operand:SWI248 0 "nonimmediate_operand" "=rm")
> (match_operand:SWI248 1 "constm1_operand"))
> (clobber (reg:CC FLAGS_REG))]
> "reload_completed"
> "or{<imodesuffix>}\t{%1, %0|%0, %1}"
> [(set_attr "type" "alu1")
> (set_attr "mode" "<MODE>")
> (set_attr "length_immediate" "1")])
>
> aren't guarded for -Oz. As a result, "and $0,mem" and "or $-1,mem" are
> generated without -Oz.
>
> 1. Change *mov<mode>_and" to define_insn_and_split and split it to
> "mov $0,mem" if not -Oz.
> 2. Change "*mov<mode>_or" to define_insn_and_split and split it to
> "mov $-1,mem" if not -Oz.
> 3. Don't transform "mov $-1,reg" to "push $-1; pop reg" for -Oz since it
> should be transformed to "or $-1,reg".
Ok for me, but please hold for a few days in case Uros or Roger has
any comments.
>
> gcc/
>
> PR target/120427
> * config/i386/i386.md (*mov<mode>_and): Changed to
> define_insn_and_split. Split it to "mov $0,mem" if not -Oz.
> (*mov<mode>_or): Changed to define_insn_and_split. Split it
> to "mov $-1,mem" if not -Oz.
> (peephole2): Don't transform "mov $-1,reg" to "push $-1; pop reg"
> for -Oz since it will be transformed to "or $-1,reg".
>
> gcc/testsuite/
>
> PR target/120427
> * gcc.target/i386/cold-attribute-4.c: Compile with -Oz.
> * gcc.target/i386/pr120427-1.c: New test.
> * gcc.target/i386/pr120427-2.c: Likewise.
> * gcc.target/i386/pr120427-3.c: Likewise.
> * gcc.target/i386/pr120427-4.c: Likewise.
>
>
> --
> H.J.
--
BR,
Hongtao
