[Bug target/78904] zero-extracts are not effective

[cvs-commit at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78904

--- Comment #15 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Uros Bizjak <u...@gcc.gnu.org>:

https://gcc.gnu.org/g:0df6d181230f0480547ed08b4e4354db68242724

commit r14-85-g0df6d181230f0480547ed08b4e4354db68242724
Author: Uros Bizjak <ubiz...@gmail.com>
Date:   Wed Apr 19 17:00:52 2023 +0200

    i386: Emit compares between high registers and memory

    Following code:

    typedef __SIZE_TYPE__ size_t;

    struct S1s
    {
      char pad1;
      char val;
      short pad2;
    };

    extern char ts[256];

    _Bool foo (struct S1s a, size_t i)
    {
      return (ts[i] > a.val);
    }

    compiles with -O2 to:

            movl    %edi, %eax
            movsbl  %ah, %edi
            cmpb    %dil, ts(%rsi)
            setg    %al
            ret

    the compare could use high register %ah instead of %dil:

            movl    %edi, %eax
            cmpb    ts(%rsi), %ah
            setl    %al
            ret

    Use any_extract code iterator to handle signed and unsigned extracts
    from high register and introduce peephole2 patterns to propagate
    norex memory opeerand into the compare insn.

    gcc/ChangeLog:

            PR target/78904
            PR target/78952
            * config/i386/i386.md (*cmpqi_ext<mode>_1_mem_rex64): New insn
pattern.
            (*cmpqi_ext<mode>_1): Use nonimmediate_operand predicate
            for operand 0. Use any_extract code iterator.
            (*cmpqi_ext<mode>_1 peephole2): New peephole2 pattern.
            (*cmpqi_ext<mode>_2): Use any_extract code iterator.
            (*cmpqi_ext<mode>_3_mem_rex64): New insn pattern.
            (*cmpqi_ext<mode>_1): Use general_operand predicate
            for operand 1. Use any_extract code iterator.
            (*cmpqi_ext<mode>_3 peephole2): New peephole2 pattern.
            (*cmpqi_ext<mode>_4): Use any_extract code iterator.

    gcc/testsuite/ChangeLog:

            PR target/78904
            PR target/78952
            * gcc.target/i386/pr78952-3.c: New test.