This patch is the latest revision of the patch originally posted at:
https://gcc.gnu.org/pipermail/gcc-patches/2022-June/596201.html

This patch extends the earlier and;cmp to not;test optimization to also
perform this transformation for TImode on TARGET_64BIT and DImode on -m32,
One motivation for this is that it's a step to fixing the current failure
of gcc.target/i386/pr65105-5.c on -m32.

A more direct benefit for x86_64 is that the following code:

int foo(__int128 x, __int128 y)
{
  return (x & y) == y;
}

improves with -O2 from 15 instructions:

        movq    %rdi, %r8
        movq    %rsi, %rax
        movq    %rax, %rdi
        movq    %r8, %rsi
        movq    %rdx, %r8
        andq    %rdx, %rsi
        andq    %rcx, %rdi
        movq    %rsi, %rax
        movq    %rdi, %rdx
        xorq    %r8, %rax
        xorq    %rcx, %rdx
        orq     %rdx, %rax
        sete    %al
        movzbl  %al, %eax
        ret

to the slightly better 13 instructions:

        movq    %rdi, %r8
        movq    %rsi, %rax
        movq    %r8, %rsi
        movq    %rax, %rdi
        notq    %rsi
        notq    %rdi
        andq    %rdx, %rsi
        andq    %rcx, %rdi
        movq    %rsi, %rax
        orq     %rdi, %rax
        sete    %al
        movzbl  %al, %eax
        ret

Now that all of the doubleword pieces are already in the tree, this
patch is now much shorter (an rtx_costs improvement and a single new
define_insn_and_split), however I couldn't resist including two very
minor pattern naming tweaks/clean-ups to fix nits.

This revised patch has been tested on x86_64-pc-linux-gnu with
make bootstrap and make -k check, where on TARGET_64BIT there are
no new failures, and on --target_board=unix{-m32} with a single new
failure; the other dg-final in gcc.target/i386/pr65105-5.c now also
fails (as that code diverges further from the expected vectorized
output).  This is progress as both FAILs in pr65105-5.c may now be
fixed by changes localized to the STV pass.  OK for mainline?


2022-07-04  Roger Sayle  <roger@nextmovesoftware.com>

gcc/ChangeLog
        * config/i386/i386.cc (ix86_rtx_costs) <COMPARE>: Provide costs
        for double word comparisons and tests (comparisons against zero).
        * config/i386/i386.md (*test<mode>_not_doubleword): Split DWI
        and;cmp into andn;cmp $0 as a pre-reload splitter.
        (*andn<dwi>3_doubleword_bmi): Use <dwi> instead of <mode> in name.
        (*<any_or><dwi>3_doubleword): Likewise.

gcc/testsuite/ChangeLog
        * gcc.target/i386/testnot-3.c: New test case.


Thanks in advance,
Roger
--