On Tue, May 19, 2026 at 6:29 AM Kito Cheng <[email protected]> wrote:
>
> Before r17-567 ("middle-end: Optimize reversed CRC table-based
> implementation"), a reversed CRC without a crc_rev optab was
> expanded as: reflect the input, run the non-reversed CRC table,
> then reflect the result. So the table that got emitted was the
> non-reversed one, and the dump printed:
>
> ;; emitting crc table crc_<N>_polynomial_<P> ...
>
> After that patch, the middle end builds a reversed CRC table
> directly and the dump prints:
>
> ;; emitting reversed crc table crc_<N>_polynomial_<P> ...
>
> Any target without a crc_rev optab hits the new path. For example,
> RISC-V's bitmanip.md defines crc_rev<ANYI1:mode><ANYI:mode>4 with
> no TARGET_ guard, so the optab is always there and the dump still
> says "using optab for ..." -- the test passes. But x86's
> crc_rev<SWI124:mode>si4 needs TARGET_CRC32, so a default x86 build
> (no SSE4.2 / -march=cascadelake) has no optab, falls back to the
> table, and prints the new "emitting reversed crc table" message.
>
> The old regex only accepted "emitting crc table", so x86 fails.
> These tests only call __builtin_rev_crc*, which always take the
> reversed path, so the non-reversed "emitting crc table" message
> cannot appear here. Just replace it with the new wording.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/crc-builtin-rev-target32.c: Match the new
> "emitting reversed crc table" dump message.
> * gcc.dg/crc-builtin-rev-target64.c: Likewise.
Ok.
> ---
> gcc/testsuite/gcc.dg/crc-builtin-rev-target32.c | 6 +++---
> gcc/testsuite/gcc.dg/crc-builtin-rev-target64.c | 6 +++---
> 2 files changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/gcc/testsuite/gcc.dg/crc-builtin-rev-target32.c
> b/gcc/testsuite/gcc.dg/crc-builtin-rev-target32.c
> index f2b63db7fd1..25dc9a226c3 100644
> --- a/gcc/testsuite/gcc.dg/crc-builtin-rev-target32.c
> +++ b/gcc/testsuite/gcc.dg/crc-builtin-rev-target32.c
> @@ -34,6 +34,6 @@ int32_t rev_crc32_data32 ()
> return __builtin_rev_crc32_data32 (0xffffffff, 0x123546ff, 0x4002123);
> }
>
> -/* { dg-final { scan-rtl-dump ";; (?:using optab for|emitting crc table)
> crc_8_polynomial_0x12" "expand" } } */
> -/* { dg-final { scan-rtl-dump ";; (?:using optab for|emitting crc table)
> crc_16_polynomial_0x1021" "expand" } } */
> -/* { dg-final { scan-rtl-dump ";; (?:using optab for|emitting crc table)
> crc_32_polynomial_0x4002123" "expand" } } */
> +/* { dg-final { scan-rtl-dump ";; (?:using optab for|emitting reversed crc
> table) crc_8_polynomial_0x12" "expand" } } */
> +/* { dg-final { scan-rtl-dump ";; (?:using optab for|emitting reversed crc
> table) crc_16_polynomial_0x1021" "expand" } } */
> +/* { dg-final { scan-rtl-dump ";; (?:using optab for|emitting reversed crc
> table) crc_32_polynomial_0x4002123" "expand" } } */
> diff --git a/gcc/testsuite/gcc.dg/crc-builtin-rev-target64.c
> b/gcc/testsuite/gcc.dg/crc-builtin-rev-target64.c
> index 97e80004d37..bc9dfa5b619 100644
> --- a/gcc/testsuite/gcc.dg/crc-builtin-rev-target64.c
> +++ b/gcc/testsuite/gcc.dg/crc-builtin-rev-target64.c
> @@ -58,6 +58,6 @@ int64_t rev_crc64_data64 ()
> 0x40021234002123);
> }
>
> -/* { dg-final { scan-rtl-dump ";; (?:using optab for|emitting crc table)
> crc_8_polynomial_0x12" "expand" } } */
> -/* { dg-final { scan-rtl-dump ";; (?:using optab for|emitting crc table)
> crc_16_polynomial_0x1021" "expand" } } */
> -/* { dg-final { scan-rtl-dump ";; (?:using optab for|emitting crc table)
> crc_32_polynomial_0x4002123" "expand" } } */
> +/* { dg-final { scan-rtl-dump ";; (?:using optab for|emitting reversed crc
> table) crc_8_polynomial_0x12" "expand" } } */
> +/* { dg-final { scan-rtl-dump ";; (?:using optab for|emitting reversed crc
> table) crc_16_polynomial_0x1021" "expand" } } */
> +/* { dg-final { scan-rtl-dump ";; (?:using optab for|emitting reversed crc
> table) crc_32_polynomial_0x4002123" "expand" } } */
> --
> 2.52.0
>
