On Tue, Jul 30, 2024 at 5:43 PM Andi Kleen <a...@linux.intel.com> wrote:
>
> From: Andi Kleen <a...@gcc.gnu.org>
>
> Host systems with only MMX and no SSE2 should be really rare now.
> Let's remove the MMX code path to keep the number of custom
> implementations the same.
>
> The SSE2 code path is also somewhat dubious now (nearly everything
> should have SSE4 4.2 which is >15 years old now), but the SSE2
> code path is used as fallback for others and also apparently
> Solaris uses it due to tool chain deficiencies.
OK if nobody objects this week.
Thanks,
Richard.
> libcpp/ChangeLog:
>
> * lex.cc (search_line_mmx): Remove function.
> (init_vectorized_lexer): Remove search_line_mmx.
> ---
> libcpp/lex.cc | 75 ---------------------------------------------------
> 1 file changed, 75 deletions(-)
>
> diff --git a/libcpp/lex.cc b/libcpp/lex.cc
> index 16f2c23af1e1..1591dcdf151a 100644
> --- a/libcpp/lex.cc
> +++ b/libcpp/lex.cc
> @@ -290,71 +290,6 @@ static const char repl_chars[4][16]
> __attribute__((aligned(16))) = {
> '?', '?', '?', '?', '?', '?', '?', '?' },
> };
>
> -/* A version of the fast scanner using MMX vectorized byte compare insns.
> -
> - This uses the PMOVMSKB instruction which was introduced with "MMX2",
> - which was packaged into SSE1; it is also present in the AMD MMX
> - extension. Mark the function as using "sse" so that we emit a real
> - "emms" instruction, rather than the 3dNOW "femms" instruction. */
> -
> -static const uchar *
> -#ifndef __SSE__
> -__attribute__((__target__("sse")))
> -#endif
> -search_line_mmx (const uchar *s, const uchar *end ATTRIBUTE_UNUSED)
> -{
> - typedef char v8qi __attribute__ ((__vector_size__ (8)));
> - typedef int __m64 __attribute__ ((__vector_size__ (8), __may_alias__));
> -
> - const v8qi repl_nl = *(const v8qi *)repl_chars[0];
> - const v8qi repl_cr = *(const v8qi *)repl_chars[1];
> - const v8qi repl_bs = *(const v8qi *)repl_chars[2];
> - const v8qi repl_qm = *(const v8qi *)repl_chars[3];
> -
> - unsigned int misalign, found, mask;
> - const v8qi *p;
> - v8qi data, t, c;
> -
> - /* Align the source pointer. While MMX doesn't generate unaligned data
> - faults, this allows us to safely scan to the end of the buffer without
> - reading beyond the end of the last page. */
> - misalign = (uintptr_t)s & 7;
> - p = (const v8qi *)((uintptr_t)s & -8);
> - data = *p;
> -
> - /* Create a mask for the bytes that are valid within the first
> - 16-byte block. The Idea here is that the AND with the mask
> - within the loop is "free", since we need some AND or TEST
> - insn in order to set the flags for the branch anyway. */
> - mask = -1u << misalign;
> -
> - /* Main loop processing 8 bytes at a time. */
> - goto start;
> - do
> - {
> - data = *++p;
> - mask = -1;
> -
> - start:
> - t = __builtin_ia32_pcmpeqb(data, repl_nl);
> - c = __builtin_ia32_pcmpeqb(data, repl_cr);
> - t = (v8qi) __builtin_ia32_por ((__m64)t, (__m64)c);
> - c = __builtin_ia32_pcmpeqb(data, repl_bs);
> - t = (v8qi) __builtin_ia32_por ((__m64)t, (__m64)c);
> - c = __builtin_ia32_pcmpeqb(data, repl_qm);
> - t = (v8qi) __builtin_ia32_por ((__m64)t, (__m64)c);
> - found = __builtin_ia32_pmovmskb (t);
> - found &= mask;
> - }
> - while (!found);
> -
> - __builtin_ia32_emms ();
> -
> - /* FOUND contains 1 in bits for which we matched a relevant
> - character. Conversion to the byte index is trivial. */
> - found = __builtin_ctz(found);
> - return (const uchar *)p + found;
> -}
>
> /* A version of the fast scanner using SSE2 vectorized byte compare insns.
> */
>
> @@ -509,8 +444,6 @@ init_vectorized_lexer (void)
> minimum = 3;
> #elif defined(__SSE2__)
> minimum = 2;
> -#elif defined(__SSE__)
> - minimum = 1;
> #endif
>
> if (minimum == 3)
> @@ -521,14 +454,6 @@ init_vectorized_lexer (void)
> impl = search_line_sse42;
> else if (minimum == 2 || (edx & bit_SSE2))
> impl = search_line_sse2;
> - else if (minimum == 1 || (edx & bit_SSE))
> - impl = search_line_mmx;
> - }
> - else if (__get_cpuid (0x80000001, &dummy, &dummy, &dummy, &edx))
> - {
> - if (minimum == 1
> - || (edx & (bit_MMXEXT | bit_CMOV)) == (bit_MMXEXT | bit_CMOV))
> - impl = search_line_mmx;
> }
>
> search_line_fast = impl;
> --
> 2.45.2
>
