Hi! gimple-ssa-store-merging.cc tests bswap_optab in 3 different places, in 2 of them it has special exception for double-word bswap using pair of word-mode bswap optabs, but in the last one it doesn't.
The following patch changes even the last spot. We don't handle 128-bit bswaps in the passes at all, because currently we just use uint64_t to represent the byte reshuffling (we'd need to use offset_int or something like that instead) and we don't have __builtin_bswap128 nor type-generic __builtin_bswap, so there is nothing for 64-bit targets there. Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? 2024-03-13 Jakub Jelinek <ja...@redhat.com> PR middle-end/114319 * gimple-ssa-store-merging.cc (imm_store_chain_info::try_coalesce_bswap): For 32-bit targets allow matching __builtin_bswap64 if there is bswapsi2 optab. * gcc.target/i386/pr114319.c: New test. --- gcc/gimple-ssa-store-merging.cc.jj 2024-01-03 11:51:29.449760086 +0100 +++ gcc/gimple-ssa-store-merging.cc 2024-03-12 23:51:30.740236577 +0100 @@ -3051,7 +3051,10 @@ imm_store_chain_info::try_coalesce_bswap return false; case 64: if (builtin_decl_explicit_p (BUILT_IN_BSWAP64) - && optab_handler (bswap_optab, DImode) != CODE_FOR_nothing) + && (optab_handler (bswap_optab, DImode) != CODE_FOR_nothing + || (word_mode == SImode + && builtin_decl_explicit_p (BUILT_IN_BSWAP32) + && optab_handler (bswap_optab, SImode) != CODE_FOR_nothing))) break; return false; default: --- gcc/testsuite/gcc.target/i386/pr114319.c.jj 2024-03-13 10:59:57.378404934 +0100 +++ gcc/testsuite/gcc.target/i386/pr114319.c 2024-03-13 10:59:46.612554118 +0100 @@ -0,0 +1,19 @@ +/* PR middle-end/114319 */ +/* { dg-do compile } */ +/* { dg-options "-O2 -masm=att -mno-movbe" } */ +/* { dg-additional-options "-march=i486" { target ia32 } } */ +/* { dg-final { scan-assembler-times "\tbswap\t%r" 1 { target { ! ia32 } } } } */ +/* { dg-final { scan-assembler-times "\tbswap\t%\[er]" 2 { target ia32 } } } */ + +void +foo (unsigned long long x, unsigned char *y) +{ + y[0] = x >> 56; + y[1] = x >> 48; + y[2] = x >> 40; + y[3] = x >> 32; + y[4] = x >> 24; + y[5] = x >> 16; + y[6] = x >> 8; + y[7] = x; +} Jakub