Hi, The patch corrects the definition of TARGET_EFFICIENT_OVERLAPPING_UNALIGNED and replace it with the call of slow_unaligned_access.
Compared with last version, https://gcc.gnu.org/pipermail/gcc-patches/2023-December/640832.html the main change is to pass alignment measured by bits to slow_unaligned_access. Bootstrapped and tested on x86 and powerpc64-linux BE and LE with no regressions. Is this OK for trunk? Thanks Gui Haochen ChangeLog rs6000: Correct definition of macro of fixed point efficient unaligned Marco TARGET_EFFICIENT_OVERLAPPING_UNALIGNED is used in rs6000-string.cc to guard the platform which is efficient on fixed point unaligned load/store. It's originally defined by TARGET_EFFICIENT_UNALIGNED_VSX which is enabled from P8 and can be disabled by mno-vsx option. So the definition is wrong. This patch corrects the problem and call slow_unaligned_access to judge if fixed point unaligned load/store is efficient or not. gcc/ * config/rs6000/rs6000.h (TARGET_EFFICIENT_OVERLAPPING_UNALIGNED): Remove. * config/rs6000/rs6000-string.cc (select_block_compare_mode): Replace TARGET_EFFICIENT_OVERLAPPING_UNALIGNED with targetm.slow_unaligned_access. (expand_block_compare_gpr): Likewise. (expand_block_compare): Likewise. (expand_strncmp_gpr_sequence): Likewise. gcc/testsuite/ * gcc.target/powerpc/block-cmp-1.c: New. * gcc.target/powerpc/block-cmp-2.c: New. patch.diff diff --git a/gcc/config/rs6000/rs6000-string.cc b/gcc/config/rs6000/rs6000-string.cc index 44a946cd453..05dc41622f4 100644 --- a/gcc/config/rs6000/rs6000-string.cc +++ b/gcc/config/rs6000/rs6000-string.cc @@ -305,7 +305,7 @@ select_block_compare_mode (unsigned HOST_WIDE_INT offset, else if (bytes == GET_MODE_SIZE (QImode)) return QImode; else if (bytes < GET_MODE_SIZE (SImode) - && TARGET_EFFICIENT_OVERLAPPING_UNALIGNED + && !targetm.slow_unaligned_access (SImode, align * BITS_PER_UNIT) && offset >= GET_MODE_SIZE (SImode) - bytes) /* This matches the case were we have SImode and 3 bytes and offset >= 1 and permits us to move back one and overlap @@ -313,7 +313,7 @@ select_block_compare_mode (unsigned HOST_WIDE_INT offset, unwanted bytes off of the input. */ return SImode; else if (word_mode_ok && bytes < UNITS_PER_WORD - && TARGET_EFFICIENT_OVERLAPPING_UNALIGNED + && !targetm.slow_unaligned_access (word_mode, align * BITS_PER_UNIT) && offset >= UNITS_PER_WORD-bytes) /* Similarly, if we can use DImode it will get matched here and can do an overlapping read that ends at the end of the block. */ @@ -1749,7 +1749,8 @@ expand_block_compare_gpr(unsigned HOST_WIDE_INT bytes, unsigned int base_align, load_mode_size = GET_MODE_SIZE (load_mode); if (bytes >= load_mode_size) cmp_bytes = load_mode_size; - else if (TARGET_EFFICIENT_OVERLAPPING_UNALIGNED) + else if (!targetm.slow_unaligned_access (load_mode, + align * BITS_PER_UNIT)) { /* Move this load back so it doesn't go past the end. P8/P9 can do this efficiently. */ @@ -2026,7 +2027,7 @@ expand_block_compare (rtx operands[]) /* The code generated for p7 and older is not faster than glibc memcmp if alignment is small and length is not short, so bail out to avoid those conditions. */ - if (!TARGET_EFFICIENT_OVERLAPPING_UNALIGNED + if (targetm.slow_unaligned_access (word_mode, base_align * BITS_PER_UNIT) && ((base_align == 1 && bytes > 16) || (base_align == 2 && bytes > 32))) return false; @@ -2168,7 +2169,8 @@ expand_strncmp_gpr_sequence (unsigned HOST_WIDE_INT bytes_to_compare, load_mode_size = GET_MODE_SIZE (load_mode); if (bytes_to_compare >= load_mode_size) cmp_bytes = load_mode_size; - else if (TARGET_EFFICIENT_OVERLAPPING_UNALIGNED) + else if (!targetm.slow_unaligned_access (load_mode, + align * BITS_PER_UNIT)) { /* Move this load back so it doesn't go past the end. P8/P9 can do this efficiently. */ diff --git a/gcc/config/rs6000/rs6000.h b/gcc/config/rs6000/rs6000.h index 326c45221e9..3971a56c588 100644 --- a/gcc/config/rs6000/rs6000.h +++ b/gcc/config/rs6000/rs6000.h @@ -483,10 +483,6 @@ extern int rs6000_vector_align[]; #define TARGET_NO_SF_SUBREG TARGET_DIRECT_MOVE_64BIT #define TARGET_ALLOW_SF_SUBREG (!TARGET_DIRECT_MOVE_64BIT) -/* This wants to be set for p8 and newer. On p7, overlapping unaligned - loads are slow. */ -#define TARGET_EFFICIENT_OVERLAPPING_UNALIGNED TARGET_EFFICIENT_UNALIGNED_VSX - /* Byte/char syncs were added as phased in for ISA 2.06B, but are not present in power7, so conditionalize them on p8 features. TImode syncs need quad memory support. */ diff --git a/gcc/testsuite/gcc.target/powerpc/block-cmp-1.c b/gcc/testsuite/gcc.target/powerpc/block-cmp-1.c new file mode 100644 index 00000000000..bcf0cb2ab4f --- /dev/null +++ b/gcc/testsuite/gcc.target/powerpc/block-cmp-1.c @@ -0,0 +1,11 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -mdejagnu-cpu=power8 -mno-vsx" } */ +/* { dg-final { scan-assembler-not {\mb[l]? memcmp\M} } } */ + +/* Test that it still can do expand for memcmpsi instead of calling library + on P8 with vsx disabled. */ + +int foo (const char* s1, const char* s2) +{ + return __builtin_memcmp (s1, s2, 20); +} diff --git a/gcc/testsuite/gcc.target/powerpc/block-cmp-2.c b/gcc/testsuite/gcc.target/powerpc/block-cmp-2.c new file mode 100644 index 00000000000..dfee15b2147 --- /dev/null +++ b/gcc/testsuite/gcc.target/powerpc/block-cmp-2.c @@ -0,0 +1,12 @@ +/* { dg-do compile } */ +/* { dg-require-effective-target opt_mstrict_align } */ +/* { dg-options "-O2 -mstrict-align" } */ +/* { dg-final { scan-assembler-times {\mb[l]? memcmp\M} 1 } } */ + +/* Test that it calls library for block memory compare when strict-align + is set. The flag causes rs6000_slow_unaligned_access returns true. */ + +int foo (const char* s1, const char* s2) +{ + return __builtin_memcmp (s1, s2, 20); +}
