Hi, This patch enables overlapped by-piece operations. On rs6000, default move/set/clear ratio is 2. So the overlap is only enabled with compare by-pieces.
Compared to previous version, the change is to remove power8 requirement from test case. https://gcc.gnu.org/pipermail/gcc-patches/2024-May/651045.html Bootstrapped and tested on powerpc64-linux BE and LE with no regressions. Is it OK for the trunk? Thanks Gui Haochen ChangeLog rs6000: Enable overlapped by-pieces operations This patch enables overlapped by-piece operations by defining TARGET_OVERLAP_OP_BY_PIECES_P to true. On rs6000, default move/set/clear ratio is 2. So the overlap is only enabled with compare by-pieces. gcc/ * config/rs6000/rs6000.cc (TARGET_OVERLAP_OP_BY_PIECES_P): Define. gcc/testsuite/ * gcc.target/powerpc/block-cmp-9.c: New. patch.diff diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc index 117999613d8..e713a1e1d57 100644 --- a/gcc/config/rs6000/rs6000.cc +++ b/gcc/config/rs6000/rs6000.cc @@ -1776,6 +1776,9 @@ static const scoped_attribute_specs *const rs6000_attribute_table[] = #undef TARGET_CONST_ANCHOR #define TARGET_CONST_ANCHOR 0x8000 +#undef TARGET_OVERLAP_OP_BY_PIECES_P +#define TARGET_OVERLAP_OP_BY_PIECES_P hook_bool_void_true + /* Processor table. */ diff --git a/gcc/testsuite/gcc.target/powerpc/block-cmp-9.c b/gcc/testsuite/gcc.target/powerpc/block-cmp-9.c new file mode 100644 index 00000000000..f16429c2ffb --- /dev/null +++ b/gcc/testsuite/gcc.target/powerpc/block-cmp-9.c @@ -0,0 +1,11 @@ +/* { dg-do compile } */ +/* { dg-options "-O2" } */ +/* { dg-final { scan-assembler-not {\ml[hb]z\M} } } */ + +/* Test if by-piece overlap compare is enabled and following case is + implemented by two overlap word loads and compares. */ + +int foo (const char* s1, const char* s2) +{ + return __builtin_memcmp (s1, s2, 7) == 0; +}