We used to expand memcmp to "repz cmpsb" via cmpstrnsi. It was changed
by
commit 9b0f6f5e511ca512e4faeabc81d2fd3abad9b02f
Author: Nick Clifton <ni...@redhat.com>
Date: Fri Aug 12 16:26:11 2011 +0000
builtins.c (expand_builtin_memcmp): Do not use cmpstrnsi pattern.
* builtins.c (expand_builtin_memcmp): Do not use cmpstrnsi
pattern.
* doc/md.texi (cmpstrn): Note that the comparison stops if both
fetched bytes are zero.
(cmpstr): Likewise.
(cmpmem): Note that the comparison does not stop if both of the
fetched bytes are zero.
Duplicate the cmpstrn pattern for cmpmem and expand cmpmem to "repz cmpsb"
for -minline-all-stringops. The only difference is that the length
argument of cmpmem is guaranteed to be less than or equal to lengths of
2 memory areas. Since cmpmem expander may pass the actual string length
directly to cmpstrnqi patterns. Pass a copy of the string length to
cmpstrnqi patterns to avoid changing the actual string length by cmpstrnqi
patterns.
Tested on Linux/x86 and Linux/x86-64. OK for master?
H.J. Lu (2):
x86: Pass a copy of the string length to cmpstrnqi
x86: Add cmpmemsi for -minline-all-stringops
gcc/config/i386/i386-expand.c | 84 ++++++++++++++
gcc/config/i386/i386-protos.h | 1 +
gcc/config/i386/i386.md | 80 ++++---------
gcc/testsuite/gcc.target/i386/pr95151-1.c | 17 +++
gcc/testsuite/gcc.target/i386/pr95151-2.c | 10 ++
gcc/testsuite/gcc.target/i386/pr95151-3.c | 18 +++
gcc/testsuite/gcc.target/i386/pr95151-4.c | 11 ++
gcc/testsuite/gcc.target/i386/pr95443-1.c | 130 ++++++++++++++++++++++
gcc/testsuite/gcc.target/i386/pr95443-2.c | 79 +++++++++++++
9 files changed, 371 insertions(+), 59 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/i386/pr95151-1.c
create mode 100644 gcc/testsuite/gcc.target/i386/pr95151-2.c
create mode 100644 gcc/testsuite/gcc.target/i386/pr95151-3.c
create mode 100644 gcc/testsuite/gcc.target/i386/pr95151-4.c
create mode 100644 gcc/testsuite/gcc.target/i386/pr95443-1.c
create mode 100644 gcc/testsuite/gcc.target/i386/pr95443-2.c
--
2.26.2
