[PATCH v1 1/7] x86: Align entry for memrchr to 64-bytes.

[Noah Goldstein <goldstein.w.n@gmail.com>]

The function was tuned around 64-byte entry alignment and performs
better for all sizes with it.

As well different code boths where explicitly written to touch the
minimum number of cache line i.e sizes <= 32 touch only the entry
cache line.
---
Tested with:

for march in "--disable-multi-arch" ""; do for ISA in "-march=x86-64-v4" "-march=x86-64-v3" "" "-march=x86-64-v2"; do echo "START: ${ISA} - $march"; rm -rf glibc-dev/build; mkdir -p glibc-dev/build/glibc/; (cd glibc-dev/build/glibc/; unset LD_LIBRARY_PATH; glibc-dev/src/glibc/configure --prefix=/usr CC="gcc ${ISA}" $march; make -j7 --silent; make -r -C glibc-dev/src/glibc/string/ objdir=`pwd` check; make -r -C glibc-dev/src/glibc/wcsmbs/ objdir=`pwd` check;); echo "DONE: ${ISA} - $march"; objdump -d build/glibc/string/memchr.o;  objdump -d build/glibc/string/rawmemchr.o; objdump -d build/glibc/wcsmbs/wmemchr.o;  cat build/glibc/string/test-memchr.out; cat build/glibc/string/test-memchr.test-result; cat build/glibc/string/test-rawmemchr.out; cat build/glibc/string/test-rawmemchr.test-result; cat build/glibc/wcsmbs/test-wmemchr.out; cat build/glibc/wcsmbs/test-wmemchr.test-result; done; done

for march in "" "--disable-multi-arch"; do rm -rf build; mkdir -p build/glibc; (cd glibc-dev/build/glibc/; unset LD_LIBRARY_PATH; glibc-dev/src/glibc/configure CC="gcc -m32" CXX="g++ -m32" --prefix=/usr --build=i686-pc-linux-gnu --host=i686-pc-linux-gnu $march; make -j7 --silent;) done


(cd glibc-dev/build/glibc/; unset LD_LIBRARY_PATH; glibc-dev/src/glibc/configure --prefix=/usr; make -j7 --silent; make -j7 check --silent);

   5155 PASS
     19 UNSUPPORTED
     18 XFAIL
      4 XPASS
    
 sysdeps/x86_64/multiarch/memrchr-avx2.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sysdeps/x86_64/multiarch/memrchr-avx2.S b/sysdeps/x86_64/multiarch/memrchr-avx2.S
index 9c83c76d3c..f300d7daf4 100644
--- a/sysdeps/x86_64/multiarch/memrchr-avx2.S
+++ b/sysdeps/x86_64/multiarch/memrchr-avx2.S
@@ -35,7 +35,7 @@
 # define VEC_SIZE			32
 # define PAGE_SIZE			4096
 	.section SECTION(.text), "ax", @progbits
-ENTRY(MEMRCHR)
+ENTRY_P2ALIGN(MEMRCHR, 6)
 # ifdef __ILP32__
 	/* Clear upper bits.  */
 	and	%RDX_LP, %RDX_LP
-- 
2.34.1