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authorRoy Li <rongqing.li@windriver.com>2016-05-05 09:52:01 +0800
committerMartin Jansa <Martin.Jansa@gmail.com>2016-05-10 20:18:30 +0200
commit4adec181e7303c0afd7fca08fec6ddc5532237a1 (patch)
treea4d004f2a6858974c3496a76001f7e21bf3681e9
parent35c7a5b63b24ecfa616dacc45c9d0415da1ca5ca (diff)
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lmbench: avoid gcc optimize-away multiplication
Change expression used in do_integer_mul and do_uint64_mul benchmarks so GCC doesn't optimize-away the loops, Signed-off-by: Roy Li <rongqing.li@windriver.com> Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
-rw-r--r--meta-oe/recipes-benchmark/lmbench/lmbench/0001-avoid-gcc-optimize-away-the-loops.patch79
-rw-r--r--meta-oe/recipes-benchmark/lmbench/lmbench_3.0-a9.bb1
2 files changed, 80 insertions, 0 deletions
diff --git a/meta-oe/recipes-benchmark/lmbench/lmbench/0001-avoid-gcc-optimize-away-the-loops.patch b/meta-oe/recipes-benchmark/lmbench/lmbench/0001-avoid-gcc-optimize-away-the-loops.patch
new file mode 100644
index 0000000000..2d8a2468a9
--- /dev/null
+++ b/meta-oe/recipes-benchmark/lmbench/lmbench/0001-avoid-gcc-optimize-away-the-loops.patch
@@ -0,0 +1,79 @@
+[PATCH] avoid gcc optimize-away the loops
+
+Upstream-Status: pending
+
+Change expression used in do_integer_mul and do_uint64_mul
+benchmarks so GCC doesn't optimize-away the loops, other
+things are same:
+- TEN(r *= s;); r -= t;
++ i = 0;
++ while ( i++ < 10)
++ r *= s;
++ r -= t;
+
+and TEN is macro:
+ #define TEN(a) a a a a a a a a a a
+
+Signed-off-by: Roy Li <rongqing.li@windriver.com>
+---
+ src/lat_ops.c | 30 +++++++++++++++++++++++++-----
+ 1 file changed, 25 insertions(+), 5 deletions(-)
+
+diff --git a/src/lat_ops.c b/src/lat_ops.c
+index d343ff3..457072b 100644
+--- a/src/lat_ops.c
++++ b/src/lat_ops.c
+@@ -126,11 +126,23 @@ do_integer_mul(iter_t iterations, void* cookie)
+ struct _state *pState = (struct _state*)cookie;
+ register int r = pState->N + 37431;
+ register int s = pState->N + 4;
+- register int t = r * s * s * s * s * s * s * s * s * s * s - r;
++ register int t = r;
++ int i = 0;
++
++ while ( i++ < 10)
++ t *= s;
++ t -= r;
+
+ while (iterations-- > 0) {
+- TEN(r *= s;); r -= t;
+- TEN(r *= s;); r -= t;
++ i = 0;
++ while ( i++ < 10)
++ r *= s;
++ r -= t;
++
++ i = 0;
++ while ( i++ < 10)
++ r *= s;
++ r -= t;
+ }
+ use_int(r);
+ }
+@@ -207,13 +219,21 @@ do_int64_mul(iter_t iterations, void* cookie)
+ register int64 r = (int64)pState->N + 37420;
+ register int64 s = (int64)pState->N + 4;
+ register int64 t;
++ int i = 0;
+
+ r += (int64)(pState->N + 6)<<32;
+ t = r * s * s * s * s * s * s * s * s * s * s - r;
+
+ while (iterations-- > 0) {
+- TEN(r *= s;); r -= t;
+- TEN(r *= s;); r -= t;
++ i = 0;
++ while ( i++ < 10)
++ r *= s;
++ r -= t;
++
++ i = 0;
++ while ( i++ < 10)
++ r *= s;
++ r -= t;
+ }
+ use_int((int)r);
+ }
+--
+2.8.1
+
diff --git a/meta-oe/recipes-benchmark/lmbench/lmbench_3.0-a9.bb b/meta-oe/recipes-benchmark/lmbench/lmbench_3.0-a9.bb
index 5459bf9cb8..a62389d094 100644
--- a/meta-oe/recipes-benchmark/lmbench/lmbench_3.0-a9.bb
+++ b/meta-oe/recipes-benchmark/lmbench/lmbench_3.0-a9.bb
@@ -18,6 +18,7 @@ SRC_URI = "${SOURCEFORGE_MIRROR}/lmbench/lmbench-${PV}.tgz \
file://use-base_libdir-instead-of-hardcoded-lib.patch \
file://lmbench_result_html_report.patch \
file://fix-lmbench-memory-check-failure.patch \
+ file://0001-avoid-gcc-optimize-away-the-loops.patch \
"
SRC_URI[md5sum] = "b3351a3294db66a72e2864a199d37cbf"
SRC_URI[sha256sum] = "cbd5777d15f44eab7666dcac418054c3c09df99826961a397d9acf43d8a2a551"