From d9f17c66b52dc49ced37b0a792eb638d7124ffcd Mon Sep 17 00:00:00 2001
From: David Monniaux <David.Monniaux@univ-grenoble-alpes.fr>
Date: Fri, 11 Feb 2022 14:26:28 +0100
Subject: experiments in division

---
 test/monniaux/division/compare_timings.c | 67 ++++++++++++++++++++++++++++++++
 test/monniaux/division/cycles.h          |  1 +
 2 files changed, 68 insertions(+)
 create mode 100644 test/monniaux/division/compare_timings.c
 create mode 120000 test/monniaux/division/cycles.h

(limited to 'test')

diff --git a/test/monniaux/division/compare_timings.c b/test/monniaux/division/compare_timings.c
new file mode 100644
index 00000000..15195d3e
--- /dev/null
+++ b/test/monniaux/division/compare_timings.c
@@ -0,0 +1,67 @@
+#include <stdint.h>
+#include <stdio.h>
+#include <inttypes.h>
+#include "cycles.h"
+
+#define CHECKS(mode, quotient) \
+void checks_##mode() {				\
+  uint64_t checksum=UINT64_C(0),		\
+    a=UINT64_C(0x10000000000),			\
+    b=UINT64_C(0x1000);				\
+  for(int i=0; i<10000; i++) {			\
+    uint64_t q = (quotient);			\
+    a += UINT64_C(0x36667);			\
+    b += UINT64_C(0x13);			\
+    checksum += q;				\
+  }						\
+  printf("checksum = %" PRIx64 "\n", checksum);	\
+}
+
+#define CHECKS2(mode, quotient) \
+void checks2_##mode() {				\
+  uint64_t checksum=UINT64_C(0),		\
+    a=UINT64_C(0x10000000000),			\
+    b=UINT64_C(0x1000);				\
+  for(int i=0; i<5000; i++) {			\
+    uint64_t q = (quotient);			\
+    a += UINT64_C(0x36667);			\
+    b += UINT64_C(0x13);			\
+    checksum += q;				\
+    q = (quotient);		 	        \
+    a += UINT64_C(0x36667);			\
+    b += UINT64_C(0x13);			\
+    checksum += q;				\
+  }						\
+  printf("checksum = %" PRIx64 "\n", checksum);	\
+}
+
+CHECKS(normal, a/b)
+CHECKS(fp, __builtin_fp_udiv64(a, b))
+
+CHECKS2(normal, a/b)
+CHECKS2(fp, __builtin_fp_udiv64(a, b))
+       
+int main() {
+  cycle_t start, stop;
+  cycle_count_config();
+
+  start = get_cycle();
+  checks_normal();
+  stop = get_cycle();
+  printf("normal division: %" PRcycle " cycles\n", stop-start);
+
+  start = get_cycle();
+  checks_fp();
+  stop = get_cycle();
+  printf("fp division: %" PRcycle " cycles\n", stop-start);
+
+  start = get_cycle();
+  checks2_normal();
+  stop = get_cycle();
+  printf("normal division x2: %" PRcycle " cycles\n", stop-start);
+
+  start = get_cycle();
+  checks2_fp();
+  stop = get_cycle();
+  printf("fp division x2: %" PRcycle " cycles\n", stop-start);
+}
diff --git a/test/monniaux/division/cycles.h b/test/monniaux/division/cycles.h
new file mode 120000
index 00000000..84e54d21
--- /dev/null
+++ b/test/monniaux/division/cycles.h
@@ -0,0 +1 @@
+../cycles.h
\ No newline at end of file
-- 
cgit