Allow bp in inline asm by tweaking measure

1 files changed, 14 insertions, 5 deletions

diff --git a/measure.c b/measure.c
index ea827f618..18f07468d 100644
--- a/measure.c
+++ b/measure.c
@@ -1,6 +1,6 @@
 /*
  * Benchmarking utilities extracted from SUPERCOP by Andres Erbsen
- * based on measure-anything.c version 20120328 and measure.c 
+ * based on measure-anything.c version 20120328 and measure.c
  * by D. J. Bernstein
  * Public domain.
  */
@@ -85,15 +85,24 @@ void limits()
 
 void UUT(unsigned char*);
 
-void measure(int n)
+// place the call to UUT in a separate function, because gcc prohibits
+// use of bp in inline assembly if you have a variable-length array or
+// alloca in the code; see
+// https://stackoverflow.com/questions/46248430/how-can-i-determine-preferably-at-compile-time-whether-gcc-is-using-rbp-based?noredirect=1#comment79462384_46248430
+void measure_helper(int n, unsigned char *buf, long long* cycles)
 {
-  unsigned char *buf = aligned_alloc(64, 1024);
-  long long* cycles = calloc(n + 1, sizeof(long long));
-
   for (int i = 0;i <= n;++i) {
 	  cycles[i] = cpucycles();
 	  UUT(buf);
   }
+}
+
+void measure(int n)
+{
+  unsigned char *buf = aligned_alloc(64, 1024);
+  long long* cycles = calloc(n + 1, sizeof(long long));
+
+  measure_helper(n, buf, cycles);
   for (int i = 0;i < n;++i) cycles[i] = cycles[i + 1] - cycles[i];
   for (int i = 0;i < n;++i) printf("%lld\n", cycles[i]);