target: Correct profiling calculation

1. high_pc should be (maximum sample + 1) (Refer to gprof source code)
2. bucket index should be

     sample offset
    --------------- x (number of bucket)
	 sample range

For example, if minimum sample is 0 and maximum sample is 5
and the number of bucket is 3.

a = sampled_address - 0
b = 3
c = 6
(a, b, c refer to source code variables)

sampled_address = 0, => a = 0, => bucket_index = 0
sampled_address = 1, => a = 1, => bucket_index = 0
sampled_address = 2, => a = 2, => bucket_index = 1
sampled_address = 3, => a = 3, => bucket_index = 1
sampled_address = 4, => a = 4, => bucket_index = 2
sampled_address = 5, => a = 5, => bucket_index = 2

Change-Id: Ia9fa0e4d9c7183e3e9d7ceaf73e63729f07aa2ce
Signed-off-by: Hsiangkai Wang <hsiangkai@gmail.com>
Reviewed-on: http://openocd.zylin.com/1607
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>

diff --git a/src/target/target.c b/src/target/target.c
index 11b12e5e84d4c20eb4e97dd1900571e09bdc5350..1ea1a61668c9d059299e6225778138ba92b2f8c8 100644 (file)
--- a/src/target/target.c
+++ b/src/target/target.c
@@ -3387,7 +3387,11 @@ static void writeGmon(uint32_t *samples, uint32_t sampleNum, const char *filenam
                        max = samples[i];
        }
 
-       int addressSpace = (max - min + 1);
+       /* max should be (largest sample + 1)
+        * Refer to binutils/gprof/hist.c (find_histogram_for_pc) */
+       max++;
+
+       int addressSpace = max - min;
        assert(addressSpace >= 2);
 
        static const uint32_t maxBuckets = 16 * 1024; /* maximum buckets. */
@@ -3403,8 +3407,8 @@ static void writeGmon(uint32_t *samples, uint32_t sampleNum, const char *filenam
        for (i = 0; i < sampleNum; i++) {
                uint32_t address = samples[i];
                long long a = address - min;
-               long long b = numBuckets - 1;
-               long long c = addressSpace - 1;
+               long long b = numBuckets;
+               long long c = addressSpace;
                int index_t = (a * b) / c; /* danger!!!! int32 overflows */
                buckets[index_t]++;
        }