Add vec-strcmp

Author: jerryz123

benchmarks/Makefile

@@ -35,6 +35,7 @@ bmarks = \
 	vec-memcpy \
 	vec-daxpy \
 	vec-sgemm \
+	vec-strcmp \
 
 #--------------------------------------------------------------------
 # Build rules

benchmarks/vec-strcmp/vec-strcmp.S

@@ -0,0 +1,32 @@
+    .text
+    .balign 4
+    .global vec_strcmp
+  # int vec_strcmp(const char *src1, const char* src2)
+vec_strcmp:
+    ##  Using LMUL=2, but same register names work for larger LMULs
+    li t1, 0                # Initial pointer bump
+loop:
+    vsetvli t0, x0, e8, m2, ta, ma  # Max length vectors of bytes
+    add a0, a0, t1          # Bump src1 pointer
+    vle8ff.v v8, (a0)       # Get src1 bytes
+    add a1, a1, t1          # Bump src2 pointer
+    vle8ff.v v16, (a1)      # Get src2 bytes
+
+    vmseq.vi v0, v8, 0      # Flag zero bytes in src1
+    vmsne.vv v1, v8, v16    # Flag if src1 != src2
+    vmor.mm v0, v0, v1      # Combine exit conditions
+    
+    vfirst.m a2, v0         # ==0 or != ?
+    csrr t1, vl             # Get number of bytes fetched
+    
+    bltz a2, loop           # Loop if all same and no zero byte
+
+    add a0, a0, a2          # Get src1 element address
+    lbu a3, (a0)            # Get src1 byte from memory
+
+    add a1, a1, a2          # Get src2 element address
+    lbu a4, (a1)            # Get src2 byte from memory
+
+    sub a0, a3, a4          # Return value.
+
+    ret

benchmarks/vec-strcmp/vec-strcmp_main.c

@@ -0,0 +1,34 @@
+// See LICENSE for license details.
+
+//**************************************************************************
+// Strcmp benchmark
+//--------------------------------------------------------------------------
+//
+// This benchmark tests a vectorized strcmp implementation.
+
+#include <string.h>
+#include "util.h"
+
+//--------------------------------------------------------------------------
+// Input/Reference Data
+
+const char* test_str = "The quick brown fox jumped over the lazy dog";
+const char* same_str = "The quick brown fox jumped over the lazy dog";
+char* diff_str = "The quick brown fox jumped over the lazy cat";
+
+//--------------------------------------------------------------------------
+// Main
+
+int vec_strcmp(const char *src1, const char* src2);
+
+int main( int argc, char* argv[] )
+{
+  // Do the strcmp
+  setStats(1);
+  int r0 = vec_strcmp(test_str, same_str);
+  int r1 = vec_strcmp(test_str, diff_str);
+  setStats(0);
+
+  // Check the results
+  return !(r0 == 0 && r1 != 0);
+}