From: Neale Ranns <nranns@cisco.com>
Date: Wed, 3 Oct 2018 18:13:27 +0000 (-0400)
Subject: clib_count_equal_*: don't read of the end of a small array and init data only if... 
X-Git-Tag: v18.10-rc1~31
X-Git-Url: https://gerrit.fd.io/r/gitweb?p=vpp.git;a=commitdiff_plain;h=2329e090fc4c158988d4f14b1edb6a8623149679

clib_count_equal_*: don't read of the end of a small array and init data only if used (VPP-1429)

Change-Id: I8afa57ecca590698d3430746968aa0a5b0070469
Signed-off-by: Neale Ranns <nranns@cisco.com>
---

diff --git a/src/vppinfra/string.h b/src/vppinfra/string.h
index 5a47725f5c3..8f165dfa18e 100644
--- a/src/vppinfra/string.h
+++ b/src/vppinfra/string.h
@@ -324,12 +324,17 @@ clib_memset_u8 (void *p, u8 val, uword count)
 static_always_inline uword
 clib_count_equal_u64 (u64 * data, uword max_count)
 {
-  uword count = 0;
-  u64 first = data[0];
+  uword count;
+  u64 first;
 
+  if (max_count == 1)
+    return 1;
   if (data[0] != data[1])
     return 1;
 
+  count = 0;
+  first = data[0];
+
 #if defined(CLIB_HAVE_VEC256)
   u64x4 splat = u64x4_splat (first);
   while (1)
@@ -369,12 +374,17 @@ clib_count_equal_u64 (u64 * data, uword max_count)
 static_always_inline uword
 clib_count_equal_u32 (u32 * data, uword max_count)
 {
-  uword count = 0;
-  u32 first = data[0];
+  uword count;
+  u32 first;
 
+  if (max_count == 1)
+    return 1;
   if (data[0] != data[1])
     return 1;
 
+  count = 0;
+  first = data[0];
+
 #if defined(CLIB_HAVE_VEC256)
   u32x8 splat = u32x8_splat (first);
   while (1)
@@ -432,12 +442,17 @@ clib_count_equal_u32 (u32 * data, uword max_count)
 static_always_inline uword
 clib_count_equal_u16 (u16 * data, uword max_count)
 {
-  uword count = 0;
-  u16 first = data[0];
+  uword count;
+  u16 first;
 
+  if (max_count == 1)
+    return 1;
   if (data[0] != data[1])
     return 1;
 
+  count = 0;
+  first = data[0];
+
 #if defined(CLIB_HAVE_VEC256)
   u16x16 splat = u16x16_splat (first);
   while (1)
@@ -495,12 +510,17 @@ clib_count_equal_u16 (u16 * data, uword max_count)
 static_always_inline uword
 clib_count_equal_u8 (u8 * data, uword max_count)
 {
-  uword count = 0;
-  u8 first = data[0];
+  uword count;
+  u8 first;
 
+  if (max_count == 1)
+    return 1;
   if (data[0] != data[1])
     return 1;
 
+  count = 0;
+  first = data[0];
+
 #if defined(CLIB_HAVE_VEC256)
   u8x32 splat = u8x32_splat (first);
   while (1)