[compiler-rt] r212715 - [msan] Fix performance issue in fast_memset.

[Evgeniy Stepanov]

Author: eugenis
Date: Thu Jul 10 07:45:56 2014
New Revision: 212715

URL: http://llvm.org/viewvc/llvm-project?rev=212715&view=rev
Log:
[msan] Fix performance issue in fast_memset.

Fast path was never triggered when called from __msan_poison.

Modified:
    compiler-rt/trunk/lib/msan/msan_interceptors.cc

Modified: compiler-rt/trunk/lib/msan/msan_interceptors.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/msan/msan_interceptors.cc?rev=212715&r1=212714&r2=212715&view=diff
==============================================================================
--- compiler-rt/trunk/lib/msan/msan_interceptors.cc (original)
+++ compiler-rt/trunk/lib/msan/msan_interceptors.cc Thu Jul 10 07:45:56 2014
@@ -1264,13 +1264,14 @@ void *fast_memset(void *ptr, int c, SIZE
   // hack until we have a really fast internal_memset
   if (sizeof(uptr) == 8 &&
       (n % 8) == 0 &&
-      ((uptr)ptr % 8) == 0 &&
-      (c == 0 || c == -1)) {
-    // Printf("memset %p %zd %x\n", ptr, n, c);
-    uptr to_store = c ? -1L : 0L;
+      ((uptr)ptr % 8) == 0) {
+    uptr c8 = (unsigned)c & 0xFF;
+    c8 = (c8 << 8) | c8;
+    c8 = (c8 << 16) | c8;
+    c8 = (c8 << 32) | c8;
     uptr *p = (uptr*)ptr;
     for (SIZE_T i = 0; i < n / 8; i++)
-      p[i] = to_store;
+      p[i] = c8;
     return ptr;
   }
   return internal_memset(ptr, c, n);