[compiler-rt] r176185 - [asan] if calloc returns a freshly-mmaped memory, don't clear it with memset. Speeds up calloc-intensive code

[Kostya Serebryany]

Author: kcc
Date: Wed Feb 27 07:38:19 2013
New Revision: 176185

URL: http://llvm.org/viewvc/llvm-project?rev=176185&view=rev
Log:
[asan] if calloc returns a freshly-mmaped memory, don't clear it with memset. Speeds up calloc-intensive code

Modified:
    compiler-rt/trunk/lib/asan/asan_allocator2.cc
    compiler-rt/trunk/lib/asan/tests/asan_noinst_test.cc

Modified: compiler-rt/trunk/lib/asan/asan_allocator2.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_allocator2.cc?rev=176185&r1=176184&r2=176185&view=diff
==============================================================================
--- compiler-rt/trunk/lib/asan/asan_allocator2.cc (original)
+++ compiler-rt/trunk/lib/asan/asan_allocator2.cc Wed Feb 27 07:38:19 2013
@@ -604,7 +604,9 @@ void *asan_malloc(uptr size, StackTrace
 void *asan_calloc(uptr nmemb, uptr size, StackTrace *stack) {
   if (CallocShouldReturnNullDueToOverflow(size, nmemb)) return 0;
   void *ptr = Allocate(nmemb * size, 8, stack, FROM_MALLOC);
-  if (ptr)
+  // If the memory comes from the secondary allocator no need to clear it
+  // as it comes directly from mmap.
+  if (ptr && allocator.FromPrimary(ptr))
     REAL(memset)(ptr, 0, nmemb * size);
   return ptr;
 }

Modified: compiler-rt/trunk/lib/asan/tests/asan_noinst_test.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/tests/asan_noinst_test.cc?rev=176185&r1=176184&r2=176185&view=diff
==============================================================================
--- compiler-rt/trunk/lib/asan/tests/asan_noinst_test.cc (original)
+++ compiler-rt/trunk/lib/asan/tests/asan_noinst_test.cc Wed Feb 27 07:38:19 2013
@@ -857,3 +857,21 @@ TEST(AddressSanitizerInterface, CallocOv
   EXPECT_EQ(0L, Ident(p));
 #endif
 }
+
+TEST(AddressSanitizerInterface, CallocReturnsZeroMem) {
+  size_t sizes[] = {16, 1000, 10000, 100000, 2100000};
+  for (size_t s = 0; s < ARRAY_SIZE(sizes); s++) {
+    size_t size = sizes[s];
+    for (size_t iter = 0; iter < 5; iter++) {
+      char *x = Ident((char*)calloc(1, size));
+      EXPECT_EQ(x[0], 0);
+      EXPECT_EQ(x[size - 1], 0);
+      EXPECT_EQ(x[size / 2], 0);
+      EXPECT_EQ(x[size / 3], 0);
+      EXPECT_EQ(x[size / 4], 0);
+      memset(x, 0x42, size);
+      free(Ident(x));
+      free(Ident(malloc(Ident(1 << 27))));  // Try to drain the quarantine.
+    }
+  }
+}