[Sanitizers] 32 bit allocator respects allocator_may_return_null flag

Summary:
Make SizeClassAllocator32 return nullptr when it encounters OOM, which
allows the entire sanitizer's allocator to follow allocator_may_return_null=1
policy, even for small allocations (LargeMmapAllocator is already fixed
by D34243).

Will add a test for OOM in primary allocator later, when
SizeClassAllocator64 can gracefully handle OOM too.

Reviewers: eugenis

Subscribers: kubamracek, llvm-commits

Differential Revision: https://reviews.llvm.org/D34433

llvm-svn: 305972

1 files changed, 5 insertions, 2 deletions

diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_posix.cc b/compiler-rt/lib/sanitizer_common/sanitizer_posix.cc
index 4184a84c73f..87c5b9add5c 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_posix.cc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_posix.cc
@@ -164,11 +164,14 @@ void *MmapOrDieOnFatalError(uptr size, const char *mem_type) {
 // We want to map a chunk of address space aligned to 'alignment'.
 // We do it by maping a bit more and then unmaping redundant pieces.
 // We probably can do it with fewer syscalls in some OS-dependent way.
-void *MmapAlignedOrDie(uptr size, uptr alignment, const char *mem_type) {
+void *MmapAlignedOrDieOnFatalError(uptr size, uptr alignment,
+                                   const char *mem_type) {
   CHECK(IsPowerOfTwo(size));
   CHECK(IsPowerOfTwo(alignment));
   uptr map_size = size + alignment;
-  uptr map_res = (uptr)MmapOrDie(map_size, mem_type);
+  uptr map_res = (uptr)MmapOrDieOnFatalError(map_size, mem_type);
+  if (!map_res)
+    return nullptr;
   uptr map_end = map_res + map_size;
   uptr res = map_res;
   if (res & (alignment - 1))  // Not aligned.