[PATCH] Implement variable-sized alloca instrumentation.

[Yury Gribov]

================
Comment at: lib/asan/asan_report.cc:992
@@ +991,3 @@
+      case kAsanAllocaLeftMagic:
+        bug_descr = "alloca-underflow";
+        break;
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kcc wrote:
> Maybe dynamic-stack-buffer-overflow (for both left and right cases)? 
I think Max did underflow to match messages for ordinary stack.

http://reviews.llvm.org/D6055