[PATCH] tsan: do not instrument not captured values

[Kostya Serebryany]

Cool. 
Do you have any numbers? (E.g. the %% of cases where it fires on SPEC)?

Two comments inlined


================
Comment at: lib/Transforms/Instrumentation/ThreadSanitizer.cpp:349
@@ +348,3 @@
+  DominatorTree DT;
+  DT.recalculate(F);
+
----------------
Don't we want to reuse DT from previous passes, i.e. require it in getAnalysisUsage() ? 

================
Comment at: test/Instrumentation/ThreadSanitizer/capture.ll:17
@@ +16,3 @@
+}
+; CHECK: define void @captured0
+; CHECK: __tsan_write
----------------
CHECK-LABEL, here and below

http://reviews.llvm.org/D7069

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