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| author | Kostya Serebryany <kcc@google.com> | 2013-11-21 07:29:28 +0000 |
|---|---|---|
| committer | Kostya Serebryany <kcc@google.com> | 2013-11-21 07:29:28 +0000 |
| commit | 42a9da35b839b3a2bb0c891ecc7e138da016f1dd (patch) | |
| tree | 3f6d9220650abb6067aa54caf06602a750fe1aa8 | |
| parent | 072ebe59e2b05af9e67a691163273b9ab2b96b3b (diff) | |
| download | llvm-42a9da35b839b3a2bb0c891ecc7e138da016f1dd.tar.gz llvm-42a9da35b839b3a2bb0c891ecc7e138da016f1dd.tar.bz2 llvm-42a9da35b839b3a2bb0c891ecc7e138da016f1dd.tar.xz | |
Don't speculate loads under ThreadSanitizer
Summary:
Don't speculate loads under ThreadSanitizer.
This fixes https://code.google.com/p/thread-sanitizer/issues/detail?id=40
Also discussed here: http://lists.cs.uiuc.edu/pipermail/llvmdev/2013-November/067929.html
Reviewers: chandlerc
Reviewed By: chandlerc
CC: llvm-commits, dvyukov
Differential Revision: http://llvm-reviews.chandlerc.com/D2227
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195324 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | lib/Analysis/ValueTracking.cpp | 4 | ||||
| -rw-r--r-- | test/Transforms/SimplifyCFG/no_speculative_loads_with_tsan.ll | 40 |
2 files changed, 43 insertions, 1 deletions
diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp index e39ee628ff..803051d0bb 100644 --- a/lib/Analysis/ValueTracking.cpp +++ b/lib/Analysis/ValueTracking.cpp @@ -2006,7 +2006,9 @@ bool llvm::isSafeToSpeculativelyExecute(const Value *V, } case Instruction::Load: { const LoadInst *LI = cast<LoadInst>(Inst); - if (!LI->isUnordered()) + if (!LI->isUnordered() || + // Speculative load may create a race that did not exist in the source. + LI->getParent()->getParent()->hasFnAttribute(Attribute::SanitizeThread)) return false; return LI->getPointerOperand()->isDereferenceablePointer(); } diff --git a/test/Transforms/SimplifyCFG/no_speculative_loads_with_tsan.ll b/test/Transforms/SimplifyCFG/no_speculative_loads_with_tsan.ll new file mode 100644 index 0000000000..b388cc5830 --- /dev/null +++ b/test/Transforms/SimplifyCFG/no_speculative_loads_with_tsan.ll @@ -0,0 +1,40 @@ +; RUN: opt -simplifycfg -S %s | FileCheck %s +; Make sure we don't speculate loads under ThreadSanitizer. +@g = global i32 0, align 4 + +define i32 @TestNoTsan(i32 %cond) nounwind readonly uwtable { +entry: + %tobool = icmp eq i32 %cond, 0 + br i1 %tobool, label %return, label %if.then + +if.then: ; preds = %entry + %0 = load i32* @g, align 4 + br label %return + +return: ; preds = %entry, %if.then + %retval = phi i32 [ %0, %if.then ], [ 0, %entry ] + ret i32 %retval +; CHECK-LABEL: @TestNoTsan +; CHECK: %[[LOAD:[^ ]*]] = load +; CHECK: select{{.*}}[[LOAD]] +; CHECK: ret i32 +} + +define i32 @TestTsan(i32 %cond) nounwind readonly uwtable sanitize_thread { +entry: + %tobool = icmp eq i32 %cond, 0 + br i1 %tobool, label %return, label %if.then + +if.then: ; preds = %entry + %0 = load i32* @g, align 4 + br label %return + +return: ; preds = %entry, %if.then + %retval = phi i32 [ %0, %if.then ], [ 0, %entry ] + ret i32 %retval +; CHECK-LABEL: @TestTsan +; CHECK: br i1 +; CHECK: load i32* @g +; CHECK: br label +; CHECK: ret i32 +} |