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[tsan] disable load widening in ThreadSanitizer mode 

llvm-svn: 175034
This commit is contained in:
Kostya Serebryany 2013-02-13 05:59:45 +00:00
parent caf11af9d3
commit 3838f27905
2 changed files with 32 additions and 0 deletions
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6
llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
View File

@ -283,6 +283,12 @@ getLoadLoadClobberFullWidthSize(const Value *MemLocBase, int64_t MemLocOffs,
const DataLayout &TD) {
// We can only extend simple integer loads.
if (!isa<IntegerType>(LI->getType()) || !LI->isSimple()) return 0;
// Load widening is hostile to ThreadSanitizer: it may cause false positives
// or make the reports more cryptic (access sizes are wrong).
if (LI->getParent()->getParent()->getAttributes().
hasAttribute(AttributeSet::FunctionIndex, Attribute::ThreadSafety))
return 0;
// Get the base of this load.
int64_t LIOffs = 0;

26
llvm/test/Instrumentation/ThreadSanitizer/tsan-vs-gvn.ll Normal file
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@ -0,0 +1,26 @@
; RUN: opt < %s -basicaa -gvn -tsan -S | FileCheck %s
; TSAN conflicts with load widening. Make sure the load widening is off with -tsan.
; 32-bit little endian target.
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128-n8:16:32"
%struct_of_8_bytes_4_aligned = type { i32, i8, i8, i8, i8}
@f = global %struct_of_8_bytes_4_aligned zeroinitializer, align 4
; Accessing bytes 4 and 6, not ok to widen to i32 if thread_safety is set.
define i32 @test_widening_bad(i8* %P) nounwind ssp noredzone thread_safety {
entry:
%tmp = load i8* getelementptr inbounds (%struct_of_8_bytes_4_aligned* @f, i64 0, i32 1), align 4
%conv = zext i8 %tmp to i32
%tmp1 = load i8* getelementptr inbounds (%struct_of_8_bytes_4_aligned* @f, i64 0, i32 3), align 1
%conv2 = zext i8 %tmp1 to i32
%add = add nsw i32 %conv, %conv2
ret i32 %add
; CHECK: @test_widening_bad
; CHECK: call void @__tsan_read1
; CHECK: call void @__tsan_read1
; CHECK-NOT: call void @__tsan_read4
; CHECK: ret i32
}