}
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();
}
--- /dev/null
+; 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
+}