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msan: Handle musttail calls

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First, avoid calling setTailCall(false) on musttail calls.  The funciton
prototypes should be "congruent", so the shadow layout should be exactly
the same.

Second, avoid inserting instrumentation after a musttail call to
propagate the return value shadow.  We don't need to propagate the
result of a tail call, it should already be in the right place.

Reviewed By: eugenis

Differential Revision: http://reviews.llvm.org/D4331

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215415 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Reid Kleckner 2014-08-12 00:12:43 +00:00
parent 2970677f21
commit 23761603fe
2 changed files with 23 additions and 0 deletions
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10
lib/Transforms/Instrumentation/MemorySanitizer.cpp
View File

@ -2356,6 +2356,12 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
VAHelper->visitCallSite(CS, IRB);
}
// If this is a musttail call site, we can't insert propagation code here.
// The return type of the caller must match the callee, so the shadow should
// already be set up for an immediate return.
if (CS.isMustTailCall())
return;
// Now, get the shadow for the RetVal.
if (!I.getType()->isSized()) return;
IRBuilder<> IRBBefore(&I);
@ -2389,6 +2395,10 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
}
void visitReturnInst(ReturnInst &I) {
// Don't propagate shadow between musttail calls and the return.
if (I.getParent()->getTerminatingMustTailCall())
return;
IRBuilder<> IRB(&I);
Value *RetVal = I.getReturnValue();
if (!RetVal) return;

13
test/Instrumentation/MemorySanitizer/msan_basic.ll
View File

@ -878,3 +878,16 @@ define void @MismatchedReturnTypeTailCall(i32 %a) sanitize_memory {
; CHECK-LABEL: define void @MismatchedReturnTypeTailCall
; CHECK: tail call i32 @InnerTailCall
; CHECK: ret void
declare i32 @InnerMustTailCall(i32 %a)
define i32 @MustTailCall(i32 %a) {
%b = musttail call i32 @InnerMustTailCall(i32 %a)
ret i32 %b
}
; Test that 'musttail' is preserved. The ABI should make this work.
; CHECK-LABEL: define i32 @MustTailCall
; CHECK: musttail call i32 @InnerMustTailCall
; CHECK-NEXT: ret i32