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[msan] Raise alignment of origin stores/loads when possible. 

Origin alignment is as high as the alignment of the corresponding application
location, but never less than 4.

llvm-svn: 171110
This commit is contained in:
Evgeniy Stepanov 2012-12-26 11:55:09 +00:00
parent d8be0c510c
commit 5eb5bf8b46
2 changed files with 20 additions and 7 deletions
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16
llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
View File

@ -100,7 +100,8 @@ static const uint64_t kShadowMask32 = 1ULL << 31;
static const uint64_t kShadowMask64 = 1ULL << 46;
static const uint64_t kOriginOffset32 = 1ULL << 30;
static const uint64_t kOriginOffset64 = 1ULL << 45;
static const uint64_t kShadowTLSAlignment = 8;
static const unsigned kMinOriginAlignment = 4;
static const unsigned kShadowTLSAlignment = 8;
/// \brief Track origins of uninitialized values.
///
@ -451,8 +452,10 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
insertCheck(Addr, &I);
if (MS.TrackOrigins) {
unsigned Alignment = std::max(kMinOriginAlignment, I.getAlignment());
if (ClStoreCleanOrigin || isa<StructType>(Shadow->getType())) {
IRB.CreateStore(getOrigin(Val), getOriginPtr(Addr, IRB));
IRB.CreateAlignedStore(getOrigin(Val), getOriginPtr(Addr, IRB),
Alignment);
} else {
Value *ConvertedShadow = convertToShadowTyNoVec(Shadow, IRB);
@ -469,7 +472,8 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false,
MS.OriginStoreWeights);
IRBuilder<> IRBNew(CheckTerm);
IRBNew.CreateStore(getOrigin(Val), getOriginPtr(Addr, IRBNew));
IRBNew.CreateAlignedStore(getOrigin(Val), getOriginPtr(Addr, IRBNew),
Alignment);
}
}
}
@ -827,8 +831,10 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
if (ClCheckAccessAddress)
insertCheck(I.getPointerOperand(), &I);
if (MS.TrackOrigins)
setOrigin(&I, IRB.CreateLoad(getOriginPtr(Addr, IRB)));
if (MS.TrackOrigins) {
unsigned Alignment = std::max(kMinOriginAlignment, I.getAlignment());
setOrigin(&I, IRB.CreateAlignedLoad(getOriginPtr(Addr, IRB), Alignment));
}
}
/// \brief Instrument StoreInst

11
llvm/test/Instrumentation/MemorySanitizer/msan_basic.ll
View File

@ -56,7 +56,7 @@ entry:
; CHECK-ORIGINS: icmp
; CHECK-ORIGINS: br i1
; CHECK-ORIGINS: <label>
; CHECK-ORIGINS-NOT: store {{.*}} align
; CHECK-ORIGINS: store {{.*}} align 32
; CHECK-ORIGINS: br label
; CHECK-ORIGINS: <label>
; CHECK-ORIGINS: store {{.*}} align 32
@ -362,7 +362,8 @@ define zeroext i1 @ICmpSLE(i32 %x) nounwind uwtable readnone {
; CHECK: ret i1
; Check that loads from shadow have the same aligment as the original loads.
; Check that loads of shadow have the same aligment as the original loads.
; Check that loads of origin have the aligment of max(4, original alignment).
define i32 @ShadowLoadAlignmentLarge() nounwind uwtable {
%y = alloca i32, align 64
@ -386,6 +387,12 @@ define i32 @ShadowLoadAlignmentSmall() nounwind uwtable {
; CHECK: load volatile i32* {{.*}} align 2
; CHECK: ret i32
; CHECK-ORIGINS: @ShadowLoadAlignmentSmall
; CHECK-ORIGINS: load i32* {{.*}} align 2
; CHECK-ORIGINS: load i32* {{.*}} align 4
; CHECK-ORIGINS: load volatile i32* {{.*}} align 2
; CHECK-ORIGINS: ret i32
; Test vector manipulation instructions.
; Check that the same bit manipulation is applied to the shadow values.