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-rw-r--r--llvm/lib/Transforms/Scalar/SROA.cpp44
-rw-r--r--llvm/test/Transforms/SROA/alignment.ll63
2 files changed, 87 insertions, 20 deletions
diff --git a/llvm/lib/Transforms/Scalar/SROA.cpp b/llvm/lib/Transforms/Scalar/SROA.cpp
index 316742a0da6..58bae0971e3 100644
--- a/llvm/lib/Transforms/Scalar/SROA.cpp
+++ b/llvm/lib/Transforms/Scalar/SROA.cpp
@@ -2170,18 +2170,36 @@ private:
return getAdjustedPtr(IRB, TD, &NewAI, Offset, PointerTy, getName(""));
}
- unsigned getAdjustedAlign(uint64_t Offset) {
+ /// \brief Compute suitable alignment to access an offset into the new alloca.
+ unsigned getOffsetAlign(uint64_t Offset) {
unsigned NewAIAlign = NewAI.getAlignment();
if (!NewAIAlign)
NewAIAlign = TD.getABITypeAlignment(NewAI.getAllocatedType());
return MinAlign(NewAIAlign, Offset);
}
- unsigned getAdjustedAlign() {
- return getAdjustedAlign(BeginOffset - NewAllocaBeginOffset);
+
+ /// \brief Compute suitable alignment to access this partition of the new
+ /// alloca.
+ unsigned getPartitionAlign() {
+ return getOffsetAlign(BeginOffset - NewAllocaBeginOffset);
}
- bool isTypeAlignSufficient(Type *Ty) {
- return TD.getABITypeAlignment(Ty) >= getAdjustedAlign();
+ /// \brief Compute suitable alignment to access a type at an offset of the
+ /// new alloca.
+ ///
+ /// \returns zero if the type's ABI alignment is a suitable alignment,
+ /// otherwise returns the maximal suitable alignment.
+ unsigned getOffsetTypeAlign(Type *Ty, uint64_t Offset) {
+ unsigned Align = getOffsetAlign(Offset);
+ return Align == TD.getABITypeAlignment(Ty) ? 0 : Align;
+ }
+
+ /// \brief Compute suitable alignment to access a type at the beginning of
+ /// this partition of the new alloca.
+ ///
+ /// See \c getOffsetTypeAlign for details; this routine delegates to it.
+ unsigned getPartitionTypeAlign(Type *Ty) {
+ return getOffsetTypeAlign(Ty, BeginOffset - NewAllocaBeginOffset);
}
ConstantInt *getIndex(IRBuilder<> &IRB, uint64_t Offset) {
@@ -2292,8 +2310,7 @@ private:
Value *NewPtr = getAdjustedAllocaPtr(IRB,
LI.getPointerOperand()->getType());
LI.setOperand(0, NewPtr);
- if (LI.getAlignment() || !isTypeAlignSufficient(LI.getType()))
- LI.setAlignment(getAdjustedAlign());
+ LI.setAlignment(getPartitionTypeAlign(LI.getType()));
DEBUG(dbgs() << " to: " << LI << "\n");
deleteIfTriviallyDead(OldOp);
@@ -2345,12 +2362,7 @@ private:
Value *NewPtr = getAdjustedAllocaPtr(IRB,
SI.getPointerOperand()->getType());
SI.setOperand(1, NewPtr);
- if (SI.getAlignment() ||
- !isTypeAlignSufficient(SI.getValueOperand()->getType()))
- SI.setAlignment(getAdjustedAlign());
- if (SI.getAlignment())
- SI.setAlignment(MinAlign(NewAI.getAlignment(),
- BeginOffset - NewAllocaBeginOffset));
+ SI.setAlignment(getPartitionTypeAlign(SI.getValueOperand()->getType()));
DEBUG(dbgs() << " to: " << SI << "\n");
deleteIfTriviallyDead(OldOp);
@@ -2367,7 +2379,7 @@ private:
if (!isa<Constant>(II.getLength())) {
II.setDest(getAdjustedAllocaPtr(IRB, II.getRawDest()->getType()));
Type *CstTy = II.getAlignmentCst()->getType();
- II.setAlignment(ConstantInt::get(CstTy, getAdjustedAlign()));
+ II.setAlignment(ConstantInt::get(CstTy, getPartitionAlign()));
deleteIfTriviallyDead(OldPtr);
return false;
@@ -2391,7 +2403,7 @@ private:
CallInst *New
= IRB.CreateMemSet(getAdjustedAllocaPtr(IRB,
II.getRawDest()->getType()),
- II.getValue(), Size, getAdjustedAlign(),
+ II.getValue(), Size, getPartitionAlign(),
II.isVolatile());
(void)New;
DEBUG(dbgs() << " to: " << *New << "\n");
@@ -2481,7 +2493,7 @@ private:
unsigned Align = II.getAlignment();
if (Align > 1)
Align = MinAlign(RelOffset.zextOrTrunc(64).getZExtValue(),
- MinAlign(II.getAlignment(), getAdjustedAlign()));
+ MinAlign(II.getAlignment(), getPartitionAlign()));
// For unsplit intrinsics, we simply modify the source and destination
// pointers in place. This isn't just an optimization, it is a matter of
diff --git a/llvm/test/Transforms/SROA/alignment.ll b/llvm/test/Transforms/SROA/alignment.ll
index 4f35a8a0ee3..f8f3270dbb9 100644
--- a/llvm/test/Transforms/SROA/alignment.ll
+++ b/llvm/test/Transforms/SROA/alignment.ll
@@ -31,8 +31,8 @@ entry:
define void @test2() {
; CHECK: @test2
; CHECK: alloca i16
-; CHECK: load i8* %{{.*}}, align 1
-; CHECK: store i8 42, i8* %{{.*}}, align 1
+; CHECK: load i8* %{{.*}}
+; CHECK: store i8 42, i8* %{{.*}}
; CHECK: ret void
entry:
@@ -41,8 +41,8 @@ entry:
%cast1 = bitcast i8* %gep1 to i16*
store volatile i16 0, i16* %cast1
%gep2 = getelementptr { i8, i8, i8, i8 }* %a, i32 0, i32 2
- %result = load i8* %gep2, align 2
- store i8 42, i8* %gep2, align 2
+ %result = load i8* %gep2
+ store i8 42, i8* %gep2
ret void
}
@@ -114,3 +114,58 @@ entry:
ret void
}
+
+define void @test5() {
+; Test that we preserve underaligned loads and stores when splitting.
+; CHECK: @test5
+; CHECK: alloca [9 x i8]
+; CHECK: alloca [9 x i8]
+; CHECK: store volatile double 0.0{{.*}}, double* %{{.*}}, align 1
+; CHECK: load i16* %{{.*}}, align 1
+; CHECK: load double* %{{.*}}, align 1
+; CHECK: store volatile double %{{.*}}, double* %{{.*}}, align 1
+; CHECK: load i16* %{{.*}}, align 1
+; CHECK: ret void
+
+entry:
+ %a = alloca [18 x i8]
+ %raw1 = getelementptr inbounds [18 x i8]* %a, i32 0, i32 0
+ %ptr1 = bitcast i8* %raw1 to double*
+ store volatile double 0.0, double* %ptr1, align 1
+ %weird_gep1 = getelementptr inbounds [18 x i8]* %a, i32 0, i32 7
+ %weird_cast1 = bitcast i8* %weird_gep1 to i16*
+ %weird_load1 = load i16* %weird_cast1, align 1
+
+ %raw2 = getelementptr inbounds [18 x i8]* %a, i32 0, i32 9
+ %ptr2 = bitcast i8* %raw2 to double*
+ %d1 = load double* %ptr1, align 1
+ store volatile double %d1, double* %ptr2, align 1
+ %weird_gep2 = getelementptr inbounds [18 x i8]* %a, i32 0, i32 16
+ %weird_cast2 = bitcast i8* %weird_gep2 to i16*
+ %weird_load2 = load i16* %weird_cast2, align 1
+
+ ret void
+}
+
+define void @test6() {
+; Test that we promote alignment when the underlying alloca switches to one
+; that innately provides it.
+; CHECK: @test6
+; CHECK: alloca double
+; CHECK: alloca double
+; CHECK-NOT: align
+; CHECK: ret void
+
+entry:
+ %a = alloca [16 x i8]
+ %raw1 = getelementptr inbounds [16 x i8]* %a, i32 0, i32 0
+ %ptr1 = bitcast i8* %raw1 to double*
+ store volatile double 0.0, double* %ptr1, align 1
+
+ %raw2 = getelementptr inbounds [16 x i8]* %a, i32 0, i32 8
+ %ptr2 = bitcast i8* %raw2 to double*
+ %val = load double* %ptr1, align 1
+ store volatile double %val, double* %ptr2, align 1
+
+ ret void
+}
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