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Generalize SROA to allow the first index of a GEP to be non-zero. Add a
missing check that an array reference doesn't go past the end of the array, and remove some redundant checks for in-bound array and vector references that are no longer needed. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91897 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -464,13 +464,6 @@ void SROA::isSafeGEP(GetElementPtrInst *GEPI, AllocaInst *AI,
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if (GEPIt == E)
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return;
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// The first GEP index must be zero.
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if (!isa<ConstantInt>(GEPIt.getOperand()) ||
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!cast<ConstantInt>(GEPIt.getOperand())->isZero())
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return MarkUnsafe(Info);
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if (++GEPIt == E)
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return;
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// Walk through the GEP type indices, checking the types that this indexes
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// into.
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for (; GEPIt != E; ++GEPIt) {
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@ -481,24 +474,10 @@ void SROA::isSafeGEP(GetElementPtrInst *GEPI, AllocaInst *AI,
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ConstantInt *IdxVal = dyn_cast<ConstantInt>(GEPIt.getOperand());
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if (!IdxVal)
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return MarkUnsafe(Info);
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if (const ArrayType *AT = dyn_cast<ArrayType>(*GEPIt)) {
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// This GEP indexes an array. Verify that this is an in-range constant
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// integer. Specifically, consider A[0][i]. We cannot know that the user
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// isn't doing invalid things like allowing i to index an out-of-range
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// subscript that accesses A[1]. Because of this, we have to reject SROA
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// of any accesses into structs where any of the components are variables.
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if (IdxVal->getZExtValue() >= AT->getNumElements())
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return MarkUnsafe(Info);
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} else {
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const VectorType *VT = cast<VectorType>(*GEPIt);
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if (IdxVal->getZExtValue() >= VT->getNumElements())
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return MarkUnsafe(Info);
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}
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}
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// All the indices are safe. Now compute the offset due to this GEP and
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// check if the alloca has a component element at that offset.
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// Compute the offset due to this GEP and check if the alloca has a
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// component element at that offset.
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SmallVector<Value*, 8> Indices(GEPI->op_begin() + 1, GEPI->op_end());
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Offset += TD->getIndexedOffset(GEPI->getPointerOperandType(),
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&Indices[0], Indices.size());
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@ -552,6 +531,8 @@ bool SROA::TypeHasComponent(const Type *T, uint64_t Offset, uint64_t Size) {
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} else if (const ArrayType *AT = dyn_cast<ArrayType>(T)) {
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EltTy = AT->getElementType();
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EltSize = TD->getTypeAllocSize(EltTy);
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if (Offset >= AT->getNumElements() * EltSize)
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return false;
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Offset %= EltSize;
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} else {
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return false;
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53
test/Transforms/ScalarRepl/nonzero-first-index.ll
Normal file
53
test/Transforms/ScalarRepl/nonzero-first-index.ll
Normal file
@ -0,0 +1,53 @@
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; RUN: opt < %s -scalarrepl -S | FileCheck %s
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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-f80:32:32-n8:16:32"
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target triple = "i386-pc-linux-gnu"
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%nested = type { i32, [4 x i32] }
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; Check that a GEP with a non-zero first index does not prevent SROA as long
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; as the resulting offset corresponds to an element in the alloca.
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define i32 @test1() {
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; CHECK: @test1
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; CHECK-NOT: = i160
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; CHECK: ret i32 undef
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%A = alloca %nested
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%B = getelementptr %nested* %A, i32 0, i32 1, i32 0
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%C = getelementptr i32* %B, i32 2
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%D = load i32* %C
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ret i32 %D
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}
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; But, if the offset is out of range, then it should not be transformed.
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define i32 @test2() {
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; CHECK: @test2
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; CHECK: i160
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%A = alloca %nested
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%B = getelementptr %nested* %A, i32 0, i32 1, i32 0
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%C = getelementptr i32* %B, i32 4
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%D = load i32* %C
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ret i32 %D
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}
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; Try it with a bitcast and single GEP....
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define i32 @test3() {
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; CHECK: @test3
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; CHECK-NOT: = i160
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; CHECK: ret i32 undef
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%A = alloca %nested
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%B = bitcast %nested* %A to i32*
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%C = getelementptr i32* %B, i32 2
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%D = load i32* %C
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ret i32 %D
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}
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; ...and again make sure that out-of-range accesses are not transformed.
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define i32 @test4() {
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; CHECK: @test4
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; CHECK: i160
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%A = alloca %nested
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%B = bitcast %nested* %A to i32*
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%C = getelementptr i32* %B, i32 -1
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%D = load i32* %C
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ret i32 %D
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}
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