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IRGen: fix the address alignment calculation of index_addr and tail_a… #4856

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Merged
merged 1 commit into from
Sep 19, 2016
Merged

IRGen: fix the address alignment calculation of index_addr and tail_a… #4856

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20 changes: 14 additions & 6 deletions lib/IRGen/GenValueWitness.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1518,7 +1518,9 @@ Address TypeInfo::indexArray(IRGenFunction &IGF, Address base,
// do a byte-level GEP with the proper stride.
const FixedTypeInfo *fixedTI = dyn_cast<FixedTypeInfo>(this);

Address dest;
llvm::Value *destValue = nullptr;
Size stride(1);

// TODO: Arrays currently lower-bound the stride to 1.
if (!fixedTI
|| std::max(Size(1), fixedTI->getFixedStride()) != fixedTI->getFixedSize()) {
Expand All @@ -1528,15 +1530,21 @@ Address TypeInfo::indexArray(IRGenFunction &IGF, Address base,
if (size->getType() != index->getType())
size = IGF.Builder.CreateZExtOrTrunc(size, index->getType());
llvm::Value *distance = IGF.Builder.CreateNSWMul(index, size);
llvm::Value *destValue = IGF.Builder.CreateInBoundsGEP(byteAddr, distance);
destValue = IGF.Builder.CreateInBoundsGEP(byteAddr, distance);
destValue = IGF.Builder.CreateBitCast(destValue, base.getType());
return Address(destValue, base.getAlignment());
} else {
// We don't expose a non-inbounds GEP operation.
llvm::Value *destValue = IGF.Builder.CreateInBoundsGEP(base.getAddress(),
index);
return Address(destValue, base.getAlignment());
destValue = IGF.Builder.CreateInBoundsGEP(base.getAddress(), index);
stride = fixedTI->getFixedStride();
}
if (auto *IndexConst = dyn_cast<llvm::ConstantInt>(index)) {
// If we know the indexing value, we can get a better guess on the
// alignment.
// This even works if the stride is not known (and assumed to be 1).
stride *= IndexConst->getValue().getZExtValue();
}
Alignment Align = base.getAlignment().alignmentAtOffset(stride);
return Address(destValue, Align);
}

Address TypeInfo::roundUpToTypeAlignment(IRGenFunction &IGF, Address base,
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40 changes: 40 additions & 0 deletions test/IRGen/tail_alloc.sil
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Original file line number Diff line number Diff line change
Expand Up @@ -160,4 +160,44 @@ bb0(%0 : $Builtin.RawPointer, %1 : $Int32):
return %r : $()
}

// sizeof(EmptyClass) = 16 bytes
class EmptyClass {
}

sil_vtable EmptyClass {}

// CHECK-LABEL: define{{( protected)?}} i8 @test_align_1_int8
// CHECK: load i8, i8* %{{.*}}, align 1
// CHECK: ret
sil @test_align_1_int8 : $@convention(thin) (EmptyClass) -> Int8 {
bb0(%0 : $EmptyClass):
%a = ref_tail_addr %0 : $EmptyClass, $Int8
%w = integer_literal $Builtin.Word, 1
%i = index_addr %a : $*Int8, %w : $Builtin.Word
%l = load %i : $*Int8
return %l : $Int8
}

// CHECK-LABEL: define{{( protected)?}} i8 @test_align_2_int8
// CHECK: load i8, i8* %{{.*}}, align 2
// CHECK: ret
sil @test_align_2_int8 : $@convention(thin) (EmptyClass) -> Int8 {
bb0(%0 : $EmptyClass):
%a = ref_tail_addr %0 : $EmptyClass, $Int8
%w = integer_literal $Builtin.Word, 2
%i = index_addr %a : $*Int8, %w : $Builtin.Word
%l = load %i : $*Int8
return %l : $Int8
}

// CHECK-LABEL: define{{( protected)?}} i32 @test_align_int32
// CHECK: load i32, i32* %{{.*}}, align 4
// CHECK: ret
sil @test_align_int32 : $@convention(thin) (EmptyClass, Builtin.Word) -> Int32 {
bb0(%0 : $EmptyClass, %1 : $Builtin.Word):
%a = ref_tail_addr %0 : $EmptyClass, $Int32
%i = index_addr %a : $*Int32, %1 : $Builtin.Word
%l = load %i : $*Int32
return %l : $Int32
}