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[DL] Optimize address space zero lookup (NFC) 

Information for pointer size/alignment/etc is queried a lot, but
the binary search based implementation makes this fairly slow.

Add an explicit check for address space zero and skip the search
in that case -- we need to specially handle the zero address space
anyway, as it serves as the fallback for all address spaces that
were not explicitly defined.

I initially wanted to simply replace the binary search with a
linear search, which would handle both address space zero and the
general case efficiently, but I was not sure whether there are
any degenerate targets that use more than a handful of declared
address spaces (in-tree, even AMDGPU only declares six).
This commit is contained in:
Nikita Popov 2020-11-29 21:21:37 +01:00
parent 048b16f7fb
commit 891170e863
2 changed files with 22 additions and 37 deletions
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7
llvm/include/llvm/IR/DataLayout.h
View File

@ -161,12 +161,7 @@ private:
using PointersTy = SmallVector<PointerAlignElem, 8>;
PointersTy Pointers;
PointersTy::const_iterator
findPointerLowerBound(uint32_t AddressSpace) const {
return const_cast<DataLayout *>(this)->findPointerLowerBound(AddressSpace);
}
PointersTy::iterator findPointerLowerBound(uint32_t AddressSpace);
const PointerAlignElem &getPointerAlignElem(uint32_t AddressSpace) const;
// The StructType -> StructLayout map.
mutable void *LayoutMap = nullptr;

52
llvm/lib/IR/DataLayout.cpp
View File

@ -582,12 +582,19 @@ Error DataLayout::setAlignment(AlignTypeEnum align_type, Align abi_align,
return Error::success();
}
DataLayout::PointersTy::iterator
DataLayout::findPointerLowerBound(uint32_t AddressSpace) {
return std::lower_bound(Pointers.begin(), Pointers.end(), AddressSpace,
[](const PointerAlignElem &A, uint32_t AddressSpace) {
return A.AddressSpace < AddressSpace;
});
const PointerAlignElem &
DataLayout::getPointerAlignElem(uint32_t AddressSpace) const {
if (AddressSpace != 0) {
auto I = lower_bound(Pointers, AddressSpace,
[](const PointerAlignElem &A, uint32_t AddressSpace) {
return A.AddressSpace < AddressSpace;
});
if (I != Pointers.end() && I->AddressSpace == AddressSpace)
return *I;
}
assert(Pointers[0].AddressSpace == 0);
return Pointers[0];
}
Error DataLayout::setPointerAlignment(uint32_t AddrSpace, Align ABIAlign,
@ -597,7 +604,10 @@ Error DataLayout::setPointerAlignment(uint32_t AddrSpace, Align ABIAlign,
return reportError(
"Preferred alignment cannot be less than the ABI alignment");
PointersTy::iterator I = findPointerLowerBound(AddrSpace);
auto I = lower_bound(Pointers, AddrSpace,
[](const PointerAlignElem &A, uint32_t AddressSpace) {
return A.AddressSpace < AddressSpace;
});
if (I == Pointers.end() || I->AddressSpace != AddrSpace) {
Pointers.insert(I, PointerAlignElem::get(AddrSpace, ABIAlign, PrefAlign,
TypeByteWidth, IndexWidth));
@ -712,30 +722,15 @@ const StructLayout *DataLayout::getStructLayout(StructType *Ty) const {
}
Align DataLayout::getPointerABIAlignment(unsigned AS) const {
PointersTy::const_iterator I = findPointerLowerBound(AS);
if (I == Pointers.end() || I->AddressSpace != AS) {
I = findPointerLowerBound(0);
assert(I->AddressSpace == 0);
}
return I->ABIAlign;
return getPointerAlignElem(AS).ABIAlign;
}
Align DataLayout::getPointerPrefAlignment(unsigned AS) const {
PointersTy::const_iterator I = findPointerLowerBound(AS);
if (I == Pointers.end() || I->AddressSpace != AS) {
I = findPointerLowerBound(0);
assert(I->AddressSpace == 0);
}
return I->PrefAlign;
return getPointerAlignElem(AS).PrefAlign;
}
unsigned DataLayout::getPointerSize(unsigned AS) const {
PointersTy::const_iterator I = findPointerLowerBound(AS);
if (I == Pointers.end() || I->AddressSpace != AS) {
I = findPointerLowerBound(0);
assert(I->AddressSpace == 0);
}
return I->TypeByteWidth;
return getPointerAlignElem(AS).TypeByteWidth;
}
unsigned DataLayout::getMaxPointerSize() const {
@ -754,12 +749,7 @@ unsigned DataLayout::getPointerTypeSizeInBits(Type *Ty) const {
}
unsigned DataLayout::getIndexSize(unsigned AS) const {
PointersTy::const_iterator I = findPointerLowerBound(AS);
if (I == Pointers.end() || I->AddressSpace != AS) {
I = findPointerLowerBound(0);
assert(I->AddressSpace == 0);
}
return I->IndexWidth;
return getPointerAlignElem(AS).IndexWidth;
}
unsigned DataLayout::getIndexTypeSizeInBits(Type *Ty) const {