diff options
author | Nikita Popov <npopov@redhat.com> | 2024-03-20 10:59:45 +0100 |
---|---|---|
committer | GitHub <noreply@github.com> | 2024-03-20 10:59:45 +0100 |
commit | 0f46e31cfbf415fcd3d3ce121bef94e92c6ccfc8 (patch) | |
tree | f7480770f05cd77458340f1f23104275c9be1614 /llvm/lib/IR/Operator.cpp | |
parent | 1f63a56cede85bcd5f4fea3663bd3a47b801a396 (diff) | |
download | llvm-0f46e31cfbf415fcd3d3ce121bef94e92c6ccfc8.zip llvm-0f46e31cfbf415fcd3d3ce121bef94e92c6ccfc8.tar.gz llvm-0f46e31cfbf415fcd3d3ce121bef94e92c6ccfc8.tar.bz2 |
[IR] Change representation of getelementptr inrange (#84341)
As part of the migration to ptradd
(https://discourse.llvm.org/t/rfc-replacing-getelementptr-with-ptradd/68699),
we need to change the representation of the `inrange` attribute, which
is used for vtable splitting.
Currently, inrange is specified as follows:
```
getelementptr inbounds ({ [4 x ptr], [4 x ptr] }, ptr @vt, i64 0, inrange i32 1, i64 2)
```
The `inrange` is placed on a GEP index, and all accesses must be "in
range" of that index. The new representation is as follows:
```
getelementptr inbounds inrange(-16, 16) ({ [4 x ptr], [4 x ptr] }, ptr @vt, i64 0, i32 1, i64 2)
```
This specifies which offsets are "in range" of the GEP result. The new
representation will continue working when canonicalizing to ptradd
representation:
```
getelementptr inbounds inrange(-16, 16) (i8, ptr @vt, i64 48)
```
The inrange offsets are relative to the return value of the GEP. An
alternative design could make them relative to the source pointer
instead. The result-relative format was chosen on the off-chance that we
want to extend support to non-constant GEPs in the future, in which case
this variant is more expressive.
This implementation "upgrades" the old inrange representation in bitcode
by simply dropping it. This is a very niche feature, and I don't think
trying to upgrade it is worthwhile. Let me know if you disagree.
Diffstat (limited to 'llvm/lib/IR/Operator.cpp')
-rw-r--r-- | llvm/lib/IR/Operator.cpp | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/llvm/lib/IR/Operator.cpp b/llvm/lib/IR/Operator.cpp index caf8fe6..b9cd219 100644 --- a/llvm/lib/IR/Operator.cpp +++ b/llvm/lib/IR/Operator.cpp @@ -37,7 +37,7 @@ bool Operator::hasPoisonGeneratingFlags() const { case Instruction::GetElementPtr: { auto *GEP = cast<GEPOperator>(this); // Note: inrange exists on constexpr only - return GEP->isInBounds() || GEP->getInRangeIndex() != std::nullopt; + return GEP->isInBounds() || GEP->getInRange() != std::nullopt; } case Instruction::ZExt: if (auto *NNI = dyn_cast<PossiblyNonNegInst>(this)) @@ -69,6 +69,12 @@ Type *GEPOperator::getResultElementType() const { return cast<GetElementPtrConstantExpr>(this)->getResultElementType(); } +std::optional<ConstantRange> GEPOperator::getInRange() const { + if (auto *CE = dyn_cast<GetElementPtrConstantExpr>(this)) + return CE->getInRange(); + return std::nullopt; +} + Align GEPOperator::getMaxPreservedAlignment(const DataLayout &DL) const { /// compute the worse possible offset for every level of the GEP et accumulate /// the minimum alignment into Result. |