================
@@ -2282,6 +2282,15 @@ Instruction
*InstCombinerImpl::visitGetElementPtrInst(GetElementPtrInst &GEP) {
if (MadeChange)
return &GEP;
+ // Canonicalize constant GEPs to i8 type.
----------------
brunodf-snps wrote:
Reading about the [planned
steps](https://www.npopov.com/2024/01/01/This-year-in-LLVM-2023.html#ptradd) to
move from getelementptr to ptradd, I would appreciate the opportunity to
**not** add more hardcoded instances of i8 (i.e. `isIntegerTy(8)` or
`getInt8Ty` below) in this effort. You don't need an 8 bit container, you want
the canonical type that has getTypeStoreSize(Ty) == 1, it would be much better
if there was a minimal API that is just a slight abstraction over i8 but that
makes this goal apparent. (I would personally use something with the
terminology "addressable unit type", so "isAddressableUnitType",
"getAddressableUnitType" etc.)
For context, we are also a downstream user in architectural contexts with
memories that are not byte addressable. This can be a main memory that is word
addressable and does not have byte or sub-word access (so the canonical unit
type is naturally i16 or i24... although i8 would still work), but also
additional memories that cannot hold integers at all, for example, a separate
memory (address space) for vectors (the canonical unit type is a vector and i8
is not storable in that memory/address space). Whenever there are hardcoded
instances of i8 in the code base, we typically have to review them in our tree
(yes, SCEVExpander). But it makes a difference whether the code is assuming an
8 bit container, or just needs a type with getTypeStoreSize(Ty) == 1.
https://github.com/llvm/llvm-project/pull/68882
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