[Mlir-commits] [mlir] [mlir][emitc] Add EmitC index types (PR #93155)

[Matthias Gehre]

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@@ -1570,6 +1570,10 @@ LogicalResult CppEmitter::emitType(Location loc, Type type) {
   }
   if (auto iType = dyn_cast<IndexType>(type))
     return (os << "size_t"), success();
+  if (auto sType = dyn_cast<emitc::SizeTType>(type))
+    return (os << "size_t"), success();
+  if (auto sType = dyn_cast<emitc::SignedSizeTType>(type))
+    return (os << "ssize_t"), success();
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mgehre-amd wrote:

Hm, this is my fault, I though `ssize_t` was standardized.  How important is that to you?

We use `ssize_t` in lowerings that need to interpret `index` as `signed` (like `index.divs`). 

Just brainstorming, we could emit this as `intmax_t`, `ptrdiff_t` (C) or `std::make_signed<std::size_t>` (C++11). 
([cppreference says](https://en.cppreference.com/w/cpp/types/ptrdiff_t): `For char arrays shorter than PTRDIFF_MAX, std::ptrdiff_t acts as the signed counterpart of std::size_t`)

https://github.com/llvm/llvm-project/pull/93155