[llvm] [AMDGPU][SDAG] Initial support for ISD::PTRADD (PR #141725)

[Fabian Ritter via llvm-commits]

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@@ -61,6 +61,14 @@ static cl::opt<bool> UseDivergentRegisterIndexing(
     cl::desc("Use indirect register addressing for divergent indexes"),
     cl::init(false));
 
+// TODO This option should be removed once we switch to always using PTRADD in
+// the SelectionDAG.
+static cl::opt<bool> UseSelectionDAGPTRADD(
+    "amdgpu-use-sdag-ptradd", cl::Hidden,
+    cl::desc("Generate ISD::PTRADD nodes for 64-bit pointer arithmetic in the "
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ritter-x2a wrote:

You mean "why only 64-bit", right? That's following [a suggestion by Matt](https://github.com/llvm/llvm-project/pull/141725#discussion_r2111263469), to start only with 64-bit pointers since it simplifies the patches and since the problem I am actually preparing to solve with this only affects codegen for the flat AS 0.

https://github.com/llvm/llvm-project/pull/141725