[llvm] [SPIRV] Expand RWBuffer load and store from HLSL (PR #122355)

[Nathan Gauër via llvm-commits]

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@@ -1018,6 +1024,25 @@ bool SPIRVInstructionSelector::selectLoad(Register ResVReg,
                                           MachineInstr &I) const {
   unsigned OpOffset = isa<GIntrinsic>(I) ? 1 : 0;
   Register Ptr = I.getOperand(1 + OpOffset).getReg();
+
+  auto *PtrDef = getVRegDef(*MRI, Ptr);
+  auto *IntPtrDef = dyn_cast<GIntrinsic>(PtrDef);
+  if (IntPtrDef &&
+      IntPtrDef->getIntrinsicID() == Intrinsic::spv_resource_getpointer) {
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Keenuts wrote:

So if the codegen/opti doesn't keep the `getpointer`/`load` duo, but adds another temporary in between, this will fail silently and generate an OpLoad no?
Could reg2mem be an issue?

https://github.com/llvm/llvm-project/pull/122355