[llvm] Add support for SPIR-V extension: SPV_INTEL_function_pointers (PR #80759)

[Michal Paszkowski via llvm-commits]

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@@ -343,9 +348,56 @@ bool SPIRVCallLowering::lowerFormalArguments(MachineIRBuilder &MIRBuilder,
                     {static_cast<uint32_t>(LnkTy)}, F.getGlobalIdentifier());
   }
 
+  // Handle function pointers decoration
+  const auto *ST =
+      static_cast<const SPIRVSubtarget *>(&MIRBuilder.getMF().getSubtarget());
+  bool hasFunctionPointers =
+      ST->canUseExtension(SPIRV::Extension::SPV_INTEL_function_pointers);
+  if (hasFunctionPointers) {
+    if (F.hasFnAttribute("referenced-indirectly")) {
+      assert((F.getCallingConv() != CallingConv::SPIR_KERNEL) &&
+             "Unexpected 'referenced-indirectly' attribute of the kernel "
+             "function");
+      buildOpDecorate(FuncVReg, MIRBuilder,
+                      SPIRV::Decoration::ReferencedIndirectlyINTEL, {});
+    }
+  }
+
   return true;
 }
 
+// Used to postpone producing of indirect function pointer types after all
+// indirect calls info is collected
+// TODO:
+// - add a topological sort of IndirectCalls to ensure the best types knowledge
+// - we may need to fix function formal parameter types if they are opaque
+//   pointers used as function pointers in these indirect calls
+void SPIRVCallLowering::produceIndirectPtrTypes(
+    MachineIRBuilder &MIRBuilder) const {
+  // Create indirect call data types if any
+  MachineFunction &MF = MIRBuilder.getMF();
+  for (auto const &IC : IndirectCalls) {
+    SPIRVType *SpirvRetTy = GR->getOrCreateSPIRVType(IC.RetTy, MIRBuilder);
+    SmallVector<SPIRVType *, 4> SpirvArgTypes;
+    for (size_t i = 0; i < IC.ArgTys.size(); ++i) {
+      SPIRVType *SPIRVTy = GR->getOrCreateSPIRVType(IC.ArgTys[i], MIRBuilder);
+      SpirvArgTypes.push_back(SPIRVTy);
+      if (!GR->getSPIRVTypeForVReg(IC.ArgRegs[i]))
+        GR->assignSPIRVTypeToVReg(SPIRVTy, IC.ArgRegs[i], MF);
+    }
+    // SPIR-V function type:
+    FunctionType *FTy =
+        FunctionType::get(const_cast<Type *>(IC.RetTy), IC.ArgTys, false);
+    SPIRVType *SpirvFuncTy = GR->getOrCreateOpTypeFunctionWithArgs(
+        FTy, SpirvRetTy, SpirvArgTypes, MIRBuilder);
+    // SPIR-V pointer to function type:
+    SPIRVType *IndirectFuncPtrTy = GR->getOrCreateSPIRVPointerType(
+        SpirvFuncTy, MIRBuilder, SPIRV::StorageClass::Function);
+    // Correct the Calee type
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michalpaszkowski wrote:

Typo: Calee -> Callee

https://github.com/llvm/llvm-project/pull/80759