Fix kernel_arg_base_type for OpenCL type arguments

The metadata node !kernel_arg_base_type must mirror !kernel_arg_type for
OpenCL builtin types (e.g. image1d_t). Unfortunately, this is
inconsistent with LLVM 16-based Common Clang.

This patch ensures that every OpenCL builtin type (*_t) listed in
!kernel_arg_type is also present in !kernel_arg_base_type at the same
position.

Author: michalpaszkowski

IGC/AdaptorOCL/preprocess_spvir/PreprocessSPVIR.cpp

@@ -177,6 +177,61 @@ void PreprocessSPVIR::visitCallInst(CallInst& CI)
     }
 }
 
+static void fixKernelArgBaseTypes(Module &M) {
+  LLVMContext &Ctx = M.getContext();
+
+  for (Function &F : M) {
+    if (F.isDeclaration())
+      continue;
+
+    MDNode *TyMD = F.getMetadata("kernel_arg_type");
+    MDNode *BaseMD = F.getMetadata("kernel_arg_base_type");
+    if (!TyMD)
+      continue;
+
+    if (!BaseMD) {
+      // OpenCL base type node missing, copy all.
+      F.setMetadata("kernel_arg_base_type", TyMD);
+      continue;
+    }
+
+    unsigned N = TyMD->getNumOperands();
+    if (BaseMD->getNumOperands() != N) {
+      // Mismatched sizes.
+      continue;
+    }
+
+    bool NeedPatch = false;
+    SmallVector<Metadata *, 8> NewBase;
+    NewBase.reserve(N);
+
+    for (unsigned i = 0; i < N; ++i) {
+      auto *TyStr = dyn_cast<MDString>(TyMD->getOperand(i));
+      auto *BaseStr = dyn_cast<MDString>(BaseMD->getOperand(i));
+      // Keep original if found non‑MDString.
+      if (!TyStr || !BaseStr) {
+        NewBase.push_back(BaseMD->getOperand(i));
+        continue;
+      }
+
+      StringRef Ty = TyStr->getString();
+      StringRef Base = BaseStr->getString();
+
+      if (Ty.endswith("_t") && Ty != Base) {
+        NeedPatch = true;
+        NewBase.push_back(MDString::get(Ctx, Ty));
+      } else {
+        NewBase.push_back(BaseStr);
+      }
+    }
+
+    if (NeedPatch) {
+      MDNode *Patched = MDNode::get(Ctx, NewBase);
+      F.setMetadata("kernel_arg_base_type", Patched);
+    }
+  }
+}
+
 bool PreprocessSPVIR::runOnModule(Module& M) {
     m_Module = static_cast<IGCLLVM::Module*>(&M);
     IRBuilder<> builder(M.getContext());
@@ -188,6 +243,13 @@ bool PreprocessSPVIR::runOnModule(Module& M) {
 
     visit(M);
 
+    // Ensure that every OpenCL builtin type (*_t) listed in !kernel_arg_type is
+    // also present in !kernel_arg_base_type at the same position. Some
+    // frontends with partial TargetExtTy support emit pointer types in
+    // !kernel_arg_base_type (instead of an actual OpenCL builtin type), this is
+    // incorrect and inconsistent with the prior behavior.
+    fixKernelArgBaseTypes(M);
+
     // Retype function arguments of OpenCL types represented as TargetExtTy to
     // use opaque pointers instead. This is necessary to match function
     // signatures generated by Clang, given that it only has partial TargetExtTy

IGC/Compiler/InitializePasses.h

@@ -271,6 +271,7 @@ void initializeIGCFunctionExternalRegPressureAnalysisPass(llvm::PassRegistry&);
 void initializePromoteConstantStructsPass(llvm::PassRegistry&);
 void initializeLowerInvokeSIMDPass(llvm::PassRegistry&);
 void initializeRemoveCodeAssumptionsPass(llvm::PassRegistry&);
+void initializePreprocessSPVIRPass(llvm::PassRegistry&);
 void initializePromoteBoolsPass(llvm::PassRegistry&);
 void initializeResolveConstExprCallsPass(llvm::PassRegistry&);
 void initializeHandleSpirvDecorationMetadataPass(llvm::PassRegistry&);

IGC/Compiler/tests/PreprocessSPVIR/fix-kernel_arg_base_type.ll

@@ -0,0 +1,24 @@
+;=========================== begin_copyright_notice ============================
+;
+; Copyright (C) 2025 Intel Corporation
+;
+; SPDX-License-Identifier: MIT
+;
+;============================ end_copyright_notice =============================
+
+; REQUIRES: llvm-16-plus
+; RUN: igc_opt --opaque-pointers -igc-preprocess-spvir -S < %s | FileCheck %s
+
+; The second element of !kernel_arg_base_type is deliberately wrong
+; ("char*" instead of "image1d_t"). The pass must make the node
+; identical to !kernel_arg_type.
+
+define spir_kernel void @testKernel(target("spirv.Image", void, 0, 0, 0, 0, 0, 0, 2) %img, ptr addrspace(1) %newImg, target("spirv.Image", void, 0, 0, 0, 0, 0, 0, 1) %storeResultsImg) !kernel_arg_type !0 !kernel_arg_base_type !1 {
+  ret void
+}
+
+!0 = !{!"image1d_t", !"image1d_t", !"image1d_t"}
+!1 = !{!"image1d_t", !"char*",     !"image1d_t"}
+
+; CHECK: !kernel_arg_base_type ![[BASE:[0-9]+]]
+; CHECK: ![[BASE]] = !{!"image1d_t", !"image1d_t", !"image1d_t"}