Fix parameter decoration metadata overwrite in entry-point wrapper

In the entry-point wrapper pattern two SPIR-V functions map to the same
LLVM function; only one carries decorated parameters.
transOCLMetadata unconditionally set spirv.ParameterDecorations for both,
so the undecorated function could overwrite the decorated one's metadata.
Skip the write when the current function has no decorations and metadata
is already present.

AI-assisted: Claude Sonnet 4.6 (commercial SaaS)

Author: vmaksimo

lib/SPIRV/SPIRVReader.cpp

@@ -4940,12 +4940,20 @@ bool SPIRVToLLVM::transOCLMetadata(SPIRVFunction *BF) {
     return ConstantAsMetadata::get(
         ConstantInt::get(Type::getInt1Ty(*Context), 1));
   });
-  // Generate metadata for spirv.ParameterDecorations
-  addKernelArgumentMetadata(Context, SPIRV_MD_PARAMETER_DECORATIONS, BF, F,
-                            [=](SPIRVFunctionParameter *Arg) {
-                              return transDecorationsToMetadataList(
-                                  Context, Arg->getDecorations());
-                            });
+  // Generate metadata for spirv.ParameterDecorations.
+  // In the entry-point wrapper pattern two SPIR-V functions map to the same
+  // LLVM function; only one carries decorated parameters.  Skip the
+  // undecorated function so it cannot overwrite the decorated one.
+  bool HasDecorations = false;
+  BF->foreachArgument([&](SPIRVFunctionParameter *Arg) {
+    HasDecorations |= Arg->getNumDecorations() > 0;
+  });
+  if (HasDecorations || !F->hasMetadata(SPIRV_MD_PARAMETER_DECORATIONS))
+    addKernelArgumentMetadata(Context, SPIRV_MD_PARAMETER_DECORATIONS, BF, F,
+                              [=](SPIRVFunctionParameter *Arg) {
+                                return transDecorationsToMetadataList(
+                                    Context, Arg->getDecorations());
+                              });
   return true;
 }
 

test/extensions/INTEL/SPV_INTEL_cache_controls/cache-controls-entry-point-wrapper.spt

@@ -0,0 +1,42 @@
+; Verify that CacheControlLoadINTEL decoration on a FunctionParameter
+; survives reverse translation of the entry-point wrapper pattern.
+
+; RUN: llvm-spirv -spirv-text --to-binary %s -o %t.spv
+; RUN: spirv-val %t.spv
+; RUN: llvm-spirv -spirv-text -r --spirv-target-env=SPV-IR %s -o - | llvm-dis | FileCheck %s --check-prefix=CHECK-LLVM
+
+; CHECK-LLVM: spirv.ParameterDecorations ![[#ParamDecs:]]
+; CHECK-LLVM: ![[#ParamDecs]] = !{![[#FirstParam:]]}
+; CHECK-LLVM: ![[#FirstParam]] = !{![[#DecoNode:]]}
+; CHECK-LLVM: ![[#DecoNode]] = !{i32 6442, i32 0, i32 1}
+
+119734787 66560 393230 14 0
+2 Capability Addresses
+2 Capability Linkage
+2 Capability Kernel
+2 Capability CacheControlsINTEL
+8 Extension "SPV_INTEL_cache_controls"
+5 ExtInstImport 1 "OpenCL.std"
+3 MemoryModel 2 2
+5 EntryPoint 6 9 "test"
+3 Source 4 100000
+4 TypeInt 2 32 0
+2 TypeVoid 3
+4 TypePointer 5 5 2
+4 TypeFunction 6 3 5
+6 Decorate 4 LinkageAttributes "test" Export
+5 Decorate 7 CacheControlLoadINTEL 0 1
+
+5 Function 3 4 0 6
+3 FunctionParameter 5 7
+2 Label 8
+4 Load 2 13 7
+1 Return
+1 FunctionEnd
+
+5 Function 3 9 0 6
+3 FunctionParameter 5 10
+2 Label 11
+5 FunctionCall 3 12 4 10
+1 Return
+1 FunctionEnd