[HLSL][SPIR-V] Fix LinkageAttribute emission for BuiltIn (#144701)

BuiltIn variables were missing the visibility attribute, which caused
the Linkage capability to be emitted by the backend.

Author: Keenuts

clang/lib/CodeGen/CGHLSLRuntime.cpp

@@ -375,6 +375,7 @@ static llvm::Value *createSPIRVBuiltinLoad(IRBuilder<> &B, llvm::Module &M,
       llvm::GlobalVariable::GeneralDynamicTLSModel,
       /* AddressSpace */ 7, /* isExternallyInitialized= */ true);
   addSPIRVBuiltinDecoration(GV, BuiltInID);
+  GV->setVisibility(llvm::GlobalValue::HiddenVisibility);
   return B.CreateLoad(Ty, GV);
 }
 

clang/test/CodeGenHLSL/semantics/SV_Position.ps.hlsl

@@ -1,6 +1,6 @@
 // RUN: %clang_cc1 -triple spirv-unknown-vulkan1.3-pixel -x hlsl -emit-llvm -finclude-default-header -disable-llvm-passes -o - %s | FileCheck %s
 
-// CHECK: @sv_position = external thread_local addrspace(7) externally_initialized constant <4 x float>, !spirv.Decorations !0
+// CHECK: @sv_position = external hidden thread_local addrspace(7) externally_initialized constant <4 x float>, !spirv.Decorations !0
 
 // CHECK: define void @main() {{.*}} {
 float4 main(float4 p : SV_Position) {

llvm/test/CodeGen/SPIRV/linkage/link-attribute-vk.ll

@@ -0,0 +1,23 @@
+; RUN: llc -verify-machineinstrs -O0 -mtriple=spirv-unknown-vulkan1.3-pixel %s -o - | FileCheck %s
+; RUN: %if spirv-tools %{ llc -O0 -mtriple=spirv-unknown-vulkan1.3-pixel %s -o - -filetype=obj | spirv-val --target-env vulkan1.3 %}
+
+@sv_position = external hidden thread_local local_unnamed_addr addrspace(7) externally_initialized constant <4 x float>, !spirv.Decorations !0
+
+; CHECK-NOT: OpDecorate %[[#var]] LinkageAttributes "sv_position" Import
+
+; CHECK-DAG: %[[#float:]] = OpTypeFloat 32
+; CHECK-DAG: %[[#float4:]] = OpTypeVector %[[#float]]
+; CHECK-DAG: %[[#type:]] = OpTypePointer Input %[[#float4]]
+; CHECK-DAG: %[[#var:]] = OpVariable %[[#type]] Input
+
+; CHECK-NOT: OpDecorate %[[#var]] LinkageAttributes "sv_position" Import
+
+define void @main() #1 {
+entry:
+  ret void
+}
+
+attributes #1 = { "hlsl.shader"="pixel" }
+
+!0 = !{!1}
+!1 = !{i32 11, i32 0}