do not emit anything if it's an internal service function

Author: VyacheslavLevytskyy

llvm/lib/Target/SPIRV/SPIRVAsmPrinter.cpp

@@ -149,6 +149,10 @@ void SPIRVAsmPrinter::outputOpFunctionEnd() {
 
 // Emit OpFunctionEnd at the end of MF and clear BBNumToRegMap.
 void SPIRVAsmPrinter::emitFunctionBodyEnd() {
+  // Do not emit anything if it's an internal service function.
+  if (MF->getFunction().getFnAttribute(SPIRV_BACKEND_SERVICE_FUN_NAME).isValid())
+    return;
+
   outputOpFunctionEnd();
   MAI->BBNumToRegMap.clear();
 }
@@ -162,7 +166,9 @@ void SPIRVAsmPrinter::emitOpLabel(const MachineBasicBlock &MBB) {
 }
 
 void SPIRVAsmPrinter::emitBasicBlockStart(const MachineBasicBlock &MBB) {
-  assert(!MBB.empty() && "MBB is empty!");
+  // Do not emit anything if it's an internal service function.
+  if (MBB.empty())
+    return;
 
   // If it's the first MBB in MF, it has OpFunction and OpFunctionParameter, so
   // OpLabel should be output after them.
@@ -600,16 +606,6 @@ void SPIRVAsmPrinter::outputModuleSections() {
 }
 
 bool SPIRVAsmPrinter::doInitialization(Module &M) {
-  // Discard the internal service function
-  for (Function &F : M) {
-    if (!F.getFnAttribute(SPIRV_BACKEND_SERVICE_FUN_NAME).isValid())
-      continue;
-    getAnalysis<MachineModuleInfoWrapperPass>()
-        .getMMI()
-        .deleteMachineFunctionFor(F);
-    break;
-  }
-
   ModuleSectionsEmitted = false;
   // We need to call the parent's one explicitly.
   return AsmPrinter::doInitialization(M);

llvm/lib/Target/SPIRV/SPIRVCallLowering.cpp

@@ -36,8 +36,11 @@ bool SPIRVCallLowering::lowerReturn(MachineIRBuilder &MIRBuilder,
                                     const Value *Val, ArrayRef<Register> VRegs,
                                     FunctionLoweringInfo &FLI,
                                     Register SwiftErrorVReg) const {
-  // Discard the internal service function
-  if (FLI.Fn && FLI.Fn->getFnAttribute(SPIRV_BACKEND_SERVICE_FUN_NAME).isValid())
+  // Ignore if called from the internal service function
+  if (MIRBuilder.getMF()
+          .getFunction()
+          .getFnAttribute(SPIRV_BACKEND_SERVICE_FUN_NAME)
+          .isValid())
     return true;
 
   // Maybe run postponed production of types for function pointers
@@ -497,6 +500,16 @@ void SPIRVCallLowering::produceIndirectPtrTypes(
 
 bool SPIRVCallLowering::lowerCall(MachineIRBuilder &MIRBuilder,
                                   CallLoweringInfo &Info) const {
+  // Ignore if called from the internal service function
+  if (MIRBuilder.getMF()
+          .getFunction()
+          .getFnAttribute(SPIRV_BACKEND_SERVICE_FUN_NAME)
+          .isValid()) {
+    // insert a no-op
+    MIRBuilder.buildTrap();
+    return true;
+  }
+
   // Currently call returns should have single vregs.
   // TODO: handle the case of multiple registers.
   if (Info.OrigRet.Regs.size() > 1)

llvm/test/CodeGen/SPIRV/extensions/SPV_INTEL_function_pointers/fp-simple-hierarchy.ll

@@ -1,4 +1,4 @@
-; RUN: llc -verify-machineinstrs -O0 -mtriple=spirv64-unknown-unknown --spirv-ext=+SPV_INTEL_function_pointers %s -o - | FileCheck %s
+; RUN: llc -O0 -mtriple=spirv64-unknown-unknown --spirv-ext=+SPV_INTEL_function_pointers %s -o - | FileCheck %s
 ; TODO: %if spirv-tools %{ llc -O0 -mtriple=spirv64-unknown-unknown %s -o - -filetype=obj | spirv-val %}
 
 ; CHECK: OpFunction