[SYCL] Fix unconditional spir_func CC on printf declaration for non-SPIR targets

llvm/lib/SYCLLowerIR/MutatePrintfAddrspace.cpp

@@ -51,7 +51,8 @@ static constexpr unsigned ConstantAddrspaceID = 2;
 // of the non-variadic (variadic template) calls.
 using FunctionVecTy = SmallVector<Function *, 8>;
 
-Function *getCASPrintfFunction(Module &M, PointerType *CASLiteralType);
+Function *getCASPrintfFunction(Module &M, PointerType *CASLiteralType,
+                               CallingConv::ID CC);
 size_t setFuncCallsOntoCASPrintf(Function *F, Function *CASPrintfFunc,
                                  FunctionVecTy &FunctionsToDrop);
 } // namespace
@@ -70,7 +71,7 @@ ModulePass *llvm::createSYCLMutatePrintfAddrspaceLegacyPass() {
 PreservedAnalyses
 SYCLMutatePrintfAddrspacePass::run(Module &M, ModuleAnalysisManager &MAM) {
   auto *CASLiteralType = PointerType::get(M.getContext(), ConstantAddrspaceID);
-  Function *CASPrintfFunc = getCASPrintfFunction(M, CASLiteralType);
+  Function *CASPrintfFunc = nullptr;
 
   FunctionVecTy FunctionsToDrop;
   bool ModuleChanged = false;
@@ -82,13 +83,21 @@ SYCLMutatePrintfAddrspacePass::run(Module &M, ModuleAnalysisManager &MAM) {
     if (F.getArg(0)->getType() == CASLiteralType)
       // No need to replace the literal type and its printf users
       continue;
+    if (F.use_empty()) {
+      FunctionsToDrop.emplace_back(&F);
+      ModuleChanged = true;
+      continue;
+    }
+    if (!CASPrintfFunc)
+      CASPrintfFunc =
+          getCASPrintfFunction(M, CASLiteralType, F.getCallingConv());
     ModuleChanged |=
         setFuncCallsOntoCASPrintf(&F, CASPrintfFunc, FunctionsToDrop);
   }
   for (Function *F : FunctionsToDrop)
     F->eraseFromParent();
 
-  return ModuleChanged ? PreservedAnalyses::all() : PreservedAnalyses::none();
+  return ModuleChanged ? PreservedAnalyses::none() : PreservedAnalyses::all();
 }
 
 /// Helper implementations
@@ -97,7 +106,8 @@ namespace {
 /// Get the constant addrspace version of the __spirv_ocl_printf declaration,
 /// or generate it if the IR module doesn't have it yet. Also make it
 /// variadic so that it could replace all non-variadic generic AS versions.
-Function *getCASPrintfFunction(Module &M, PointerType *CASLiteralType) {
+Function *getCASPrintfFunction(Module &M, PointerType *CASLiteralType,
+                               CallingConv::ID CC) {
   Type *Int32Type = Type::getInt32Ty(M.getContext());
   auto *CASPrintfFuncTy = FunctionType::get(Int32Type, CASLiteralType,
                                             /*isVarArg=*/true);
@@ -106,7 +116,7 @@ Function *getCASPrintfFunction(Module &M, PointerType *CASLiteralType) {
   FunctionCallee CASPrintfFuncCallee =
       M.getOrInsertFunction("_Z18__spirv_ocl_printfPU3AS2Kcz", CASPrintfFuncTy);
   auto *CASPrintfFunc = cast<Function>(CASPrintfFuncCallee.getCallee());
-  CASPrintfFunc->setCallingConv(CallingConv::SPIR_FUNC);
+  CASPrintfFunc->setCallingConv(CC);
   CASPrintfFunc->setDSOLocal(true);
   return CASPrintfFunc;
 }

llvm/test/SYCLLowerIR/printf_addrspace/no_printf_no_decl.ll

@@ -0,0 +1,14 @@
+;; Verify that the pass does NOT insert a printf declaration when the module
+;; has no printf functions that need transformation.
+
+; RUN: opt < %s -passes=SYCLMutatePrintfAddrspace -S | FileCheck %s
+
+target datalayout = "e-i64:64-v16:16-v24:32-v32:32-v48:64-v96:128-v192:256-v256:256-v512:512-v1024:1024-n8:16:32:64"
+target triple = "spir64-unknown-unknown"
+
+define spir_kernel void @no_printf_kernel() {
+entry:
+  ret void
+}
+
+; CHECK-NOT: @_Z18__spirv_ocl_printfPU3AS2Kcz

llvm/test/SYCLLowerIR/printf_addrspace/non_spir_target.ll

@@ -0,0 +1,21 @@
+;; Verify that the pass does NOT set spir_func calling convention on the
+;; printf declaration when the target triple is not SPIR/SPIR-V.
+
+; RUN: opt < %s -passes=SYCLMutatePrintfAddrspace -S | FileCheck %s
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@.str = private unnamed_addr constant [6 x i8] c"hello\00", align 1
+
+define void @test_printf() {
+entry:
+  %call = call i32 @_Z18__spirv_ocl_printfIJEEiPKcDpT_(ptr @.str)
+  ret void
+}
+
+; CHECK: call i32 (ptr addrspace(2), ...) @_Z18__spirv_ocl_printfPU3AS2Kcz(ptr addrspace(2)
+; The declaration should NOT have spir_func CC for non-SPIR targets.
+; CHECK: declare dso_local i32 @_Z18__spirv_ocl_printfPU3AS2Kcz(ptr addrspace(2), ...)
+
+declare i32 @_Z18__spirv_ocl_printfIJEEiPKcDpT_(ptr)

llvm/test/SYCLLowerIR/printf_addrspace/unused_printf_decl.ll

@@ -0,0 +1,21 @@
+;; Verify that the pass does NOT insert an AS2 printf declaration when
+;; the module has a matching printf declaration with no call users, and
+;; that the unused declaration itself is removed from the module.
+
+; RUN: opt < %s -passes=SYCLMutatePrintfAddrspace -S | FileCheck %s
+
+target datalayout = "e-i64:64-v16:16-v24:32-v32:32-v48:64-v96:128-v192:256-v256:256-v512:512-v1024:1024-n8:16:32:64"
+target triple = "spir64-unknown-unknown"
+
+define spir_kernel void @kernel() {
+entry:
+  ret void
+}
+
+; This declaration matches the printf name prefix but has no users.
+declare dso_local spir_func i32 @_Z18__spirv_ocl_printfIJfEEiPKcDpT_(ptr addrspace(4), float)
+
+; No AS2 printf declaration should be created.
+; CHECK-NOT: @_Z18__spirv_ocl_printfPU3AS2Kcz
+; The unused generic-AS printf declaration should be removed.
+; CHECK-NOT: @_Z18__spirv_ocl_printfIJfEEiPKcDpT_