[Mlir-commits] [mlir] [MLIR][NVVM] Reduce the scope of the LLVM_HAS_NVPTX_TARGET guard (PR #97349)

[Mehdi Amini]

https://github.com/joker-eph created https://github.com/llvm/llvm-project/pull/97349

Most of the code here does not depend on the NVPTX target. In particular the simple offload can just emit LLVM IR and we can use this without the NVVM backend being built, which can be useful for a frontend that just need to serialize the IR and leave it up to the runtime to JIT further.

>From 2d05903b35ab54d36ff3b3f004e5fa3c0db6ba2e Mon Sep 17 00:00:00 2001
From: Mehdi Amini <joker.eph at gmail.com>
Date: Mon, 1 Jul 2024 14:04:04 -0700
Subject: [PATCH] [MLIR][NVVM] Reduce the scope of the LLVM_HAS_NVPTX_TARGET
 guard

Most of the code here does not depend on the NVPTX target. In particular
the simple offload can just emit LLVM IR and we can use this without
the NVVM backend being built, which can be useful for a frontend that
just need to serialize the IR and leave it up to the runtime to JIT
further.
---
 mlir/lib/Dialect/GPU/Transforms/ModuleToBinary.cpp |  2 --
 mlir/lib/Target/LLVM/NVVM/Target.cpp               | 14 ++++++--------
 2 files changed, 6 insertions(+), 10 deletions(-)

diff --git a/mlir/lib/Dialect/GPU/Transforms/ModuleToBinary.cpp b/mlir/lib/Dialect/GPU/Transforms/ModuleToBinary.cpp
index 1e7596e8cc4af..62b438656f03f 100644
--- a/mlir/lib/Dialect/GPU/Transforms/ModuleToBinary.cpp
+++ b/mlir/lib/Dialect/GPU/Transforms/ModuleToBinary.cpp
@@ -48,9 +48,7 @@ void GpuModuleToBinaryPass::getDependentDialects(
   // Register all GPU related translations.
   registry.insert<gpu::GPUDialect>();
   registry.insert<LLVM::LLVMDialect>();
-#if LLVM_HAS_NVPTX_TARGET
   registry.insert<NVVM::NVVMDialect>();
-#endif
 #if MLIR_ENABLE_ROCM_CONVERSIONS
   registry.insert<ROCDL::ROCDLDialect>();
 #endif
diff --git a/mlir/lib/Target/LLVM/NVVM/Target.cpp b/mlir/lib/Target/LLVM/NVVM/Target.cpp
index acb903aa37caf..c32ccf90cbbbc 100644
--- a/mlir/lib/Target/LLVM/NVVM/Target.cpp
+++ b/mlir/lib/Target/LLVM/NVVM/Target.cpp
@@ -157,7 +157,6 @@ SerializeGPUModuleBase::loadBitcodeFiles(llvm::Module &module) {
   return std::move(bcFiles);
 }
 
-#if LLVM_HAS_NVPTX_TARGET
 namespace {
 class NVPTXSerializer : public SerializeGPUModuleBase {
 public:
@@ -532,6 +531,12 @@ NVPTXSerializer::moduleToObject(llvm::Module &llvmModule) {
   if (targetOptions.getCompilationTarget() == gpu::CompilationTarget::Offload)
     return SerializeGPUModuleBase::moduleToObject(llvmModule);
 
+#if ! LLVM_HAS_NVPTX_TARGET
+  getOperation()->emitError(
+      "The `NVPTX` target was not built. Please enable it when building LLVM.");
+  return std::nullopt;
+#endif // LLVM_HAS_NVPTX_TARGET
+
   // Emit PTX code.
   std::optional<llvm::TargetMachine *> targetMachine =
       getOrCreateTargetMachine();
@@ -569,7 +574,6 @@ NVPTXSerializer::moduleToObject(llvm::Module &llvmModule) {
   return compileToBinary(*serializedISA);
 #endif // MLIR_ENABLE_NVPTXCOMPILER
 }
-#endif // LLVM_HAS_NVPTX_TARGET
 
 std::optional<SmallVector<char, 0>>
 NVVMTargetAttrImpl::serializeToObject(Attribute attribute, Operation *module,
@@ -581,15 +585,9 @@ NVVMTargetAttrImpl::serializeToObject(Attribute attribute, Operation *module,
     module->emitError("Module must be a GPU module.");
     return std::nullopt;
   }
-#if LLVM_HAS_NVPTX_TARGET
   NVPTXSerializer serializer(*module, cast<NVVMTargetAttr>(attribute), options);
   serializer.init();
   return serializer.run();
-#else
-  module->emitError(
-      "The `NVPTX` target was not built. Please enable it when building LLVM.");
-  return std::nullopt;
-#endif // LLVM_HAS_NVPTX_TARGET
 }
 
 Attribute