Use llvm.func to define functions with wrapped LLVM IR function type

This function-like operation allows one to define functions that have wrapped
LLVM IR function type, in particular variadic functions. The operation was
added in parallel to the existing lowering flow, this commit only switches the
flow to use it.

Using a custom function type makes the LLVM IR dialect type system more
consistent and avoids complex conversion rules for functions that previously
had to use the built-in function type instead of a wrapped LLVM IR dialect type
and perform conversions during the analysis.

PiperOrigin-RevId: 273910855

1 files changed, 5 insertions, 13 deletions

diff --git a/mlir/lib/Support/JitRunner.cpp b/mlir/lib/Support/JitRunner.cpp
index 372e69f8855..c877daed2c5 100644
--- a/mlir/lib/Support/JitRunner.cpp
+++ b/mlir/lib/Support/JitRunner.cpp
@@ -177,7 +177,7 @@ compileAndExecute(ModuleOp module, StringRef entryPoint,
 static Error compileAndExecuteVoidFunction(
     ModuleOp module, StringRef entryPoint,
     std::function<llvm::Error(llvm::Module *)> transformer) {
-  FuncOp mainFunction = module.lookupSymbol<FuncOp>(entryPoint);
+  auto mainFunction = module.lookupSymbol<LLVM::LLVMFuncOp>(entryPoint);
   if (!mainFunction || mainFunction.getBlocks().empty())
     return make_string_error("entry point not found");
   void *empty = nullptr;
@@ -187,22 +187,14 @@ static Error compileAndExecuteVoidFunction(
 static Error compileAndExecuteSingleFloatReturnFunction(
     ModuleOp module, StringRef entryPoint,
     std::function<llvm::Error(llvm::Module *)> transformer) {
-  FuncOp mainFunction = module.lookupSymbol<FuncOp>(entryPoint);
-  if (!mainFunction || mainFunction.isExternal()) {
+  auto mainFunction = module.lookupSymbol<LLVM::LLVMFuncOp>(entryPoint);
+  if (!mainFunction || mainFunction.isExternal())
     return make_string_error("entry point not found");
-  }
 
-  if (!mainFunction.getType().getInputs().empty())
+  if (mainFunction.getType().getFunctionNumParams() != 0)
     return make_string_error("function inputs not supported");
 
-  if (mainFunction.getType().getResults().size() != 1)
-    return make_string_error("only single f32 function result supported");
-
-  auto t = mainFunction.getType().getResults()[0].dyn_cast<LLVM::LLVMType>();
-  if (!t)
-    return make_string_error("only single llvm.f32 function result supported");
-  auto *llvmTy = t.getUnderlyingType();
-  if (llvmTy != llvmTy->getFloatTy(llvmTy->getContext()))
+  if (!mainFunction.getType().getFunctionResultType().isFloatTy())
     return make_string_error("only single llvm.f32 function result supported");
 
   float res;