[clang] [CIR] Upstream minimal builtin function call support (PR #142981)

[Andy Kaylor via cfe-commits]

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@@ -0,0 +1,453 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This contains code to emit Builtin calls as CIR or a function call to be
+// later resolved.
+//
+//===----------------------------------------------------------------------===//
+
+#include "CIRGenCall.h"
+#include "CIRGenFunction.h"
+#include "CIRGenModule.h"
+#include "CIRGenValue.h"
+#include "clang/AST/Expr.h"
+#include "clang/CIR/Dialect/IR/CIRAttrs.h"
+#include "clang/CIR/Dialect/IR/CIRTypes.h"
+#include "clang/CIR/MissingFeatures.h"
+#include "llvm/IR/Intrinsics.h"
+
+#include "clang/AST/GlobalDecl.h"
+#include "clang/Basic/Builtins.h"
+
+#include "mlir/IR/BuiltinAttributes.h"
+#include "mlir/IR/Value.h"
+#include "mlir/Support/LLVM.h"
+#include "clang/CIR/Dialect/IR/CIRDialect.h"
+#include "llvm/Support/ErrorHandling.h"
+
+using namespace clang;
+using namespace clang::CIRGen;
+using namespace cir;
+using namespace llvm;
+
+static RValue emitLibraryCall(CIRGenFunction &cgf, const FunctionDecl *fd,
+                              const CallExpr *e, mlir::Operation *calleeValue) {
+  CIRGenCallee callee = CIRGenCallee::forDirect(calleeValue, GlobalDecl(fd));
+  return cgf.emitCall(e->getCallee()->getType(), callee, e, ReturnValueSlot());
+}
+
+static mlir::Type
+decodeFixedType(CIRGenFunction &cgf,
+                ArrayRef<llvm::Intrinsic::IITDescriptor> &infos) {
+  using namespace llvm::Intrinsic;
+
+  auto *context = &cgf.getMLIRContext();
+  IITDescriptor descriptor = infos.front();
+  infos = infos.slice(1);
+
+  switch (descriptor.Kind) {
+  case IITDescriptor::Void:
+    return VoidType::get(context);
+  case IITDescriptor::Integer:
+    return IntType::get(context, descriptor.Integer_Width, /*isSigned=*/true);
+  case IITDescriptor::Float:
+    return SingleType::get(context);
+  case IITDescriptor::Double:
+    return DoubleType::get(context);
+  default:
+    cgf.cgm.errorNYI("intrinsic return types");
+    return VoidType::get(context);
+  }
+}
+
+// llvm::Intrinsics accepts only LLVMContext. We need to reimplement it here.
+static cir::FuncType getIntrinsicType(CIRGenFunction &cgf,
+                                      llvm::Intrinsic::ID id) {
+  using namespace llvm::Intrinsic;
+
+  SmallVector<IITDescriptor, 8> table;
+  getIntrinsicInfoTableEntries(id, table);
+
+  ArrayRef<IITDescriptor> tableRef = table;
----------------
andykaylor wrote:

It wasn't clear to my why we were getting a local `ArrayRef` rather than just using the `table` variable. I _think_ the reason is that the calls to `decodeFixedType` are taking the first element out of the set we're working with without actually changing the original vector. Can you add a comment explaining that (or whatever else is going on if I'm wrong)?

https://github.com/llvm/llvm-project/pull/142981