[clang] [CIR] Upstream basic alloca and load support (PR #128792)

[Erich Keane via cfe-commits]

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@@ -0,0 +1,128 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 Expr nodes as CIR code.
+//
+//===----------------------------------------------------------------------===//
+
+#include "Address.h"
+#include "CIRGenFunction.h"
+#include "CIRGenValue.h"
+#include "clang/AST/Attr.h"
+#include "clang/AST/CharUnits.h"
+#include "clang/AST/Decl.h"
+#include "clang/AST/Expr.h"
+#include "clang/CIR/Dialect/IR/CIRDialect.h"
+#include "clang/CIR/MissingFeatures.h"
+
+using namespace clang;
+using namespace clang::CIRGen;
+using namespace cir;
+
+mlir::Value CIRGenFunction::emitLoadOfScalar(LValue lvalue,
+                                             SourceLocation loc) {
+  assert(!cir::MissingFeatures::opLoadThreadLocal());
+  assert(!cir::MissingFeatures::opLoadEmitScalarRangeCheck());
+  assert(!cir::MissingFeatures::opLoadBooleanRepresentation());
+
+  Address addr = lvalue.getAddress();
+  mlir::Type eltTy = addr.getElementType();
+
+  auto ptr = addr.getPointer();
+  if (mlir::isa<cir::VoidType>(eltTy))
+    cgm.errorNYI(loc, "emitLoadOfScalar: void type");
+
+  auto loadOp = builder.CIRBaseBuilderTy::createLoad(getLoc(loc), ptr,
+                                                     false /*isVolatile*/);
+
+  return loadOp;
+}
+
+/// Given an expression that represents a value lvalue, this
+/// method emits the address of the lvalue, then loads the result as an rvalue,
+/// returning the rvalue.
+RValue CIRGenFunction::emitLoadOfLValue(LValue lv, SourceLocation loc) {
+  assert(!lv.getType()->isFunctionType());
+  assert(!(lv.getType()->isConstantMatrixType()) && "not implemented");
+
+  if (lv.isSimple())
+    return RValue::get(emitLoadOfScalar(lv, loc));
+
+  cgm.errorNYI(loc, "emitLoadOfLValue");
----------------
erichkeane wrote:

We did, we're only doing unreachable in cases where its the 'final' thing more or less.  And IIRC, Clang believes that `assert(false` is for things someone MIGHT reach, and `unreachable` is for things that we expect will NEVER be reached.

https://github.com/llvm/llvm-project/pull/128792