[clang] [CIR] Upstream SelectOp and ShiftOp (PR #133405)

[Bruno Cardoso Lopes via cfe-commits]

================
@@ -1117,6 +1117,91 @@ mlir::LogicalResult CIRToLLVMBinOpLowering::matchAndRewrite(
   return mlir::LogicalResult::success();
 }
 
+mlir::LogicalResult CIRToLLVMShiftOpLowering::matchAndRewrite(
+    cir::ShiftOp op, OpAdaptor adaptor,
+    mlir::ConversionPatternRewriter &rewriter) const {
+  auto cirAmtTy = mlir::dyn_cast<cir::IntType>(op.getAmount().getType());
+  auto cirValTy = mlir::dyn_cast<cir::IntType>(op.getValue().getType());
+
+  // Operands could also be vector type
+  assert(!cir::MissingFeatures::vectorType());
+  mlir::Type llvmTy = getTypeConverter()->convertType(op.getType());
+  mlir::Value amt = adaptor.getAmount();
+  mlir::Value val = adaptor.getValue();
+
+  // TODO(cir): Assert for vector types
+  assert((cirValTy && cirAmtTy) &&
+         "shift input type must be integer or vector type, otherwise NYI");
+
+  assert((cirValTy == op.getType()) && "inconsistent operands' types NYI");
+
+  // Ensure shift amount is the same type as the value. Some undefined
+  // behavior might occur in the casts below as per [C99 6.5.7.3].
+  // Vector type shift amount needs no cast as type consistency is expected to
+  // be already be enforced at CIRGen.
+  if (cirAmtTy)
+    amt = getLLVMIntCast(rewriter, amt, mlir::cast<mlir::IntegerType>(llvmTy),
+                         !cirAmtTy.isSigned(), cirAmtTy.getWidth(),
+                         cirValTy.getWidth());
+
+  // Lower to the proper LLVM shift operation.
+  if (op.getIsShiftleft()) {
+    rewriter.replaceOpWithNewOp<mlir::LLVM::ShlOp>(op, llvmTy, val, amt);
+  } else {
+    assert(!cir::MissingFeatures::vectorType());
+    bool isUnsigned = !cirValTy.isSigned();
+    if (isUnsigned)
+      rewriter.replaceOpWithNewOp<mlir::LLVM::LShrOp>(op, llvmTy, val, amt);
+    else
+      rewriter.replaceOpWithNewOp<mlir::LLVM::AShrOp>(op, llvmTy, val, amt);
+  }
+
+  return mlir::success();
+}
+
+mlir::LogicalResult CIRToLLVMSelectOpLowering::matchAndRewrite(
+    cir::SelectOp op, OpAdaptor adaptor,
+    mlir::ConversionPatternRewriter &rewriter) const {
+  auto getConstantBool = [](mlir::Value value) -> std::optional<bool> {
----------------
bcardosolopes wrote:

Let's rely on MLIR's usage of value semantics here.
This lambda should just return an `cir::BoolAttr`, so you can write:
```
cir::BoolAttr trueValue = getConstantBool(op.getTrueValue());
...
if (trueValue && !trueValue.getValue()) {
}
``` 
The lambda should return `{}`/`nullptr` in the case attribute not found.

https://github.com/llvm/llvm-project/pull/133405