================
@@ -232,6 +233,161 @@ LValue CIRGenFunction::emitUnaryOpLValue(const
UnaryOperator *e) {
llvm_unreachable("Unknown unary operator kind!");
}
+/// If the specified expr is a simple decay from an array to pointer,
+/// return the array subexpression.
+/// FIXME: this could be abstracted into a common AST helper.
+static const Expr *isSimpleArrayDecayOperand(const Expr *e) {
+ // If this isn't just an array->pointer decay, bail out.
+ const auto *castExpr = dyn_cast<CastExpr>(e);
+ if (!castExpr || castExpr->getCastKind() != CK_ArrayToPointerDecay)
+ return nullptr;
+
+ // If this is a decay from variable width array, bail out.
+ const Expr *subExpr = castExpr->getSubExpr();
+ if (subExpr->getType()->isVariableArrayType())
+ return nullptr;
+
+ return subExpr;
+}
+
+static mlir::IntegerAttr getConstantIndexOrNull(mlir::Value idx) {
+ // TODO(cir): should we consider using MLIRs IndexType instead of
IntegerAttr?
+ if (auto constantOp = dyn_cast<cir::ConstantOp>(idx.getDefiningOp()))
+ return mlir::dyn_cast<mlir::IntegerAttr>(constantOp.getValue());
+ return {};
+}
+
+static CharUnits getArrayElementAlign(CharUnits arrayAlign, mlir::Value idx,
+ CharUnits eltSize) {
+ // If we have a constant index, we can use the exact offset of the
+ // element we're accessing.
+ const mlir::IntegerAttr constantIdx = getConstantIndexOrNull(idx);
+ if (constantIdx) {
+ const CharUnits offset = constantIdx.getValue().getZExtValue() * eltSize;
+ return arrayAlign.alignmentAtOffset(offset);
----------------
andykaylor wrote:
Do we have a test case where this would return something different than
`alignmentOfArrayElement(eltSize)`?
https://github.com/llvm/llvm-project/pull/134536
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