[c++20] Add CXXRewrittenBinaryOperator to represent a comparison
operator that is rewritten as a call to multiple other operators.
No functionality change yet: nothing creates these expressions.
llvm-svn: 375305
diff --git a/clang/lib/AST/ExprCXX.cpp b/clang/lib/AST/ExprCXX.cpp
index a9b7c00..0b0d3c6 100644
--- a/clang/lib/AST/ExprCXX.cpp
+++ b/clang/lib/AST/ExprCXX.cpp
@@ -58,6 +58,76 @@
}
}
+CXXRewrittenBinaryOperator::DecomposedForm
+CXXRewrittenBinaryOperator::getDecomposedForm() const {
+ DecomposedForm Result = {};
+ const Expr *E = getSemanticForm()->IgnoreImplicit();
+
+ // Remove an outer '!' if it exists (only happens for a '!=' rewrite).
+ bool SkippedNot = false;
+ if (auto *NotEq = dyn_cast<UnaryOperator>(E)) {
+ assert(NotEq->getOpcode() == UO_LNot);
+ E = NotEq->getSubExpr()->IgnoreImplicit();
+ SkippedNot = true;
+ }
+
+ // Decompose the outer binary operator.
+ if (auto *BO = dyn_cast<BinaryOperator>(E)) {
+ assert(!SkippedNot || BO->getOpcode() == BO_EQ);
+ Result.Opcode = SkippedNot ? BO_NE : BO->getOpcode();
+ Result.LHS = BO->getLHS();
+ Result.RHS = BO->getRHS();
+ Result.InnerBinOp = BO;
+ } else if (auto *BO = dyn_cast<CXXOperatorCallExpr>(E)) {
+ assert(!SkippedNot || BO->getOperator() == OO_Equal);
+ assert(BO->isInfixBinaryOp());
+ switch (BO->getOperator()) {
+ case OO_Less: Result.Opcode = BO_LT; break;
+ case OO_LessEqual: Result.Opcode = BO_LE; break;
+ case OO_Greater: Result.Opcode = BO_GT; break;
+ case OO_GreaterEqual: Result.Opcode = BO_GE; break;
+ case OO_Spaceship: Result.Opcode = BO_Cmp; break;
+ case OO_EqualEqual: Result.Opcode = SkippedNot ? BO_NE : BO_EQ; break;
+ default: llvm_unreachable("unexpected binop in rewritten operator expr");
+ }
+ Result.LHS = BO->getArg(0);
+ Result.RHS = BO->getArg(1);
+ Result.InnerBinOp = BO;
+ } else {
+ llvm_unreachable("unexpected rewritten operator form");
+ }
+
+ // Put the operands in the right order for == and !=, and canonicalize the
+ // <=> subexpression onto the LHS for all other forms.
+ if (isReversed())
+ std::swap(Result.LHS, Result.RHS);
+
+ // If this isn't a spaceship rewrite, we're done.
+ if (Result.Opcode == BO_EQ || Result.Opcode == BO_NE)
+ return Result;
+
+ // Otherwise, we expect a <=> to now be on the LHS.
+ E = Result.InnerBinOp->IgnoreImplicit();
+ if (auto *BO = dyn_cast<BinaryOperator>(E)) {
+ assert(BO->getOpcode() == BO_Cmp);
+ Result.LHS = BO->getLHS();
+ Result.RHS = BO->getRHS();
+ Result.InnerBinOp = BO;
+ } else if (auto *BO = dyn_cast<CXXOperatorCallExpr>(E)) {
+ assert(BO->getOperator() == OO_Spaceship);
+ Result.LHS = BO->getArg(0);
+ Result.RHS = BO->getArg(1);
+ Result.InnerBinOp = BO;
+ } else {
+ llvm_unreachable("unexpected rewritten operator form");
+ }
+
+ // Put the comparison operands in the right order.
+ if (isReversed())
+ std::swap(Result.LHS, Result.RHS);
+ return Result;
+}
+
bool CXXTypeidExpr::isPotentiallyEvaluated() const {
if (isTypeOperand())
return false;