================
@@ -233,6 +327,126 @@ RegBankLegalizeRules::getRulesForOpc(MachineInstr &MI)
const {
return GRules.at(GRulesAlias.at(Opc));
}
+// Syntactic sugar wrapper for predicate lambda that enables '&&', '||' and
'!'.
+class Predicate {
+public:
+ struct Elt {
+ // Save formula composed of Pred, '&&', '||' and '!' as a jump table.
+ // Sink ! to Pred. For example !((A && !B) || C) -> (!A || B) && !C
+ // Sequences of && and || will be represented by jumps, for example:
+ // (A && B && ... X) or (A && B && ... X) || Y
+ // A == true jump to B
+ // A == false jump to end or Y, result is A(false) or Y
+ // (A || B || ... X) or (A || B || ... X) && Y
+ // A == true jump to end or Y, result is B(true) or Y
+ // A == false jump to B
+ // Notice that when negating expression, we simply flip Neg on each Pred
+ // and swap TJumpOffset and FJumpOffset (&& becomes ||, || becomes &&).
+ std::function<bool(const MachineInstr &)> Pred;
+ bool Neg; // Neg of Pred is calculated before jump
+ unsigned TJumpOffset;
+ unsigned FJumpOffset;
+ };
+
+ SmallVector<Elt, 8> Expression;
+
+ Predicate(std::function<bool(const MachineInstr &)> Pred) {
+ Expression.push_back({Pred, false, 1, 1});
+ };
+
+ Predicate(SmallVectorImpl<Elt> &Expr) { Expression.swap(Expr); };
----------------
nhaehnle wrote:
I find having a constructor that is destructive on its argument in this way to
be quite surprising. It is against good patterns in modern C++. Better have it
take an rvalue reference (&&-reference). Then its callers have to explicitly
`std::move`, but that makes it more obvious what happens at the call sites.
Also, this constructor should be private just like `Elt`.
https://github.com/llvm/llvm-project/pull/112882
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