if (isa<UndefValue>(Op1)) // X icmp undef -> undef
return ReplaceInstUsesWith(I, UndefValue::get(Type::Int1Ty));
-
+
+ // (icmp cond (sub m A) 0) ->
+ // (icmp cond m A)
+ {
+ ConstantInt *C1, *C2;
+ Value *A;
+ // Check both arguments of the compare for a matching subtract.
+ if (match(Op0, m_ConstantInt(C1)) && C1->getValue() == 0 &&
+ match(Op1, m_Sub(m_ConstantInt(C2), m_Value(A)))) {
+ // We managed to fold the add into the RHS of the select condition.
+ return new ICmpInst(I.getPredicate(), A, C2);
+ } else if (match(Op1, m_ConstantInt(C1)) && C1->getValue() == 0 &&
+ match(Op0, m_Sub(m_ConstantInt(C2), m_Value(A)))) {
+ // We managed to fold the add into the LHS of the select condition.
+ return new ICmpInst(I.getPredicate(), C2, A);
+ }
+ }
+
// icmp <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
// addresses never equal each other! We already know that Op0 != Op1.
if ((isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0) ||