ConstantExpr::getZExt(RHS, Cast->getSrcTy()));
}
}
-
+
+ // If the LHS is an AND of a zext, and we have an equality compare, we can
+ // shrink the and/compare to the smaller type, eliminating the cast.
+ if (ZExtInst *Cast = dyn_cast<ZExtInst>(LHSI->getOperand(0))) {
+ const IntegerType *Ty = cast<IntegerType>(Cast->getSrcTy());
+ // Make sure we don't compare the upper bits, SimplifyDemandedBits
+ // should fold the icmp to true/false in that case.
+ if (ICI.isEquality() && RHSV.getActiveBits() <= Ty->getBitWidth()) {
+ Value *NewAnd =
+ Builder->CreateAnd(Cast->getOperand(0),
+ ConstantExpr::getTrunc(AndCST, Ty));
+ NewAnd->takeName(LHSI);
+ return new ICmpInst(ICI.getPredicate(), NewAnd,
+ ConstantExpr::getTrunc(RHS, Ty));
+ }
+ }
+
// If this is: (X >> C1) & C2 != C3 (where any shift and any compare
// could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
// happens a LOT in code produced by the C front-end, for bitfield
%z = icmp eq i32 %x, %y
ret i1 %z
}
+
+; CHECK: @test54
+; CHECK-NEXT: %and = and i8 %a, -64
+; CHECK-NEXT icmp eq i8 %and, -128
+define i1 @test54(i8 %a) nounwind {
+ %ext = zext i8 %a to i32
+ %and = and i32 %ext, 192
+ %ret = icmp eq i32 %and, 128
+ ret i1 %ret
+}