return nullptr;
}
-static Value *foldCttzCtlz(IntrinsicInst &II, InstCombiner &IC) {
+static Instruction *foldCttzCtlz(IntrinsicInst &II, InstCombiner &IC) {
+ assert((II.getIntrinsicID() == Intrinsic::cttz ||
+ II.getIntrinsicID() == Intrinsic::ctlz) &&
+ "Expected cttz or ctlz intrinsic");
Value *Op0 = II.getArgOperand(0);
// FIXME: Try to simplify vectors of integers.
auto *IT = dyn_cast<IntegerType>(Op0->getType());
// zero, this value is constant.
// FIXME: This should be in InstSimplify because we're replacing an
// instruction with a constant.
- if ((Mask & KnownZero) == Mask)
- return ConstantInt::get(IT, APInt(BitWidth, NumMaskBits));
+ if ((Mask & KnownZero) == Mask) {
+ auto *C = ConstantInt::get(IT, APInt(BitWidth, NumMaskBits));
+ return IC.replaceInstUsesWith(II, C);
+ }
+
+ // If the input to cttz/ctlz is known to be non-zero,
+ // then change the 'ZeroIsUndef' parameter to 'true'
+ // because we know the zero behavior can't affect the result.
+ if (KnownOne != 0 || isKnownNonZero(Op0, IC.getDataLayout())) {
+ if (!match(II.getArgOperand(1), m_One())) {
+ II.setOperand(1, IC.Builder->getTrue());
+ return &II;
+ }
+ }
return nullptr;
}
case Intrinsic::cttz:
case Intrinsic::ctlz:
- if (Value *V = foldCttzCtlz(*II, *this))
- return replaceInstUsesWith(*II, V);
+ if (auto *I = foldCttzCtlz(*II, *this))
+ return I;
break;
case Intrinsic::uadd_with_overflow:
}
+define i32 @ctlz_make_undef(i32 %a) {
+ %or = or i32 %a, 8
+ %ctlz = tail call i32 @llvm.ctlz.i32(i32 %or, i1 false)
+ ret i32 %ctlz
+; CHECK-LABEL: @ctlz_make_undef(
+; CHECK-NEXT: %or = or i32 %a, 8
+; CHECK-NEXT: %ctlz = tail call i32 @llvm.ctlz.i32(i32 %or, i1 true)
+; CHECK-NEXT: ret i32 %ctlz
+}
+
define i32 @cttz_undef(i32 %Value) nounwind {
; CHECK-LABEL: @cttz_undef(
; CHECK-NEXT: ret i32 undef
}
+define i32 @cttz_make_undef(i32 %a) {
+ %or = or i32 %a, 8
+ %cttz = tail call i32 @llvm.cttz.i32(i32 %or, i1 false)
+ ret i32 %cttz
+; CHECK-LABEL: @cttz_make_undef(
+; CHECK-NEXT: %or = or i32 %a, 8
+; CHECK-NEXT: %cttz = tail call i32 @llvm.cttz.i32(i32 %or, i1 true)
+; CHECK-NEXT: ret i32 %cttz
+}
+
define i32 @ctlz_select(i32 %Value) nounwind {
; CHECK-LABEL: @ctlz_select(
; CHECK-NEXT: [[TMP1:%.*]] = call i32 @llvm.ctlz.i32(i32 %Value, i1 false)