[ValueTracking] Add support for trunc nuw/nsw in isKnowNonZero
#89643
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goldsteinn
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trunc nuw/nsw in isKnowNonZero
|
@llvm/pr-subscribers-llvm-analysis Author: None (goldsteinn) Changes
Proofs: https://alive2.llvm.org/ce/z/iujmk6 Full diff: https://github.com/llvm/llvm-project/pull/89643.diff 2 Files Affected:
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 21e3f8a4cc52c7..e17c7b94181c1b 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -2632,6 +2632,13 @@ static bool isKnownNonZeroFromOperator(const Operator *I,
Q.DL.getTypeSizeInBits(I->getType()).getFixedValue())
return isKnownNonZero(I->getOperand(0), Q, Depth);
break;
+ case Instruction::Trunc: {
+ auto *TI = cast<TruncInst>(I);
+ // nuw/nsw trunc preserves zero/non-zero status of input.
+ if (TI->hasNoSignedWrap() || TI->hasNoUnsignedWrap())
+ return isKnownNonZero(TI->getOperand(0), Q, Depth + 1);
+ break;
+ }
case Instruction::Sub:
return isNonZeroSub(DemandedElts, Depth, Q, BitWidth, I->getOperand(0),
I->getOperand(1));
@@ -3785,7 +3792,8 @@ static unsigned ComputeNumSignBitsImpl(const Value *V,
// truncation, then we can make use of that. Otherwise we don't know
// anything.
Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q);
- unsigned OperandTyBits = U->getOperand(0)->getType()->getScalarSizeInBits();
+ unsigned OperandTyBits =
+ U->getOperand(0)->getType()->getScalarSizeInBits();
if (Tmp > (OperandTyBits - TyBits))
return Tmp - (OperandTyBits - TyBits);
diff --git a/llvm/test/Analysis/ValueTracking/known-non-zero.ll b/llvm/test/Analysis/ValueTracking/known-non-zero.ll
index 0159050d925c3e..c00e47fba8c727 100644
--- a/llvm/test/Analysis/ValueTracking/known-non-zero.ll
+++ b/llvm/test/Analysis/ValueTracking/known-non-zero.ll
@@ -1202,7 +1202,6 @@ define <2 x i1> @cmp_excludes_zero_with_nonsplat_vec_wpoison(<2 x i8> %a, <2 x i
ret <2 x i1> %r
}
-
define <2 x i1> @cmp_excludes_zero_with_nonsplat_vec_fail(<2 x i8> %a, <2 x i8> %b) {
; CHECK-LABEL: @cmp_excludes_zero_with_nonsplat_vec_fail(
; CHECK-NEXT: [[C:%.*]] = icmp sge <2 x i8> [[A:%.*]], <i8 0, i8 4>
@@ -1314,8 +1313,8 @@ define i1 @range_attr(i8 range(i8 1, 0) %x, i8 %y) {
define i1 @neg_range_attr(i8 range(i8 -1, 1) %x, i8 %y) {
; CHECK-LABEL: @neg_range_attr(
-; CHECK-NEXT: [[I:%.*]] = or i8 [[Y:%.*]], [[X:%.*]]
-; CHECK-NEXT: [[CMP:%.*]] = icmp eq i8 [[I]], 0
+; CHECK-NEXT: [[OR:%.*]] = or i8 [[Y:%.*]], [[X:%.*]]
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq i8 [[OR]], 0
; CHECK-NEXT: ret i1 [[CMP]]
;
%or = or i8 %y, %x
@@ -1328,7 +1327,7 @@ declare range(i8 -1, 1) i8 @returns_contain_zero_range_helper()
define i1 @range_return(i8 %y) {
; CHECK-LABEL: @range_return(
-; CHECK-NEXT: [[I:%.*]] = call i8 @returns_non_zero_range_helper()
+; CHECK-NEXT: [[X:%.*]] = call i8 @returns_non_zero_range_helper()
; CHECK-NEXT: ret i1 false
;
%x = call i8 @returns_non_zero_range_helper()
@@ -1339,8 +1338,8 @@ define i1 @range_return(i8 %y) {
define i1 @neg_range_return(i8 %y) {
; CHECK-LABEL: @neg_range_return(
-; CHECK-NEXT: [[I:%.*]] = call i8 @returns_contain_zero_range_helper()
-; CHECK-NEXT: [[OR:%.*]] = or i8 [[Y:%.*]], [[I]]
+; CHECK-NEXT: [[X:%.*]] = call i8 @returns_contain_zero_range_helper()
+; CHECK-NEXT: [[OR:%.*]] = or i8 [[Y:%.*]], [[X]]
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i8 [[OR]], 0
; CHECK-NEXT: ret i1 [[CMP]]
;
@@ -1354,7 +1353,7 @@ declare i8 @returns_i8_helper()
define i1 @range_call(i8 %y) {
; CHECK-LABEL: @range_call(
-; CHECK-NEXT: [[I:%.*]] = call range(i8 1, 0) i8 @returns_i8_helper()
+; CHECK-NEXT: [[X:%.*]] = call range(i8 1, 0) i8 @returns_i8_helper()
; CHECK-NEXT: ret i1 false
;
%x = call range(i8 1, 0) i8 @returns_i8_helper()
@@ -1365,8 +1364,8 @@ define i1 @range_call(i8 %y) {
define i1 @neg_range_call(i8 %y) {
; CHECK-LABEL: @neg_range_call(
-; CHECK-NEXT: [[I:%.*]] = call range(i8 -1, 1) i8 @returns_i8_helper()
-; CHECK-NEXT: [[OR:%.*]] = or i8 [[Y:%.*]], [[I]]
+; CHECK-NEXT: [[X:%.*]] = call range(i8 -1, 1) i8 @returns_i8_helper()
+; CHECK-NEXT: [[OR:%.*]] = or i8 [[Y:%.*]], [[X]]
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i8 [[OR]], 0
; CHECK-NEXT: ret i1 [[CMP]]
;
@@ -1401,7 +1400,7 @@ declare range(i8 -1, 1) <2 x i8> @returns_contain_zero_range_helper_vec()
define <2 x i1> @range_return_vec(<2 x i8> %y) {
; CHECK-LABEL: @range_return_vec(
-; CHECK-NEXT: [[I:%.*]] = call <2 x i8> @returns_non_zero_range_helper_vec()
+; CHECK-NEXT: [[X:%.*]] = call <2 x i8> @returns_non_zero_range_helper_vec()
; CHECK-NEXT: ret <2 x i1> <i1 true, i1 true>
;
%x = call <2 x i8> @returns_non_zero_range_helper_vec()
@@ -1412,8 +1411,8 @@ define <2 x i1> @range_return_vec(<2 x i8> %y) {
define <2 x i1> @neg_range_return_vec(<2 x i8> %y) {
; CHECK-LABEL: @neg_range_return_vec(
-; CHECK-NEXT: [[I:%.*]] = call <2 x i8> @returns_contain_zero_range_helper_vec()
-; CHECK-NEXT: [[OR:%.*]] = or <2 x i8> [[Y:%.*]], [[I]]
+; CHECK-NEXT: [[X:%.*]] = call <2 x i8> @returns_contain_zero_range_helper_vec()
+; CHECK-NEXT: [[OR:%.*]] = or <2 x i8> [[Y:%.*]], [[X]]
; CHECK-NEXT: [[CMP:%.*]] = icmp ne <2 x i8> [[OR]], zeroinitializer
; CHECK-NEXT: ret <2 x i1> [[CMP]]
;
@@ -1427,7 +1426,7 @@ declare <2 x i8> @returns_i8_helper_vec()
define <2 x i1> @range_call_vec(<2 x i8> %y) {
; CHECK-LABEL: @range_call_vec(
-; CHECK-NEXT: [[I:%.*]] = call range(i8 1, 0) <2 x i8> @returns_i8_helper_vec()
+; CHECK-NEXT: [[X:%.*]] = call range(i8 1, 0) <2 x i8> @returns_i8_helper_vec()
; CHECK-NEXT: ret <2 x i1> <i1 true, i1 true>
;
%x = call range(i8 1, 0) <2 x i8> @returns_i8_helper_vec()
@@ -1438,8 +1437,8 @@ define <2 x i1> @range_call_vec(<2 x i8> %y) {
define <2 x i1> @neg_range_call_vec(<2 x i8> %y) {
; CHECK-LABEL: @neg_range_call_vec(
-; CHECK-NEXT: [[I:%.*]] = call range(i8 -1, 1) <2 x i8> @returns_i8_helper_vec()
-; CHECK-NEXT: [[OR:%.*]] = or <2 x i8> [[Y:%.*]], [[I]]
+; CHECK-NEXT: [[X:%.*]] = call range(i8 -1, 1) <2 x i8> @returns_i8_helper_vec()
+; CHECK-NEXT: [[OR:%.*]] = or <2 x i8> [[Y:%.*]], [[X]]
; CHECK-NEXT: [[CMP:%.*]] = icmp ne <2 x i8> [[OR]], zeroinitializer
; CHECK-NEXT: ret <2 x i1> [[CMP]]
;
@@ -1449,5 +1448,53 @@ define <2 x i1> @neg_range_call_vec(<2 x i8> %y) {
ret <2 x i1> %cmp
}
+define i1 @trunc_nsw_non_zero(i8 %x) {
+; CHECK-LABEL: @trunc_nsw_non_zero(
+; CHECK-NEXT: [[X_NE_Z:%.*]] = icmp ne i8 [[X:%.*]], 0
+; CHECK-NEXT: call void @llvm.assume(i1 [[X_NE_Z]])
+; CHECK-NEXT: ret i1 true
+;
+ %x_ne_z = icmp ne i8 %x, 0
+ call void @llvm.assume(i1 %x_ne_z)
+ %v = trunc nsw i8 %x to i4
+ %r = icmp ne i4 %v, 0
+ ret i1 %r
+}
+
+define i1 @trunc_nuw_non_zero(i8 %xx) {
+; CHECK-LABEL: @trunc_nuw_non_zero(
+; CHECK-NEXT: ret i1 false
+;
+ %x = add nuw i8 %xx, 1
+ %v = trunc nuw i8 %x to i4
+ %r = icmp eq i4 %v, 0
+ ret i1 %r
+}
+
+define i1 @trunc_non_zero_fail(i8 %x) {
+; CHECK-LABEL: @trunc_non_zero_fail(
+; CHECK-NEXT: [[X_NE_Z:%.*]] = icmp ne i8 [[X:%.*]], 0
+; CHECK-NEXT: call void @llvm.assume(i1 [[X_NE_Z]])
+; CHECK-NEXT: [[R:%.*]] = trunc i8 [[X]] to i1
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %x_ne_z = icmp ne i8 %x, 0
+ call void @llvm.assume(i1 %x_ne_z)
+ %r = trunc i8 %x to i1
+ ret i1 %r
+}
+
+define i1 @trunc_nsw_nuw_non_zero_fail(i8 %xx) {
+; CHECK-LABEL: @trunc_nsw_nuw_non_zero_fail(
+; CHECK-NEXT: [[X:%.*]] = add nsw i8 [[XX:%.*]], 1
+; CHECK-NEXT: [[V:%.*]] = trunc nuw nsw i8 [[X]] to i4
+; CHECK-NEXT: [[R:%.*]] = icmp eq i4 [[V]], 0
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %x = add nsw i8 %xx, 1
+ %v = trunc nsw nuw i8 %x to i4
+ %r = icmp eq i4 %v, 0
+ ret i1 %r
+}
declare i32 @llvm.experimental.get.vector.length.i32(i32, i32, i1)
|
nikic
approved these changes
Apr 23, 2024
llvm/lib/Analysis/ValueTracking.cpp
Outdated
| @@ -3785,7 +3792,8 @@ static unsigned ComputeNumSignBitsImpl(const Value *V, | |||
| // truncation, then we can make use of that. Otherwise we don't know | |||
| // anything. | |||
| Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
| unsigned OperandTyBits = U->getOperand(0)->getType()->getScalarSizeInBits(); | |||
| unsigned OperandTyBits = | |||
| U->getOperand(0)->getType()->getScalarSizeInBits(); | |||
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Unrelated formatting change?
dtcxzyw
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dtcxzyw
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Apr 23, 2024
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dtcxzyw
reviewed
Apr 23, 2024
nikic
reviewed
Apr 23, 2024
With `nsw`/`nuw`, the `trunc` is non-zero if its operand is non-zero. Proofs: https://alive2.llvm.org/ce/z/iujmk6
goldsteinn
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I will re-test this patch later :) |
dtcxzyw
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trunc nuw/nsw; NFCtrunc nuw/nswin isKnowNonZeroWith
nsw/nuw, thetruncis non-zero if its operand is non-zero.Proofs: https://alive2.llvm.org/ce/z/iujmk6