[InstSimplify] Simplify 'x u>= 1' to true when x is known non-zero #145204
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llvmbot
added
llvm:instcombine
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@llvm/pr-subscribers-llvm-transforms Author: Iris Shi (el-ev) ChangesThere is a common pattern where Godbolt Example: https://godbolt.org/z/zGzTTYe57 Full diff: https://github.com/llvm/llvm-project/pull/145204.diff 2 Files Affected:
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index d1ac8d9fbdfd1..cb1dae92faf92 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -2981,7 +2981,7 @@ static Value *simplifyICmpWithZero(CmpPredicate Pred, Value *LHS, Value *RHS,
}
static Value *simplifyICmpWithConstant(CmpPredicate Pred, Value *LHS,
- Value *RHS, const InstrInfoQuery &IIQ) {
+ Value *RHS, const SimplifyQuery &Q) {
Type *ITy = getCompareTy(RHS); // The return type.
Value *X;
@@ -3007,7 +3007,7 @@ static Value *simplifyICmpWithConstant(CmpPredicate Pred, Value *LHS,
return ConstantInt::getTrue(ITy);
ConstantRange LHS_CR =
- computeConstantRange(LHS, CmpInst::isSigned(Pred), IIQ.UseInstrInfo);
+ computeConstantRange(LHS, CmpInst::isSigned(Pred), Q.IIQ.UseInstrInfo);
if (!LHS_CR.isFullSet()) {
if (RHS_CR.contains(LHS_CR))
return ConstantInt::getTrue(ITy);
@@ -3018,13 +3018,16 @@ static Value *simplifyICmpWithConstant(CmpPredicate Pred, Value *LHS,
// (mul nuw/nsw X, MulC) != C --> true (if C is not a multiple of MulC)
// (mul nuw/nsw X, MulC) == C --> false (if C is not a multiple of MulC)
const APInt *MulC;
- if (IIQ.UseInstrInfo && ICmpInst::isEquality(Pred) &&
+ if (Q.IIQ.UseInstrInfo && ICmpInst::isEquality(Pred) &&
((match(LHS, m_NUWMul(m_Value(), m_APIntAllowPoison(MulC))) &&
*MulC != 0 && C->urem(*MulC) != 0) ||
(match(LHS, m_NSWMul(m_Value(), m_APIntAllowPoison(MulC))) &&
*MulC != 0 && C->srem(*MulC) != 0)))
return ConstantInt::get(ITy, Pred == ICmpInst::ICMP_NE);
+ if (Pred == ICmpInst::ICMP_UGE && C->isOne() && isKnownNonZero(LHS, Q))
+ return ConstantInt::getTrue(ITy);
+
return nullptr;
}
@@ -3776,7 +3779,7 @@ static Value *simplifyICmpInst(CmpPredicate Pred, Value *LHS, Value *RHS,
if (Value *V = simplifyICmpWithZero(Pred, LHS, RHS, Q))
return V;
- if (Value *V = simplifyICmpWithConstant(Pred, LHS, RHS, Q.IIQ))
+ if (Value *V = simplifyICmpWithConstant(Pred, LHS, RHS, Q))
return V;
// If both operands have range metadata, use the metadata
diff --git a/llvm/test/Transforms/InstSimplify/umax-1.ll b/llvm/test/Transforms/InstSimplify/umax-1.ll
new file mode 100644
index 0000000000000..77863acb02327
--- /dev/null
+++ b/llvm/test/Transforms/InstSimplify/umax-1.ll
@@ -0,0 +1,120 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt < %s -passes=instsimplify -S | FileCheck %s
+
+define i32 @known_non_zero_by_or(i32 %x, i32 %y) {
+; CHECK-LABEL: define i32 @known_non_zero_by_or(
+; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
+; CHECK-NEXT: [[COND:%.*]] = icmp ne i32 [[X]], 0
+; CHECK-NEXT: br i1 [[COND]], label %[[IF_THEN:.*]], label %[[IF_ELSE:.*]]
+; CHECK: [[IF_THEN]]:
+; CHECK-NEXT: [[VAL:%.*]] = or i32 [[X]], [[Y]]
+; CHECK-NEXT: ret i32 [[VAL]]
+; CHECK: [[IF_ELSE]]:
+; CHECK-NEXT: ret i32 0
+;
+ %cond = icmp ne i32 %x, 0
+ br i1 %cond, label %if.then, label %if.else
+
+if.then:
+ %val = or i32 %x, %y
+ %max = call i32 @llvm.umax.i32(i32 %val, i32 1)
+ ret i32 %max
+
+if.else:
+ ret i32 0
+}
+
+define i32 @known_non_zero_by_mul(i32 %x) {
+; CHECK-LABEL: define i32 @known_non_zero_by_mul(
+; CHECK-SAME: i32 [[X:%.*]]) {
+; CHECK-NEXT: [[COND:%.*]] = icmp ne i32 [[X]], 0
+; CHECK-NEXT: br i1 [[COND]], label %[[IF_THEN:.*]], label %[[IF_ELSE:.*]]
+; CHECK: [[IF_THEN]]:
+; CHECK-NEXT: [[NONZERO1:%.*]] = mul nuw i32 [[X]], 3
+; CHECK-NEXT: ret i32 [[NONZERO1]]
+; CHECK: [[IF_ELSE]]:
+; CHECK-NEXT: ret i32 0
+;
+ %cond = icmp ne i32 %x, 0
+ br i1 %cond, label %if.then, label %if.else
+
+if.then:
+ %nonzero = mul nuw i32 %x, 3
+ %max = call i32 @llvm.umax.i32(i32 %nonzero, i32 1)
+ ret i32 %max
+
+if.else:
+ ret i32 0
+}
+
+define i32 @known_non_zero_commute(i32 %x, i32 %y) {
+; CHECK-LABEL: define i32 @known_non_zero_commute(
+; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
+; CHECK-NEXT: [[COND:%.*]] = icmp ne i32 [[X]], 0
+; CHECK-NEXT: br i1 [[COND]], label %[[IF_THEN:.*]], label %[[IF_ELSE:.*]]
+; CHECK: [[IF_THEN]]:
+; CHECK-NEXT: [[VAL:%.*]] = or i32 [[X]], [[Y]]
+; CHECK-NEXT: ret i32 [[VAL]]
+; CHECK: [[IF_ELSE]]:
+; CHECK-NEXT: ret i32 0
+;
+ %cond = icmp ne i32 %x, 0
+ br i1 %cond, label %if.then, label %if.else
+
+if.then:
+ %val = or i32 %x, %y
+ %max = call i32 @llvm.umax.i32(i32 1, i32 %val)
+ ret i32 %max
+
+if.else:
+ ret i32 0
+}
+
+; Negative
+define i32 @umax_ge_2(i32 %x, i32 %y) {
+; CHECK-LABEL: define i32 @umax_ge_2(
+; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
+; CHECK-NEXT: [[COND:%.*]] = icmp ne i32 [[X]], 0
+; CHECK-NEXT: br i1 [[COND]], label %[[IF_THEN:.*]], label %[[IF_ELSE:.*]]
+; CHECK: [[IF_THEN]]:
+; CHECK-NEXT: [[VAL:%.*]] = or i32 [[X]], [[Y]]
+; CHECK-NEXT: [[MAX:%.*]] = call i32 @llvm.umax.i32(i32 [[VAL]], i32 2)
+; CHECK-NEXT: ret i32 [[MAX]]
+; CHECK: [[IF_ELSE]]:
+; CHECK-NEXT: ret i32 0
+;
+ %cond = icmp ne i32 %x, 0
+ br i1 %cond, label %if.then, label %if.else
+
+if.then:
+ %val = or i32 %x, %y
+ %max = call i32 @llvm.umax.i32(i32 %val, i32 2)
+ ret i32 %max
+
+if.else:
+ ret i32 0
+}
+
+define i32 @unknown_by_and(i32 %x, i32 %y) {
+; CHECK-LABEL: define i32 @unknown_by_and(
+; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
+; CHECK-NEXT: [[COND:%.*]] = icmp ne i32 [[X]], 0
+; CHECK-NEXT: br i1 [[COND]], label %[[IF_THEN:.*]], label %[[IF_ELSE:.*]]
+; CHECK: [[IF_THEN]]:
+; CHECK-NEXT: [[VAL:%.*]] = and i32 [[X]], [[Y]]
+; CHECK-NEXT: [[MAX:%.*]] = call i32 @llvm.umax.i32(i32 [[VAL]], i32 1)
+; CHECK-NEXT: ret i32 [[MAX]]
+; CHECK: [[IF_ELSE]]:
+; CHECK-NEXT: ret i32 0
+;
+ %cond = icmp ne i32 %x, 0
+ br i1 %cond, label %if.then, label %if.else
+
+if.then:
+ %val = and i32 %x, %y
+ %max = call i32 @llvm.umax.i32(i32 %val, i32 1)
+ ret i32 %max
+
+if.else:
+ ret i32 0
+}
|
Member
|
@llvm/pr-subscribers-llvm-analysis Author: Iris Shi (el-ev) ChangesThere is a common pattern where Godbolt Example: https://godbolt.org/z/zGzTTYe57 Full diff: https://github.com/llvm/llvm-project/pull/145204.diff 2 Files Affected:
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index d1ac8d9fbdfd1..cb1dae92faf92 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -2981,7 +2981,7 @@ static Value *simplifyICmpWithZero(CmpPredicate Pred, Value *LHS, Value *RHS,
}
static Value *simplifyICmpWithConstant(CmpPredicate Pred, Value *LHS,
- Value *RHS, const InstrInfoQuery &IIQ) {
+ Value *RHS, const SimplifyQuery &Q) {
Type *ITy = getCompareTy(RHS); // The return type.
Value *X;
@@ -3007,7 +3007,7 @@ static Value *simplifyICmpWithConstant(CmpPredicate Pred, Value *LHS,
return ConstantInt::getTrue(ITy);
ConstantRange LHS_CR =
- computeConstantRange(LHS, CmpInst::isSigned(Pred), IIQ.UseInstrInfo);
+ computeConstantRange(LHS, CmpInst::isSigned(Pred), Q.IIQ.UseInstrInfo);
if (!LHS_CR.isFullSet()) {
if (RHS_CR.contains(LHS_CR))
return ConstantInt::getTrue(ITy);
@@ -3018,13 +3018,16 @@ static Value *simplifyICmpWithConstant(CmpPredicate Pred, Value *LHS,
// (mul nuw/nsw X, MulC) != C --> true (if C is not a multiple of MulC)
// (mul nuw/nsw X, MulC) == C --> false (if C is not a multiple of MulC)
const APInt *MulC;
- if (IIQ.UseInstrInfo && ICmpInst::isEquality(Pred) &&
+ if (Q.IIQ.UseInstrInfo && ICmpInst::isEquality(Pred) &&
((match(LHS, m_NUWMul(m_Value(), m_APIntAllowPoison(MulC))) &&
*MulC != 0 && C->urem(*MulC) != 0) ||
(match(LHS, m_NSWMul(m_Value(), m_APIntAllowPoison(MulC))) &&
*MulC != 0 && C->srem(*MulC) != 0)))
return ConstantInt::get(ITy, Pred == ICmpInst::ICMP_NE);
+ if (Pred == ICmpInst::ICMP_UGE && C->isOne() && isKnownNonZero(LHS, Q))
+ return ConstantInt::getTrue(ITy);
+
return nullptr;
}
@@ -3776,7 +3779,7 @@ static Value *simplifyICmpInst(CmpPredicate Pred, Value *LHS, Value *RHS,
if (Value *V = simplifyICmpWithZero(Pred, LHS, RHS, Q))
return V;
- if (Value *V = simplifyICmpWithConstant(Pred, LHS, RHS, Q.IIQ))
+ if (Value *V = simplifyICmpWithConstant(Pred, LHS, RHS, Q))
return V;
// If both operands have range metadata, use the metadata
diff --git a/llvm/test/Transforms/InstSimplify/umax-1.ll b/llvm/test/Transforms/InstSimplify/umax-1.ll
new file mode 100644
index 0000000000000..77863acb02327
--- /dev/null
+++ b/llvm/test/Transforms/InstSimplify/umax-1.ll
@@ -0,0 +1,120 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt < %s -passes=instsimplify -S | FileCheck %s
+
+define i32 @known_non_zero_by_or(i32 %x, i32 %y) {
+; CHECK-LABEL: define i32 @known_non_zero_by_or(
+; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
+; CHECK-NEXT: [[COND:%.*]] = icmp ne i32 [[X]], 0
+; CHECK-NEXT: br i1 [[COND]], label %[[IF_THEN:.*]], label %[[IF_ELSE:.*]]
+; CHECK: [[IF_THEN]]:
+; CHECK-NEXT: [[VAL:%.*]] = or i32 [[X]], [[Y]]
+; CHECK-NEXT: ret i32 [[VAL]]
+; CHECK: [[IF_ELSE]]:
+; CHECK-NEXT: ret i32 0
+;
+ %cond = icmp ne i32 %x, 0
+ br i1 %cond, label %if.then, label %if.else
+
+if.then:
+ %val = or i32 %x, %y
+ %max = call i32 @llvm.umax.i32(i32 %val, i32 1)
+ ret i32 %max
+
+if.else:
+ ret i32 0
+}
+
+define i32 @known_non_zero_by_mul(i32 %x) {
+; CHECK-LABEL: define i32 @known_non_zero_by_mul(
+; CHECK-SAME: i32 [[X:%.*]]) {
+; CHECK-NEXT: [[COND:%.*]] = icmp ne i32 [[X]], 0
+; CHECK-NEXT: br i1 [[COND]], label %[[IF_THEN:.*]], label %[[IF_ELSE:.*]]
+; CHECK: [[IF_THEN]]:
+; CHECK-NEXT: [[NONZERO1:%.*]] = mul nuw i32 [[X]], 3
+; CHECK-NEXT: ret i32 [[NONZERO1]]
+; CHECK: [[IF_ELSE]]:
+; CHECK-NEXT: ret i32 0
+;
+ %cond = icmp ne i32 %x, 0
+ br i1 %cond, label %if.then, label %if.else
+
+if.then:
+ %nonzero = mul nuw i32 %x, 3
+ %max = call i32 @llvm.umax.i32(i32 %nonzero, i32 1)
+ ret i32 %max
+
+if.else:
+ ret i32 0
+}
+
+define i32 @known_non_zero_commute(i32 %x, i32 %y) {
+; CHECK-LABEL: define i32 @known_non_zero_commute(
+; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
+; CHECK-NEXT: [[COND:%.*]] = icmp ne i32 [[X]], 0
+; CHECK-NEXT: br i1 [[COND]], label %[[IF_THEN:.*]], label %[[IF_ELSE:.*]]
+; CHECK: [[IF_THEN]]:
+; CHECK-NEXT: [[VAL:%.*]] = or i32 [[X]], [[Y]]
+; CHECK-NEXT: ret i32 [[VAL]]
+; CHECK: [[IF_ELSE]]:
+; CHECK-NEXT: ret i32 0
+;
+ %cond = icmp ne i32 %x, 0
+ br i1 %cond, label %if.then, label %if.else
+
+if.then:
+ %val = or i32 %x, %y
+ %max = call i32 @llvm.umax.i32(i32 1, i32 %val)
+ ret i32 %max
+
+if.else:
+ ret i32 0
+}
+
+; Negative
+define i32 @umax_ge_2(i32 %x, i32 %y) {
+; CHECK-LABEL: define i32 @umax_ge_2(
+; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
+; CHECK-NEXT: [[COND:%.*]] = icmp ne i32 [[X]], 0
+; CHECK-NEXT: br i1 [[COND]], label %[[IF_THEN:.*]], label %[[IF_ELSE:.*]]
+; CHECK: [[IF_THEN]]:
+; CHECK-NEXT: [[VAL:%.*]] = or i32 [[X]], [[Y]]
+; CHECK-NEXT: [[MAX:%.*]] = call i32 @llvm.umax.i32(i32 [[VAL]], i32 2)
+; CHECK-NEXT: ret i32 [[MAX]]
+; CHECK: [[IF_ELSE]]:
+; CHECK-NEXT: ret i32 0
+;
+ %cond = icmp ne i32 %x, 0
+ br i1 %cond, label %if.then, label %if.else
+
+if.then:
+ %val = or i32 %x, %y
+ %max = call i32 @llvm.umax.i32(i32 %val, i32 2)
+ ret i32 %max
+
+if.else:
+ ret i32 0
+}
+
+define i32 @unknown_by_and(i32 %x, i32 %y) {
+; CHECK-LABEL: define i32 @unknown_by_and(
+; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
+; CHECK-NEXT: [[COND:%.*]] = icmp ne i32 [[X]], 0
+; CHECK-NEXT: br i1 [[COND]], label %[[IF_THEN:.*]], label %[[IF_ELSE:.*]]
+; CHECK: [[IF_THEN]]:
+; CHECK-NEXT: [[VAL:%.*]] = and i32 [[X]], [[Y]]
+; CHECK-NEXT: [[MAX:%.*]] = call i32 @llvm.umax.i32(i32 [[VAL]], i32 1)
+; CHECK-NEXT: ret i32 [[MAX]]
+; CHECK: [[IF_ELSE]]:
+; CHECK-NEXT: ret i32 0
+;
+ %cond = icmp ne i32 %x, 0
+ br i1 %cond, label %if.then, label %if.else
+
+if.then:
+ %val = and i32 %x, %y
+ %max = call i32 @llvm.umax.i32(i32 %val, i32 1)
+ ret i32 %max
+
+if.else:
+ ret i32 0
+}
|
nikic
reviewed
Jun 22, 2025
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There is a common pattern where
umax(x, 1)is generated in loop preheaders. When we can prove thatxis non-zero, such call could be eliminated.Godbolt Example: https://godbolt.org/z/zGzTTYe57
Bench: dtcxzyw/llvm-opt-benchmark#2484