[ValueTracking] Handle range attributes (#85143)

Handle the range attribute in ValueTracking.

llvm/include/llvm/IR/Argument.h

@@ -16,9 +16,12 @@
 #include "llvm/ADT/Twine.h"
 #include "llvm/IR/Attributes.h"
 #include "llvm/IR/Value.h"
+#include <optional>
 
 namespace llvm {
 
+class ConstantRange;
+
 /// This class represents an incoming formal argument to a Function. A formal
 /// argument, since it is ``formal'', does not contain an actual value but
 /// instead represents the type, argument number, and attributes of an argument
@@ -67,6 +70,10 @@ class Argument final : public Value {
   /// disallowed floating-point values. Otherwise, fcNone is returned.
   FPClassTest getNoFPClass() const;
 
+  /// If this argument has a range attribute, return the value range of the
+  /// argument. Otherwise, std::nullopt is returned.
+  std::optional<ConstantRange> getRange() const;
+
   /// Return true if this argument has the byval attribute.
   bool hasByValAttr() const;
 

llvm/include/llvm/IR/InstrTypes.h

@@ -43,6 +43,7 @@ namespace llvm {
 class StringRef;
 class Type;
 class Value;
+class ConstantRange;
 
 namespace Intrinsic {
 typedef unsigned ID;
@@ -1917,7 +1918,7 @@ class CallBase : public Instruction {
 
     // Look at the callee, if available.
     if (const Function *F = getCalledFunction())
-      return F->getAttributes().getRetAttr(Kind);
+      return F->getRetAttribute(Kind);
     return Attribute();
   }
 
@@ -2154,6 +2155,10 @@ class CallBase : public Instruction {
   /// parameter.
   FPClassTest getParamNoFPClass(unsigned i) const;
 
+  /// If this return value has a range attribute, return the value range of the
+  /// argument. Otherwise, std::nullopt is returned.
+  std::optional<ConstantRange> getRange() const;
+
   /// Return true if the return value is known to be not null.
   /// This may be because it has the nonnull attribute, or because at least
   /// one byte is dereferenceable and the pointer is in addrspace(0).

llvm/lib/Analysis/InstructionSimplify.cpp

@@ -3736,15 +3736,10 @@ static std::optional<ConstantRange> getRange(Value *V,
     if (MDNode *MD = IIQ.getMetadata(I, LLVMContext::MD_range))
       return getConstantRangeFromMetadata(*MD);
 
-  Attribute Range;
-  if (const Argument *A = dyn_cast<Argument>(V)) {
-    Range = A->getAttribute(llvm::Attribute::Range);
-  } else if (const CallBase *CB = dyn_cast<CallBase>(V)) {
-    Range = CB->getRetAttr(llvm::Attribute::Range);
-  }
-
-  if (Range.isValid())
-    return Range.getRange();
+  if (const Argument *A = dyn_cast<Argument>(V))
+    return A->getRange();
+  else if (const CallBase *CB = dyn_cast<CallBase>(V))
+    return CB->getRange();
 
   return std::nullopt;
 }

llvm/lib/Analysis/ValueTracking.cpp

@@ -1500,14 +1500,20 @@ static void computeKnownBitsFromOperator(const Operator *I,
     break;
   }
   case Instruction::Call:
-  case Instruction::Invoke:
+  case Instruction::Invoke: {
     // If range metadata is attached to this call, set known bits from that,
     // and then intersect with known bits based on other properties of the
     // function.
     if (MDNode *MD =
             Q.IIQ.getMetadata(cast<Instruction>(I), LLVMContext::MD_range))
       computeKnownBitsFromRangeMetadata(*MD, Known);
-    if (const Value *RV = cast<CallBase>(I)->getReturnedArgOperand()) {
+
+    const auto *CB = cast<CallBase>(I);
+
+    if (std::optional<ConstantRange> Range = CB->getRange())
+      Known = Known.unionWith(Range->toKnownBits());
+
+    if (const Value *RV = CB->getReturnedArgOperand()) {
       if (RV->getType() == I->getType()) {
         computeKnownBits(RV, Known2, Depth + 1, Q);
         Known = Known.unionWith(Known2);
@@ -1679,6 +1685,7 @@ static void computeKnownBitsFromOperator(const Operator *I,
       }
     }
     break;
+  }
   case Instruction::ShuffleVector: {
     auto *Shuf = dyn_cast<ShuffleVectorInst>(I);
     // FIXME: Do we need to handle ConstantExpr involving shufflevectors?
@@ -1933,6 +1940,10 @@ void computeKnownBits(const Value *V, const APInt &DemandedElts,
   // assumptions.  Confirm that we've handled them all.
   assert(!isa<ConstantData>(V) && "Unhandled constant data!");
 
+  if (const auto *A = dyn_cast<Argument>(V))
+    if (std::optional<ConstantRange> Range = A->getRange())
+      Known = Range->toKnownBits();
+
   // All recursive calls that increase depth must come after this.
   if (Depth == MaxAnalysisRecursionDepth)
     return;
@@ -2783,6 +2794,11 @@ static bool isKnownNonZeroFromOperator(const Operator *I,
     } else {
       if (MDNode *Ranges = Q.IIQ.getMetadata(Call, LLVMContext::MD_range))
         return rangeMetadataExcludesValue(Ranges, APInt::getZero(BitWidth));
+      if (std::optional<ConstantRange> Range = Call->getRange()) {
+        const APInt ZeroValue(Range->getBitWidth(), 0);
+        if (!Range->contains(ZeroValue))
+          return true;
+      }
       if (const Value *RV = Call->getReturnedArgOperand())
         if (RV->getType() == I->getType() && isKnownNonZero(RV, Depth, Q))
           return true;
@@ -2921,6 +2937,13 @@ bool isKnownNonZero(const Value *V, const APInt &DemandedElts, unsigned Depth,
       return false;
   }
 
+  if (const auto *A = dyn_cast<Argument>(V))
+    if (std::optional<ConstantRange> Range = A->getRange()) {
+      const APInt ZeroValue(Range->getBitWidth(), 0);
+      if (!Range->contains(ZeroValue))
+        return true;
+    }
+
   if (!isa<Constant>(V) && isKnownNonZeroFromAssume(V, Q))
     return true;
 
@@ -9146,12 +9169,19 @@ ConstantRange llvm::computeConstantRange(const Value *V, bool ForSigned,
     // TODO: Return ConstantRange.
     setLimitForFPToI(cast<Instruction>(V), Lower, Upper);
     CR = ConstantRange::getNonEmpty(Lower, Upper);
-  }
+  } else if (const auto *A = dyn_cast<Argument>(V))
+    if (std::optional<ConstantRange> Range = A->getRange())
+      CR = *Range;
 
-  if (auto *I = dyn_cast<Instruction>(V))
+  if (auto *I = dyn_cast<Instruction>(V)) {
     if (auto *Range = IIQ.getMetadata(I, LLVMContext::MD_range))
       CR = CR.intersectWith(getConstantRangeFromMetadata(*Range));
 
+    if (const auto *CB = dyn_cast<CallBase>(V))
+      if (std::optional<ConstantRange> Range = CB->getRange())
+        CR = CR.intersectWith(*Range);
+  }
+
   if (CtxI && AC) {
     // Try to restrict the range based on information from assumptions.
     for (auto &AssumeVH : AC->assumptionsFor(V)) {

llvm/lib/IR/Function.cpp

@@ -24,6 +24,7 @@
 #include "llvm/IR/Attributes.h"
 #include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/Constant.h"
+#include "llvm/IR/ConstantRange.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/GlobalValue.h"
@@ -256,6 +257,13 @@ FPClassTest Argument::getNoFPClass() const {
   return getParent()->getParamNoFPClass(getArgNo());
 }
 
+std::optional<ConstantRange> Argument::getRange() const {
+  const Attribute RangeAttr = getAttribute(llvm::Attribute::Range);
+  if (RangeAttr.isValid())
+    return RangeAttr.getRange();
+  return std::nullopt;
+}
+
 bool Argument::hasNestAttr() const {
   if (!getType()->isPointerTy()) return false;
   return hasAttribute(Attribute::Nest);

llvm/lib/IR/Instructions.cpp

@@ -19,6 +19,7 @@
 #include "llvm/IR/Attributes.h"
 #include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/Constant.h"
+#include "llvm/IR/ConstantRange.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/DerivedTypes.h"
@@ -395,6 +396,13 @@ FPClassTest CallBase::getParamNoFPClass(unsigned i) const {
   return Mask;
 }
 
+std::optional<ConstantRange> CallBase::getRange() const {
+  const Attribute RangeAttr = getRetAttr(llvm::Attribute::Range);
+  if (RangeAttr.isValid())
+    return RangeAttr.getRange();
+  return std::nullopt;
+}
+
 bool CallBase::isReturnNonNull() const {
   if (hasRetAttr(Attribute::NonNull))
     return true;

llvm/test/Analysis/ValueTracking/known-non-zero.ll

@@ -1303,4 +1303,151 @@ define <2 x i1> @range_metadata_vec(ptr %p, <2 x i32> %x) {
   ret <2 x i1> %cmp
 }
 
+define i1 @range_attr(i8 range(i8 1, 0) %x, i8 %y) {
+; CHECK-LABEL: @range_attr(
+; CHECK-NEXT:    ret i1 false
+;
+  %or = or i8 %y, %x
+  %cmp = icmp eq i8 %or, 0
+  ret i1 %cmp
+}
+
+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:    ret i1 [[CMP]]
+;
+  %or = or i8 %y, %x
+  %cmp = icmp eq i8 %or, 0
+  ret i1 %cmp
+}
+
+declare range(i8 1, 0) i8 @returns_non_zero_range_helper()
+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:    ret i1 false
+;
+  %x = call i8 @returns_non_zero_range_helper()
+  %or = or i8 %y, %x
+  %cmp = icmp eq i8 %or, 0
+  ret i1 %cmp
+}
+
+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:    [[CMP:%.*]] = icmp eq i8 [[OR]], 0
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %x = call i8 @returns_contain_zero_range_helper()
+  %or = or i8 %y, %x
+  %cmp = icmp eq i8 %or, 0
+  ret i1 %cmp
+}
+
+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:    ret i1 false
+;
+  %x = call range(i8 1, 0) i8 @returns_i8_helper()
+  %or = or i8 %y, %x
+  %cmp = icmp eq i8 %or, 0
+  ret i1 %cmp
+}
+
+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:    [[CMP:%.*]] = icmp eq i8 [[OR]], 0
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %x = call range(i8 -1, 1) i8 @returns_i8_helper()
+  %or = or i8 %y, %x
+  %cmp = icmp eq i8 %or, 0
+  ret i1 %cmp
+}
+
+define <2 x i1> @range_attr_vec(<2 x i8> range(i8 1, 0) %x, <2 x i8> %y) {
+; CHECK-LABEL: @range_attr_vec(
+; CHECK-NEXT:    ret <2 x i1> <i1 true, i1 true>
+;
+  %or = or <2 x i8> %y, %x
+  %cmp = icmp ne <2 x i8> %or, zeroinitializer
+  ret <2 x i1> %cmp
+}
+
+define <2 x i1> @neg_range_attr_vec(<2 x i8> range(i8 -1, 1) %x, <2 x i8> %y) {
+; CHECK-LABEL: @neg_range_attr_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]]
+;
+  %or = or <2 x i8> %y, %x
+  %cmp = icmp ne <2 x i8> %or, zeroinitializer
+  ret <2 x i1> %cmp
+}
+
+declare range(i8 1, 0) <2 x i8> @returns_non_zero_range_helper_vec()
+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:    ret <2 x i1> <i1 true, i1 true>
+;
+  %x = call <2 x i8> @returns_non_zero_range_helper_vec()
+  %or = or <2 x i8> %y, %x
+  %cmp = icmp ne <2 x i8> %or, zeroinitializer
+  ret <2 x i1> %cmp
+}
+
+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:    [[CMP:%.*]] = icmp ne <2 x i8> [[OR]], zeroinitializer
+; CHECK-NEXT:    ret <2 x i1> [[CMP]]
+;
+  %x = call <2 x i8> @returns_contain_zero_range_helper_vec()
+  %or = or <2 x i8> %y, %x
+  %cmp = icmp ne <2 x i8> %or, zeroinitializer
+  ret <2 x i1> %cmp
+}
+
+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:    ret <2 x i1> <i1 true, i1 true>
+;
+  %x = call range(i8 1, 0) <2 x i8> @returns_i8_helper_vec()
+  %or = or <2 x i8> %y, %x
+  %cmp = icmp ne <2 x i8> %or, zeroinitializer
+  ret <2 x i1> %cmp
+}
+
+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:    [[CMP:%.*]] = icmp ne <2 x i8> [[OR]], zeroinitializer
+; CHECK-NEXT:    ret <2 x i1> [[CMP]]
+;
+  %x = call range(i8 -1, 1) <2 x i8> @returns_i8_helper_vec()
+  %or = or <2 x i8> %y, %x
+  %cmp = icmp ne <2 x i8> %or, zeroinitializer
+  ret <2 x i1> %cmp
+}
+
+
 declare i32 @llvm.experimental.get.vector.length.i32(i32, i32, i1)