[IPSCCP] Add getCompare which returns either true, false, undef or null.

[fhahn]

Summary

getCompare returns true, false or undef constants if the comparison can
be evaluated, or nullptr if it cannot. This is in line with what
ConstantExpr::getCompare returns. It also allows us to use
ConstantExpr::getCompare for comparing constants.

[fhahn]

Improve checks in test case

[fhahn]

ping

[davide]

lgtm.

include/llvm/Analysis/ValueLattice.h

public:
   }
 
   ConstantInt *getConstantInt() const {
     assert(isConstant() && isa<ConstantInt>(getConstant()) &&
            "No integer constant");
     return cast<ConstantInt>(getConstant());
   }
 
-  bool satisfiesPredicate(CmpInst::Predicate Pred,
-                          const ValueLatticeElement &Other) const {
-    // TODO: share with LVI getPredicateResult.
-
+  /// Compares this symbolic value with Other using Pred and returns either
+  /// true, false or undef constants, or nullptr if the comparison cannot be
+  /// evaluated.
+  Constant *getCompare(CmpInst::Predicate Pred, Type *Ty,
     if (isUndefined() || Other.isUndefined())
-      return true;
+      return UndefValue::get(Ty);
 
-    if (isConstant() && Other.isConstant() && Pred == CmpInst::FCMP_OEQ)
-      return getConstant() == Other.getConstant();
+    if (isConstant() && Other.isConstant())
+      return ConstantExpr::getCompare(Pred, getConstant(), Other.getConstant());
 
     // Integer constants are represented as ConstantRanges with single
     // elements.
     if (!isConstantRange() || !Other.isConstantRange())
-      return false;
+      return nullptr;
 
     const auto &CR = getConstantRange();
     const auto &OtherCR = Other.getConstantRange();
-    return ConstantRange::makeSatisfyingICmpRegion(Pred, OtherCR).contains(CR);
+    if (ConstantRange::makeSatisfyingICmpRegion(Pred, OtherCR).contains(CR))
+      return ConstantInt::getTrue(Ty);
+    if (ConstantRange::makeSatisfyingICmpRegion(
+            CmpInst::getInversePredicate(Pred), OtherCR)
+            .contains(CR))
+      return ConstantInt::getFalse(Ty);
+
+    return nullptr;
   }
 };
 
 raw_ostream &operator<<(raw_ostream &OS, const ValueLatticeElement &Val);
 
 } // end namespace llvm
 #endif

lib/Transforms/Scalar/SCCP.cpp

auto getIcmpLatticeValue = [&](Value *Op) {
       if (auto *C = dyn_cast<Constant>(Op))
         return ValueLatticeElement::get(C);
       return Solver.getLatticeValueFor(Op);
     };
 
     ValueLatticeElement A = getIcmpLatticeValue(Icmp->getOperand(0));
     ValueLatticeElement B = getIcmpLatticeValue(Icmp->getOperand(1));
 
-    Constant *C = nullptr;
-    if (A.satisfiesPredicate(Icmp->getPredicate(), B))
-      C = ConstantInt::getTrue(Icmp->getType());
-    else if (A.satisfiesPredicate(Icmp->getInversePredicate(), B))
-      C = ConstantInt::getFalse(Icmp->getType());
-
+    Constant *C = A.getCompare(Icmp->getPredicate(), Icmp->getType(), B);
     if (C) {
       Icmp->replaceAllUsesWith(C);
       DEBUG(dbgs() << "Replacing " << *Icmp << " with " << *C
                    << ", because of range information " << A << " " << B
                    << "\n");
       Icmp->eraseFromParent();
       Changed = true;
     }

test/Transforms/SCCP/ip-constant-ranges.ll

 
 ; Check that we do not attempt to get range info for non-integer types and
 ; crash.
 define double @test_struct({ double, double } %test) {
     %v = extractvalue { double, double } %test, 0
     %r = fmul double %v, %v
     ret double %r
 }
+
+; Constant range for %x is [47, 302)
+; CHECK-LABEL: f5
+; %res1 = select i1 undef, i32 1, i32 2
+; %res2 = select i1 undef, i32 3, i32 4
+define internal i32 @f5(i32 %x) {
+entry:
+  %cmp = icmp sgt i32 %x, undef
+  %cmp2 = icmp ne i32 undef, %x
+  %res1 = select i1 %cmp, i32 1, i32 2
+  %res2 = select i1 %cmp2, i32 3, i32 4
+
+  %res = add i32 %res1, %res2
+  ret i32 %res
+}
+
+define i32 @caller4() {
+entry:
+  %call1 = tail call i32 @f5(i32 47)
+  %call2 = tail call i32 @f5(i32 301)
+  %res = add nsw i32 %call1, %call2
+  ret i32 %res
+}

unittests/Analysis/ValueLatticeTest.cpp

TEST_F(ValueLatticeTest, MergeIn) {
   EXPECT_EQ(LV2.getConstantRange().getLower().getLimitedValue(), 1U);
   EXPECT_EQ(LV2.getConstantRange().getUpper().getLimitedValue(), 100U);
 
   // Merge with overdefined.
   LV1.mergeIn(ValueLatticeElement::getOverdefined(), M.getDataLayout());
   EXPECT_TRUE(LV1.isOverdefined());
 }
 
-TEST_F(ValueLatticeTest, satisfiesPredicateIntegers) {
-  auto I32Ty = IntegerType::get(Context, 32);
+TEST_F(ValueLatticeTest, getCompareIntegers) {
+  auto *I32Ty = IntegerType::get(Context, 32);
+  auto *I1Ty = IntegerType::get(Context, 1);
   auto *C1 = ConstantInt::get(I32Ty, 1);
   auto LV1 = ValueLatticeElement::get(C1);
 
-  // Check satisfiesPredicate for equal integer constants.
-  EXPECT_TRUE(LV1.satisfiesPredicate(CmpInst::ICMP_EQ, LV1));
-  EXPECT_TRUE(LV1.satisfiesPredicate(CmpInst::ICMP_SGE, LV1));
-  EXPECT_TRUE(LV1.satisfiesPredicate(CmpInst::ICMP_SLE, LV1));
-  EXPECT_FALSE(LV1.satisfiesPredicate(CmpInst::ICMP_NE, LV1));
-  EXPECT_FALSE(LV1.satisfiesPredicate(CmpInst::ICMP_SLT, LV1));
-  EXPECT_FALSE(LV1.satisfiesPredicate(CmpInst::ICMP_SGT, LV1));
+  // Check getCompare for equal integer constants.
+  EXPECT_TRUE(LV1.getCompare(CmpInst::ICMP_EQ, I1Ty, LV1)->isOneValue());
+  EXPECT_TRUE(LV1.getCompare(CmpInst::ICMP_SGE, I1Ty, LV1)->isOneValue());
+  EXPECT_TRUE(LV1.getCompare(CmpInst::ICMP_SLE, I1Ty, LV1)->isOneValue());
+  EXPECT_TRUE(LV1.getCompare(CmpInst::ICMP_NE, I1Ty, LV1)->isZeroValue());
+  EXPECT_TRUE(LV1.getCompare(CmpInst::ICMP_SLT, I1Ty, LV1)->isZeroValue());
+  EXPECT_TRUE(LV1.getCompare(CmpInst::ICMP_SGT, I1Ty, LV1)->isZeroValue());
 
   auto LV2 =
       ValueLatticeElement::getRange({APInt(32, 10, true), APInt(32, 20, true)});
-  // Check satisfiesPredicate with distinct integer ranges.
-  EXPECT_TRUE(LV1.satisfiesPredicate(CmpInst::ICMP_SLT, LV2));
-  EXPECT_TRUE(LV1.satisfiesPredicate(CmpInst::ICMP_SLE, LV2));
-  EXPECT_TRUE(LV1.satisfiesPredicate(CmpInst::ICMP_NE, LV2));
-  EXPECT_FALSE(LV1.satisfiesPredicate(CmpInst::ICMP_EQ, LV2));
-  EXPECT_FALSE(LV1.satisfiesPredicate(CmpInst::ICMP_SGE, LV2));
-  EXPECT_FALSE(LV1.satisfiesPredicate(CmpInst::ICMP_SGT, LV2));
+  // Check getCompare with distinct integer ranges.
+  EXPECT_TRUE(LV1.getCompare(CmpInst::ICMP_SLT, I1Ty, LV2)->isOneValue());
+  EXPECT_TRUE(LV1.getCompare(CmpInst::ICMP_SLE, I1Ty, LV2)->isOneValue());
+  EXPECT_TRUE(LV1.getCompare(CmpInst::ICMP_NE, I1Ty, LV2)->isOneValue());
+  EXPECT_TRUE(LV1.getCompare(CmpInst::ICMP_EQ, I1Ty, LV2)->isZeroValue());
+  EXPECT_TRUE(LV1.getCompare(CmpInst::ICMP_SGE, I1Ty, LV2)->isZeroValue());
+  EXPECT_TRUE(LV1.getCompare(CmpInst::ICMP_SGT, I1Ty, LV2)->isZeroValue());
 
   auto LV3 =
       ValueLatticeElement::getRange({APInt(32, 15, true), APInt(32, 19, true)});
-  // Check satisfiesPredicate with a subset integer ranges.
-  EXPECT_FALSE(LV2.satisfiesPredicate(CmpInst::ICMP_SLT, LV3));
-  EXPECT_FALSE(LV2.satisfiesPredicate(CmpInst::ICMP_SLE, LV3));
-  EXPECT_FALSE(LV2.satisfiesPredicate(CmpInst::ICMP_NE, LV3));
-  EXPECT_FALSE(LV2.satisfiesPredicate(CmpInst::ICMP_EQ, LV3));
-  EXPECT_FALSE(LV2.satisfiesPredicate(CmpInst::ICMP_SGE, LV3));
-  EXPECT_FALSE(LV2.satisfiesPredicate(CmpInst::ICMP_SGT, LV3));
+  // Check getCompare with a subset integer ranges.
+  EXPECT_EQ(LV2.getCompare(CmpInst::ICMP_SLT, I1Ty, LV3), nullptr);
+  EXPECT_EQ(LV2.getCompare(CmpInst::ICMP_SLE, I1Ty, LV3), nullptr);
+  EXPECT_EQ(LV2.getCompare(CmpInst::ICMP_NE, I1Ty, LV3), nullptr);
+  EXPECT_EQ(LV2.getCompare(CmpInst::ICMP_EQ, I1Ty, LV3), nullptr);
+  EXPECT_EQ(LV2.getCompare(CmpInst::ICMP_SGE, I1Ty, LV3), nullptr);
+  EXPECT_EQ(LV2.getCompare(CmpInst::ICMP_SGT, I1Ty, LV3), nullptr);
 
   auto LV4 =
       ValueLatticeElement::getRange({APInt(32, 15, true), APInt(32, 25, true)});
-  // Check satisfiesPredicate with overlapping integer ranges.
-  EXPECT_FALSE(LV3.satisfiesPredicate(CmpInst::ICMP_SLT, LV4));
-  EXPECT_FALSE(LV3.satisfiesPredicate(CmpInst::ICMP_SLE, LV4));
-  EXPECT_FALSE(LV3.satisfiesPredicate(CmpInst::ICMP_NE, LV4));
-  EXPECT_FALSE(LV3.satisfiesPredicate(CmpInst::ICMP_EQ, LV4));
-  EXPECT_FALSE(LV3.satisfiesPredicate(CmpInst::ICMP_SGE, LV4));
-  EXPECT_FALSE(LV3.satisfiesPredicate(CmpInst::ICMP_SGT, LV4));
+  // Check getCompare with overlapping integer ranges.
+  EXPECT_EQ(LV3.getCompare(CmpInst::ICMP_SLT, I1Ty, LV4), nullptr);
+  EXPECT_EQ(LV3.getCompare(CmpInst::ICMP_SLE, I1Ty, LV4), nullptr);
+  EXPECT_EQ(LV3.getCompare(CmpInst::ICMP_NE, I1Ty, LV4), nullptr);
+  EXPECT_EQ(LV3.getCompare(CmpInst::ICMP_EQ, I1Ty, LV4), nullptr);
+  EXPECT_EQ(LV3.getCompare(CmpInst::ICMP_SGE, I1Ty, LV4), nullptr);
+  EXPECT_EQ(LV3.getCompare(CmpInst::ICMP_SGT, I1Ty, LV4), nullptr);
 }
 
-TEST_F(ValueLatticeTest, satisfiesPredicateFloat) {
-  auto FloatTy = IntegerType::getFloatTy(Context);
+TEST_F(ValueLatticeTest, getCompareFloat) {
+  auto *FloatTy = IntegerType::getFloatTy(Context);
+  auto *I1Ty = IntegerType::get(Context, 1);
   auto *C1 = ConstantFP::get(FloatTy, 1.0);
   auto LV1 = ValueLatticeElement::get(C1);
   auto LV2 = ValueLatticeElement::get(C1);
 
-  // Check satisfiesPredicate for equal floating point constants.
-  EXPECT_TRUE(LV1.satisfiesPredicate(CmpInst::FCMP_OEQ, LV2));
-  EXPECT_FALSE(LV1.satisfiesPredicate(CmpInst::FCMP_OGE, LV2));
-  EXPECT_FALSE(LV1.satisfiesPredicate(CmpInst::FCMP_OLE, LV2));
-  EXPECT_FALSE(LV1.satisfiesPredicate(CmpInst::FCMP_ONE, LV2));
-  EXPECT_FALSE(LV1.satisfiesPredicate(CmpInst::FCMP_OLT, LV2));
-  EXPECT_FALSE(LV1.satisfiesPredicate(CmpInst::FCMP_OGT, LV2));
+  // Check getCompare for equal floating point constants.
+  EXPECT_TRUE(LV1.getCompare(CmpInst::FCMP_OEQ, I1Ty, LV2)->isOneValue());
+  EXPECT_TRUE(LV1.getCompare(CmpInst::FCMP_OGE, I1Ty, LV2)->isOneValue());
+  EXPECT_TRUE(LV1.getCompare(CmpInst::FCMP_OLE, I1Ty, LV2)->isOneValue());
+  EXPECT_TRUE(LV1.getCompare(CmpInst::FCMP_ONE, I1Ty, LV2)->isZeroValue());
+  EXPECT_TRUE(LV1.getCompare(CmpInst::FCMP_OLT, I1Ty, LV2)->isZeroValue());
+  EXPECT_TRUE(LV1.getCompare(CmpInst::FCMP_OGT, I1Ty, LV2)->isZeroValue());
 
   LV1.mergeIn(ValueLatticeElement::get(ConstantFP::get(FloatTy, 2.2)),
               M.getDataLayout());
-  EXPECT_FALSE(LV1.satisfiesPredicate(CmpInst::FCMP_OEQ, LV2));
-  EXPECT_FALSE(LV1.satisfiesPredicate(CmpInst::FCMP_OGE, LV2));
-  EXPECT_FALSE(LV1.satisfiesPredicate(CmpInst::FCMP_OLE, LV2));
-  EXPECT_FALSE(LV1.satisfiesPredicate(CmpInst::FCMP_ONE, LV2));
-  EXPECT_FALSE(LV1.satisfiesPredicate(CmpInst::FCMP_OLT, LV2));
-  EXPECT_FALSE(LV1.satisfiesPredicate(CmpInst::FCMP_OGT, LV2));
+  EXPECT_EQ(LV1.getCompare(CmpInst::FCMP_OEQ, I1Ty, LV2), nullptr);
+  EXPECT_EQ(LV1.getCompare(CmpInst::FCMP_OGE, I1Ty, LV2), nullptr);
+  EXPECT_EQ(LV1.getCompare(CmpInst::FCMP_OLE, I1Ty, LV2), nullptr);
+  EXPECT_EQ(LV1.getCompare(CmpInst::FCMP_ONE, I1Ty, LV2), nullptr);
+  EXPECT_EQ(LV1.getCompare(CmpInst::FCMP_OLT, I1Ty, LV2), nullptr);
+  EXPECT_EQ(LV1.getCompare(CmpInst::FCMP_OGT, I1Ty, LV2), nullptr);
+}
+
+TEST_F(ValueLatticeTest, getCompareUndef) {
+  auto *I32Ty = IntegerType::get(Context, 32);
+  auto *I1Ty = IntegerType::get(Context, 1);
+
+  auto LV1 = ValueLatticeElement::get(UndefValue::get(I32Ty));
+  auto LV2 =
+      ValueLatticeElement::getRange({APInt(32, 10, true), APInt(32, 20, true)});
+  EXPECT_TRUE(isa<UndefValue>(LV1.getCompare(CmpInst::ICMP_SLT, I1Ty, LV2)));
+  EXPECT_TRUE(isa<UndefValue>(LV1.getCompare(CmpInst::ICMP_SLE, I1Ty, LV2)));
+  EXPECT_TRUE(isa<UndefValue>(LV1.getCompare(CmpInst::ICMP_NE, I1Ty, LV2)));
+  EXPECT_TRUE(isa<UndefValue>(LV1.getCompare(CmpInst::ICMP_EQ, I1Ty, LV2)));
+  EXPECT_TRUE(isa<UndefValue>(LV1.getCompare(CmpInst::ICMP_SGE, I1Ty, LV2)));
+  EXPECT_TRUE(isa<UndefValue>(LV1.getCompare(CmpInst::ICMP_SGT, I1Ty, LV2)));
+
+  auto *FloatTy = IntegerType::getFloatTy(Context);
+  auto LV3 = ValueLatticeElement::get(ConstantFP::get(FloatTy, 1.0));
+  EXPECT_TRUE(isa<UndefValue>(LV1.getCompare(CmpInst::FCMP_OEQ, I1Ty, LV3)));
+  EXPECT_TRUE(isa<UndefValue>(LV1.getCompare(CmpInst::FCMP_OGE, I1Ty, LV3)));
+  EXPECT_TRUE(isa<UndefValue>(LV1.getCompare(CmpInst::FCMP_OLE, I1Ty, LV3)));
+  EXPECT_TRUE(isa<UndefValue>(LV1.getCompare(CmpInst::FCMP_ONE, I1Ty, LV3)));
+  EXPECT_TRUE(isa<UndefValue>(LV1.getCompare(CmpInst::FCMP_OLT, I1Ty, LV3)));
+  EXPECT_TRUE(isa<UndefValue>(LV1.getCompare(CmpInst::FCMP_OGT, I1Ty, LV3)));
 }
 
 } // end anonymous namespace
 } // end namespace llvm