[APInt][PatternMatch] Add 'is non-positive' predicate

It will be useful for implementing the fold mentioned in
https://bugs.llvm.org/show_bug.cgi?id=44100#c4

Author: LebedevRI

llvm/include/llvm/ADT/APInt.h

@@ -389,6 +389,11 @@ class LLVM_NODISCARD APInt {
   /// \returns true if this APInt is positive.
   bool isStrictlyPositive() const { return isNonNegative() && !isNullValue(); }
 
+  /// Determine if this APInt Value is non-positive (<= 0).
+  ///
+  /// \returns true if this APInt is non-positive.
+  bool isNonPositive() const { return !isStrictlyPositive(); }
+
   /// Determine if all bits are set
   ///
   /// This checks to see if the value has all bits of the APInt are set or not.

llvm/include/llvm/IR/PatternMatch.h

@@ -366,7 +366,7 @@ inline api_pred_ty<is_negative> m_Negative(const APInt *&V) {
 struct is_nonnegative {
   bool isValue(const APInt &C) { return C.isNonNegative(); }
 };
-/// Match an integer or vector of nonnegative values.
+/// Match an integer or vector of non-negative values.
 /// For vectors, this includes constants with undefined elements.
 inline cst_pred_ty<is_nonnegative> m_NonNegative() {
   return cst_pred_ty<is_nonnegative>();
@@ -375,6 +375,28 @@ inline api_pred_ty<is_nonnegative> m_NonNegative(const APInt *&V) {
   return V;
 }
 
+struct is_strictlypositive {
+  bool isValue(const APInt &C) { return C.isStrictlyPositive(); }
+};
+/// Match an integer or vector of strictly positive values.
+/// For vectors, this includes constants with undefined elements.
+inline cst_pred_ty<is_strictlypositive> m_StrictlyPositive() {
+  return cst_pred_ty<is_strictlypositive>();
+}
+inline api_pred_ty<is_strictlypositive> m_StrictlyPositive(const APInt *&V) {
+  return V;
+}
+
+struct is_nonpositive {
+  bool isValue(const APInt &C) { return C.isNonPositive(); }
+};
+/// Match an integer or vector of non-positive values.
+/// For vectors, this includes constants with undefined elements.
+inline cst_pred_ty<is_nonpositive> m_NonPositive() {
+  return cst_pred_ty<is_nonpositive>();
+}
+inline api_pred_ty<is_nonpositive> m_NonPositive(const APInt *&V) { return V; }
+
 struct is_one {
   bool isValue(const APInt &C) { return C.isOneValue(); }
 };

llvm/unittests/ADT/APIntTest.cpp

@@ -2845,4 +2845,21 @@ TEST(APIntTest, GetMostSignificantDifferentBitExaustive) {
   }
 }
 
+TEST(APIntTest, SignbitZeroChecks) {
+  EXPECT_TRUE(APInt(8, -1).isNegative());
+  EXPECT_FALSE(APInt(8, -1).isNonNegative());
+  EXPECT_FALSE(APInt(8, -1).isStrictlyPositive());
+  EXPECT_TRUE(APInt(8, -1).isNonPositive());
+
+  EXPECT_FALSE(APInt(8, 0).isNegative());
+  EXPECT_TRUE(APInt(8, 0).isNonNegative());
+  EXPECT_FALSE(APInt(8, 0).isStrictlyPositive());
+  EXPECT_TRUE(APInt(8, 0).isNonPositive());
+
+  EXPECT_FALSE(APInt(8, 1).isNegative());
+  EXPECT_TRUE(APInt(8, 1).isNonNegative());
+  EXPECT_TRUE(APInt(8, 1).isStrictlyPositive());
+  EXPECT_FALSE(APInt(8, 1).isNonPositive());
+}
+
 } // end anonymous namespace

llvm/unittests/IR/PatternMatch.cpp

@@ -182,6 +182,30 @@ TEST_F(PatternMatchTest, SpecificIntUGT) {
           .match(NegOne));
 }
 
+TEST_F(PatternMatchTest, SignbitZeroChecks) {
+  Type *IntTy = IRB.getInt32Ty();
+  unsigned BitWidth = IntTy->getScalarSizeInBits();
+
+  Value *Zero = ConstantInt::get(IntTy, 0);
+  Value *One = ConstantInt::get(IntTy, 1);
+  Value *NegOne = ConstantInt::get(IntTy, -1);
+
+  EXPECT_TRUE(m_Negative().match(NegOne));
+  EXPECT_FALSE(m_NonNegative().match(NegOne));
+  EXPECT_FALSE(m_StrictlyPositive().match(NegOne));
+  EXPECT_TRUE(m_NonPositive().match(NegOne));
+
+  EXPECT_FALSE(m_Negative().match(Zero));
+  EXPECT_TRUE(m_NonNegative().match(Zero));
+  EXPECT_FALSE(m_StrictlyPositive().match(Zero));
+  EXPECT_TRUE(m_NonPositive().match(Zero));
+
+  EXPECT_FALSE(m_Negative().match(One));
+  EXPECT_TRUE(m_NonNegative().match(One));
+  EXPECT_TRUE(m_StrictlyPositive().match(One));
+  EXPECT_FALSE(m_NonPositive().match(One));
+}
+
 TEST_F(PatternMatchTest, SpecificIntUGE) {
   Type *IntTy = IRB.getInt32Ty();
   unsigned BitWidth = IntTy->getScalarSizeInBits();