[IR][Patternmatch] Add m_SpecificInt_ULT() predicate

LebedevRI · LebedevRI · commit fe107fcde4d2 · 2019-06-29T11:51:37.000Z
Summary: Match an integer or vector with every element unsigned less than the Threshold. For vectors, this includes constants with undefined elements. FIXME: is it worth generalizing this to simply take ICmpInst::Predicate? Reviewers: craig.topper, spatel, nikic Reviewed By: spatel Subscribers: llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D63811 llvm-svn: 364711
diff --git a/llvm/include/llvm/IR/PatternMatch.h b/llvm/include/llvm/IR/PatternMatch.h
@@ -418,6 +418,20 @@ inline cst_pred_ty<is_lowbit_mask> m_LowBitMask() {
   return cst_pred_ty<is_lowbit_mask>();
 }
 
+struct is_unsigned_less_than {
+  const APInt *Thr;
+  bool isValue(const APInt &C) { return C.ult(*Thr); }
+};
+/// Match an integer or vector with every element unsigned less than the
+/// Threshold. For vectors, this includes constants with undefined elements.
+/// FIXME: is it worth generalizing this to simply take ICmpInst::Predicate?
+inline cst_pred_ty<is_unsigned_less_than>
+m_SpecificInt_ULT(const APInt &Threshold) {
+  cst_pred_ty<is_unsigned_less_than> P;
+  P.Thr = &Threshold;
+  return P;
+}
+
 struct is_nan {
   bool isValue(const APFloat &C) { return C.isNaN(); }
 };
diff --git a/llvm/unittests/IR/PatternMatch.cpp b/llvm/unittests/IR/PatternMatch.cpp
@@ -64,6 +64,27 @@ TEST_F(PatternMatchTest, OneUse) {
   EXPECT_FALSE(m_OneUse(m_Value()).match(Leaf));
 }
 
+TEST_F(PatternMatchTest, SpecificIntULT) {
+  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_FALSE(m_SpecificInt_ULT(APInt(BitWidth, 0)).match(Zero));
+  EXPECT_FALSE(m_SpecificInt_ULT(APInt(BitWidth, 0)).match(One));
+  EXPECT_FALSE(m_SpecificInt_ULT(APInt(BitWidth, 0)).match(NegOne));
+
+  EXPECT_TRUE(m_SpecificInt_ULT(APInt(BitWidth, 1)).match(Zero));
+  EXPECT_FALSE(m_SpecificInt_ULT(APInt(BitWidth, 1)).match(One));
+  EXPECT_FALSE(m_SpecificInt_ULT(APInt(BitWidth, 1)).match(NegOne));
+
+  EXPECT_TRUE(m_SpecificInt_ULT(APInt(BitWidth, -1)).match(Zero));
+  EXPECT_TRUE(m_SpecificInt_ULT(APInt(BitWidth, -1)).match(One));
+  EXPECT_FALSE(m_SpecificInt_ULT(APInt(BitWidth, -1)).match(NegOne));
+}
+
 TEST_F(PatternMatchTest, CommutativeDeferredValue) {
   Value *X = IRB.getInt32(1);
   Value *Y = IRB.getInt32(2);
