[InstCombine] Add m_Negative pattern matching

Allows us to add non-uniform constant vector support for "X urem C -> X < C ? X : X - C, where C >= signbit."

llvm-svn: 324631

3 files changed, 13 insertions, 4 deletions

diff --git a/llvm/include/llvm/IR/PatternMatch.h b/llvm/include/llvm/IR/PatternMatch.h
index 3072bb5..bb22544 100644
--- a/llvm/include/llvm/IR/PatternMatch.h
+++ b/llvm/include/llvm/IR/PatternMatch.h
@@ -339,6 +339,14 @@ template <typename Predicate> struct api_pred_ty : public Predicate {
   }
 };
 
+struct is_negative {
+  bool isValue(const APInt &C) { return C.isNegative(); }
+};
+
+/// \brief Match an integer or vector of negative values.
+inline cst_pred_ty<is_negative> m_Negative() { return cst_pred_ty<is_negative>(); }
+inline api_pred_ty<is_negative> m_Negative(const APInt *&V) { return V; }
+
 struct is_power2 {
   bool isValue(const APInt &C) { return C.isPowerOf2(); }
 };
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
index 9bbabd9..2131825 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -1604,8 +1604,7 @@ Instruction *InstCombiner::visitURem(BinaryOperator &I) {
   }
 
   // X urem C -> X < C ? X : X - C, where C >= signbit.
-  const APInt *DivisorC;
-  if (match(Op1, m_APInt(DivisorC)) && DivisorC->isNegative()) {
+  if (match(Op1, m_Negative())) {
     Value *Cmp = Builder.CreateICmpULT(Op0, Op1);
     Value *Sub = Builder.CreateSub(Op0, Op1);
     return SelectInst::Create(Cmp, Op0, Sub);
diff --git a/llvm/test/Transforms/InstCombine/vector-urem.ll b/llvm/test/Transforms/InstCombine/vector-urem.ll
index eede680..7dad59fd 100644
--- a/llvm/test/Transforms/InstCombine/vector-urem.ll
+++ b/llvm/test/Transforms/InstCombine/vector-urem.ll
@@ -59,8 +59,10 @@ define <4 x i32> @test_v4i32_negconstsplat(<4 x i32> %a0) {
 
 define <4 x i32> @test_v4i32_negconst(<4 x i32> %a0) {
 ; CHECK-LABEL: @test_v4i32_negconst(
-; CHECK-NEXT:    [[TMP1:%.*]] = urem <4 x i32> [[A0:%.*]], <i32 -3, i32 -5, i32 -7, i32 -9>
-; CHECK-NEXT:    ret <4 x i32> [[TMP1]]
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp ult <4 x i32> [[A0:%.*]], <i32 -3, i32 -5, i32 -7, i32 -9>
+; CHECK-NEXT:    [[TMP2:%.*]] = add <4 x i32> [[A0]], <i32 3, i32 5, i32 7, i32 9>
+; CHECK-NEXT:    [[TMP3:%.*]] = select <4 x i1> [[TMP1]], <4 x i32> [[A0]], <4 x i32> [[TMP2]]
+; CHECK-NEXT:    ret <4 x i32> [[TMP3]]
 ;
   %1 = urem <4 x i32> %a0, <i32 -3, i32 -5, i32 -7, i32 -9>
   ret <4 x i32> %1