[InstCombine] Replace calls to getNumUses with hasNUses or hasNUsesOrMore

getNumUses is a linear time operation. It traverses the user linked list to the end and counts as it goes. Since we are only interested in small constant counts, we should use hasNUses or hasNUsesMore more that terminate the traversal as soon as it can provide the answer.

There are still two other locations in InstCombine, but changing those would force a rebase of D44266 which if accepted would remove them.

Differential Revision: https://reviews.llvm.org/D44398

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@327315 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index 44d1103..1b84eea 100644 (file)
--- a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -1192,7 +1192,7 @@ Instruction *InstCombiner::narrowMaskedBinOp(BinaryOperator &And) {
     return nullptr;
 
   Value *X;
-  if (!match(Op1, m_ZExt(m_Value(X))) || Op1->getNumUses() > 2)
+  if (!match(Op1, m_ZExt(m_Value(X))) || Op1->hasNUsesOrMore(3))
     return nullptr;
 
   Type *Ty = And.getType();
@@ -2471,13 +2471,13 @@ Instruction *InstCombiner::visitXor(BinaryOperator &I) {
   // We're relying on the fact that we only do this transform when the shift has
   // exactly 2 uses and the add has exactly 1 use (otherwise, we might increase
   // instructions).
-  if (Op0->getNumUses() == 2)
+  if (Op0->hasNUses(2))
     std::swap(Op0, Op1);
 
   const APInt *ShAmt;
   Type *Ty = I.getType();
   if (match(Op1, m_AShr(m_Value(A), m_APInt(ShAmt))) &&
-      Op1->getNumUses() == 2 && *ShAmt == Ty->getScalarSizeInBits() - 1 &&
+      Op1->hasNUses(2) && *ShAmt == Ty->getScalarSizeInBits() - 1 &&
       match(Op0, m_OneUse(m_c_Add(m_Specific(A), m_Specific(Op1))))) {
     // B = ashr i32 A, 31 ; smear the sign bit
     // xor (add A, B), B  ; add -1 and flip bits if negative

diff --git a/lib/Transforms/InstCombine/InstCombineSelect.cpp b/lib/Transforms/InstCombine/InstCombineSelect.cpp
index de1971c..1f89ca6 100644 (file)
--- a/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -1333,7 +1333,7 @@ static Instruction *factorizeMinMaxTree(SelectPatternFlavor SPF, Value *LHS,
   // the select.
   Value *MinMaxOp = nullptr;
   Value *ThirdOp = nullptr;
-  if (LHS->getNumUses() <= 2 && RHS->getNumUses() > 2) {
+  if (!LHS->hasNUsesOrMore(3) && RHS->hasNUsesOrMore(3)) {
     // If the LHS is only used in this chain and the RHS is used outside of it,
     // reuse the RHS min/max because that will eliminate the LHS.
     if (D == A || C == A) {
@@ -1347,7 +1347,7 @@ static Instruction *factorizeMinMaxTree(SelectPatternFlavor SPF, Value *LHS,
       MinMaxOp = RHS;
       ThirdOp = A;
     }
-  } else if (RHS->getNumUses() <= 2) {
+  } else if (!RHS->hasNUsesOrMore(3)) {
     // Reuse the LHS. This will eliminate the RHS.
     if (D == A || D == B) {
       // min(min(a, b), min(c, a)) --> min(min(a, b), c)