[PATCH] D44398: [InstCombine] Replace calls to getNumUses with hasNUses or hasNUsesOrMore

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.
craig.topper added a reviewer: spatel.

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 https://reviews.llvm.org/D44266 which if accepted would remove them.


https://reviews.llvm.org/D44398

Files:
  lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
  lib/Transforms/InstCombine/InstCombineSelect.cpp


Index: lib/Transforms/InstCombine/InstCombineSelect.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -1333,7 +1333,7 @@
   // 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 @@
       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)
Index: lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -1192,7 +1192,7 @@
     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 @@
   // 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


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D44398.138062.patch
Type: text/x-patch
Size: 2120 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20180312/02b7b589/attachment.bin>