[llvm] [JumpThreading] Use SmallDenseSet (NFC) (PR #95674)

[Kazu Hirata via llvm-commits]

https://github.com/kazutakahirata created https://github.com/llvm/llvm-project/pull/95674

The use of SmallDenseSet here saves 0.58% of heap allocations during
the compilation of a large preprocessed file, namely
X86ISelLowering.cpp, for the X86 target.

>From bb36f942ef5b946d451008f01fc1864a765f5187 Mon Sep 17 00:00:00 2001
From: Kazu Hirata <kazu at google.com>
Date: Sun, 21 Jan 2024 17:54:58 -0800
Subject: [PATCH] [JumpThreading] Use SmallDenseSet (NFC)

The use of SmallDenseSet here saves 0.58% of heap allocations during
the compilation of a large preprocessed file, namely
X86ISelLowering.cpp, for the X86 target.
---
 llvm/include/llvm/Transforms/Scalar/JumpThreading.h | 4 ++--
 llvm/lib/Transforms/Scalar/JumpThreading.cpp        | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/llvm/include/llvm/Transforms/Scalar/JumpThreading.h b/llvm/include/llvm/Transforms/Scalar/JumpThreading.h
index 65d43775bdc1d..1bf79fdcb697e 100644
--- a/llvm/include/llvm/Transforms/Scalar/JumpThreading.h
+++ b/llvm/include/llvm/Transforms/Scalar/JumpThreading.h
@@ -130,13 +130,13 @@ class JumpThreadingPass : public PassInfoMixin<JumpThreadingPass> {
   bool computeValueKnownInPredecessorsImpl(
       Value *V, BasicBlock *BB, jumpthreading::PredValueInfo &Result,
       jumpthreading::ConstantPreference Preference,
-      DenseSet<Value *> &RecursionSet, Instruction *CxtI = nullptr);
+      SmallDenseSet<Value *> &RecursionSet, Instruction *CxtI = nullptr);
   bool
   computeValueKnownInPredecessors(Value *V, BasicBlock *BB,
                                   jumpthreading::PredValueInfo &Result,
                                   jumpthreading::ConstantPreference Preference,
                                   Instruction *CxtI = nullptr) {
-    DenseSet<Value *> RecursionSet;
+    SmallDenseSet<Value *> RecursionSet;
     return computeValueKnownInPredecessorsImpl(V, BB, Result, Preference,
                                                RecursionSet, CxtI);
   }
diff --git a/llvm/lib/Transforms/Scalar/JumpThreading.cpp b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
index b9583836aea06..a4a04d5d16d4a 100644
--- a/llvm/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
@@ -558,7 +558,7 @@ static Constant *getKnownConstant(Value *Val, ConstantPreference Preference) {
 /// This returns true if there were any known values.
 bool JumpThreadingPass::computeValueKnownInPredecessorsImpl(
     Value *V, BasicBlock *BB, PredValueInfo &Result,
-    ConstantPreference Preference, DenseSet<Value *> &RecursionSet,
+    ConstantPreference Preference, SmallDenseSet<Value *> &RecursionSet,
     Instruction *CxtI) {
   const DataLayout &DL = BB->getModule()->getDataLayout();