From 396a4a55e535728e2023aa331401c1a2b782cb9a Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Sat, 29 Nov 2008 21:33:22 +0000
Subject: [PATCH] Change MemDep::getNonLocalDependency to return its results as
 a smallvector instead of a DenseMap.  This speeds up GVN by 5% on 403.gcc.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60255 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/Analysis/MemoryDependenceAnalysis.h |  3 ++-
 lib/Analysis/MemoryDependenceAnalysis.cpp        | 13 ++++++-------
 lib/Transforms/Scalar/GVN.cpp                    | 10 +++++-----
 3 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/include/llvm/Analysis/MemoryDependenceAnalysis.h b/include/llvm/Analysis/MemoryDependenceAnalysis.h
index faffe375563..10aeb290c84 100644
--- a/include/llvm/Analysis/MemoryDependenceAnalysis.h
+++ b/include/llvm/Analysis/MemoryDependenceAnalysis.h
@@ -175,7 +175,8 @@ namespace llvm {
     /// This method assumes the instruction returns a "nonlocal" dependency
     /// within its own block.
     void getNonLocalDependency(Instruction *QueryInst,
-                               DenseMap<BasicBlock*, MemDepResult> &Result);
+                               SmallVectorImpl<std::pair<BasicBlock*, 
+                                                       MemDepResult> > &Result);
     
     /// removeInstruction - Remove an instruction from the dependence analysis,
     /// updating the dependence of instructions that previously depended on it.
diff --git a/lib/Analysis/MemoryDependenceAnalysis.cpp b/lib/Analysis/MemoryDependenceAnalysis.cpp
index f59be5ec03b..099d43492cd 100644
--- a/lib/Analysis/MemoryDependenceAnalysis.cpp
+++ b/lib/Analysis/MemoryDependenceAnalysis.cpp
@@ -104,8 +104,10 @@ getCallSiteDependency(CallSite C, BasicBlock::iterator ScanIt,
 /// This method assumes the instruction returns a "nonlocal" dependency
 /// within its own block.
 ///
-void MemoryDependenceAnalysis::getNonLocalDependency(Instruction *QueryInst,
-                                  DenseMap<BasicBlock*, MemDepResult> &Result) {
+void MemoryDependenceAnalysis::
+getNonLocalDependency(Instruction *QueryInst,
+                      SmallVectorImpl<std::pair<BasicBlock*, 
+                                                      MemDepResult> > &Result) {
   assert(getDependency(QueryInst).isNonLocal() &&
      "getNonLocalDependency should only be used on insts with non-local deps!");
   DenseMap<BasicBlock*, DepResultTy> &Cache = NonLocalDeps[QueryInst];
@@ -128,10 +130,7 @@ void MemoryDependenceAnalysis::getNonLocalDependency(Instruction *QueryInst,
   } else {
     // Seed DirtyBlocks with each of the preds of QueryInst's block.
     BasicBlock *QueryBB = QueryInst->getParent();
-    // FIXME: use range insertion/append.
-    for (pred_iterator PI = pred_begin(QueryBB), E = pred_end(QueryBB);
-         PI != E; ++PI)
-      DirtyBlocks.push_back(*PI);
+    DirtyBlocks.append(pred_begin(QueryBB), pred_end(QueryBB));
     NumUncacheNonlocal++;
   }
 
@@ -173,7 +172,7 @@ void MemoryDependenceAnalysis::getNonLocalDependency(Instruction *QueryInst,
   // Copy the result into the output set.
   for (DenseMap<BasicBlock*, DepResultTy>::iterator I = Cache.begin(),
        E = Cache.end(); I != E; ++I)
-    Result[I->first] = ConvToResult(I->second);
+    Result.push_back(std::make_pair(I->first, ConvToResult(I->second)));
 }
 
 /// getDependency - Return the instruction on which a memory operation
diff --git a/lib/Transforms/Scalar/GVN.cpp b/lib/Transforms/Scalar/GVN.cpp
index a6cc9931efa..1522dbab47d 100644
--- a/lib/Transforms/Scalar/GVN.cpp
+++ b/lib/Transforms/Scalar/GVN.cpp
@@ -495,11 +495,11 @@ uint32_t ValueTable::lookup_or_add(Value* V) {
       }
       
       
-      DenseMap<BasicBlock*, MemDepResult> deps;
+      SmallVector<std::pair<BasicBlock*, MemDepResult>, 32> deps;
       MD->getNonLocalDependency(C, deps);
       CallInst* cdep = 0;
       
-      for (DenseMap<BasicBlock*, MemDepResult>
+      for (SmallVector<std::pair<BasicBlock*, MemDepResult>, 32>
              ::iterator I = deps.begin(), E = deps.end(); I != E; ++I) {
         if (I->second.isNone()) {
           valueNumbering.insert(std::make_pair(V, nextValueNumber));
@@ -871,7 +871,7 @@ bool GVN::processNonLocalLoad(LoadInst* L,
   MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
   
   // Find the non-local dependencies of the load
-  DenseMap<BasicBlock*, MemDepResult> deps;
+  SmallVector<std::pair<BasicBlock*, MemDepResult>, 32> deps;
   MD.getNonLocalDependency(L, deps);
   
   // If we had to process more than one hundred blocks to find the
@@ -885,8 +885,8 @@ bool GVN::processNonLocalLoad(LoadInst* L,
   DenseMap<BasicBlock*, Value*> repl;
   
   // Filter out useless results (non-locals, etc)
-  for (DenseMap<BasicBlock*, MemDepResult>::iterator I = deps.begin(),
-       E = deps.end(); I != E; ++I) {
+  for (SmallVector<std::pair<BasicBlock*, MemDepResult>, 32>::iterator
+       I = deps.begin(), E = deps.end(); I != E; ++I) {
     if (I->second.isNone()) {
       repl[I->first] = UndefValue::get(L->getType());
       continue;