Use a DenseMap for mapping reg->reg. This improves the LiveInterval

analysis running time from 2.7869secs to 2.5226secs on 176.gcc.

llvm-svn: 16244

2 files changed, 12 insertions, 9 deletions

diff --git a/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp b/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
index 3ebd9075860..e0fefc3870f 100644
--- a/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -619,6 +619,8 @@ namespace {
 
 void LiveIntervals::joinIntervals() {
   DEBUG(std::cerr << "********** JOINING INTERVALS ***********\n");
+  // reserve space for the reg2reg map
+  r2rMap_.grow(mf_->getSSARegMap()->getLastVirtReg());
 
   const LoopInfo &LI = getAnalysis<LoopInfo>();
   if (LI.begin() == LI.end()) {
@@ -644,9 +646,9 @@ void LiveIntervals::joinIntervals() {
   }
 
   DEBUG(std::cerr << "*** Register mapping ***\n");
-  DEBUG(for (std::map<unsigned, unsigned>::iterator I = r2rMap_.begin(),
-               E = r2rMap_.end(); I != E; ++I)
-        std::cerr << "  reg " << I->first << " -> reg " << I->second << "\n";);
+  DEBUG(for (int i = 0, e = r2rMap_.size(); i != e; ++i)
+          if (r2rMap_[i])
+             std::cerr << "  reg " << i << " -> reg " << r2rMap_[i] << "\n");
 }
 
 /// Return true if the two specified registers belong to different register
diff --git a/llvm/lib/CodeGen/LiveIntervalAnalysis.h b/llvm/lib/CodeGen/LiveIntervalAnalysis.h
index 73d730a647e..b90be627041 100644
--- a/llvm/lib/CodeGen/LiveIntervalAnalysis.h
+++ b/llvm/lib/CodeGen/LiveIntervalAnalysis.h
@@ -20,6 +20,7 @@
 #ifndef LLVM_CODEGEN_LIVEINTERVAL_ANALYSIS_H
 #define LLVM_CODEGEN_LIVEINTERVAL_ANALYSIS_H
 
+#include "llvm/ADT/DenseMap.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
 #include "LiveInterval.h"
 
@@ -44,7 +45,7 @@ namespace llvm {
     typedef std::map<unsigned, LiveInterval> Reg2IntervalMap;
     Reg2IntervalMap r2iMap_;
 
-    typedef std::map<unsigned, unsigned> Reg2RegMap;
+    typedef DenseMap<unsigned> Reg2RegMap;
     Reg2RegMap r2rMap_;
 
     std::vector<bool> allocatableRegs_;
@@ -171,11 +172,11 @@ namespace llvm {
     }
 
     /// rep - returns the representative of this register
-    unsigned rep(unsigned reg) {
-      Reg2RegMap::iterator it = r2rMap_.find(reg);
-      if (it != r2rMap_.end())
-        return it->second = rep(it->second);
-      return reg;
+    unsigned rep(unsigned Reg) {
+      unsigned Rep = r2rMap_[Reg];
+      if (Rep)
+        return r2rMap_[Reg] = rep(Rep);
+      return Reg;
     }
 
     void printRegName(unsigned reg) const;