[llvm] r231189 - Recommit r231175: Change LiveStackAnalysis::SS2IntervalMap from std::map to std::unordered_map

[David Blaikie]

Author: dblaikie
Date: Tue Mar  3 19:15:53 2015
New Revision: 231189

URL: http://llvm.org/viewvc/llvm-project?rev=231189&view=rev
Log:
Recommit r231175: Change LiveStackAnalysis::SS2IntervalMap from std::map to std::unordered_map

The order of this container was needed at one point - so, at that point
create a temporary array of pointers, sort those, then iterate them.
This keeps lookup efficient (& the lesser issue, of allowing the use of
emplace... ), object identity preserved, and ordered iteration in the
one place that requires it.

While this has no functional change, I realize it does mean allocating
an extra data structure and performing a sort - so if this looks suspect
to anyone regarding perf characteristics, I'm all ears.

Modified:
    llvm/trunk/include/llvm/CodeGen/LiveStackAnalysis.h
    llvm/trunk/lib/CodeGen/StackSlotColoring.cpp

Modified: llvm/trunk/include/llvm/CodeGen/LiveStackAnalysis.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/LiveStackAnalysis.h?rev=231189&r1=231188&r2=231189&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/LiveStackAnalysis.h (original)
+++ llvm/trunk/include/llvm/CodeGen/LiveStackAnalysis.h Tue Mar  3 19:15:53 2015
@@ -21,6 +21,7 @@
 #include "llvm/Support/Allocator.h"
 #include "llvm/Target/TargetRegisterInfo.h"
 #include <map>
+#include <unordered_map>
 
 namespace llvm {
 
@@ -33,7 +34,7 @@ namespace llvm {
 
     /// S2IMap - Stack slot indices to live interval mapping.
     ///
-    typedef std::map<int, LiveInterval> SS2IntervalMap;
+    typedef std::unordered_map<int, LiveInterval> SS2IntervalMap;
     SS2IntervalMap S2IMap;
 
     /// S2RCMap - Stack slot indices to register class mapping.

Modified: llvm/trunk/lib/CodeGen/StackSlotColoring.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/StackSlotColoring.cpp?rev=231189&r1=231188&r2=231189&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/StackSlotColoring.cpp (original)
+++ llvm/trunk/lib/CodeGen/StackSlotColoring.cpp Tue Mar  3 19:15:53 2015
@@ -184,10 +184,18 @@ void StackSlotColoring::InitializeSlots(
   UsedColors.resize(LastFI);
   Assignments.resize(LastFI);
 
+  typedef std::iterator_traits<LiveStacks::iterator>::value_type Pair;
+  SmallVector<Pair *, 16> Intervals;
+  Intervals.reserve(LS->getNumIntervals());
+  for (auto &I : *LS)
+    Intervals.push_back(&I);
+  std::sort(Intervals.begin(), Intervals.end(),
+            [](Pair *LHS, Pair *RHS) { return LHS->first < RHS->first; });
+
   // Gather all spill slots into a list.
   DEBUG(dbgs() << "Spill slot intervals:\n");
-  for (LiveStacks::iterator i = LS->begin(), e = LS->end(); i != e; ++i) {
-    LiveInterval &li = i->second;
+  for (auto *I : Intervals) {
+    LiveInterval &li = I->second;
     DEBUG(li.dump());
     int FI = TargetRegisterInfo::stackSlot2Index(li.reg);
     if (MFI->isDeadObjectIndex(FI))