From 99ec779a93cf7a09ac336b63d2d67818960343a1 Mon Sep 17 00:00:00 2001
From: Evan Cheng <evan.cheng@apple.com>
Date: Mon, 23 Jun 2008 21:03:19 +0000
Subject: [PATCH] Instead of adding an isSS field to LiveInterval to denote
 stack slot. Use top bit of 'reg' instead. If the top bit is set, than the
 LiveInterval represents a stack slot live interval.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52639 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/CodeGen/LiveInterval.h | 12 ++++++++----
 lib/CodeGen/LiveInterval.cpp        |  4 ++--
 lib/CodeGen/StackSlotColoring.cpp   |  5 ++---
 3 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/include/llvm/CodeGen/LiveInterval.h b/include/llvm/CodeGen/LiveInterval.h
index b6f38dfc357..5e5e4b19572 100644
--- a/include/llvm/CodeGen/LiveInterval.h
+++ b/include/llvm/CodeGen/LiveInterval.h
@@ -101,8 +101,8 @@ namespace llvm {
     typedef SmallVector<LiveRange,4> Ranges;
     typedef SmallVector<VNInfo*,4> VNInfoList;
 
-    bool isSS;           // True if this represents a stack slot
     unsigned reg;        // the register or stack slot of this interval
+                         // if the top bits is set, it represents a stack slot.
     unsigned preference; // preferred register to allocate for this interval
     float weight;        // weight of this interval
     Ranges ranges;       // the ranges in which this register is live
@@ -110,7 +110,9 @@ namespace llvm {
 
   public:
     LiveInterval(unsigned Reg, float Weight, bool IsSS = false)
-      : isSS(IsSS), reg(Reg), preference(0), weight(Weight) {
+      : reg(Reg), preference(0), weight(Weight) {
+      if (IsSS)
+        reg = reg | (1U << (sizeof(unsigned)*8-1));
     }
 
     typedef Ranges::iterator iterator;
@@ -143,13 +145,15 @@ namespace llvm {
 
     /// isStackSlot - Return true if this is a stack slot interval.
     ///
-    bool isStackSlot() const { return isSS; }
+    bool isStackSlot() const {
+      return reg & (1U << (sizeof(unsigned)*8-1));
+    }
 
     /// getStackSlotIndex - Return stack slot index if this is a stack slot
     /// interval.
     int getStackSlotIndex() const {
       assert(isStackSlot() && "Interval is not a stack slot interval!");
-      return reg;
+      return reg & ~(1U << (sizeof(unsigned)*8-1));
     }
 
     bool containsOneValue() const { return valnos.size() == 1; }
diff --git a/lib/CodeGen/LiveInterval.cpp b/lib/CodeGen/LiveInterval.cpp
index 24081b99c0e..0f5de9257a7 100644
--- a/lib/CodeGen/LiveInterval.cpp
+++ b/lib/CodeGen/LiveInterval.cpp
@@ -678,8 +678,8 @@ void LiveRange::dump() const {
 
 void LiveInterval::print(std::ostream &OS,
                          const TargetRegisterInfo *TRI) const {
-  if (isSS)
-    OS << "SS#" << reg;
+  if (isStackSlot())
+    OS << "SS#" << getStackSlotIndex();
   else if (TRI && TargetRegisterInfo::isPhysicalRegister(reg))
     OS << TRI->getName(reg);
   else
diff --git a/lib/CodeGen/StackSlotColoring.cpp b/lib/CodeGen/StackSlotColoring.cpp
index 24bd028afda..b6a043c0dae 100644
--- a/lib/CodeGen/StackSlotColoring.cpp
+++ b/lib/CodeGen/StackSlotColoring.cpp
@@ -1,4 +1,4 @@
-//===-- StackSlotColoring.cpp - Sinking for machine instructions ----------===//
+//===-- StackSlotColoring.cpp - Stack slot coloring pass. -----------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
@@ -12,9 +12,9 @@
 //===----------------------------------------------------------------------===//
 
 #define DEBUG_TYPE "stackcoloring"
+#include "llvm/CodeGen/Passes.h"
 #include "llvm/CodeGen/LiveStackAnalysis.h"
 #include "llvm/CodeGen/MachineFrameInfo.h"
-#include "llvm/CodeGen/Passes.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/Debug.h"
@@ -201,7 +201,6 @@ int StackSlotColoring::ColorSlot(LiveInterval *li) {
 bool StackSlotColoring::ColorSlots(MachineFunction &MF) {
   unsigned NumObjs = MFI->getObjectIndexEnd();
   std::vector<int> SlotMapping(NumObjs, -1);
-  SlotMapping.resize(NumObjs, -1);
 
   bool Changed = false;
   for (unsigned i = 0, e = SSIntervals.size(); i != e; ++i) {