Merging the linear scan register allocator in trunk. It currently passes most tests under test/Programs/SingleSource/Benchmarks/Shootout so development will continue on trunk. The allocator is not enabled by default. You will need to pass -regallo=linearscan to lli or llc to use it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10103 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/LiveIntervalAnalysis.h

@@ -0,0 +1,211 @@
+//===-- llvm/CodeGen/LiveInterval.h - Live Interval Analysis ----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the LiveInterval analysis pass.  Given some
+// numbering of each the machine instructions (in this implemention
+// depth-first order) an interval [i, j] is said to be a live interval
+// for register v if there is no instruction with number j' > j such
+// that v is live at j' abd there is no instruction with number i' < i
+// such that v is live at i'. In this implementation intervals can
+// have holes, i.e. an interval might look like [1,20], [50,65],
+// [1000,1001]
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_LIVEINTERVALS_H
+#define LLVM_CODEGEN_LIVEINTERVALS_H
+
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineBasicBlock.h"
+#include <iostream>
+#include <map>
+
+namespace llvm {
+
+    class LiveVariables;
+    class MRegisterInfo;
+
+    class LiveIntervals : public MachineFunctionPass
+    {
+    public:
+        struct Interval {
+            typedef std::pair<unsigned, unsigned> Range;
+            typedef std::vector<Range> Ranges;
+            unsigned reg;   // the register of this interval
+            Ranges ranges; // the ranges this register is valid
+
+            Interval(unsigned r)
+                : reg(r) {
+
+            }
+
+            unsigned start() const {
+                assert(!ranges.empty() && "empty interval for register");
+                return ranges.front().first;
+            }
+
+            unsigned end() const {
+                assert(!ranges.empty() && "empty interval for register");
+                return ranges.back().second;
+            }
+
+            bool expired(unsigned index) const {
+                return end() <= index;
+            }
+
+            bool overlaps(unsigned index) const {
+                for (Ranges::const_iterator
+                         i = ranges.begin(), e = ranges.end(); i != e; ++i) {
+                    if (index >= i->first && index < i->second) {
+                        return true;
+                    }
+                }
+                return false;
+            }
+
+            void addRange(unsigned start, unsigned end) {
+                Range range = std::make_pair(start, end);
+                Ranges::iterator it =
+                    std::lower_bound(ranges.begin(), ranges.end(), range);
+
+                if (it == ranges.end()) {
+                    it = ranges.insert(it, range);
+                    goto exit;
+                }
+
+                assert(range.first <= it->first && "got wrong iterator?");
+                // merge ranges if necesary
+                if (range.first < it->first) {
+                    if (range.second >= it->first) {
+                        it->first = range.first;
+                    }
+                    else {
+                        it = ranges.insert(it, range);
+                        assert(it != ranges.end() && "wtf?");
+                        goto exit;
+                    }
+                }
+
+            exit:
+                mergeRangesIfNecessary(it);
+            }
+
+        private:
+            void mergeRangesIfNecessary(Ranges::iterator it) {
+                while (it != ranges.begin()) {
+                    Ranges::iterator prev = it - 1;
+                    if (prev->second < it->first) {
+                        break;
+                    }
+                    prev->second = it->second;
+                    ranges.erase(it);
+                    it = prev;
+                }
+            }
+        };
+
+        struct StartPointComp {
+            bool operator()(const Interval& lhs, const Interval& rhs) {
+                return lhs.ranges.front().first < rhs.ranges.front().first;
+            }
+        };
+
+        struct EndPointComp {
+            bool operator()(const Interval& lhs, const Interval& rhs) {
+                return lhs.ranges.back().second < rhs.ranges.back().second;
+            }
+        };
+
+        typedef std::vector<Interval> Intervals;
+        typedef std::vector<MachineBasicBlock*> MachineBasicBlockPtrs;
+
+    private:
+        MachineFunction* mf_;
+        const TargetMachine* tm_;
+        const MRegisterInfo* mri_;
+        MachineBasicBlock* currentMbb_;
+        MachineBasicBlock::iterator currentInstr_;
+        LiveVariables* lv_;
+
+        std::vector<bool> allocatableRegisters_;
+
+        typedef std::map<unsigned, MachineBasicBlock*> MbbIndex2MbbMap;
+        MbbIndex2MbbMap mbbi2mbbMap_;
+
+        typedef std::map<MachineInstr*, unsigned> Mi2IndexMap;
+        Mi2IndexMap mi2iMap_;
+
+        typedef std::map<unsigned, unsigned> Reg2IntervalMap;
+        Reg2IntervalMap r2iMap_;
+
+        Intervals intervals_;
+
+    public:
+        virtual void getAnalysisUsage(AnalysisUsage &AU) const;
+        Intervals& getIntervals() { return intervals_; }
+        MachineBasicBlockPtrs getOrderedMachineBasicBlockPtrs() const {
+            MachineBasicBlockPtrs result;
+            for (MbbIndex2MbbMap::const_iterator
+                     it = mbbi2mbbMap_.begin(), itEnd = mbbi2mbbMap_.end();
+                 it != itEnd; ++it) {
+                result.push_back(it->second);
+            }
+            return result;
+        }
+
+    private:
+        /// runOnMachineFunction - pass entry point
+        bool runOnMachineFunction(MachineFunction&);
+
+        /// computeIntervals - compute live intervals
+        void computeIntervals();
+
+
+        /// handleRegisterDef - update intervals for a register def
+        /// (calls handlePhysicalRegisterDef and
+        /// handleVirtualRegisterDef)
+        void handleRegisterDef(MachineBasicBlock* mbb,
+                               MachineBasicBlock::iterator mi,
+                               unsigned reg);
+
+        /// handleVirtualRegisterDef - update intervals for a virtual
+        /// register def
+        void handleVirtualRegisterDef(MachineBasicBlock* mbb,
+                                      MachineBasicBlock::iterator mi,
+                                      unsigned reg);
+
+        /// handlePhysicalRegisterDef - update intervals for a
+        /// physical register def
+        void handlePhysicalRegisterDef(MachineBasicBlock* mbb,
+                                       MachineBasicBlock::iterator mi,
+                                       unsigned reg);
+
+        unsigned getInstructionIndex(MachineInstr* instr) const;
+
+        void printRegName(unsigned reg) const;
+    };
+
+    inline bool operator==(const LiveIntervals::Interval& lhs,
+                           const LiveIntervals::Interval& rhs) {
+        return lhs.reg == rhs.reg;
+    }
+
+    inline std::ostream& operator<<(std::ostream& os,
+                                    const LiveIntervals::Interval& li) {
+        os << "%reg" << li.reg << " = ";
+        for (LiveIntervals::Interval::Ranges::const_iterator
+                 i = li.ranges.begin(), e = li.ranges.end(); i != e; ++i) {
+            os << "[" << i->first << ", " << i->second << "]";
+        }
+        return os;
+    }
+
+} // End llvm namespace
+
+#endif