Jakob's review of the basic register allocator.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@117384 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/RegAllocBase.h b/lib/CodeGen/RegAllocBase.h
index d543635..1534c0d 100644
--- a/lib/CodeGen/RegAllocBase.h
+++ b/lib/CodeGen/RegAllocBase.h
@@ -37,17 +37,29 @@
#ifndef LLVM_CODEGEN_REGALLOCBASE
#define LLVM_CODEGEN_REGALLOCBASE
-#include "LiveIntervalUnion.h"
-#include "VirtRegMap.h"
-#include "llvm/CodeGen/LiveIntervalAnalysis.h"
-#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/ADT/OwningPtr.h"
-#include <vector>
-#include <queue>
namespace llvm {
+template<typename T> class SmallVectorImpl;
+class TargetRegisterInfo;
class VirtRegMap;
+class LiveIntervals;
+
+// Heuristic that determines the priority of assigning virtual to physical
+// registers. The main impact of the heuristic is expected to be compile time.
+// The default is to simply compare spill weights.
+struct LessSpillWeightPriority
+ : public std::binary_function<LiveInterval,LiveInterval, bool> {
+ bool operator()(const LiveInterval *left, const LiveInterval *right) const {
+ return left->weight < right->weight;
+ }
+};
+
+// Forward declare a priority queue of live virtual registers. If an
+// implementation needs to prioritize by anything other than spill weight, then
+// this will become an abstract base class with virtual calls to push/get.
+class LiveVirtRegQueue;
/// RegAllocBase provides the register allocation driver and interface that can
/// be extended to add interesting heuristics.
@@ -58,9 +70,6 @@
/// standard comparator.
class RegAllocBase {
protected:
- typedef SmallVector<LiveInterval*, 4> LiveVirtRegs;
- typedef LiveVirtRegs::iterator LVRIter;
-
// Array of LiveIntervalUnions indexed by physical register.
class LIUArray {
unsigned nRegs_;
@@ -92,18 +101,20 @@
// A RegAlloc pass should call this before allocatePhysRegs.
void init(const TargetRegisterInfo &tri, VirtRegMap &vrm, LiveIntervals &lis);
- // The top-level driver. Specialize with the comparator that determines the
- // priority of assigning live virtual registers. The output is a VirtRegMap
- // that us updated with physical register assignments.
- template<typename LICompare>
- void allocatePhysRegs(LICompare liCompare);
+ // The top-level driver. The output is a VirtRegMap that us updated with
+ // physical register assignments.
+ //
+ // If an implementation wants to override the LiveInterval comparator, we
+ // should modify this interface to allow passing in an instance derived from
+ // LiveVirtRegQueue.
+ void allocatePhysRegs();
// A RegAlloc pass should override this to provide the allocation heuristics.
- // Each call must guarantee forward progess by returning an available
- // PhysReg or new set of split LiveVirtRegs. It is up to the splitter to
+ // Each call must guarantee forward progess by returning an available PhysReg
+ // or new set of split live virtual registers. It is up to the splitter to
// converge quickly toward fully spilled live ranges.
virtual unsigned selectOrSplit(LiveInterval &lvr,
- LiveVirtRegs &splitLVRs) = 0;
+ SmallVectorImpl<LiveInterval*> &splitLVRs) = 0;
// A RegAlloc pass should call this when PassManager releases its memory.
virtual void releaseMemory();
@@ -113,69 +124,9 @@
bool checkPhysRegInterference(LiveIntervalUnion::Query &query, unsigned preg);
private:
- template<typename PQ>
- void seedLiveVirtRegs(PQ &lvrQ);
+ void seedLiveVirtRegs(LiveVirtRegQueue &lvrQ);
};
-// Heuristic that determines the priority of assigning virtual to physical
-// registers. The main impact of the heuristic is expected to be compile time.
-// The default is to simply compare spill weights.
-struct LessSpillWeightPriority
- : public std::binary_function<LiveInterval,LiveInterval, bool> {
- bool operator()(const LiveInterval *left, const LiveInterval *right) const {
- return left->weight < right->weight;
- }
-};
-
-// Visit all the live virtual registers. If they are already assigned to a
-// physical register, unify them with the corresponding LiveIntervalUnion,
-// otherwise push them on the priority queue for later assignment.
-template<typename PQ>
-void RegAllocBase::seedLiveVirtRegs(PQ &lvrQ) {
- for (LiveIntervals::iterator liItr = lis_->begin(), liEnd = lis_->end();
- liItr != liEnd; ++liItr) {
- unsigned reg = liItr->first;
- LiveInterval &li = *liItr->second;
- if (TargetRegisterInfo::isPhysicalRegister(reg)) {
- physReg2liu_[reg].unify(li);
- }
- else {
- lvrQ.push(&li);
- }
- }
-}
-
-// Top-level driver to manage the queue of unassigned LiveVirtRegs and call the
-// selectOrSplit implementation.
-template<typename LICompare>
-void RegAllocBase::allocatePhysRegs(LICompare liCompare) {
- typedef std::priority_queue
- <LiveInterval*, std::vector<LiveInterval*>, LICompare> LiveVirtRegQueue;
-
- LiveVirtRegQueue lvrQ(liCompare);
- seedLiveVirtRegs(lvrQ);
- while (!lvrQ.empty()) {
- LiveInterval *lvr = lvrQ.top();
- lvrQ.pop();
- LiveVirtRegs splitLVRs;
- unsigned availablePhysReg = selectOrSplit(*lvr, splitLVRs);
- if (availablePhysReg) {
- assert(splitLVRs.empty() && "inconsistent splitting");
- assert(!vrm_->hasPhys(lvr->reg) && "duplicate vreg in interval unions");
- vrm_->assignVirt2Phys(lvr->reg, availablePhysReg);
- physReg2liu_[availablePhysReg].unify(*lvr);
- }
- else {
- for (LVRIter lvrI = splitLVRs.begin(), lvrEnd = splitLVRs.end();
- lvrI != lvrEnd; ++lvrI ) {
- assert(TargetRegisterInfo::isVirtualRegister((*lvrI)->reg) &&
- "expect split value in virtual register");
- lvrQ.push(*lvrI);
- }
- }
- }
-}
-
} // end namespace llvm
#endif // !defined(LLVM_CODEGEN_REGALLOCBASE)