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Thinking about it, we don't need MachineDominatorTree after all. The DomValue

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map discovers the iterated dominance frontier for free.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@111400 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen
2010-08-18 20:29:53 +00:00
parent e16068240e
commit ff3ae8691c
2 changed files with 27 additions and 20 deletions
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42
lib/CodeGen/SplitKit.cpp
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@@ -17,7 +17,6 @@
#include "VirtRegMap.h" #include "VirtRegMap.h"
#include "llvm/CodeGen/CalcSpillWeights.h" #include "llvm/CodeGen/CalcSpillWeights.h"
#include "llvm/CodeGen/LiveIntervalAnalysis.h" #include "llvm/CodeGen/LiveIntervalAnalysis.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineInstrBuilder.h" #include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineLoopInfo.h" #include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h" #include "llvm/CodeGen/MachineRegisterInfo.h"
@@ -423,31 +422,41 @@ VNInfo *LiveIntervalMap::mapValue(const VNInfo *ParentVNI, SlotIndex Idx) {
// Yes, VNI dominates MBB. Track the path back to IdxMBB, creating phi-defs // Yes, VNI dominates MBB. Track the path back to IdxMBB, creating phi-defs
// as needed along the way. // as needed along the way.
for (unsigned PI = IDFI.getPathLength()-1; PI != 0; --PI) { for (unsigned PI = IDFI.getPathLength()-1; PI != 0; --PI) {
// Start from MBB's immediate successor. // Start from MBB's immediate successor. End at IdxMBB.
MachineBasicBlock *Succ = IDFI.getPath(PI-1); MachineBasicBlock *Succ = IDFI.getPath(PI-1);
std::pair<MBBValueMap::iterator, bool> InsP = std::pair<MBBValueMap::iterator, bool> InsP =
DomValue.insert(MBBValueMap::value_type(Succ, VNI)); DomValue.insert(MBBValueMap::value_type(Succ, VNI));
SlotIndex Start = lis_.getMBBStartIdx(Succ);
if (InsP.second) { // This is the first time we backtrack to Succ.
// This is the first time we backtrack to Succ. Verify dominance. if (InsP.second)
if (Succ->pred_size() == 1 || dt_.dominates(MBB, Succ)) continue;
continue;
} else if (InsP.first->second == VNI || // We reached Succ again with the same VNI. Nothing is going to change.
InsP.first->second->def == Start) { VNInfo *OVNI = InsP.first->second;
// We have previously backtracked VNI to Succ, or Succ already has a if (OVNI == VNI)
// phi-def. No need to backtrack further.
break; break;
}
// VNI does not dominate Succ, we need a new phi-def. // Succ already has a phi-def. No need to continue.
SlotIndex Start = lis_.getMBBStartIdx(Succ);
if (OVNI->def == Start)
break;
// We have a collision between the old and new VNI at Succ. That means
// neither dominates and we need a new phi-def.
VNI = li_.getNextValue(Start, 0, true, lis_.getVNInfoAllocator()); VNI = li_.getNextValue(Start, 0, true, lis_.getVNInfoAllocator());
VNI->setIsPHIDef(true); VNI->setIsPHIDef(true);
InsP.first->second = VNI; InsP.first->second = VNI;
MBB = Succ;
// Replace OVNI with VNI in the remaining path.
for (; PI > 1 ; --PI) {
MBBValueMap::iterator I = DomValue.find(IDFI.getPath(PI-2));
if (I == DomValue.end() || I->second != OVNI)
break;
I->second = VNI;
}
} }
// No need to search the children, we found a dominating value. // No need to search the children, we found a dominating value.
// FIXME: We could prune up to the last phi-def we inserted, need df_iterator
// for that.
IDFI.skipChildren(); IDFI.skipChildren();
} }
@@ -468,6 +477,7 @@ VNInfo *LiveIntervalMap::mapValue(const VNInfo *ParentVNI, SlotIndex Idx) {
// Don't add full liveness to IdxMBB, stop at Idx. // Don't add full liveness to IdxMBB, stop at Idx.
if (Start != Idx) if (Start != Idx)
li_.addRange(LiveRange(Start, Idx, VNI)); li_.addRange(LiveRange(Start, Idx, VNI));
// The caller had better add some liveness to IdxVNI, or it leaks.
IdxVNI = VNI; IdxVNI = VNI;
} else } else
li_.addRange(LiveRange(Start, lis_.getMBBEndIdx(MBB), VNI)); li_.addRange(LiveRange(Start, lis_.getMBBEndIdx(MBB), VNI));

5
lib/CodeGen/SplitKit.h
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@@ -20,7 +20,6 @@ namespace llvm {
class LiveInterval; class LiveInterval;
class LiveIntervals; class LiveIntervals;
class MachineDominatorTree;
class MachineInstr; class MachineInstr;
class MachineLoop; class MachineLoop;
class MachineLoopInfo; class MachineLoopInfo;
@@ -147,7 +146,6 @@ public:
/// Values in parentli_ may map to any number of openli_ values, including 0. /// Values in parentli_ may map to any number of openli_ values, including 0.
class LiveIntervalMap { class LiveIntervalMap {
LiveIntervals &lis_; LiveIntervals &lis_;
MachineDominatorTree &dt_;
// The parent interval is never changed. // The parent interval is never changed.
const LiveInterval &parentli_; const LiveInterval &parentli_;
@@ -174,10 +172,9 @@ class LiveIntervalMap {
public: public:
LiveIntervalMap(LiveIntervals &lis, LiveIntervalMap(LiveIntervals &lis,
MachineDominatorTree &dt,
const LiveInterval &parentli, const LiveInterval &parentli,
LiveInterval &li) LiveInterval &li)
: lis_(lis), dt_(dt), parentli_(parentli), li_(li) {} : lis_(lis), parentli_(parentli), li_(li) {}
/// defValue - define a value in li_ from the parentli_ value VNI and Idx. /// defValue - define a value in li_ from the parentli_ value VNI and Idx.
/// Idx does not have to be ParentVNI->def, but it must be contained within /// Idx does not have to be ParentVNI->def, but it must be contained within