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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
View File

@ -17,7 +17,6 @@
#include "VirtRegMap.h"
#include "llvm/CodeGen/CalcSpillWeights.h"
#include "llvm/CodeGen/LiveIntervalAnalysis.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineLoopInfo.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
// as needed along the way.
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);
std::pair<MBBValueMap::iterator, bool> InsP =
DomValue.insert(MBBValueMap::value_type(Succ, VNI));
SlotIndex Start = lis_.getMBBStartIdx(Succ);
if (InsP.second) {
// This is the first time we backtrack to Succ. Verify dominance.
if (Succ->pred_size() == 1 || dt_.dominates(MBB, Succ))
continue;
} else if (InsP.first->second == VNI ||
InsP.first->second->def == Start) {
// We have previously backtracked VNI to Succ, or Succ already has a
// phi-def. No need to backtrack further.
// This is the first time we backtrack to Succ.
if (InsP.second)
continue;
// We reached Succ again with the same VNI. Nothing is going to change.
VNInfo *OVNI = InsP.first->second;
if (OVNI == VNI)
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->setIsPHIDef(true);
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.
// FIXME: We could prune up to the last phi-def we inserted, need df_iterator
// for that.
IDFI.skipChildren();
}
@ -468,6 +477,7 @@ VNInfo *LiveIntervalMap::mapValue(const VNInfo *ParentVNI, SlotIndex Idx) {
// Don't add full liveness to IdxMBB, stop at Idx.
if (Start != Idx)
li_.addRange(LiveRange(Start, Idx, VNI));
// The caller had better add some liveness to IdxVNI, or it leaks.
IdxVNI = VNI;
} else
li_.addRange(LiveRange(Start, lis_.getMBBEndIdx(MBB), VNI));

5
lib/CodeGen/SplitKit.h
View File

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