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LiveVariables::VarInfo contains an AliveBlocks BitVector, which has as many

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entries as there are basic blocks in the function.  LiveVariables::getVarInfo
creates a VarInfo struct for every register in the function, leading to
quadratic space use.  This patch changes the BitVector to a SparseBitVector,
which doesn't help the worst-case memory use but does reduce the actual use in
very long functions with short-lived variables.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72426 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jeffrey Yasskin
2009-05-26 18:27:15 +00:00
parent 91bb61a1e2
commit 493a3d015c
4 changed files with 17 additions and 19 deletions
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17
lib/CodeGen/LiveVariables.cpp
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@@ -52,8 +52,9 @@ void LiveVariables::getAnalysisUsage(AnalysisUsage &AU) const {
void LiveVariables::VarInfo::dump() const {
cerr << " Alive in blocks: ";
for (int i = AliveBlocks.find_first(); i != -1; i = AliveBlocks.find_next(i))
cerr << i << ", ";
for (SparseBitVector<>::iterator I = AliveBlocks.begin(),
E = AliveBlocks.end(); I != E; ++I)
cerr << *I << ", ";
cerr << "\n Killed by:";
if (Kills.empty())
cerr << " No instructions.\n";
@@ -75,9 +76,7 @@ LiveVariables::VarInfo &LiveVariables::getVarInfo(unsigned RegIdx) {
else
VirtRegInfo.resize(2*VirtRegInfo.size());
}
VarInfo &VI = VirtRegInfo[RegIdx];
VI.AliveBlocks.resize(MF->getNumBlockIDs());
return VI;
return VirtRegInfo[RegIdx];
}
void LiveVariables::MarkVirtRegAliveInBlock(VarInfo& VRInfo,
@@ -96,11 +95,11 @@ void LiveVariables::MarkVirtRegAliveInBlock(VarInfo& VRInfo,
if (MBB == DefBlock) return; // Terminate recursion
if (VRInfo.AliveBlocks[BBNum])
if (VRInfo.AliveBlocks.test(BBNum))
return; // We already know the block is live
// Mark the variable known alive in this bb
VRInfo.AliveBlocks[BBNum] = true;
VRInfo.AliveBlocks.set(BBNum);
for (MachineBasicBlock::const_pred_reverse_iterator PI = MBB->pred_rbegin(),
E = MBB->pred_rend(); PI != E; ++PI)
@@ -163,7 +162,7 @@ void LiveVariables::HandleVirtRegUse(unsigned reg, MachineBasicBlock *MBB,
// Add a new kill entry for this basic block. If this virtual register is
// already marked as alive in this basic block, that means it is alive in at
// least one of the successor blocks, it's not a kill.
if (!VRInfo.AliveBlocks[BBNum])
if (!VRInfo.AliveBlocks.test(BBNum))
VRInfo.Kills.push_back(MI);
// Update all dominating blocks to mark them as "known live".
@@ -175,7 +174,7 @@ void LiveVariables::HandleVirtRegUse(unsigned reg, MachineBasicBlock *MBB,
void LiveVariables::HandleVirtRegDef(unsigned Reg, MachineInstr *MI) {
VarInfo &VRInfo = getVarInfo(Reg);
if (VRInfo.AliveBlocks.none())
if (VRInfo.AliveBlocks.empty())
// If vr is not alive in any block, then defaults to dead.
VRInfo.Kills.push_back(MI);
}