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[CodeGen] Preserved additional analyses in StackSlotColoring pass. #93779

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merged 4 commits into from
Jun 11, 2024
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[CodeGen] Preserved additional analyses in StackSlotColoring pass. #93779

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[CodeGen] Preserved additional analyses in StackSlotColoring pass.
vg0204 May 30, 2024
c8079d7
Add recommended changes addressing the grammatical issue with comments.
vg0204 Jun 3, 2024
c56007d
Addressed requested changes after review in StackSlotColoring.cpp.
vg0204 Jun 7, 2024
eb410b8
Removed unnecessary braces from stackSlotColoring.cpp
vg0204 Jun 10, 2024
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15 changes: 14 additions & 1 deletion llvm/lib/CodeGen/StackSlotColoring.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,7 @@
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/LiveDebugVariables.h"
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Could probably avoid the include by using the PassID

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@vg0204 vg0204 Jun 6, 2024 •
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For that, "char &llvm::passID = pass::ID", need to be added in the respective pass (not presently there in LiveDebugVariables.cpp), followed by exposing it via extern in Passes.h. So, I think this is better option.

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But those should be there

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As I was going through the Codegen passes, while most of them have it, others don't. What should be the right practice?

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They all should (but the PassID will go away in new PM so it's probably not worth fixing all of the missing instances)

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So, what should be supposed to be my final take on it!

#include "llvm/CodeGen/LiveInterval.h"
#include "llvm/CodeGen/LiveIntervalUnion.h"
#include "llvm/CodeGen/LiveIntervals.h"
Expand Down Expand Up @@ -64,6 +65,7 @@ namespace {
MachineFrameInfo *MFI = nullptr;
const TargetInstrInfo *TII = nullptr;
const MachineBlockFrequencyInfo *MBFI = nullptr;
SlotIndexes *Indexes = nullptr;

// SSIntervals - Spill slot intervals.
std::vector<LiveInterval*> SSIntervals;
Expand Down Expand Up @@ -152,6 +154,14 @@ namespace {
AU.addRequired<MachineBlockFrequencyInfo>();
AU.addPreserved<MachineBlockFrequencyInfo>();
AU.addPreservedID(MachineDominatorsID);

// As in some Target's pipeline, register allocation (RA) might be
// splitted into multiple phases based on register class. So, this pass
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// may be invoked multiple times requiring it to save these analyses to be
// used by RA later.
AU.addPreserved<LiveIntervals>();
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Do you need to addPreserved<SlotIndexes>? I'm also surprised you don't need to refer to LiveIntervals to maintain them?

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@vg0204 vg0204 Jun 6, 2024 •
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"addPreserved < SlotIndexes > " was already there before. As for LiveIntervals, it would be needed to be preserved for maybe the upcoming regAlloc pass for remaining register classes, else it is being re-computed, which somehow creating problem.

AU.addPreserved<LiveDebugVariables>();

MachineFunctionPass::getAnalysisUsage(AU);
}

Expand Down Expand Up @@ -496,8 +506,10 @@ bool StackSlotColoring::RemoveDeadStores(MachineBasicBlock* MBB) {
++I;
}

for (MachineInstr *MI : toErase)
for (MachineInstr *MI : toErase) {
MI->eraseFromParent();
Indexes->removeMachineInstrFromMaps(*MI);
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}

return changed;
}
Expand All @@ -515,6 +527,7 @@ bool StackSlotColoring::runOnMachineFunction(MachineFunction &MF) {
TII = MF.getSubtarget().getInstrInfo();
LS = &getAnalysis<LiveStacks>();
MBFI = &getAnalysis<MachineBlockFrequencyInfo>();
Indexes = &getAnalysis<SlotIndexes>();

bool Changed = false;

Expand Down
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