[PATCH] D100188: [AMDGPU] SIFoldOperands: eagerly erase dead REG_SEQUENCEs
Jay Foad via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Fri Apr 9 12:42:49 PDT 2021
This revision was automatically updated to reflect the committed changes.
Closed by commit rGd19a42eba98f: [AMDGPU] SIFoldOperands: eagerly erase dead REG_SEQUENCEs (authored by foad).
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D100188/new/
https://reviews.llvm.org/D100188
Files:
llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
Index: llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
+++ llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
@@ -1596,6 +1596,10 @@
LLVM_DEBUG(dbgs() << "Folded " << *RS << " into " << *UseMI);
+ // Erase the REG_SEQUENCE eagerly, unless we followed a chain of COPY users,
+ // in which case we can erase them all later in runOnMachineFunction.
+ if (MRI->use_nodbg_empty(MI.getOperand(0).getReg()))
+ MI.eraseFromParentAndMarkDBGValuesForRemoval();
return true;
}
@@ -1786,8 +1790,23 @@
// If we managed to fold all uses of this copy then we might as well
// delete it now.
- if (MRI->use_nodbg_empty(MI.getOperand(0).getReg()))
- MI.eraseFromParentAndMarkDBGValuesForRemoval();
+ // The only reason we need to follow chains of copies here is that
+ // tryFoldRegSequence looks forward through copies before folding a
+ // REG_SEQUENCE into its eventual users.
+ auto *InstToErase = &MI;
+ while (MRI->use_nodbg_empty(InstToErase->getOperand(0).getReg())) {
+ auto &SrcOp = InstToErase->getOperand(1);
+ auto SrcReg = SrcOp.isReg() ? SrcOp.getReg() : Register();
+ InstToErase->eraseFromParentAndMarkDBGValuesForRemoval();
+ if (!SrcReg || SrcReg.isPhysical())
+ break;
+ InstToErase = MRI->getVRegDef(SrcReg);
+ if (!InstToErase || !TII->isFoldableCopy(*InstToErase))
+ break;
+ }
+ if (InstToErase && InstToErase->isRegSequence() &&
+ MRI->use_nodbg_empty(InstToErase->getOperand(0).getReg()))
+ InstToErase->eraseFromParentAndMarkDBGValuesForRemoval();
}
}
return true;
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