[PATCH] D150606: [RegisterCoalescer] Remove DbgMergedVRegNums (NFC)

[Heejin Ahn via Phabricator via llvm-commits]

aheejin created this revision.
aheejin added a reviewer: jmorse.
Herald added subscribers: wingo, tpr, hiraditya, qcolombet, MatzeB.
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Not sure what this was originally intended for, but this seems to be
unused. It didn't seem to be used when it was first added in D64630 <https://reviews.llvm.org/D64630>
either.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D150606

Files:
  llvm/lib/CodeGen/RegisterCoalescer.cpp


Index: llvm/lib/CodeGen/RegisterCoalescer.cpp
===================================================================
--- llvm/lib/CodeGen/RegisterCoalescer.cpp
+++ llvm/lib/CodeGen/RegisterCoalescer.cpp
@@ -153,12 +153,6 @@
     using DbgValueLoc = std::pair<SlotIndex, MachineInstr*>;
     DenseMap<Register, std::vector<DbgValueLoc>> DbgVRegToValues;
 
-    /// VRegs may be repeatedly coalesced, and have many DBG_VALUEs attached.
-    /// To avoid repeatedly merging sets of DbgValueLocs, instead record
-    /// which vregs have been coalesced, and where to. This map is from
-    /// vreg => {set of vregs merged in}.
-    DenseMap<Register, SmallVector<Register, 4>> DbgMergedVRegNums;
-
     /// A LaneMask to remember on which subregister live ranges we need to call
     /// shrinkToUses() later.
     LaneBitmask ShrinkMask;
@@ -3759,18 +3753,9 @@
     checkMergingChangesDbgValuesImpl(Reg, LHS, RHS, RHSVals);
   };
 
-  // Scan for potentially unsound DBG_VALUEs: examine first the register number
-  // Reg, and then any other vregs that may have been merged into  it.
-  auto PerformScan = [this](Register Reg, std::function<void(Register)> Func) {
-    Func(Reg);
-    if (DbgMergedVRegNums.count(Reg))
-      for (Register X : DbgMergedVRegNums[Reg])
-        Func(X);
-  };
-
   // Scan for unsound updates of both the source and destination register.
-  PerformScan(CP.getSrcReg(), ScanForSrcReg);
-  PerformScan(CP.getDstReg(), ScanForDstReg);
+  ScanForSrcReg(CP.getSrcReg());
+  ScanForDstReg(CP.getDstReg());
 }
 
 void RegisterCoalescer::checkMergingChangesDbgValuesImpl(Register Reg,
@@ -4151,7 +4136,6 @@
     MF->verify(this, "Before register coalescing");
 
   DbgVRegToValues.clear();
-  DbgMergedVRegNums.clear();
   buildVRegToDbgValueMap(fn);
 
   RegClassInfo.runOnMachineFunction(fn);


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