[llvm] 3eccb40 - [RegisterCoalescer] Remove DbgMergedVRegNums (NFC)

[Heejin Ahn via llvm-commits]

Author: Heejin Ahn
Date: 2023-05-18T16:02:51-07:00
New Revision: 3eccb40fa983401bba1c72d7733c7268217d3e08

URL: https://github.com/llvm/llvm-project/commit/3eccb40fa983401bba1c72d7733c7268217d3e08
DIFF: https://github.com/llvm/llvm-project/commit/3eccb40fa983401bba1c72d7733c7268217d3e08.diff

LOG: [RegisterCoalescer] Remove DbgMergedVRegNums (NFC)

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
either.

Reviewed By: jmorse

Differential Revision: https://reviews.llvm.org/D150606

Added: 
    

Modified: 
    llvm/lib/CodeGen/RegisterCoalescer.cpp

Removed: 
    


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diff  --git a/llvm/lib/CodeGen/RegisterCoalescer.cpp b/llvm/lib/CodeGen/RegisterCoalescer.cpp
index b84c3071ab27..f72d0d50f470 100644
--- a/llvm/lib/CodeGen/RegisterCoalescer.cpp
+++ b/llvm/lib/CodeGen/RegisterCoalescer.cpp
@@ -153,12 +153,6 @@ namespace {
     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;
@@ -3768,18 +3762,9 @@ void RegisterCoalescer::checkMergingChangesDbgValues(CoalescerPair &CP,
     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,
@@ -4160,7 +4145,6 @@ bool RegisterCoalescer::runOnMachineFunction(MachineFunction &fn) {
     MF->verify(this, "Before register coalescing");
 
   DbgVRegToValues.clear();
-  DbgMergedVRegNums.clear();
   buildVRegToDbgValueMap(fn);
 
   RegClassInfo.runOnMachineFunction(fn);