[Debug-info][InstrRef] Avoid an unnecessary map ordering

We keep a record of substitutions between debug value numbers post-isel,
however we never actually look them up until the end of compilation. As a
result, there's nothing gained by the collection being a std::map. This
patch downgrades it to being a vector, that's then sorted at the end of
compilation in LiveDebugValues.

Differential Revision: https://reviews.llvm.org/D105029

1 files changed, 1 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/MachineFunction.cpp b/llvm/lib/CodeGen/MachineFunction.cpp
index 7cb7d089..d26f581 100644
--- a/llvm/lib/CodeGen/MachineFunction.cpp
+++ b/llvm/lib/CodeGen/MachineFunction.cpp
@@ -973,9 +973,7 @@ void MachineFunction::makeDebugValueSubstitution(DebugInstrOperandPair A,
                                                  unsigned Subreg) {
   // Catch any accidental self-loops.
   assert(A.first != B.first);
-  auto Result = DebugValueSubstitutions.insert({A, {B, Subreg}});
-  (void)Result;
-  assert(Result.second && "Substitution for an already substituted value?");
+  DebugValueSubstitutions.push_back({A, B, Subreg});
 }
 
 void MachineFunction::substituteDebugValuesForInst(const MachineInstr &Old,