[llvm] r281916 - [RegisterBankInfo] Avoid heap allocation in most cases.

[Quentin Colombet via llvm-commits]

Author: qcolombet
Date: Mon Sep 19 12:33:55 2016
New Revision: 281916

URL: http://llvm.org/viewvc/llvm-project?rev=281916&view=rev
Log:
[RegisterBankInfo] Avoid heap allocation in most cases.

The OperandsMapper class is used heavy in RegBankSelect and each
instantiation triggered a heap allocation for the array of operands.
Instead, use a SmallVector with a big enough size such that most of the
cases do not have to use dynamically allocated memory.

This improves the compile time of the RegBankSelect pass.

Modified:
    llvm/trunk/include/llvm/CodeGen/GlobalISel/RegisterBankInfo.h
    llvm/trunk/lib/CodeGen/GlobalISel/RegisterBankInfo.cpp

Modified: llvm/trunk/include/llvm/CodeGen/GlobalISel/RegisterBankInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/GlobalISel/RegisterBankInfo.h?rev=281916&r1=281915&r2=281916&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/GlobalISel/RegisterBankInfo.h (original)
+++ llvm/trunk/include/llvm/CodeGen/GlobalISel/RegisterBankInfo.h Mon Sep 19 12:33:55 2016
@@ -193,7 +193,8 @@ public:
   class OperandsMapper {
     /// The OpIdx-th cell contains the index in NewVRegs where the VRegs of the
     /// OpIdx-th operand starts. -1 means we do not have such mapping yet.
-    std::unique_ptr<int[]> OpToNewVRegIdx;
+    /// Note: We use a SmallVector to avoid heap allocation for most cases.
+    SmallVector<int, 8> OpToNewVRegIdx;
     /// Hold the registers that will be used to map MI with InstrMapping.
     SmallVector<unsigned, 8> NewVRegs;
     /// Current MachineRegisterInfo, used to create new virtual registers.

Modified: llvm/trunk/lib/CodeGen/GlobalISel/RegisterBankInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/GlobalISel/RegisterBankInfo.cpp?rev=281916&r1=281915&r2=281916&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/GlobalISel/RegisterBankInfo.cpp (original)
+++ llvm/trunk/lib/CodeGen/GlobalISel/RegisterBankInfo.cpp Mon Sep 19 12:33:55 2016
@@ -513,7 +513,7 @@ RegisterBankInfo::OperandsMapper::Operan
     MachineRegisterInfo &MRI)
     : MRI(MRI), MI(MI), InstrMapping(InstrMapping) {
   unsigned NumOpds = MI.getNumOperands();
-  OpToNewVRegIdx.reset(new int[NumOpds]);
+  OpToNewVRegIdx.resize(NumOpds);
   std::fill(&OpToNewVRegIdx[0], &OpToNewVRegIdx[NumOpds],
             OperandsMapper::DontKnowIdx);
   assert(InstrMapping.verify(MI) && "Invalid mapping for MI");