Delete the linear scan register allocator.

RegAllocGreedy has been the default for six months now.

Deleting RegAllocLinearScan makes it possible to also delete
VirtRegRewriter and clean up the spiller code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@144475 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/LinkAllCodegenComponents.h

@@ -35,7 +35,6 @@ namespace {
 
       (void) llvm::createFastRegisterAllocator();
       (void) llvm::createBasicRegisterAllocator();
-      (void) llvm::createLinearScanRegisterAllocator();
       (void) llvm::createGreedyRegisterAllocator();
       (void) llvm::createDefaultPBQPRegisterAllocator();
 

include/llvm/CodeGen/Passes.h

@@ -118,11 +118,6 @@ namespace llvm {
   ///
   FunctionPass *createGreedyRegisterAllocator();
 
-  /// LinearScanRegisterAllocation Pass - This pass implements the linear scan
-  /// register allocation algorithm, a global register allocator.
-  ///
-  FunctionPass *createLinearScanRegisterAllocator();
-
   /// PBQPRegisterAllocation Pass - This pass implements the Partitioned Boolean
   /// Quadratic Prograaming (PBQP) based register allocator.
   ///

lib/CodeGen/CMakeLists.txt

@@ -70,7 +70,6 @@ add_llvm_library(LLVMCodeGen
   RegAllocBasic.cpp
   RegAllocFast.cpp
   RegAllocGreedy.cpp
-  RegAllocLinearScan.cpp
   RegAllocPBQP.cpp
   RegisterClassInfo.cpp
   RegisterCoalescer.cpp

lib/CodeGen/Passes.cpp

@@ -55,11 +55,6 @@ FunctionPass *llvm::createRegisterAllocator(CodeGenOpt::Level OptLevel) {
     RegisterRegAlloc::setDefault(RegAlloc);
   }
 
-  // This forces linking of the linear scan register allocator,
-  // so -regalloc=linearscan still works in clang.
-  if (Ctor == createLinearScanRegisterAllocator)
-    return createLinearScanRegisterAllocator();
-
   if (Ctor != createDefaultRegisterAllocator)
     return Ctor();