[MachineFunction] Introduce a reset method.

This method allows to reset the state of a MachineFunction as if it was
just created. This will be used during the bring-up of GlobalISel to
provide a way to fallback on SelectionDAG. That way, we can start doing
correctness testing even if we are not able to select all functions via
the global instruction selector.

llvm-svn: 279876

1 files changed, 14 insertions, 5 deletions

diff --git a/llvm/lib/CodeGen/MachineFunction.cpp b/llvm/lib/CodeGen/MachineFunction.cpp
index f5c8147d859..08c93f20946 100644
--- a/llvm/lib/CodeGen/MachineFunction.cpp
+++ b/llvm/lib/CodeGen/MachineFunction.cpp
@@ -100,6 +100,11 @@ MachineFunction::MachineFunction(const Function *F, const TargetMachine &TM,
                                  unsigned FunctionNum, MachineModuleInfo &mmi)
     : Fn(F), Target(TM), STI(TM.getSubtargetImpl(*F)), Ctx(mmi.getContext()),
       MMI(mmi) {
+  FunctionNumber = FunctionNum;
+  init();
+}
+
+void MachineFunction::init() {
   // Assume the function starts in SSA form with correct liveness.
   Properties.set(MachineFunctionProperties::Property::IsSSA);
   Properties.set(MachineFunctionProperties::Property::TracksLiveness);
@@ -112,11 +117,11 @@ MachineFunction::MachineFunction(const Function *F, const TargetMachine &TM,
   // We can realign the stack if the target supports it and the user hasn't
   // explicitly asked us not to.
   bool CanRealignSP = STI->getFrameLowering()->isStackRealignable() &&
-                      !F->hasFnAttribute("no-realign-stack");
+                      !Fn->hasFnAttribute("no-realign-stack");
   FrameInfo = new (Allocator) MachineFrameInfo(
       getFnStackAlignment(STI, Fn), /*StackRealignable=*/CanRealignSP,
       /*ForceRealign=*/CanRealignSP &&
-          F->hasFnAttribute(Attribute::StackAlignment));
+          Fn->hasFnAttribute(Attribute::StackAlignment));
 
   if (Fn->hasFnAttribute(Attribute::StackAlignment))
     FrameInfo->ensureMaxAlignment(Fn->getFnStackAlignment());
@@ -133,15 +138,14 @@ MachineFunction::MachineFunction(const Function *F, const TargetMachine &TM,
   if (AlignAllFunctions)
     Alignment = AlignAllFunctions;
 
-  FunctionNumber = FunctionNum;
   JumpTableInfo = nullptr;
 
   if (isFuncletEHPersonality(classifyEHPersonality(
-          F->hasPersonalityFn() ? F->getPersonalityFn() : nullptr))) {
+          Fn->hasPersonalityFn() ? Fn->getPersonalityFn() : nullptr))) {
     WinEHInfo = new (Allocator) WinEHFuncInfo();
   }
 
-  assert(TM.isCompatibleDataLayout(getDataLayout()) &&
+  assert(Target.isCompatibleDataLayout(getDataLayout()) &&
          "Can't create a MachineFunction using a Module with a "
          "Target-incompatible DataLayout attached\n");
 
@@ -149,6 +153,11 @@ MachineFunction::MachineFunction(const Function *F, const TargetMachine &TM,
 }
 
 MachineFunction::~MachineFunction() {
+  clear();
+}
+
+void MachineFunction::clear() {
+  Properties.reset();
   // Don't call destructors on MachineInstr and MachineOperand. All of their
   // memory comes from the BumpPtrAllocator which is about to be purged.
   //