Allow ARM if-converter to be run after post allocation scheduling.

- This fixed a number of bugs in if-converter, tail merging, and post-allocation
  scheduler. If-converter now runs branch folding / tail merging first to
  maximize if-conversion opportunities.
- Also changed the t2IT instruction slightly. It now defines the ITSTATE
  register which is read by instructions in the IT block.
- Added Thumb2 specific hazard recognizer to ensure the scheduler doesn't
  change the instruction ordering in the IT block (since IT mask has been
  finalized). It also ensures no other instructions can be scheduled between
  instructions in the IT block.

This is not yet enabled.

llvm-svn: 106344

1 files changed, 4 insertions, 24 deletions

diff --git a/llvm/lib/CodeGen/PostRASchedulerList.cpp b/llvm/lib/CodeGen/PostRASchedulerList.cpp
index f3c725d..4af8e07 100644
--- a/llvm/lib/CodeGen/PostRASchedulerList.cpp
+++ b/llvm/lib/CodeGen/PostRASchedulerList.cpp
@@ -79,6 +79,7 @@ AntiDepBreaker::~AntiDepBreaker() { }
 namespace {
   class PostRAScheduler : public MachineFunctionPass {
     AliasAnalysis *AA;
+    const TargetInstrInfo *TII;
     CodeGenOpt::Level OptLevel;
 
   public:
@@ -181,30 +182,9 @@ namespace {
   };
 }
 
-/// isSchedulingBoundary - Test if the given instruction should be
-/// considered a scheduling boundary. This primarily includes labels
-/// and terminators.
-///
-static bool isSchedulingBoundary(const MachineInstr *MI,
-                                 const MachineFunction &MF) {
-  // Terminators and labels can't be scheduled around.
-  if (MI->getDesc().isTerminator() || MI->isLabel())
-    return true;
-
-  // Don't attempt to schedule around any instruction that defines
-  // a stack-oriented pointer, as it's unlikely to be profitable. This
-  // saves compile time, because it doesn't require every single
-  // stack slot reference to depend on the instruction that does the
-  // modification.
-  const TargetLowering &TLI = *MF.getTarget().getTargetLowering();
-  if (MI->definesRegister(TLI.getStackPointerRegisterToSaveRestore()))
-    return true;
-
-  return false;
-}
-
 bool PostRAScheduler::runOnMachineFunction(MachineFunction &Fn) {
   AA = &getAnalysis<AliasAnalysis>();
+  TII = Fn.getTarget().getInstrInfo();
 
   // Check for explicit enable/disable of post-ra scheduling.
   TargetSubtarget::AntiDepBreakMode AntiDepMode = TargetSubtarget::ANTIDEP_NONE;
@@ -265,8 +245,8 @@ bool PostRAScheduler::runOnMachineFunction(MachineFunction &Fn) {
     MachineBasicBlock::iterator Current = MBB->end();
     unsigned Count = MBB->size(), CurrentCount = Count;
     for (MachineBasicBlock::iterator I = Current; I != MBB->begin(); ) {
-      MachineInstr *MI = prior(I);
-      if (isSchedulingBoundary(MI, Fn)) {
+      MachineInstr *MI = llvm::prior(I);
+      if (TII->isSchedulingBoundary(MI, MBB, Fn)) {
         Scheduler.Run(MBB, I, Current, CurrentCount);
         Scheduler.EmitSchedule();
         Current = MI;