Fix dynamic linking on PPC64.

Dynamic linking on PPC64 has had problems since we had to move the top-down
hazard-detection logic post-ra. For dynamic linking to work there needs to be
a nop placed after every call. It turns out that it is really hard to guarantee
that nothing will be placed in between the call (bl) and the nop during post-ra
scheduling. Previous attempts at fixing this by placing logic inside the
hazard detector only partially worked.

This is now fixed in a different way: call+nop codegen-only instructions. As far
as CodeGen is concerned the pair is now a single instruction and cannot be split.
This solution works much better than previous attempts.

The scoreboard hazard detector is also renamed to be more generic, there is currently
no cpu-specific logic in it.

llvm-svn: 153816

1 files changed, 7 insertions, 7 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCHazardRecognizers.h b/llvm/lib/Target/PowerPC/PPCHazardRecognizers.h
index d80a3850b01..55b45d01b20 100644
--- a/llvm/lib/Target/PowerPC/PPCHazardRecognizers.h
+++ b/llvm/lib/Target/PowerPC/PPCHazardRecognizers.h
@@ -21,16 +21,19 @@
 
 namespace llvm {
 
-/// PPCHazardRecognizer440 - This class implements a scoreboard-based
-/// hazard recognizer for the PPC 440 and friends.
-class PPCHazardRecognizer440 : public ScoreboardHazardRecognizer {
+/// PPCScoreboardHazardRecognizer - This class implements a scoreboard-based
+/// hazard recognizer for generic PPC processors.
+class PPCScoreboardHazardRecognizer : public ScoreboardHazardRecognizer {
   const ScheduleDAG *DAG;
 public:
-  PPCHazardRecognizer440(const InstrItineraryData *ItinData,
+  PPCScoreboardHazardRecognizer(const InstrItineraryData *ItinData,
                          const ScheduleDAG *DAG_) :
     ScoreboardHazardRecognizer(ItinData, DAG_), DAG(DAG_) {}
 
+  virtual HazardType getHazardType(SUnit *SU, int Stalls);
   virtual void EmitInstruction(SUnit *SU);
+  virtual void AdvanceCycle();
+  virtual void Reset();
 };
 
 /// PPCHazardRecognizer970 - This class defines a finite state automata that
@@ -49,9 +52,6 @@ class PPCHazardRecognizer970 : public ScheduleHazardRecognizer {
   // HasCTRSet - If the CTR register is set in this group, disallow BCTRL.
   bool HasCTRSet;
 
-  // Was the last instruction issued a BL8_ELF
-  bool LastWasBL8_ELF;
-
   // StoredPtr - Keep track of the address of any store.  If we see a load from
   // the same address (or one that aliases it), disallow the store.  We can have
   // up to four stores in one dispatch group, hence we track up to 4.