We are missing opportunites to use ldm. Take code like this:

void t(int *cp0, int *cp1, int *dp, int fmd) {
  int c0, c1, d0, d1, d2, d3;
  c0 = (*cp0++ & 0xffff) | ((*cp1++ << 16) & 0xffff0000);
  c1 = (*cp0++ & 0xffff) | ((*cp1++ << 16) & 0xffff0000);
  /* ... */
}

It code gens into something pretty bad. But with this change (analogous to the
X86 back-end), it will use ldm and generate few instructions.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106693 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 20 insertions, 0 deletions

diff --git a/lib/Target/ARM/ARMBaseInstrInfo.h b/lib/Target/ARM/ARMBaseInstrInfo.h
index bc82e14..d7d9f52 100644
--- a/lib/Target/ARM/ARMBaseInstrInfo.h
+++ b/lib/Target/ARM/ARMBaseInstrInfo.h
@@ -320,6 +320,26 @@ public:
   virtual bool produceSameValue(const MachineInstr *MI0,
                                 const MachineInstr *MI1) const;
 
+  /// areLoadsFromSameBasePtr - This is used by the pre-regalloc scheduler to
+  /// determine if two loads are loading from the same base address. It should
+  /// only return true if the base pointers are the same and the only
+  /// differences between the two addresses is the offset. It also returns the
+  /// offsets by reference.
+  virtual bool areLoadsFromSameBasePtr(SDNode *Load1, SDNode *Load2,
+                                       int64_t &Offset1, int64_t &Offset2)const;
+
+  /// shouldScheduleLoadsNear - This is a used by the pre-regalloc scheduler to
+  /// determine (in conjuction with areLoadsFromSameBasePtr) if two loads should
+  /// be scheduled togther. On some targets if two loads are loading from
+  /// addresses in the same cache line, it's better if they are scheduled
+  /// together. This function takes two integers that represent the load offsets
+  /// from the common base address. It returns true if it decides it's desirable
+  /// to schedule the two loads together. "NumLoads" is the number of loads that
+  /// have already been scheduled after Load1.
+  virtual bool shouldScheduleLoadsNear(SDNode *Load1, SDNode *Load2,
+                                       int64_t Offset1, int64_t Offset2,
+                                       unsigned NumLoads) const;
+
   virtual bool isSchedulingBoundary(const MachineInstr *MI,
                                     const MachineBasicBlock *MBB,
                                     const MachineFunction &MF) const;