Some enhancements for memcpy / memset inline expansion.

1. Teach it to use overlapping unaligned load / store to copy / set the trailing
   bytes. e.g. On 86, use two pairs of movups / movaps for 17 - 31 byte copies.
2. Use f64 for memcpy / memset on targets where i64 is not legal but f64 is. e.g.
   x86 and ARM.
3. When memcpy from a constant string, do *not* replace the load with a constant
   if it's not possible to materialize an integer immediate with a single
   instruction (required a new target hook: TLI.isIntImmLegal()).
4. Use unaligned load / stores more aggressively if target hooks indicates they
   are "fast".
5. Update ARM target hooks to use unaligned load / stores. e.g. vld1.8 / vst1.8.
   Also increase the threshold to something reasonable (8 for memset, 4 pairs
   for memcpy).

This significantly improves Dhrystone, up to 50% on ARM iOS devices.

rdar://12760078


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169791 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 5 insertions, 2 deletions

diff --git a/lib/Target/ARM/ARMISelLowering.h b/lib/Target/ARM/ARMISelLowering.h
index 1d5aa4f..5cf4023 100644
--- a/lib/Target/ARM/ARMISelLowering.h
+++ b/lib/Target/ARM/ARMISelLowering.h
@@ -285,8 +285,9 @@ namespace llvm {
     bool isDesirableToTransformToIntegerOp(unsigned Opc, EVT VT) const;
 
     /// allowsUnalignedMemoryAccesses - Returns true if the target allows
-    /// unaligned memory accesses. of the specified type.
-    virtual bool allowsUnalignedMemoryAccesses(EVT VT) const;
+    /// unaligned memory accesses of the specified type. Returns whether it
+    /// is "fast" by reference in the second argument.
+    virtual bool allowsUnalignedMemoryAccesses(EVT VT, bool *Fast) const;
 
     virtual EVT getOptimalMemOpType(uint64_t Size,
                                     unsigned DstAlign, unsigned SrcAlign,
@@ -386,6 +387,8 @@ namespace llvm {
     /// materialize the FP immediate as a load from a constant pool.
     virtual bool isFPImmLegal(const APFloat &Imm, EVT VT) const;
 
+    virtual bool isIntImmLegal(const APInt &Imm, EVT VT) const;
+
     virtual bool getTgtMemIntrinsic(IntrinsicInfo &Info,
                                     const CallInst &I,
                                     unsigned Intrinsic) const;