[X86] Use push-pop for materializing small constants under 'minsize'

Use the 3-byte (4 with REX prefix) push-pop sequence for materializing
small constants. This is smaller than using a mov (5, 6 or 7 bytes
depending on size and REX prefix), but it's likely to be slower, so
only used for 'minsize'.

This is a follow-up to r255656.

Differential Revision: http://reviews.llvm.org/D15549

llvm-svn: 255936

1 files changed, 4 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/X86InstrInfo.h b/llvm/lib/Target/X86/X86InstrInfo.h
index edd09d61759..9d40334206b 100644
--- a/llvm/lib/Target/X86/X86InstrInfo.h
+++ b/llvm/lib/Target/X86/X86InstrInfo.h
@@ -23,6 +23,7 @@
 #include "X86GenInstrInfo.inc"
 
 namespace llvm {
+  class MachineInstrBuilder;
   class X86RegisterInfo;
   class X86Subtarget;
 
@@ -564,6 +565,9 @@ private:
   /// operand and follow operands form a reference to the stack frame.
   bool isFrameOperand(const MachineInstr *MI, unsigned int Op,
                       int &FrameIndex) const;
+
+  /// Expand the MOVImmSExti8 pseudo-instructions.
+  bool ExpandMOVImmSExti8(MachineInstrBuilder &MIB) const;
 };
 
 } // End llvm namespace