zext / truncate is free on msp430. Inform codegen about this.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@93556 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 17 insertions, 0 deletions

diff --git a/lib/Target/MSP430/MSP430ISelLowering.h b/lib/Target/MSP430/MSP430ISelLowering.h
index 4921500d39..6152a055be 100644
--- a/lib/Target/MSP430/MSP430ISelLowering.h
+++ b/lib/Target/MSP430/MSP430ISelLowering.h
@@ -99,6 +99,23 @@ namespace llvm {
     std::pair<unsigned, const TargetRegisterClass*>
     getRegForInlineAsmConstraint(const std::string &Constraint, EVT VT) const;
 
+    /// isTruncateFree - Return true if it's free to truncate a value of type
+    /// Ty1 to type Ty2. e.g. On msp430 it's free to truncate a i16 value in
+    /// register R15W to i8 by referencing its sub-register R15B.
+    virtual bool isTruncateFree(const Type *Ty1, const Type *Ty2) const;
+    virtual bool isTruncateFree(EVT VT1, EVT VT2) const;
+
+    /// isZExtFree - Return true if any actual instruction that defines a value
+    /// of type Ty1 implicit zero-extends the value to Ty2 in the result
+    /// register. This does not necessarily include registers defined in unknown
+    /// ways, such as incoming arguments, or copies from unknown virtual
+    /// registers. Also, if isTruncateFree(Ty2, Ty1) is true, this does not
+    /// necessarily apply to truncate instructions. e.g. on msp430, all
+    /// instructions that define 8-bit values implicit zero-extend the result
+    /// out to 16 bits.
+    virtual bool isZExtFree(const Type *Ty1, const Type *Ty2) const;
+    virtual bool isZExtFree(EVT VT1, EVT VT2) const;
+
     MachineBasicBlock* EmitInstrWithCustomInserter(MachineInstr *MI,
                                                    MachineBasicBlock *BB,
                     DenseMap<MachineBasicBlock*, MachineBasicBlock*> *EM) const;