Merging r261441, r261447, and r261546:

[oota-llvm.git] / lib / Target / PowerPC / PPCFrameLowering.h

diff --git a/lib/Target/PowerPC/PPCFrameLowering.h b/lib/Target/PowerPC/PPCFrameLowering.h
index bbe1329a535213f70432fb7990224bc3f2be48d7..f1f3f0b831a70b000587cf2806657f3ee5cc1c98 100644 (file)
--- a/lib/Target/PowerPC/PPCFrameLowering.h
+++ b/lib/Target/PowerPC/PPCFrameLowering.h
@@ -30,28 +30,41 @@ class PPCFrameLowering: public TargetFrameLowering {
   const unsigned BasePointerSaveOffset;
 
   /**
-   * \brief Find a register that can be used in function prologue and epilogue
+   * \brief Find register[s] that can be used in function prologue and epilogue
    *
-   * Find a register that can be use as the scratch register in function
+   * Find register[s] that can be use as scratch register[s] in function
    * prologue and epilogue to save various registers (Link Register, Base
-   * Pointer, etc.). Prefer R0, if it is available. If it is not available,
-   * then choose a different register.
+   * Pointer, etc.). Prefer R0/R12, if available. Otherwise choose whatever
+   * register[s] are available.
    *
-   * This method will return true if an available register was found (including
-   * R0). If no available registers are found, the method returns false and sets
-   * ScratchRegister to R0, as per the recommendation in the ABI.
+   * This method will return true if it is able to find enough unique scratch
+   * registers (1 or 2 depending on the requirement). If it is unable to find
+   * enough available registers in the block, it will return false and set
+   * any passed output parameter that corresponds to a required unique register
+   * to PPC::NoRegister.
    *
    * \param[in] MBB The machine basic block to find an available register for
    * \param[in] UseAtEnd Specify whether the scratch register will be used at
    *                     the end of the basic block (i.e., will the scratch
    *                     register kill a register defined in the basic block)
-   * \param[out] ScratchRegister The scratch register to use
-   * \return true if a scratch register was found. false of a scratch register
-   *         was not found and R0 is being used as the default.
+   * \param[in] TwoUniqueRegsRequired Specify whether this basic block will
+   *                                  require two unique scratch registers.
+   * \param[out] SR1 The scratch register to use
+   * \param[out] SR2 The second scratch register. If this pointer is not null
+   *                 the function will attempt to set it to an available
+   *                 register regardless of whether there is a hard requirement
+   *                 for two unique scratch registers.
+   * \return true if the required number of registers was found.
+   *         false if the required number of scratch register weren't available.
+   *         If either output parameter refers to a required scratch register
+   *         that isn't available, it will be set to an invalid value.
    */
   bool findScratchRegister(MachineBasicBlock *MBB,
                            bool UseAtEnd,
-                           unsigned *ScratchRegister) const;
+                           bool TwoUniqueRegsRequired = false,
+                           unsigned *SR1 = nullptr,
+                           unsigned *SR2 = nullptr) const;
+  bool twoUniqueScratchRegsRequired(MachineBasicBlock *MBB) const;
 
 public:
   PPCFrameLowering(const PPCSubtarget &STI);