Follow up to r138791.

Add a instruction flag: hasPostISelHook which tells the pre-RA scheduler to
call a target hook to adjust the instruction. For ARM, this is used to
adjust instructions which may be setting the 's' flag. ADC, SBC, RSB, and RSC
instructions have implicit def of CPSR (required since it now uses CPSR physical
register dependency rather than "glue"). If the carry flag is used, then the
target hook will *fill in* the optional operand with CPSR. Otherwise, the hook
will remove the CPSR implicit def from the MachineInstr.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@138810 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 17 insertions, 0 deletions

diff --git a/include/llvm/MC/MCInstrDesc.h b/include/llvm/MC/MCInstrDesc.h
index 5f5fa4c2f3..7061fcb012 100644
--- a/include/llvm/MC/MCInstrDesc.h
+++ b/include/llvm/MC/MCInstrDesc.h
@@ -116,6 +116,7 @@ namespace MCID {
     Commutable,
     ConvertibleTo3Addr,
     UsesCustomInserter,
+    HasPostISelHook,
     Rematerializable,
     CheapAsAMove,
     ExtraSrcRegAllocReq,
@@ -476,6 +477,14 @@ public:
     return Flags & (1 << MCID::UsesCustomInserter);
   }
 
+  /// hasPostISelHook - Return true if this instruction requires *adjustment*
+  /// after instruction selection by calling a target hook. For example, this
+  /// can be used to fill in ARM 's' optional operand depending on whether
+  /// the conditional flag register is used.
+  bool hasPostISelHook() const {
+    return Flags & (1 << MCID::HasPostISelHook);
+  }
+
   /// isRematerializable - Returns true if this instruction is a candidate for
   /// remat.  This flag is deprecated, please don't use it anymore.  If this
   /// flag is set, the isReallyTriviallyReMaterializable() method is called to
diff --git a/include/llvm/Target/Target.td b/include/llvm/Target/Target.td
index 06c22996dc..b709b873f9 100644
--- a/include/llvm/Target/Target.td
+++ b/include/llvm/Target/Target.td
@@ -328,6 +328,7 @@ class Instruction {
   bit isPredicable = 0;     // Is this instruction predicable?
   bit hasDelaySlot = 0;     // Does this instruction have an delay slot?
   bit usesCustomInserter = 0; // Pseudo instr needing special help.
+  bit hasPostISelHook = 0;  // To be *adjusted* after isel by target hook.
   bit hasCtrlDep   = 0;     // Does this instruction r/w ctrl-flow chains?
   bit isNotDuplicable = 0;  // Is it unsafe to duplicate this instruction?
   bit isAsCheapAsAMove = 0; // As cheap (or cheaper) than a move instruction.
diff --git a/include/llvm/Target/TargetLowering.h b/include/llvm/Target/TargetLowering.h
index d960d76840..b5d739a2cb 100644
--- a/include/llvm/Target/TargetLowering.h
+++ b/include/llvm/Target/TargetLowering.h
@@ -1471,6 +1471,13 @@ public:
   virtual MachineBasicBlock *
     EmitInstrWithCustomInserter(MachineInstr *MI, MachineBasicBlock *MBB) const;
 
+  /// AdjustInstrPostInstrSelection - This method should be implemented by
+  /// targets that mark instructions with the 'hasPostISelHook' flag. These
+  /// instructions must be adjusted after instruction selection by target hooks.
+  /// e.g. To fill in optional defs for ARM 's' setting instructions.
+  virtual void
+  AdjustInstrPostInstrSelection(MachineInstr *MI, SDNode *Node) const;
+
   //===--------------------------------------------------------------------===//
   // Addressing mode description hooks (used by LSR etc).
   //