From 7fb0ead09156200e5174ae2cd8ee2dc39104ae73 Mon Sep 17 00:00:00 2001
From: Sanjiv Gupta <sanjiv.gupta@microchip.com>
Date: Wed, 23 Dec 2009 10:56:02 +0000
Subject: [PATCH] Added missing patterns for subtract instruction.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91995 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/PIC16/PIC16ISelLowering.cpp | 61 ++++++++++++++++----------
 lib/Target/PIC16/PIC16InstrInfo.td     | 37 +++++++++++-----
 2 files changed, 64 insertions(+), 34 deletions(-)

diff --git a/lib/Target/PIC16/PIC16ISelLowering.cpp b/lib/Target/PIC16/PIC16ISelLowering.cpp
index 4d2096edcf1..c4f45fe157b 100644
--- a/lib/Target/PIC16/PIC16ISelLowering.cpp
+++ b/lib/Target/PIC16/PIC16ISelLowering.cpp
@@ -1561,30 +1561,47 @@ SDValue PIC16TargetLowering::LowerSUB(SDValue Op, SelectionDAG &DAG) {
   DebugLoc dl = Op.getDebugLoc();
   // We should have handled larger operands in type legalizer itself.
   assert (Op.getValueType() == MVT::i8 && "illegal sub to lower");
+  unsigned MemOp = 1;
+  SDVTList Tys = DAG.getVTList(MVT::i8, MVT::Flag);
 
-  // Nothing to do if the first operand is already a direct load and it has
-  // only one use.
-  if (isDirectLoad(Op.getOperand(0)) && Op.getOperand(0).hasOneUse())
-    return Op;
-
-  // Put first operand on stack.
-  SDValue NewVal = ConvertToMemOperand (Op.getOperand(0), DAG, dl);
+  // Since we don't have an instruction for X - c , 
+  // we can change it to X + (-c)
+  ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op.getOperand(1));
+  if (C && (Op.getOpcode() == ISD::SUB))
+    {
+      return DAG.getNode(ISD::ADD, 
+                         dl, MVT::i8, Op.getOperand(0), 
+                         DAG.getConstant(0-(C->getZExtValue()), MVT::i8));
+    }
 
-  SDVTList Tys = DAG.getVTList(MVT::i8, MVT::Flag);
-  switch (Op.getOpcode()) {
-    default:
-      assert (0 && "Opcode unknown."); 
-    case ISD::SUBE:
-      return DAG.getNode(Op.getOpcode(), dl, Tys, NewVal, Op.getOperand(1),
-                         Op.getOperand(2));
-      break;
-    case ISD::SUBC:
-      return DAG.getNode(Op.getOpcode(), dl, Tys, NewVal, Op.getOperand(1));
-      break;
-    case ISD::SUB:
-      return DAG.getNode(Op.getOpcode(), dl, MVT::i8, NewVal, Op.getOperand(1));
-      break;
-  }
+  if (NeedToConvertToMemOp(Op, MemOp) ||
+      (isDirectLoad(Op.getOperand(1)) && 
+       (!isDirectLoad(Op.getOperand(0))) &&
+       (Op.getOperand(0).getOpcode() != ISD::Constant)))
+    {
+      // Put first operand on stack.
+      SDValue NewVal = ConvertToMemOperand (Op.getOperand(0), DAG, dl);
+      
+      switch (Op.getOpcode()) {
+      default:
+        assert (0 && "Opcode unknown."); 
+      case ISD::SUBE:
+        return DAG.getNode(Op.getOpcode(), 
+                           dl, Tys, NewVal, Op.getOperand(1),
+                           Op.getOperand(2));
+        break;
+      case ISD::SUBC:
+        return DAG.getNode(Op.getOpcode(), 
+                           dl, Tys, NewVal, Op.getOperand(1));
+        break;
+      case ISD::SUB:
+        return DAG.getNode(Op.getOpcode(), 
+                           dl, MVT::i8, NewVal, Op.getOperand(1));
+        break;
+      }
+    }
+  else 
+    return Op;
 }
 
 void PIC16TargetLowering::InitReservedFrameCount(const Function *F) {
diff --git a/lib/Target/PIC16/PIC16InstrInfo.td b/lib/Target/PIC16/PIC16InstrInfo.td
index bf4baf39402..24df251b508 100644
--- a/lib/Target/PIC16/PIC16InstrInfo.td
+++ b/lib/Target/PIC16/PIC16InstrInfo.td
@@ -161,7 +161,7 @@ class BinOpWF<bits<6> OpCode, string OpcStr, SDNode OpNode>:
 
 // W = W Op L : Do Op of L with W and place result in W.
 let isTwoAddress = 1 in
-class BinOpLW<bits<6> opcode, string OpcStr, SDNode OpNode> :
+class BinOpWL<bits<6> opcode, string OpcStr, SDNode OpNode> :
   LiteralFormat<opcode, (outs GPR:$dst),
                 (ins GPR:$src, i8imm:$literal),
                 !strconcat(OpcStr, " $literal"),
@@ -404,33 +404,46 @@ def subwf_cc: SUBWF<0, "subwf", PIC16Subcc>;
 
 // addlw 
 let Defs = [STATUS] in {
-def addlw_1 : BinOpLW<0, "addlw", add>;
-def addlw_2 : BinOpLW<0, "addlw", addc>;
+def addlw_1 : BinOpWL<0, "addlw", add>;
+def addlw_2 : BinOpWL<0, "addlw", addc>;
 
 let Uses = [STATUS] in
-def addlwc : BinOpLW<0, "addlwc", adde>; // With Carry. (Assembler macro).
+def addlwc : BinOpWL<0, "addlwc", adde>; // With Carry. (Assembler macro).
 
 // bitwise operations involving a literal and w.
-def andlw : BinOpLW<0, "andlw", and>;
-def xorlw : BinOpLW<0, "xorlw", xor>;
-def orlw  : BinOpLW<0, "iorlw", or>;
+def andlw : BinOpWL<0, "andlw", and>;
+def xorlw : BinOpWL<0, "xorlw", xor>;
+def orlw  : BinOpWL<0, "iorlw", or>;
 }
 
 // sublw 
 // W = C - W ; sub W from literal. (Without borrow).
 let isTwoAddress = 1 in
-class SUBLW<bits<6> opcode, SDNode OpNode> :
+class SUBLW<bits<6> opcode, string OpcStr, SDNode OpNode> :
   LiteralFormat<opcode, (outs GPR:$dst),
                 (ins GPR:$src, i8imm:$literal),
-                "sublw $literal",
+                !strconcat(OpcStr, " $literal"),
                 [(set GPR:$dst, (OpNode (i8 imm:$literal), GPR:$src))]>;
+// subwl 
+// W = W - C ; sub literal from W  (Without borrow).
+let isTwoAddress = 1 in
+class SUBWL<bits<6> opcode, string OpcStr, SDNode OpNode> :
+  LiteralFormat<opcode, (outs GPR:$dst),
+                (ins GPR:$src, i8imm:$literal),
+                !strconcat(OpcStr, " $literal"),
+                [(set GPR:$dst, (OpNode GPR:$src, (i8 imm:$literal)))]>;
 
 let Defs = [STATUS] in {
-def sublw_1 : SUBLW<0, sub>;
-def sublw_2 : SUBLW<0, subc>;
+def sublw_1 : SUBLW<0, "sublw", sub>;
+def sublw_2 : SUBLW<0, "sublw", subc>;
+def sublw_3 : SUBLW<0, "sublwb", sube>; // With borrow (Assembler macro).
+
+def sublw_4 : SUBWL<0, "subwl", sub>;   // Assembler macro replace with addlw
+def sublw_5 : SUBWL<0, "subwl", subc>;  // Assembler macro replace with addlw
+def sublw_6 : SUBWL<0, "subwlb", sube>; // With borrow (Assembler macro).
 }
 let Defs = [STATUS], isTerminator = 1 in 
-def sublw_cc : SUBLW<0, PIC16Subcc>;
+def sublw_cc : SUBLW<0, "sublw", PIC16Subcc>;
 
 // Call instruction.
 let isCall = 1,
-- 
2.34.1