From 5a457de4b20d38f62e5906b39a53b5591253f642 Mon Sep 17 00:00:00 2001
From: Richard Osborne <richard@xmos.com>
Date: Wed, 10 Mar 2010 17:10:35 +0000
Subject: [PATCH] Extract recognition of patterns such as
 add(add(mul(x,y),a),b) into a seperate function.

llvm-svn: 98162
---
 llvm/lib/Target/XCore/XCoreISelLowering.cpp | 114 +++++++++++---------
 1 file changed, 66 insertions(+), 48 deletions(-)

diff --git a/llvm/lib/Target/XCore/XCoreISelLowering.cpp b/llvm/lib/Target/XCore/XCoreISelLowering.cpp
index 90d29871d8e2..7dc0274f2685 100644
--- a/llvm/lib/Target/XCore/XCoreISelLowering.cpp
+++ b/llvm/lib/Target/XCore/XCoreISelLowering.cpp
@@ -583,6 +583,64 @@ LowerUMUL_LOHI(SDValue Op, SelectionDAG &DAG)
   return DAG.getMergeValues(Ops, 2, dl);
 }
 
+/// isADDADDMUL - Return whether Op is in a form that is equivalent to
+/// add(add(mul(x,y),a),b). If requireIntermediatesHaveOneUse is true then
+/// each intermediate result in the calculation must also have a single use.
+/// If the Op is in the correct form the constituent parts are written to Mul0,
+/// Mul1, Addend0 and Addend1.
+static bool
+isADDADDMUL(SDValue Op, SDValue &Mul0, SDValue &Mul1, SDValue &Addend0,
+            SDValue &Addend1, bool requireIntermediatesHaveOneUse)
+{
+  if (Op.getOpcode() != ISD::ADD)
+    return false;
+  SDValue N0 = Op.getOperand(0);
+  SDValue N1 = Op.getOperand(1);
+  SDValue AddOp;
+  SDValue OtherOp;
+  if (N0.getOpcode() == ISD::ADD) {
+    AddOp = N0;
+    OtherOp = N1;
+  } else if (N1.getOpcode() == ISD::ADD) {
+    AddOp = N1;
+    OtherOp = N0;
+  } else {
+    return false;
+  }
+  if (OtherOp.getOpcode() == ISD::MUL) {
+    // add(add(a,b),mul(x,y))
+    if (requireIntermediatesHaveOneUse &&
+        (!OtherOp.hasOneUse() || !AddOp.hasOneUse()))
+      return false;
+    Mul0 = OtherOp.getOperand(0);
+    Mul1 = OtherOp.getOperand(1);
+    Addend0 = AddOp.getOperand(0);
+    Addend1 = AddOp.getOperand(1);
+    return true;
+  }
+  if (AddOp.getOperand(0).getOpcode() == ISD::MUL) {
+    // add(add(mul(x,y),a),b)
+    if (requireIntermediatesHaveOneUse && !AddOp.getOperand(0).hasOneUse())
+      return false;
+    Mul0 = AddOp.getOperand(0).getOperand(0);
+    Mul1 = AddOp.getOperand(0).getOperand(1);
+    Addend0 = AddOp.getOperand(1);
+    Addend1 = OtherOp;
+    return true;
+  }
+  if (AddOp.getOperand(1).getOpcode() == ISD::MUL) {
+    // add(add(a,mul(x,y)),b)
+    if (requireIntermediatesHaveOneUse && !AddOp.getOperand(1).hasOneUse())
+      return false;
+    Mul0 = AddOp.getOperand(1).getOperand(0);
+    Mul1 = AddOp.getOperand(1).getOperand(1);
+    Addend0 = AddOp.getOperand(0);
+    Addend1 = OtherOp;
+    return true;
+  }
+  return false;
+}
+
 SDValue XCoreTargetLowering::
 TryExpandADDWithMul(SDNode *N, SelectionDAG &DAG)
 {
@@ -1286,55 +1344,15 @@ SDValue XCoreTargetLowering::PerformDAGCombine(SDNode *N,
     // Fold expressions such as add(add(mul(x,y),a),b) -> lmul(x, y, a, b).
     // This is only profitable if the intermediate results are unused
     // elsewhere.
-    SDValue N0 = N->getOperand(0);
-    SDValue N1 = N->getOperand(1);
-    SDValue AddOp;
-    SDValue OtherOp;
-    if (N0.getOpcode() == ISD::ADD) {
-      AddOp = N0;
-      OtherOp = N1;
-    } else if (N1.getOpcode() == ISD::ADD) {
-      AddOp = N1;
-      OtherOp = N0;
-    } else {
-      break;
+    SDValue Mul0, Mul1, Addend0, Addend1;
+    if (isADDADDMUL(SDValue(N, 0), Mul0, Mul1, Addend0, Addend1, true)) {
+      SDValue Zero = DAG.getConstant(0, MVT::i32);
+      SDValue Ignored = DAG.getNode(XCoreISD::LMUL, dl,
+                                    DAG.getVTList(MVT::i32, MVT::i32), Mul0,
+                                    Mul1, Addend0, Addend1);
+      SDValue Result(Ignored.getNode(), 1);
+      return Result;
     }
-    SDValue Addend0, Addend1;
-    SDValue Mul0;
-    SDValue Mul1;
-    if (OtherOp.getOpcode() == ISD::MUL) {
-      // add(add(a,b),mul(x,y))
-      if (!OtherOp.hasOneUse() || !AddOp.hasOneUse())
-        break;
-      Mul0 = OtherOp.getOperand(0);
-      Mul1 = OtherOp.getOperand(1);
-      Addend0 = AddOp.getOperand(0);
-      Addend1 = AddOp.getOperand(1);
-    } else if (AddOp.getOperand(0).getOpcode() == ISD::MUL) {
-      // add(add(mul(x,y),a),b)
-      if (!AddOp.getOperand(0).hasOneUse())
-        break;
-      Mul0 = AddOp.getOperand(0).getOperand(0);
-      Mul1 = AddOp.getOperand(0).getOperand(1);
-      Addend0 = AddOp.getOperand(1);
-      Addend1 = OtherOp;
-    } else if (AddOp.getOperand(1).getOpcode() == ISD::MUL) {
-      // add(add(a,mul(x,y)),b)
-      if (!AddOp.getOperand(1).hasOneUse())
-        break;
-      Mul0 = AddOp.getOperand(1).getOperand(0);
-      Mul1 = AddOp.getOperand(1).getOperand(1);
-      Addend0 = AddOp.getOperand(0);
-      Addend1 = OtherOp;
-    } else {
-      break;
-    }
-    SDValue Zero = DAG.getConstant(0, MVT::i32);
-    SDValue Ignored = DAG.getNode(XCoreISD::LMUL, dl,
-                                  DAG.getVTList(MVT::i32, MVT::i32), Mul0,
-                                  Mul1, Addend0, Addend1);
-    SDValue Result(Ignored.getNode(), 1);
-    return Result;
   }
   break;
   case ISD::STORE: {