Update GATHER instructions to support 2 read-write operands. Patch from myself and Manman Ren.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160110 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 44 insertions, 16 deletions

diff --git a/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp b/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
index 52506fa185..4a38324d08 100644
--- a/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
+++ b/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
@@ -572,8 +572,14 @@ void X86MCCodeEmitter::EmitVEXOpcodePrefix(uint64_t TSFlags, unsigned &CurByte,
   // Classify VEX_B, VEX_4V, VEX_R, VEX_X
   unsigned NumOps = Desc.getNumOperands();
   unsigned CurOp = 0;
-  if (NumOps > 1 && Desc.getOperandConstraint(1, MCOI::TIED_TO) != -1)
+  if (NumOps > 1 && Desc.getOperandConstraint(1, MCOI::TIED_TO) == 0)
     ++CurOp;
+  else if (NumOps > 3 && Desc.getOperandConstraint(2, MCOI::TIED_TO) == 0) {
+    assert(Desc.getOperandConstraint(NumOps - 1, MCOI::TIED_TO) == 1);
+    // Special case for GATHER with 2 TIED_TO operands
+    // Skip the first 2 operands: dst, mask_wb
+    CurOp += 2;
+  }
 
   switch (TSFlags & X86II::FormMask) {
   case X86II::MRMInitReg: llvm_unreachable("FIXME: Remove this!");
@@ -971,11 +977,14 @@ EncodeInstruction(const MCInst &MI, raw_ostream &OS,
   // FIXME: This should be handled during MCInst lowering.
   unsigned NumOps = Desc.getNumOperands();
   unsigned CurOp = 0;
-  if (NumOps > 1 && Desc.getOperandConstraint(1, MCOI::TIED_TO) != -1)
+  if (NumOps > 1 && Desc.getOperandConstraint(1, MCOI::TIED_TO) == 0)
     ++CurOp;
-  else if (NumOps > 2 && Desc.getOperandConstraint(NumOps-1, MCOI::TIED_TO)== 0)
-    // Skip the last source operand that is tied_to the dest reg. e.g. LXADD32
-    --NumOps;
+  else if (NumOps > 3 && Desc.getOperandConstraint(2, MCOI::TIED_TO) == 0) {
+    assert(Desc.getOperandConstraint(NumOps - 1, MCOI::TIED_TO) == 1);
+    // Special case for GATHER with 2 TIED_TO operands
+    // Skip the first 2 operands: dst, mask_wb
+    CurOp += 2;
+  }
 
   // Keep track of the current byte being emitted.
   unsigned CurByte = 0;
diff --git a/lib/Target/X86/X86CodeEmitter.cpp b/lib/Target/X86/X86CodeEmitter.cpp
index 3079dfa7cf..977cc50c13 100644
--- a/lib/Target/X86/X86CodeEmitter.cpp
+++ b/lib/Target/X86/X86CodeEmitter.cpp
@@ -935,8 +935,15 @@ void Emitter<CodeEmitter>::emitVEXOpcodePrefix(uint64_t TSFlags,
   // Classify VEX_B, VEX_4V, VEX_R, VEX_X
   unsigned NumOps = Desc->getNumOperands();
   unsigned CurOp = 0;
-  if (NumOps > 1 && Desc->getOperandConstraint(1, MCOI::TIED_TO) != -1)
+  if (NumOps > 1 && Desc->getOperandConstraint(1, MCOI::TIED_TO) == 0)
     ++CurOp;
+  else if (NumOps > 3 && Desc->getOperandConstraint(2, MCOI::TIED_TO) == 0) {
+    assert(Desc->getOperandConstraint(NumOps - 1, MCOI::TIED_TO) == 1);
+    // Special case for GATHER with 2 TIED_TO operands
+    // Skip the first 2 operands: dst, mask_wb
+    CurOp += 2;
+  }
+
   switch (TSFlags & X86II::FormMask) {
     case X86II::MRMInitReg:
       // Duplicate register.
@@ -1117,11 +1124,14 @@ void Emitter<CodeEmitter>::emitInstruction(MachineInstr &MI,
   // If this is a two-address instruction, skip one of the register operands.
   unsigned NumOps = Desc->getNumOperands();
   unsigned CurOp = 0;
-  if (NumOps > 1 && Desc->getOperandConstraint(1, MCOI::TIED_TO) != -1)
+  if (NumOps > 1 && Desc->getOperandConstraint(1, MCOI::TIED_TO) == 0)
     ++CurOp;
-  else if (NumOps > 2 && Desc->getOperandConstraint(NumOps-1,MCOI::TIED_TO)== 0)
-    // Skip the last source operand that is tied_to the dest reg. e.g. LXADD32
-    --NumOps;
+  else if (NumOps > 3 && Desc->getOperandConstraint(2, MCOI::TIED_TO) == 0) {
+    assert(Desc->getOperandConstraint(NumOps - 1, MCOI::TIED_TO) == 1);
+    // Special case for GATHER with 2 TIED_TO operands
+    // Skip the first 2 operands: dst, mask_wb
+    CurOp += 2;
+  }
 
   uint64_t TSFlags = Desc->TSFlags;
 
diff --git a/lib/Target/X86/X86ISelDAGToDAG.cpp b/lib/Target/X86/X86ISelDAGToDAG.cpp
index 817013011c..5186482a0d 100644
--- a/lib/Target/X86/X86ISelDAGToDAG.cpp
+++ b/lib/Target/X86/X86ISelDAGToDAG.cpp
@@ -1966,14 +1966,22 @@ SDNode *X86DAGToDAGISel::SelectGather(SDNode *Node, unsigned Opc) {
   if (!Scale)
     return 0;
 
+  SDVTList VTs = CurDAG->getVTList(VSrc.getValueType(), VSrc.getValueType(),
+                                   MVT::Other);
+
   // Memory Operands: Base, Scale, Index, Disp, Segment
   SDValue Disp = CurDAG->getTargetConstant(0, MVT::i32);
   SDValue Segment = CurDAG->getRegister(0, MVT::i32);
   const SDValue Ops[] = { VSrc, Base, getI8Imm(Scale->getSExtValue()), VIdx,
                           Disp, Segment, VMask, Chain};
   SDNode *ResNode = CurDAG->getMachineNode(Opc, Node->getDebugLoc(),
-                                           VSrc.getValueType(), MVT::Other,
-                                           Ops, array_lengthof(Ops));
+                                           VTs, Ops, array_lengthof(Ops));
+  // Node has 2 outputs: VDst and MVT::Other.
+  // ResNode has 3 outputs: VDst, VMask_wb, and MVT::Other.
+  // We replace VDst of Node with VDst of ResNode, and Other of Node with Other
+  // of ResNode.
+  ReplaceUses(SDValue(Node, 0), SDValue(ResNode, 0));
+  ReplaceUses(SDValue(Node, 1), SDValue(ResNode, 2));
   return ResNode;
 }
 
@@ -2034,7 +2042,8 @@ SDNode *X86DAGToDAGISel::Select(SDNode *Node) {
       }
       SDNode *RetVal = SelectGather(Node, Opc);
       if (RetVal)
-        return RetVal;
+        // We already called ReplaceUses inside SelectGather.
+        return NULL;
       break;
     }
     }
diff --git a/lib/Target/X86/X86InstrSSE.td b/lib/Target/X86/X86InstrSSE.td
index 5e96eecf8a..0ad92413ff 100644
--- a/lib/Target/X86/X86InstrSSE.td
+++ b/lib/Target/X86/X86InstrSSE.td
@@ -8038,19 +8038,19 @@ defm VPSRAVD : avx2_var_shift<0x46, "vpsravd", sra, v4i32, v8i32>;
 // VGATHER - GATHER Operations
 multiclass avx2_gather<bits<8> opc, string OpcodeStr,
                        RegisterClass RC256, X86MemOperand memop256> {
-  def rm  : AVX28I<opc, MRMSrcMem, (outs VR128:$dst),
+  def rm  : AVX28I<opc, MRMSrcMem, (outs VR128:$dst, VR128:$mask_wb),
             (ins VR128:$src1, v128mem:$src2, VR128:$mask),
             !strconcat(OpcodeStr,
               "\t{$mask, $src2, $dst|$dst, $src2, $mask}"),
             []>, VEX_4VOp3;
-  def Yrm : AVX28I<opc, MRMSrcMem, (outs RC256:$dst),
+  def Yrm : AVX28I<opc, MRMSrcMem, (outs RC256:$dst, RC256:$mask_wb),
             (ins RC256:$src1, memop256:$src2, RC256:$mask),
             !strconcat(OpcodeStr,
               "\t{$mask, $src2, $dst|$dst, $src2, $mask}"),
             []>, VEX_4VOp3, VEX_L;
 }
 
-let Constraints = "$src1 = $dst" in {
+let Constraints = "$src1 = $dst, $mask = $mask_wb" in {
   defm VGATHERDPD : avx2_gather<0x92, "vgatherdpd", VR256, v128mem>, VEX_W;
   defm VGATHERQPD : avx2_gather<0x93, "vgatherqpd", VR256, v256mem>, VEX_W;
   defm VGATHERDPS : avx2_gather<0x92, "vgatherdps", VR256, v256mem>;