R600/SI: Emit s_mov_b32 m0, -1 before every DS instruction

This s_mov_b32 will write to a virtual register from the M0Reg
class and all the ds instructions now take an extra M0Reg explicit
argument.

This change is necessary to prevent issues with the scheduler
mixing together instructions that expect different values in the m0
registers.

llvm-svn: 222583
diff --git a/llvm/lib/Target/R600/SIISelLowering.cpp b/llvm/lib/Target/R600/SIISelLowering.cpp
index 8d4164a..fb45684 100644
--- a/llvm/lib/Target/R600/SIISelLowering.cpp
+++ b/llvm/lib/Target/R600/SIISelLowering.cpp
@@ -1986,6 +1986,7 @@
   const SIInstrInfo *TII = static_cast<const SIInstrInfo *>(
       getTargetMachine().getSubtargetImpl()->getInstrInfo());
 
+  MachineRegisterInfo &MRI = MI->getParent()->getParent()->getRegInfo();
   TII->legalizeOperands(MI);
 
   if (TII->isMIMG(MI->getOpcode())) {
@@ -2005,7 +2006,6 @@
 
     unsigned NewOpcode = TII->getMaskedMIMGOp(MI->getOpcode(), BitsSet);
     MI->setDesc(TII->get(NewOpcode));
-    MachineRegisterInfo &MRI = MI->getParent()->getParent()->getRegInfo();
     MRI.setRegClass(VReg, RC);
     return;
   }
diff --git a/llvm/lib/Target/R600/SIInstrFormats.td b/llvm/lib/Target/R600/SIInstrFormats.td
index 10e0a3f..ee1a52b 100644
--- a/llvm/lib/Target/R600/SIInstrFormats.td
+++ b/llvm/lib/Target/R600/SIInstrFormats.td
@@ -546,6 +546,7 @@
 
   let LGKM_CNT = 1;
   let UseNamedOperandTable = 1;
+  let DisableEncoding = "$m0";
 }
 
 class MUBUF <bits<7> op, dag outs, dag ins, string asm, list<dag> pattern> :
diff --git a/llvm/lib/Target/R600/SIInstrInfo.td b/llvm/lib/Target/R600/SIInstrInfo.td
index 713e84e..392c272 100644
--- a/llvm/lib/Target/R600/SIInstrInfo.td
+++ b/llvm/lib/Target/R600/SIInstrInfo.td
@@ -948,7 +948,7 @@
 class DS_Load_Helper <bits<8> op, string asm, RegisterClass regClass> : DS_1A <
   op,
   (outs regClass:$vdst),
-  (ins i1imm:$gds, VReg_32:$addr, ds_offset:$offset),
+  (ins i1imm:$gds, VReg_32:$addr, ds_offset:$offset, M0Reg:$m0),
   asm#" $vdst, $addr"#"$offset"#" [M0]",
   []> {
   let data0 = 0;
@@ -960,7 +960,8 @@
 class DS_Load2_Helper <bits<8> op, string asm, RegisterClass regClass> : DS <
   op,
   (outs regClass:$vdst),
-  (ins i1imm:$gds, VReg_32:$addr, ds_offset0:$offset0, ds_offset1:$offset1),
+  (ins i1imm:$gds, VReg_32:$addr, ds_offset0:$offset0, ds_offset1:$offset1,
+        M0Reg:$m0),
   asm#" $vdst, $addr"#"$offset0"#"$offset1 [M0]",
   []> {
   let data0 = 0;
@@ -973,7 +974,7 @@
 class DS_Store_Helper <bits<8> op, string asm, RegisterClass regClass> : DS_1A <
   op,
   (outs),
-  (ins i1imm:$gds, VReg_32:$addr, regClass:$data0, ds_offset:$offset),
+  (ins i1imm:$gds, VReg_32:$addr, regClass:$data0, ds_offset:$offset, M0Reg:$m0),
   asm#" $addr, $data0"#"$offset"#" [M0]",
   []> {
   let data1 = 0;
@@ -986,7 +987,7 @@
   op,
   (outs),
   (ins i1imm:$gds, VReg_32:$addr, regClass:$data0, regClass:$data1,
-       ds_offset0:$offset0, ds_offset1:$offset1),
+       ds_offset0:$offset0, ds_offset1:$offset1, M0Reg:$m0),
   asm#" $addr, $data0, $data1"#"$offset0"#"$offset1 [M0]",
   []> {
   let mayStore = 1;
@@ -999,7 +1000,7 @@
 class DS_1A1D_RET <bits<8> op, string asm, RegisterClass rc, string noRetOp = ""> : DS_1A <
   op,
   (outs rc:$vdst),
-  (ins i1imm:$gds, VReg_32:$addr, rc:$data0, ds_offset:$offset),
+  (ins i1imm:$gds, VReg_32:$addr, rc:$data0, ds_offset:$offset, M0Reg:$m0),
   asm#" $vdst, $addr, $data0"#"$offset"#" [M0]", []>,
   AtomicNoRet<noRetOp, 1> {
 
@@ -1014,7 +1015,7 @@
 class DS_1A2D_RET <bits<8> op, string asm, RegisterClass rc, string noRetOp = ""> : DS_1A <
   op,
   (outs rc:$vdst),
-  (ins i1imm:$gds, VReg_32:$addr, rc:$data0, rc:$data1, ds_offset:$offset),
+  (ins i1imm:$gds, VReg_32:$addr, rc:$data0, rc:$data1, ds_offset:$offset, M0Reg:$m0),
   asm#" $vdst, $addr, $data0, $data1"#"$offset"#" [M0]",
   []>,
   AtomicNoRet<noRetOp, 1> {
@@ -1027,7 +1028,7 @@
 class DS_1A2D_NORET <bits<8> op, string asm, RegisterClass rc, string noRetOp = asm> : DS_1A <
   op,
   (outs),
-  (ins i1imm:$gds, VReg_32:$addr, rc:$data0, rc:$data1, ds_offset:$offset),
+  (ins i1imm:$gds, VReg_32:$addr, rc:$data0, rc:$data1, ds_offset:$offset, M0Reg:$m0),
   asm#" $addr, $data0, $data1"#"$offset"#" [M0]",
   []>,
   AtomicNoRet<noRetOp, 0> {
@@ -1039,7 +1040,7 @@
 class DS_1A1D_NORET <bits<8> op, string asm, RegisterClass rc, string noRetOp = asm> : DS_1A <
   op,
   (outs),
-  (ins i1imm:$gds, VReg_32:$addr, rc:$data0, ds_offset:$offset),
+  (ins i1imm:$gds, VReg_32:$addr, rc:$data0, ds_offset:$offset, M0Reg:$m0),
   asm#" $addr, $data0"#"$offset"#" [M0]",
   []>,
   AtomicNoRet<noRetOp, 0> {
diff --git a/llvm/lib/Target/R600/SIInstructions.td b/llvm/lib/Target/R600/SIInstructions.td
index bd91577..e1eb955 100644
--- a/llvm/lib/Target/R600/SIInstructions.td
+++ b/llvm/lib/Target/R600/SIInstructions.td
@@ -2614,7 +2614,7 @@
 
 class DSReadPat <DS inst, ValueType vt, PatFrag frag> : Pat <
   (vt (frag (DS1Addr1Offset i32:$ptr, i32:$offset))),
-  (inst (i1 0), $ptr, (as_i16imm $offset))
+  (inst (i1 0), $ptr, (as_i16imm $offset), (S_MOV_B32 -1))
 >;
 
 def : DSReadPat <DS_READ_I8,  i32, sextloadi8_local>;
@@ -2632,12 +2632,12 @@
 def : Pat <
   (v2i32 (local_load (DS64Bit4ByteAligned i32:$ptr, i8:$offset0,
                                                     i8:$offset1))),
-  (DS_READ2_B32 (i1 0), $ptr, $offset0, $offset1)
+  (DS_READ2_B32 (i1 0), $ptr, $offset0, $offset1, (S_MOV_B32 -1))
 >;
 
 class DSWritePat <DS inst, ValueType vt, PatFrag frag> : Pat <
   (frag vt:$value, (DS1Addr1Offset i32:$ptr, i32:$offset)),
-  (inst (i1 0), $ptr, $value, (as_i16imm $offset))
+  (inst (i1 0), $ptr, $value, (as_i16imm $offset), (S_MOV_B32 -1))
 >;
 
 def : DSWritePat <DS_WRITE_B8, i32, truncstorei8_local>;
@@ -2653,12 +2653,13 @@
   (local_store v2i32:$value, (DS64Bit4ByteAligned i32:$ptr, i8:$offset0,
                                                             i8:$offset1)),
   (DS_WRITE2_B32 (i1 0), $ptr, (EXTRACT_SUBREG $value, sub0),
-                        (EXTRACT_SUBREG $value, sub1), $offset0, $offset1)
+                        (EXTRACT_SUBREG $value, sub1), $offset0, $offset1,
+                        (S_MOV_B32 -1))
 >;
 
 class DSAtomicRetPat<DS inst, ValueType vt, PatFrag frag> : Pat <
   (frag (DS1Addr1Offset i32:$ptr, i32:$offset), vt:$value),
-  (inst (i1 0), $ptr, $value, (as_i16imm $offset))
+  (inst (i1 0), $ptr, $value, (as_i16imm $offset), (S_MOV_B32 -1))
 >;
 
 // Special case of DSAtomicRetPat for add / sub 1 -> inc / dec
@@ -2674,13 +2675,13 @@
 class DSAtomicIncRetPat<DS inst, ValueType vt,
                         Instruction LoadImm, PatFrag frag> : Pat <
   (frag (DS1Addr1Offset i32:$ptr, i32:$offset), (vt 1)),
-  (inst (i1 0), $ptr, (LoadImm (vt -1)), (as_i16imm $offset))
+  (inst (i1 0), $ptr, (LoadImm (vt -1)), (as_i16imm $offset), (S_MOV_B32 -1))
 >;
 
 
 class DSAtomicCmpXChg <DS inst, ValueType vt, PatFrag frag> : Pat <
   (frag (DS1Addr1Offset i32:$ptr, i32:$offset), vt:$cmp, vt:$swap),
-  (inst (i1 0), $ptr, $cmp, $swap, (as_i16imm $offset))
+  (inst (i1 0), $ptr, $cmp, $swap, (as_i16imm $offset), (S_MOV_B32 -1))
 >;
 
 
diff --git a/llvm/lib/Target/R600/SILoadStoreOptimizer.cpp b/llvm/lib/Target/R600/SILoadStoreOptimizer.cpp
index 4140196..a092bcc 100644
--- a/llvm/lib/Target/R600/SILoadStoreOptimizer.cpp
+++ b/llvm/lib/Target/R600/SILoadStoreOptimizer.cpp
@@ -222,6 +222,7 @@
   // Be careful, since the addresses could be subregisters themselves in weird
   // cases, like vectors of pointers.
   const MachineOperand *AddrReg = TII->getNamedOperand(*I, AMDGPU::OpName::addr);
+  const MachineOperand *M0Reg = TII->getNamedOperand(*I, AMDGPU::OpName::m0);
 
   unsigned DestReg0 = TII->getNamedOperand(*I, AMDGPU::OpName::vdst)->getReg();
   unsigned DestReg1
@@ -262,6 +263,7 @@
     .addOperand(*AddrReg) // addr
     .addImm(NewOffset0) // offset0
     .addImm(NewOffset1) // offset1
+    .addOperand(*M0Reg) // M0
     .addMemOperand(*I->memoperands_begin())
     .addMemOperand(*Paired->memoperands_begin());
 
@@ -280,6 +282,9 @@
   LiveInterval &AddrRegLI = LIS->getInterval(AddrReg->getReg());
   LIS->shrinkToUses(&AddrRegLI);
 
+  LiveInterval &M0RegLI = LIS->getInterval(M0Reg->getReg());
+  LIS->shrinkToUses(&M0RegLI);
+
   LIS->getInterval(DestReg); // Create new LI
 
   DEBUG(dbgs() << "Inserted read2: " << *Read2 << '\n');
@@ -295,6 +300,7 @@
   // Be sure to use .addOperand(), and not .addReg() with these. We want to be
   // sure we preserve the subregister index and any register flags set on them.
   const MachineOperand *Addr = TII->getNamedOperand(*I, AMDGPU::OpName::addr);
+  const MachineOperand *M0Reg = TII->getNamedOperand(*I, AMDGPU::OpName::m0);
   const MachineOperand *Data0 = TII->getNamedOperand(*I, AMDGPU::OpName::data0);
   const MachineOperand *Data1
     = TII->getNamedOperand(*Paired, AMDGPU::OpName::data0);
@@ -333,11 +339,13 @@
     .addOperand(*Data1) // data1
     .addImm(NewOffset0) // offset0
     .addImm(NewOffset1) // offset1
+    .addOperand(*M0Reg)  // m0
     .addMemOperand(*I->memoperands_begin())
     .addMemOperand(*Paired->memoperands_begin());
 
   // XXX - How do we express subregisters here?
-  unsigned OrigRegs[] = { Data0->getReg(), Data1->getReg(), Addr->getReg() };
+  unsigned OrigRegs[] = { Data0->getReg(), Data1->getReg(), Addr->getReg(),
+                          M0Reg->getReg()};
 
   LIS->RemoveMachineInstrFromMaps(I);
   LIS->RemoveMachineInstrFromMaps(Paired);
diff --git a/llvm/lib/Target/R600/SILowerControlFlow.cpp b/llvm/lib/Target/R600/SILowerControlFlow.cpp
index 9702565..20e8cec 100644
--- a/llvm/lib/Target/R600/SILowerControlFlow.cpp
+++ b/llvm/lib/Target/R600/SILowerControlFlow.cpp
@@ -88,7 +88,6 @@
   void Kill(MachineInstr &MI);
   void Branch(MachineInstr &MI);
 
-  void InitM0ForLDS(MachineBasicBlock::iterator MI);
   void LoadM0(MachineInstr &MI, MachineInstr *MovRel);
   void IndirectSrc(MachineInstr &MI);
   void IndirectDst(MachineInstr &MI);
@@ -325,14 +324,6 @@
   MI.eraseFromParent();
 }
 
-/// The m0 register stores the maximum allowable address for LDS reads and
-/// writes.  Its value must be at least the size in bytes of LDS allocated by
-/// the shader.  For simplicity, we set it to the maximum possible value.
-void SILowerControlFlowPass::InitM0ForLDS(MachineBasicBlock::iterator MI) {
-    BuildMI(*MI->getParent(), MI, MI->getDebugLoc(),  TII->get(AMDGPU::S_MOV_B32),
-            AMDGPU::M0).addImm(0xffffffff);
-}
-
 void SILowerControlFlowPass::LoadM0(MachineInstr &MI, MachineInstr *MovRel) {
 
   MachineBasicBlock &MBB = *MI.getParent();
@@ -391,12 +382,6 @@
             .addReg(Save);
 
   }
-  // FIXME: Are there any values other than the LDS address clamp that need to
-  // be stored in the m0 register and may be live for more than a few
-  // instructions?  If so, we should save the m0 register at the beginning
-  // of this function and restore it here.
-  // FIXME: Add support for LDS direct loads.
-  InitM0ForLDS(&MI);
   MI.eraseFromParent();
 }
 
@@ -465,7 +450,6 @@
 
       MachineInstr &MI = *I;
       if (TII->isDS(MI.getOpcode())) {
-        NeedM0 = true;
         NeedWQM = true;
       }
 
@@ -544,13 +528,6 @@
     }
   }
 
-  if (NeedM0) {
-    MachineBasicBlock &MBB = MF.front();
-    // Initialize M0 to a value that won't cause LDS access to be discarded
-    // due to offset clamping
-    InitM0ForLDS(MBB.getFirstNonPHI());
-  }
-
   if (NeedWQM && MFI->getShaderType() == ShaderType::PIXEL) {
     MachineBasicBlock &MBB = MF.front();
     BuildMI(MBB, MBB.getFirstNonPHI(), DebugLoc(), TII->get(AMDGPU::S_WQM_B64),
diff --git a/llvm/test/CodeGen/R600/shl_add_ptr.ll b/llvm/test/CodeGen/R600/shl_add_ptr.ll
index 047cf25..fdb3d39 100644
--- a/llvm/test/CodeGen/R600/shl_add_ptr.ll
+++ b/llvm/test/CodeGen/R600/shl_add_ptr.ll
@@ -68,7 +68,8 @@
 ; pointer can be used with an offset into the second one.
 
 ; SI-LABEL: {{^}}load_shl_base_lds_2:
-; SI: v_lshlrev_b32_e32 [[PTR:v[0-9]+]], 2, {{v[0-9]+}}
+; SI: s_mov_b32 m0, -1
+; SI-NEXT: v_lshlrev_b32_e32 [[PTR:v[0-9]+]], 2, {{v[0-9]+}}
 ; SI-NEXT: ds_read2st64_b32 {{v\[[0-9]+:[0-9]+\]}}, [[PTR]] offset0:1 offset1:9 [M0]
 ; SI: s_endpgm
 define void @load_shl_base_lds_2(float addrspace(1)* %out) #0 {