AMDGPU: Follow up to r275203

I meant to squash this into it.

llvm-svn: 275220

6 files changed, 218 insertions, 39 deletions

diff --git a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
index d98fedbacb0..72175ea581b 100644
--- a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
@@ -1070,9 +1070,64 @@ unsigned SITargetLowering::getRegisterByName(const char* RegName, EVT VT,
                            + StringRef(RegName) + "\"."));
 }
 
-MachineBasicBlock *
-SITargetLowering::EmitInstrWithCustomInserter(MachineInstr &MI,
-                                              MachineBasicBlock *BB) const {
+// If kill is not the last instruction, split the block so kill is always a
+// proper terminator.
+MachineBasicBlock *SITargetLowering::splitKillBlock(MachineInstr &MI,
+                                                    MachineBasicBlock *BB) const {
+  const SIInstrInfo *TII = getSubtarget()->getInstrInfo();
+
+  MachineBasicBlock::iterator SplitPoint(&MI);
+  ++SplitPoint;
+
+  if (SplitPoint == BB->end()) {
+    // Don't bother with a new block.
+    MI.setDesc(TII->get(AMDGPU::SI_KILL_TERMINATOR));
+    return BB;
+  }
+
+  MachineFunction *MF = BB->getParent();
+  MachineBasicBlock *SplitBB
+    = MF->CreateMachineBasicBlock(BB->getBasicBlock());
+
+  SmallSet<unsigned, 8> SplitDefRegs;
+  for (auto I = SplitPoint, E = BB->end(); I != E; ++I) {
+    for (MachineOperand &Def : I->defs())
+      SplitDefRegs.insert(Def.getReg());
+  }
+
+  // Fix the block phi references to point to the new block for the defs in the
+  // second piece of the block.
+  for (MachineBasicBlock *Succ : BB->successors()) {
+    for (MachineInstr &MI : *Succ) {
+      if (!MI.isPHI())
+        break;
+
+      for (unsigned I = 1, E = MI.getNumOperands(); I != E; I += 2) {
+        unsigned IncomingReg = MI.getOperand(I).getReg();
+        MachineOperand &FromBB = MI.getOperand(I + 1);
+        if (BB == FromBB.getMBB()) {
+          if (SplitDefRegs.count(IncomingReg))
+            FromBB.setMBB(SplitBB);
+
+          break;
+        }
+      }
+    }
+  }
+
+  MF->insert(++MachineFunction::iterator(BB), SplitBB);
+  SplitBB->splice(SplitBB->begin(), BB, SplitPoint, BB->end());
+
+
+  SplitBB->transferSuccessors(BB);
+  BB->addSuccessor(SplitBB);
+
+  MI.setDesc(TII->get(AMDGPU::SI_KILL_TERMINATOR));
+  return SplitBB;
+}
+
+MachineBasicBlock *SITargetLowering::EmitInstrWithCustomInserter(
+  MachineInstr &MI, MachineBasicBlock *BB) const {
   switch (MI.getOpcode()) {
   case AMDGPU::SI_INIT_M0: {
     const SIInstrInfo *TII = getSubtarget()->getInstrInfo();
@@ -1096,6 +1151,8 @@ SITargetLowering::EmitInstrWithCustomInserter(MachineInstr &MI,
     MI.eraseFromParent();
     return BB;
   }
+  case AMDGPU::SI_KILL:
+    return splitKillBlock(MI, BB);
   default:
     return AMDGPUTargetLowering::EmitInstrWithCustomInserter(MI, BB);
   }
diff --git a/llvm/lib/Target/AMDGPU/SIISelLowering.h b/llvm/lib/Target/AMDGPU/SIISelLowering.h
index 6833e15e4fd..8e055eea58c 100644
--- a/llvm/lib/Target/AMDGPU/SIISelLowering.h
+++ b/llvm/lib/Target/AMDGPU/SIISelLowering.h
@@ -123,6 +123,9 @@ public:
   unsigned getRegisterByName(const char* RegName, EVT VT,
                              SelectionDAG &DAG) const override;
 
+  MachineBasicBlock *splitKillBlock(MachineInstr &MI,
+                                    MachineBasicBlock *BB) const;
+
   MachineBasicBlock *
   EmitInstrWithCustomInserter(MachineInstr &MI,
                               MachineBasicBlock *BB) const override;
diff --git a/llvm/lib/Target/AMDGPU/SIInstructions.td b/llvm/lib/Target/AMDGPU/SIInstructions.td
index 7cf5faa216d..858505bea3b 100644
--- a/llvm/lib/Target/AMDGPU/SIInstructions.td
+++ b/llvm/lib/Target/AMDGPU/SIInstructions.td
@@ -1989,8 +1989,16 @@ def SI_END_CF : PseudoInstSI <
 let Uses = [EXEC], Defs = [EXEC,VCC] in {
 def SI_KILL : PseudoInstSI <
   (outs), (ins VSrc_32:$src),
-  [(int_AMDGPU_kill f32:$src)]
->;
+  [(int_AMDGPU_kill f32:$src)]> {
+  let isConvergent = 1;
+  let usesCustomInserter = 1;
+}
+
+def SI_KILL_TERMINATOR : PseudoInstSI <
+  (outs), (ins VSrc_32:$src)> {
+  let isTerminator = 1;
+}
+
 } // End Uses = [EXEC], Defs = [EXEC,VCC]
 
 } // End mayLoad = 1, mayStore = 1, hasSideEffects = 1
diff --git a/llvm/lib/Target/AMDGPU/SILowerControlFlow.cpp b/llvm/lib/Target/AMDGPU/SILowerControlFlow.cpp
index f989b5b9bb0..adb0919231c 100644
--- a/llvm/lib/Target/AMDGPU/SILowerControlFlow.cpp
+++ b/llvm/lib/Target/AMDGPU/SILowerControlFlow.cpp
@@ -76,7 +76,7 @@ private:
   bool shouldSkip(MachineBasicBlock *From, MachineBasicBlock *To);
 
   void Skip(MachineInstr &From, MachineOperand &To);
-  bool skipIfDead(MachineInstr &MI);
+  bool skipIfDead(MachineInstr &MI, MachineBasicBlock &NextBB);
 
   void If(MachineInstr &MI);
   void Else(MachineInstr &MI, bool ExecModified);
@@ -89,6 +89,9 @@ private:
   void Kill(MachineInstr &MI);
   void Branch(MachineInstr &MI);
 
+  MachineBasicBlock *insertSkipBlock(MachineBasicBlock &MBB,
+                                     MachineBasicBlock::iterator I) const;
+
   std::pair<MachineBasicBlock *, MachineBasicBlock *>
   splitBlock(MachineBasicBlock &MBB, MachineBasicBlock::iterator I);
 
@@ -205,27 +208,22 @@ void SILowerControlFlow::Skip(MachineInstr &From, MachineOperand &To) {
     .addOperand(To);
 }
 
-bool SILowerControlFlow::skipIfDead(MachineInstr &MI) {
+bool SILowerControlFlow::skipIfDead(MachineInstr &MI, MachineBasicBlock &NextBB) {
   MachineBasicBlock &MBB = *MI.getParent();
+  MachineFunction *MF = MBB.getParent();
 
-  if (MBB.getParent()->getFunction()->getCallingConv() != CallingConv::AMDGPU_PS ||
+  if (MF->getFunction()->getCallingConv() != CallingConv::AMDGPU_PS ||
       !shouldSkip(&MBB, &MBB.getParent()->back()))
     return false;
 
-  LivePhysRegs RemainderLiveRegs(TRI);
-  RemainderLiveRegs.addLiveOuts(MBB);
-
-  MachineBasicBlock *SkipBB;
-  MachineBasicBlock *RemainderBB;
-  std::tie(SkipBB, RemainderBB) = splitBlock(MBB, MI.getIterator());
+  MachineBasicBlock *SkipBB = insertSkipBlock(MBB, MI.getIterator());
+  SkipBB->addSuccessor(&NextBB);
 
   const DebugLoc &DL = MI.getDebugLoc();
 
   // If the exec mask is non-zero, skip the next two instructions
   BuildMI(&MBB, DL, TII->get(AMDGPU::S_CBRANCH_EXECNZ))
-    .addMBB(RemainderBB);
-
-  MBB.addSuccessor(RemainderBB);
+    .addMBB(&NextBB);
 
   MachineBasicBlock::iterator Insert = SkipBB->begin();
 
@@ -244,15 +242,6 @@ bool SILowerControlFlow::skipIfDead(MachineInstr &MI) {
   // ... and terminate wavefront.
   BuildMI(*SkipBB, Insert, DL, TII->get(AMDGPU::S_ENDPGM));
 
-  for (const MachineInstr &Inst : reverse(*RemainderBB))
-    RemainderLiveRegs.stepBackward(Inst);
-
-  const MachineRegisterInfo &MRI = MBB.getParent()->getRegInfo();
-  for (unsigned Reg : RemainderLiveRegs) {
-    if (MRI.isAllocatable(Reg))
-      RemainderBB->addLiveIn(Reg);
-  }
-
   return true;
 }
 
@@ -495,6 +484,20 @@ void SILowerControlFlow::emitLoadM0FromVGPRLoop(MachineBasicBlock &LoopBB,
     .addMBB(&LoopBB);
 }
 
+MachineBasicBlock *SILowerControlFlow::insertSkipBlock(
+  MachineBasicBlock &MBB, MachineBasicBlock::iterator I) const {
+  MachineFunction *MF = MBB.getParent();
+
+  MachineBasicBlock *SkipBB = MF->CreateMachineBasicBlock();
+  MachineFunction::iterator MBBI(MBB);
+  ++MBBI;
+
+  MF->insert(MBBI, SkipBB);
+  MBB.addSuccessor(SkipBB);
+
+  return SkipBB;
+}
+
 std::pair<MachineBasicBlock *, MachineBasicBlock *>
 SILowerControlFlow::splitBlock(MachineBasicBlock &MBB,
                                MachineBasicBlock::iterator I) {
@@ -745,7 +748,7 @@ bool SILowerControlFlow::runOnMachineFunction(MachineFunction &MF) {
           if (--Depth == 0 && HaveKill) {
             HaveKill = false;
 
-            if (skipIfDead(MI)) {
+            if (skipIfDead(MI, *NextBB)) {
               NextBB = std::next(BI);
               BE = MF.end();
               Next = MBB.end();
@@ -754,9 +757,9 @@ bool SILowerControlFlow::runOnMachineFunction(MachineFunction &MF) {
           EndCf(MI);
           break;
 
-        case AMDGPU::SI_KILL:
+        case AMDGPU::SI_KILL_TERMINATOR:
           if (Depth == 0) {
-            if (skipIfDead(MI)) {
+            if (skipIfDead(MI, *NextBB)) {
               NextBB = std::next(BI);
               BE = MF.end();
               Next = MBB.end();
diff --git a/llvm/lib/Target/AMDGPU/SIWholeQuadMode.cpp b/llvm/lib/Target/AMDGPU/SIWholeQuadMode.cpp
index 100fb2896dd..dafc772ea4f 100644
--- a/llvm/lib/Target/AMDGPU/SIWholeQuadMode.cpp
+++ b/llvm/lib/Target/AMDGPU/SIWholeQuadMode.cpp
@@ -223,7 +223,7 @@ void SIWholeQuadMode::propagateInstruction(const MachineInstr &MI,
   // Control flow-type instructions that are followed by WQM computations
   // must themselves be in WQM.
   if ((II.OutNeeds & StateWQM) && !(II.Needs & StateWQM) &&
-      (MI.isBranch() || MI.isTerminator() || MI.getOpcode() == AMDGPU::SI_KILL)) {
+      (MI.isBranch() || MI.isTerminator())) {
     Instructions[&MI].Needs = StateWQM;
     II.Needs = StateWQM;
   }
@@ -444,9 +444,6 @@ void SIWholeQuadMode::processBlock(MachineBasicBlock &MBB, unsigned LiveMaskReg,
 
       State = Needs;
     }
-
-    if (MI.getOpcode() == AMDGPU::SI_KILL)
-      WQMFromExec = false;
   }
 
   if ((BI.OutNeeds & StateWQM) && State != StateWQM) {
diff --git a/llvm/test/CodeGen/AMDGPU/skip-if-dead.ll b/llvm/test/CodeGen/AMDGPU/skip-if-dead.ll
index 1999c0cd683..54fc0bf0b68 100644
--- a/llvm/test/CodeGen/AMDGPU/skip-if-dead.ll
+++ b/llvm/test/CodeGen/AMDGPU/skip-if-dead.ll
@@ -2,6 +2,7 @@
 
 ; CHECK-LABEL: {{^}}test_kill_depth_0_imm_pos:
 ; CHECK-NEXT: ; BB#0:
+; CHECK-NEXT: ; BB#1:
 ; CHECK-NEXT: s_endpgm
 define amdgpu_ps void @test_kill_depth_0_imm_pos() #0 {
   call void @llvm.AMDGPU.kill(float 0.0)
@@ -11,28 +12,87 @@ define amdgpu_ps void @test_kill_depth_0_imm_pos() #0 {
 ; CHECK-LABEL: {{^}}test_kill_depth_0_imm_neg:
 ; CHECK-NEXT: ; BB#0:
 ; CHECK-NEXT: s_mov_b64 exec, 0
+; CHECK-NEXT: ; BB#1:
 ; CHECK-NEXT: s_endpgm
 define amdgpu_ps void @test_kill_depth_0_imm_neg() #0 {
   call void @llvm.AMDGPU.kill(float -0.0)
   ret void
 }
 
+; FIXME: Ideally only one would be emitted
+; CHECK-LABEL: {{^}}test_kill_depth_0_imm_neg_x2:
+; CHECK-NEXT: ; BB#0:
+; CHECK-NEXT: s_mov_b64 exec, 0
+; CHECK-NEXT: ; BB#1:
+; CHECK-NEXT: s_mov_b64 exec, 0
+; CHECK-NEXT: ; BB#2:
+; CHECK-NEXT: s_endpgm
+define amdgpu_ps void @test_kill_depth_0_imm_neg_x2() #0 {
+  call void @llvm.AMDGPU.kill(float -0.0)
+  call void @llvm.AMDGPU.kill(float -1.0)
+  ret void
+}
+
 ; CHECK-LABEL: {{^}}test_kill_depth_var:
 ; CHECK-NEXT: ; BB#0:
 ; CHECK-NEXT: v_cmpx_le_f32_e32 vcc, 0, v0
+; CHECK-NEXT: ; BB#1:
 ; CHECK-NEXT: s_endpgm
 define amdgpu_ps void @test_kill_depth_var(float %x) #0 {
   call void @llvm.AMDGPU.kill(float %x)
   ret void
 }
 
+; FIXME: Ideally only one would be emitted
+; CHECK-LABEL: {{^}}test_kill_depth_var_x2_same:
+; CHECK-NEXT: ; BB#0:
+; CHECK-NEXT: v_cmpx_le_f32_e32 vcc, 0, v0
+; CHECK-NEXT: ; BB#1:
+; CHECK-NEXT: v_cmpx_le_f32_e32 vcc, 0, v0
+; CHECK-NEXT: ; BB#2:
+; CHECK-NEXT: s_endpgm
+define amdgpu_ps void @test_kill_depth_var_x2_same(float %x) #0 {
+  call void @llvm.AMDGPU.kill(float %x)
+  call void @llvm.AMDGPU.kill(float %x)
+  ret void
+}
+
+; CHECK-LABEL: {{^}}test_kill_depth_var_x2:
+; CHECK-NEXT: ; BB#0:
+; CHECK-NEXT: v_cmpx_le_f32_e32 vcc, 0, v0
+; CHECK-NEXT: ; BB#1:
+; CHECK-NEXT: v_cmpx_le_f32_e32 vcc, 0, v1
+; CHECK-NEXT: ; BB#2:
+; CHECK-NEXT: s_endpgm
+define amdgpu_ps void @test_kill_depth_var_x2(float %x, float %y) #0 {
+  call void @llvm.AMDGPU.kill(float %x)
+  call void @llvm.AMDGPU.kill(float %y)
+  ret void
+}
+
+; CHECK-LABEL: {{^}}test_kill_depth_var_x2_instructions:
+; CHECK-NEXT: ; BB#0:
+; CHECK-NEXT: v_cmpx_le_f32_e32 vcc, 0, v0
+; CHECK-NEXT: ; BB#1:
+; CHECK: v_mov_b32_e64 v7, -1
+; CHECK: v_cmpx_le_f32_e32 vcc, 0, v7
+; CHECK-NEXT: ; BB#2:
+; CHECK-NEXT: s_endpgm
+define amdgpu_ps void @test_kill_depth_var_x2_instructions(float %x) #0 {
+  call void @llvm.AMDGPU.kill(float %x)
+  %y = call float asm sideeffect "v_mov_b32_e64 v7, -1", "={VGPR7}"()
+  call void @llvm.AMDGPU.kill(float %y)
+  ret void
+}
+
 ; FIXME: why does the skip depend on the asm length in the same block?
 
 ; CHECK-LABEL: {{^}}test_kill_control_flow:
 ; CHECK: s_cmp_lg_i32 s{{[0-9]+}}, 0
 ; CHECK: s_cbranch_scc1 [[RETURN_BB:BB[0-9]+_[0-9]+]]
 
-; CHECK: ; BB#1:
+; CHECK-NEXT: ; BB#1:
+; CHECK: v_mov_b32_e64 v7, -1
 ; CHECK: v_nop_e64
 ; CHECK: v_nop_e64
 ; CHECK: v_nop_e64
@@ -44,14 +104,13 @@ define amdgpu_ps void @test_kill_depth_var(float %x) #0 {
 ; CHECK: v_nop_e64
 ; CHECK: v_nop_e64
 
-; CHECK: s_cbranch_execnz [[SPLIT_BB:BB[0-9]+_[0-9]+]]
+; CHECK: v_cmpx_le_f32_e32 vcc, 0, v7
+; CHECK-NEXT: s_cbranch_execnz [[SPLIT_BB:BB[0-9]+_[0-9]+]]
 ; CHECK-NEXT: ; BB#3:
 ; CHECK-NEXT: exp 0, 9, 0, 1, 1, v0, v0, v0, v0
 ; CHECK-NEXT: s_endpgm
 
 ; CHECK-NEXT: {{^}}[[SPLIT_BB]]:
-; CHECK-NEXT: v_cmpx_le_f32_e32 vcc, 0, v7
-; CHECK-NEXT: {{^}}BB{{[0-9]+_[0-9]+}}:
 ; CHECK-NEXT: s_endpgm
 define amdgpu_ps void @test_kill_control_flow(i32 inreg %arg) #0 {
 entry:
@@ -95,14 +154,14 @@ exit:
 ; CHECK: ;;#ASMEND
 ; CHECK: v_mov_b32_e64 v8, -1
 ; CHECK: ;;#ASMEND
+; CHECK: v_cmpx_le_f32_e32 vcc, 0, v7
 ; CHECK-NEXT: s_cbranch_execnz [[SPLIT_BB:BB[0-9]+_[0-9]+]]
 
-; CHECK-NEXT: ; BB#3:
+; CHECK-NEXT: ; BB#4:
 ; CHECK-NEXT: exp 0, 9, 0, 1, 1, v0, v0, v0, v0
 ; CHECK-NEXT: s_endpgm
 
 ; CHECK-NEXT: {{^}}[[SPLIT_BB]]:
-; CHECK-NEXT: v_cmpx_le_f32_e32 vcc, 0, v7
 ; CHECK: buffer_store_dword v8
 ; CHECK: v_mov_b32_e64 v9, -2
 
@@ -140,6 +199,58 @@ exit:
   ret void
 }
 
+; CHECK-LABEL: {{^}}test_kill_divergent_loop:
+; CHECK: v_cmp_eq_i32_e32 vcc, 0, v0
+; CHECK-NEXT: s_and_saveexec_b64 [[SAVEEXEC:s\[[0-9]+:[0-9]+\]]], vcc
+; CHECK-NEXT: s_xor_b64 [[SAVEEXEC]], exec, [[SAVEEXEC]]
+; CHECK-NEXT: s_cbranch_execz [[EXIT:BB[0-9]+_[0-9]+]]
+; CHECK-NEXT: ; mask branch [[EXIT]]
+
+; CHECK: [[LOOP_BB:BB[0-9]+_[0-9]+]]:
+
+; CHECK: v_mov_b32_e64 v7, -1
+; CHECK: v_nop_e64
+; CHECK: v_cmpx_le_f32_e32 vcc, 0, v7
+
+; CHECK-NEXT: ; BB#3:
+; CHECK: buffer_load_dword [[LOAD:v[0-9]+]]
+; CHECK: v_cmp_eq_i32_e32 vcc, 0, [[LOAD]]
+; CHECK-NEXT: s_and_b64 vcc, exec, vcc
+; CHECK-NEXT: s_cbranch_vccnz [[LOOP_BB]]
+
+; CHECK-NEXT: {{^}}[[EXIT]]:
+; CHECK: s_or_b64 exec, exec, [[SAVEEXEC]]
+; CHECK: buffer_store_dword
+; CHECK: s_endpgm
+define amdgpu_ps void @test_kill_divergent_loop(i32 %arg) #0 {
+entry:
+  %cmp = icmp eq i32 %arg, 0
+  br i1 %cmp, label %bb, label %exit
+
+bb:
+  %var = call float asm sideeffect "
+    v_mov_b32_e64 v7, -1
+    v_nop_e64
+    v_nop_e64
+    v_nop_e64
+    v_nop_e64
+    v_nop_e64
+    v_nop_e64
+    v_nop_e64
+    v_nop_e64
+    v_nop_e64
+    v_nop_e64", "={VGPR7}"()
+  call void @llvm.AMDGPU.kill(float %var)
+  %vgpr = load volatile i32, i32 addrspace(1)* undef
+  %loop.cond = icmp eq i32 %vgpr, 0
+  br i1 %loop.cond, label %bb, label %exit
+
+exit:
+  store volatile i32 8, i32 addrspace(1)* undef
+  ret void
+}
+
+
 declare void @llvm.AMDGPU.kill(float) #0
 
 attributes #0 = { nounwind }