[AMDGPU] Divergence driven ISel. Assign register class for cross block values according to the divergence.

    Details: To make instruction selection really divergence driven it is necessary to assign
             the correct register classes to the cross block values beforehand. For the divergent targets
             same value type requires different register classes dependent on the value divergence.

    Reviewers: rampitec, nhaehnle

    Differential Revision: https://reviews.llvm.org/D59990

    This commit was reverted because of the build failure.
    The reason was mlformed patch.
    Build failure fixed.

llvm-svn: 361741

1 files changed, 90 insertions, 1 deletions

diff --git a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
index c2cda5ef4d7..8f93c63046c 100644
--- a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
@@ -9637,7 +9637,8 @@ SDNode *SITargetLowering::PostISelFolding(MachineSDNode *Node,
       break;
 
     MVT VT = Src0.getValueType().getSimpleVT();
-    const TargetRegisterClass *RC = getRegClassFor(VT);
+    const TargetRegisterClass *RC =
+        getRegClassFor(VT, Src0.getNode()->isDivergent());
 
     MachineRegisterInfo &MRI = DAG.getMachineFunction().getRegInfo();
     SDValue UndefReg = DAG.getRegister(MRI.createVirtualRegister(RC), VT);
@@ -10171,3 +10172,91 @@ SITargetLowering::shouldExpandAtomicRMWInIR(AtomicRMWInst *RMW) const {
 
   return AMDGPUTargetLowering::shouldExpandAtomicRMWInIR(RMW);
 }
+
+const TargetRegisterClass *
+SITargetLowering::getRegClassFor(MVT VT, bool isDivergent) const {
+  const TargetRegisterClass *RC = TargetLoweringBase::getRegClassFor(VT, false);
+  const SIRegisterInfo *TRI = Subtarget->getRegisterInfo();
+  if (RC == &AMDGPU::VReg_1RegClass && !isDivergent)
+    return &AMDGPU::SReg_64RegClass;
+  if (!TRI->isSGPRClass(RC) && !isDivergent)
+    return TRI->getEquivalentSGPRClass(RC);
+  else if (TRI->isSGPRClass(RC) && isDivergent)
+    return TRI->getEquivalentVGPRClass(RC);
+
+  return RC;
+}
+
+static bool hasIfBreakUser(const Value *V, SetVector<const Value *> &Visited) {
+  if (Visited.count(V))
+    return false;
+  Visited.insert(V);
+  bool Result = false;
+  for (auto U : V->users()) {
+    if (const IntrinsicInst *Intrinsic = dyn_cast<IntrinsicInst>(U)) {
+      if ((Intrinsic->getIntrinsicID() == Intrinsic::amdgcn_if_break) &&
+          (V == U->getOperand(1)))
+        Result = true;
+    } else {
+      Result = hasIfBreakUser(U, Visited);
+    }
+    if (Result)
+      break;
+  }
+  return Result;
+}
+
+bool SITargetLowering::requiresUniformRegister(MachineFunction &MF,
+                                               const Value *V) const {
+  if (const IntrinsicInst *Intrinsic = dyn_cast<IntrinsicInst>(V)) {
+    switch (Intrinsic->getIntrinsicID()) {
+    default:
+      return false;
+    case Intrinsic::amdgcn_if_break:
+      return true;
+    }
+  }
+  if (const ExtractValueInst *ExtValue = dyn_cast<ExtractValueInst>(V)) {
+    if (const IntrinsicInst *Intrinsic =
+            dyn_cast<IntrinsicInst>(ExtValue->getOperand(0))) {
+      switch (Intrinsic->getIntrinsicID()) {
+      default:
+        return false;
+      case Intrinsic::amdgcn_if:
+      case Intrinsic::amdgcn_else: {
+        ArrayRef<unsigned> Indices = ExtValue->getIndices();
+        if (Indices.size() == 1 && Indices[0] == 1) {
+          return true;
+        }
+      }
+      }
+    }
+  }
+  if (const CallInst *CI = dyn_cast<CallInst>(V)) {
+    if (isa<InlineAsm>(CI->getCalledValue())) {
+      const SIRegisterInfo *SIRI = Subtarget->getRegisterInfo();
+      ImmutableCallSite CS(CI);
+      TargetLowering::AsmOperandInfoVector TargetConstraints = ParseConstraints(
+          MF.getDataLayout(), Subtarget->getRegisterInfo(), CS);
+      for (auto &TC : TargetConstraints) {
+        if (TC.Type == InlineAsm::isOutput) {
+          ComputeConstraintToUse(TC, SDValue());
+          unsigned AssignedReg;
+          const TargetRegisterClass *RC;
+          std::tie(AssignedReg, RC) = getRegForInlineAsmConstraint(
+              SIRI, TC.ConstraintCode,
+              getSimpleValueType(MF.getDataLayout(), CS.getType()));
+          if (RC) {
+            MachineRegisterInfo &MRI = MF.getRegInfo();
+            if (AssignedReg != 0 && SIRI->isSGPRReg(MRI, AssignedReg))
+              return true;
+            else if (SIRI->isSGPRClass(RC))
+              return true;
+          }
+        }
+      }
+    }
+  }
+  SetVector<const Value *> Visited;
+  return hasIfBreakUser(V, Visited);
+}