AMDGPU/GlobalISel: Report RegBankLegalize errors using reportGISelFailure

Use standard GlobalISel error reporting with reportGISelFailure
and pass returning false instead of llvm_unreachable.
Also enables -global-isel-abort=0 or 2 for -global-isel -new-reg-bank-select.
Note: new-reg-bank-select with abort 0 or 2 runs LCSSA,
while "intended use" without abort or with abort 1 does not run LCSSA.

Author: petar-avramovic

llvm/lib/Target/AMDGPU/AMDGPURegBankLegalize.cpp

@@ -435,7 +435,8 @@ bool AMDGPURegBankLegalize::runOnMachineFunction(MachineFunction &MF) {
     unsigned Opc = MI->getOpcode();
     // Insert point for use operands needs some calculation.
     if (Opc == AMDGPU::G_PHI) {
-      RBLHelper.applyMappingPHI(*MI);
+      if (!RBLHelper.applyMappingPHI(*MI))
+        return false;
       continue;
     }
 
@@ -466,7 +467,8 @@ bool AMDGPURegBankLegalize::runOnMachineFunction(MachineFunction &MF) {
       // S1 rules are in RegBankLegalizeRules.
     }
 
-    RBLHelper.findRuleAndApplyMapping(*MI);
+    if (!RBLHelper.findRuleAndApplyMapping(*MI))
+      return false;
   }
 
   // Sgpr S1 clean up combines:

llvm/lib/Target/AMDGPU/AMDGPURegBankLegalizeHelper.cpp

@@ -32,28 +32,45 @@ using namespace AMDGPU;
 RegBankLegalizeHelper::RegBankLegalizeHelper(
     MachineIRBuilder &B, const MachineUniformityInfo &MUI,
     const RegisterBankInfo &RBI, const RegBankLegalizeRules &RBLRules)
-    : ST(B.getMF().getSubtarget<GCNSubtarget>()), B(B), MRI(*B.getMRI()),
-      MUI(MUI), RBI(RBI), RBLRules(RBLRules), IsWave32(ST.isWave32()),
+    : MF(B.getMF()), ST(MF.getSubtarget<GCNSubtarget>()), B(B),
+      MRI(*B.getMRI()), MUI(MUI), RBI(RBI), MORE(MF, nullptr),
+      RBLRules(RBLRules), IsWave32(ST.isWave32()),
       SgprRB(&RBI.getRegBank(AMDGPU::SGPRRegBankID)),
       VgprRB(&RBI.getRegBank(AMDGPU::VGPRRegBankID)),
       VccRB(&RBI.getRegBank(AMDGPU::VCCRegBankID)) {}
 
-void RegBankLegalizeHelper::findRuleAndApplyMapping(MachineInstr &MI) {
-  const SetOfRulesForOpcode &RuleSet = RBLRules.getRulesForOpc(MI);
-  const RegBankLLTMapping &Mapping = RuleSet.findMappingForMI(MI, MRI, MUI);
+bool RegBankLegalizeHelper::findRuleAndApplyMapping(MachineInstr &MI) {
+  const SetOfRulesForOpcode *RuleSet = RBLRules.getRulesForOpc(MI);
+  if (!RuleSet) {
+    reportGISelFailure(MF, MORE, "amdgpu-regbanklegalize",
+                       "No AMDGPU RegBankLegalize rules defined for opcode",
+                       MI);
+    return false;
+  }
+
+  const RegBankLLTMapping *Mapping = RuleSet->findMappingForMI(MI, MRI, MUI);
+  if (!Mapping) {
+    reportGISelFailure(MF, MORE, "amdgpu-regbanklegalize",
+                       "AMDGPU RegBankLegalize: none of the rules defined with "
+                       "'Any' for MI's opcode matched MI",
+                       MI);
+    return false;
+  }
 
   SmallSet<Register, 4> WaterfallSgprs;
   unsigned OpIdx = 0;
-  if (Mapping.DstOpMapping.size() > 0) {
+  if (Mapping->DstOpMapping.size() > 0) {
     B.setInsertPt(*MI.getParent(), std::next(MI.getIterator()));
-    applyMappingDst(MI, OpIdx, Mapping.DstOpMapping);
+    if (!applyMappingDst(MI, OpIdx, Mapping->DstOpMapping))
+      return false;
   }
-  if (Mapping.SrcOpMapping.size() > 0) {
+  if (Mapping->SrcOpMapping.size() > 0) {
     B.setInstr(MI);
-    applyMappingSrc(MI, OpIdx, Mapping.SrcOpMapping, WaterfallSgprs);
+    applyMappingSrc(MI, OpIdx, Mapping->SrcOpMapping, WaterfallSgprs);
   }
 
-  lower(MI, Mapping, WaterfallSgprs);
+  lower(MI, *Mapping, WaterfallSgprs);
+  return true;
 }
 
 bool RegBankLegalizeHelper::executeInWaterfallLoop(
@@ -1055,7 +1072,7 @@ RegBankLegalizeHelper::getRegBankFromID(RegBankLLTMappingApplyID ID) {
   }
 }
 
-void RegBankLegalizeHelper::applyMappingDst(
+bool RegBankLegalizeHelper::applyMappingDst(
     MachineInstr &MI, unsigned &OpIdx,
     const SmallVectorImpl<RegBankLLTMappingApplyID> &MethodIDs) {
   // Defs start from operand 0
@@ -1180,13 +1197,17 @@ void RegBankLegalizeHelper::applyMappingDst(
       break;
     }
     case InvalidMapping: {
-      LLVM_DEBUG(dbgs() << "Instruction with Invalid mapping: "; MI.dump(););
-      llvm_unreachable("missing fast rule for MI");
+      reportGISelFailure(
+          MF, MORE, "amdgpu-regbanklegalize",
+          "AMDGPU RegBankLegalize: missing fast rule ('Div' or 'Uni') for", MI);
+      return false;
     }
     default:
       llvm_unreachable("ID not supported");
     }
   }
+
+  return true;
 }
 
 void RegBankLegalizeHelper::applyMappingSrc(
@@ -1348,7 +1369,7 @@ void RegBankLegalizeHelper::applyMappingSrc(
   }
 }
 
-void RegBankLegalizeHelper::applyMappingPHI(MachineInstr &MI) {
+bool RegBankLegalizeHelper::applyMappingPHI(MachineInstr &MI) {
   Register Dst = MI.getOperand(0).getReg();
   LLT Ty = MRI.getType(Dst);
 
@@ -1371,28 +1392,31 @@ void RegBankLegalizeHelper::applyMappingPHI(MachineInstr &MI) {
       MI.getOperand(i).setReg(NewUse.getReg(0));
     }
 
-    return;
+    return true;
   }
 
-  // ALL divergent i1 phis should be already lowered and inst-selected into PHI
-  // with sgpr reg class and S1 LLT.
+  // ALL divergent i1 phis should have been lowered and inst-selected into PHI
+  // with sgpr reg class and S1 LLT in AMDGPUGlobalISelDivergenceLowering pass.
   // Note: this includes divergent phis that don't require lowering.
   if (Ty == LLT::scalar(1) && MUI.isDivergent(Dst)) {
-    LLVM_DEBUG(dbgs() << "Divergent S1 G_PHI: "; MI.dump(););
-    llvm_unreachable("Make sure to run AMDGPUGlobalISelDivergenceLowering "
-                     "before RegBankLegalize to lower lane mask(vcc) phis");
+    reportGISelFailure(MF, MORE, "amdgpu-regbanklegalize",
+                       "AMDGPU RegBankLegalize: Can't lower divergent S1 G_PHI",
+                       MI);
+    return false;
   }
 
   // We accept all types that can fit in some register class.
   // Uniform G_PHIs have all sgpr registers.
   // Divergent G_PHIs have vgpr dst but inputs can be sgpr or vgpr.
   if (Ty == LLT::scalar(32) || Ty == LLT::pointer(1, 64) ||
       Ty == LLT::pointer(4, 64)) {
-    return;
+    return true;
   }
 
-  LLVM_DEBUG(dbgs() << "G_PHI not handled: "; MI.dump(););
-  llvm_unreachable("type not supported");
+  reportGISelFailure(MF, MORE, "amdgpu-regbanklegalize",
+                     "AMDGPU RegBankLegalize: type not supported for G_PHI",
+                     MI);
+  return false;
 }
 
 [[maybe_unused]] static bool verifyRegBankOnOperands(MachineInstr &MI,

llvm/lib/Target/AMDGPU/AMDGPURegBankLegalizeHelper.h

@@ -12,6 +12,7 @@
 #include "AMDGPURegBankLegalizeRules.h"
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/CodeGen/GlobalISel/GenericMachineInstrs.h"
+#include "llvm/CodeGen/MachineOptimizationRemarkEmitter.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 
 namespace llvm {
@@ -27,11 +28,13 @@ namespace AMDGPU {
 // to replace instruction. In other case InstApplyMethod will create new
 // instruction(s).
 class RegBankLegalizeHelper {
+  MachineFunction &MF;
   const GCNSubtarget &ST;
   MachineIRBuilder &B;
   MachineRegisterInfo &MRI;
   const MachineUniformityInfo &MUI;
   const RegisterBankInfo &RBI;
+  MachineOptimizationRemarkEmitter MORE;
   const RegBankLegalizeRules &RBLRules;
   const bool IsWave32;
   const RegisterBank *SgprRB;
@@ -81,10 +84,10 @@ class RegBankLegalizeHelper {
                         const RegisterBankInfo &RBI,
                         const RegBankLegalizeRules &RBLRules);
 
-  void findRuleAndApplyMapping(MachineInstr &MI);
+  bool findRuleAndApplyMapping(MachineInstr &MI);
 
   // Manual apply helpers.
-  void applyMappingPHI(MachineInstr &MI);
+  bool applyMappingPHI(MachineInstr &MI);
   void applyMappingTrivial(MachineInstr &MI);
 
 private:
@@ -97,7 +100,7 @@ class RegBankLegalizeHelper {
 
   const RegisterBank *getRegBankFromID(RegBankLLTMappingApplyID ID);
 
-  void
+  bool
   applyMappingDst(MachineInstr &MI, unsigned &OpIdx,
                   const SmallVectorImpl<RegBankLLTMappingApplyID> &MethodIDs);
 

llvm/lib/Target/AMDGPU/AMDGPURegBankLegalizeRules.cpp

@@ -243,7 +243,7 @@ UniformityLLTOpPredicateID LLTToBId(LLT Ty) {
   return _;
 }
 
-const RegBankLLTMapping &
+const RegBankLLTMapping *
 SetOfRulesForOpcode::findMappingForMI(const MachineInstr &MI,
                                       const MachineRegisterInfo &MRI,
                                       const MachineUniformityInfo &MUI) const {
@@ -260,17 +260,16 @@ SetOfRulesForOpcode::findMappingForMI(const MachineInstr &MI,
       Slot = getFastPredicateSlot(LLTToId(MRI.getType(Reg)));
 
     if (Slot != -1)
-      return MUI.isUniform(Reg) ? Uni[Slot] : Div[Slot];
+      return MUI.isUniform(Reg) ? &Uni[Slot] : &Div[Slot];
   }
 
   // Slow search for more complex rules.
   for (const RegBankLegalizeRule &Rule : Rules) {
     if (Rule.Predicate.match(MI, MUI, MRI))
-      return Rule.OperandMapping;
+      return &Rule.OperandMapping;
   }
 
-  LLVM_DEBUG(dbgs() << "MI: "; MI.dump(););
-  llvm_unreachable("None of the rules defined for MI's opcode matched MI");
+  return nullptr;
 }
 
 void SetOfRulesForOpcode::addRule(RegBankLegalizeRule Rule) {
@@ -353,27 +352,23 @@ RegBankLegalizeRules::addRulesForIOpcs(std::initializer_list<unsigned> OpcList,
   return RuleSetInitializer(OpcList, IRulesAlias, IRules, FastTypes);
 }
 
-const SetOfRulesForOpcode &
+const SetOfRulesForOpcode *
 RegBankLegalizeRules::getRulesForOpc(MachineInstr &MI) const {
   unsigned Opc = MI.getOpcode();
   if (Opc == AMDGPU::G_INTRINSIC || Opc == AMDGPU::G_INTRINSIC_CONVERGENT ||
       Opc == AMDGPU::G_INTRINSIC_W_SIDE_EFFECTS ||
       Opc == AMDGPU::G_INTRINSIC_CONVERGENT_W_SIDE_EFFECTS) {
     unsigned IntrID = cast<GIntrinsic>(MI).getIntrinsicID();
     auto IRAIt = IRulesAlias.find(IntrID);
-    if (IRAIt == IRulesAlias.end()) {
-      LLVM_DEBUG(dbgs() << "MI: "; MI.dump(););
-      llvm_unreachable("No rules defined for intrinsic opcode");
-    }
-    return IRules.at(IRAIt->second);
+    if (IRAIt == IRulesAlias.end())
+      return nullptr;
+    return &IRules.at(IRAIt->second);
   }
 
   auto GRAIt = GRulesAlias.find(Opc);
-  if (GRAIt == GRulesAlias.end()) {
-    LLVM_DEBUG(dbgs() << "MI: "; MI.dump(););
-    llvm_unreachable("No rules defined for generic opcode");
-  }
-  return GRules.at(GRAIt->second);
+  if (GRAIt == GRulesAlias.end())
+    return nullptr;
+  return &GRules.at(GRAIt->second);
 }
 
 // Syntactic sugar wrapper for predicate lambda that enables '&&', '||' and '!'.

llvm/lib/Target/AMDGPU/AMDGPURegBankLegalizeRules.h

@@ -287,7 +287,7 @@ class SetOfRulesForOpcode {
   SetOfRulesForOpcode();
   SetOfRulesForOpcode(FastRulesTypes FastTypes);
 
-  const RegBankLLTMapping &
+  const RegBankLLTMapping *
   findMappingForMI(const MachineInstr &MI, const MachineRegisterInfo &MRI,
                    const MachineUniformityInfo &MUI) const;
 
@@ -385,7 +385,7 @@ class RegBankLegalizeRules {
     MRI = &_MRI;
   };
 
-  const SetOfRulesForOpcode &getRulesForOpc(MachineInstr &MI) const;
+  const SetOfRulesForOpcode *getRulesForOpc(MachineInstr &MI) const;
 };
 
 } // end namespace AMDGPU