[FastISel] Implement translation of entry_value dbg.value intrinsics

[fdeazeve]

Summary

For dbg.value intrinsics targeting an llvm::Argument address whose expression
starts with an entry value, we lower this to a DEBUG_VALUE targeting the livein
physical register corresponding to that Argument.

Depends on D151332

[fdeazeve]

Fix incorrect format of commit message

[fdeazeve]

Fix mess up with patch upload

llvm/lib/CodeGen/SelectionDAG/FastISel.cpp

case Intrinsic::dbg_declare: {
     }
     return true;
   }
   case Intrinsic::dbg_value: {
     // This form of DBG_VALUE is target-independent.
     const DbgValueInst *DI = cast<DbgValueInst>(II);
     const MCInstrDesc &II = TII.get(TargetOpcode::DBG_VALUE);
     const Value *V = DI->getValue();
-    assert(DI->getVariable()->isValidLocationForIntrinsic(MIMD.getDL()) &&
+    DIExpression *Expr = DI->getExpression();
+    DILocalVariable *Var = DI->getVariable();
+    assert(Var->isValidLocationForIntrinsic(MIMD.getDL()) &&
            "Expected inlined-at fields to agree");
     if (!V || isa<UndefValue>(V) || DI->hasArgList()) {
       // DI is either undef or cannot produce a valid DBG_VALUE, so produce an
       // undef DBG_VALUE to terminate any prior location.
       BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, MIMD.getDL(), II, false, 0U,
-              DI->getVariable(), DI->getExpression());
+              Var, Expr);
       return true;
     }
     if (const auto *CI = dyn_cast<ConstantInt>(V)) {
       // See if there's an expression to constant-fold.
-      DIExpression *Expr = DI->getExpression();
       if (Expr)
         std::tie(Expr, CI) = Expr->constantFold(CI);
       if (CI->getBitWidth() > 64)
         BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, MIMD, II)
             .addCImm(CI)
             .addImm(0U)
-            .addMetadata(DI->getVariable())
+            .addMetadata(Var)
             .addMetadata(Expr);
       else
         BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, MIMD, II)
             .addImm(CI->getZExtValue())
             .addImm(0U)
-            .addMetadata(DI->getVariable())
+            .addMetadata(Var)
             .addMetadata(Expr);
       return true;
     }
     if (const auto *CF = dyn_cast<ConstantFP>(V)) {
       BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, MIMD, II)
           .addFPImm(CF)
           .addImm(0U)
-          .addMetadata(DI->getVariable())
-          .addMetadata(DI->getExpression());
+          .addMetadata(Var)
+          .addMetadata(Expr);
       return true;
     }
     if (Register Reg = lookUpRegForValue(V)) {
       // FIXME: This does not handle register-indirect values at offset 0.
       if (!FuncInfo.MF->useDebugInstrRef()) {
         bool IsIndirect = false;
         BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, MIMD.getDL(), II, IsIndirect,
-                Reg, DI->getVariable(), DI->getExpression());
+                Reg, Var, Expr);
         return true;
       }
       // If using instruction referencing, produce this as a DBG_INSTR_REF,
       // to be later patched up by finalizeDebugInstrRefs.
       SmallVector<MachineOperand, 1> MOs({MachineOperand::CreateReg(
           /* Reg */ Reg, /* isDef */ false, /* isImp */ false,
           /* isKill */ false, /* isDead */ false,
           /* isUndef */ false, /* isEarlyClobber */ false,
           /* SubReg */ 0, /* isDebug */ true)});
       SmallVector<uint64_t, 2> Ops({dwarf::DW_OP_LLVM_arg, 0});
-      auto *NewExpr = DIExpression::prependOpcodes(DI->getExpression(), Ops);
+      auto *NewExpr = DIExpression::prependOpcodes(Expr, Ops);
       BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, MIMD.getDL(),
               TII.get(TargetOpcode::DBG_INSTR_REF), /*IsIndirect*/ false, MOs,
-              DI->getVariable(), NewExpr);
+              Var, NewExpr);
       return true;
     }
     // We don't know how to handle other cases, so we drop.
     LLVM_DEBUG(dbgs() << "Dropping debug info for " << *DI << "\n");
     return true;
   }
   case Intrinsic::dbg_label: {
     const DbgLabelInst *DI = cast<DbgLabelInst>(II);