[IRTranslator][NFC] Refactor if/else chain into early returns

[fdeazeve]

Summary

This will make it easier to add more cases in a subsequent commit and also
better conforms to the coding guidelines.

[fdeazeve]

Rebased

llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp

case Intrinsic::dbg_value: {
     const Value *V = DI.getValue();
     assert(DI.getVariable()->isValidLocationForIntrinsic(
                MIRBuilder.getDebugLoc()) &&
            "Expected inlined-at fields to agree");
     if (!V || DI.hasArgList()) {
       // DI cannot produce a valid DBG_VALUE, so produce an undef DBG_VALUE to
       // terminate any prior location.
       MIRBuilder.buildIndirectDbgValue(0, DI.getVariable(), DI.getExpression());
-    } else if (const auto *CI = dyn_cast<Constant>(V)) {
+      return true;
+    }
+    if (const auto *CI = dyn_cast<Constant>(V)) {
       MIRBuilder.buildConstDbgValue(*CI, DI.getVariable(), DI.getExpression());
-    } else if (auto *AI = dyn_cast<AllocaInst>(V);
-               AI && AI->isStaticAlloca() &&
-               DI.getExpression()->startsWithDeref()) {
+      return true;
+    }
+    if (auto *AI = dyn_cast<AllocaInst>(V);
+        AI && AI->isStaticAlloca() && DI.getExpression()->startsWithDeref()) {
       // If the value is an alloca and the expression starts with a
       // dereference, track a stack slot instead of a register, as registers
       // may be clobbered.
       auto ExprOperands = DI.getExpression()->getElements();
       auto *ExprDerefRemoved =
           DIExpression::get(AI->getContext(), ExprOperands.drop_front());
       MIRBuilder.buildFIDbgValue(getOrCreateFrameIndex(*AI), DI.getVariable(),
                                  ExprDerefRemoved);
-    } else {
-      for (Register Reg : getOrCreateVRegs(*V)) {
-        // FIXME: This does not handle register-indirect values at offset 0. The
-        // direct/indirect thing shouldn't really be handled by something as
-        // implicit as reg+noreg vs reg+imm in the first place, but it seems
-        // pretty baked in right now.
-        MIRBuilder.buildDirectDbgValue(Reg, DI.getVariable(), DI.getExpression());
-      }
-    }
+      return true;
+    }
     return true;
   }
   case Intrinsic::uadd_with_overflow:
     return translateOverflowIntrinsic(CI, TargetOpcode::G_UADDO, MIRBuilder);
   case Intrinsic::sadd_with_overflow:
     return translateOverflowIntrinsic(CI, TargetOpcode::G_SADDO, MIRBuilder);
   case Intrinsic::usub_with_overflow:
     return translateOverflowIntrinsic(CI, TargetOpcode::G_USUBO, MIRBuilder);