AsmPrinter: Rewrite initialization of DbgVariable, NFC

There are three types of `DbgVariable`:
  - alloca variables, created based on the MMI table,
  - register variables, created based on DBG_VALUE instructions, and
  - optimized-out variables.

This commit reconfigures `DbgVariable` to make it easier to tell which
kind we have, and make initialization a little clearer.

For MMI/alloca variables, `FrameIndex.size()` must always equal
`Expr.size()`, and there shouldn't be an `MInsn`.  For register
variables (with a `MInsn`), `FrameIndex` must be empty, and `Expr`
should have 0 or 1 element depending on whether it has a complex
expression (registers with multiple locations use `DebugLocListIndex`).
Optimized-out variables shouldn't have any of these fields.

Moreover, this separates DBG_VALUE initialization until after the
variable is created, simplifying logic in a future commit that changes
`collectVariableInfo()` to stop creating empty .debug_loc entries/lists.

llvm-svn: 240243

1 files changed, 3 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index 45c56fbb446..4ee47ffa537 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -508,7 +508,7 @@ DwarfCompileUnit::constructVariableDIEImpl(const DbgVariable &DV,
   }
 
   // .. else use frame index.
-  if (DV.getFrameIndex().back() == ~0)
+  if (DV.getFrameIndex().empty())
     return VariableDie;
 
   auto Expr = DV.getExpression().begin();
@@ -686,7 +686,7 @@ void DwarfCompileUnit::collectDeadVariables(const DISubprogram *SP) {
     SPDIE = getDIE(SP);
   assert(SPDIE);
   for (const DILocalVariable *DV : Variables) {
-    DbgVariable NewVar(DV, /* IA */ nullptr, /* Expr */ nullptr, DD);
+    DbgVariable NewVar(DV, /* IA */ nullptr, DD);
     auto VariableDie = constructVariableDIE(NewVar);
     applyVariableAttributes(NewVar, *VariableDie);
     SPDIE->addChild(std::move(VariableDie));
@@ -725,7 +725,7 @@ void DwarfCompileUnit::addGlobalType(const DIType *Ty, const DIE &Die,
 /// DbgVariable based on provided MachineLocation.
 void DwarfCompileUnit::addVariableAddress(const DbgVariable &DV, DIE &Die,
                                           MachineLocation Location) {
-  if (DV.variableHasComplexAddress())
+  if (DV.hasComplexAddress())
     addComplexAddress(DV, Die, dwarf::DW_AT_location, Location);
   else if (DV.isBlockByrefVariable())
     addBlockByrefAddress(DV, Die, dwarf::DW_AT_location, Location);