[NFC][DebugInfo] getDwarfCompileUnitID

[kyulee]

Summary

This is a refactoring for the use in https://reviews.llvm.org/D108261

[dblaikie]

Perhaps the name of the function should have something to do with line tables, since this is only for use when generating line tables (& in non-line table situations the code should use the CU.getUniqueID directly, I think?)?

[kyulee]

In D108271#2953310, @dblaikie wrote:

Perhaps the name of the function should have something to do with line tables, since this is only for use when generating line tables (& in non-line table situations the code should use the CU.getUniqueID directly, I think?)?

What about getDwarfCompileUnitIDForLineTable?

[dblaikie]

In D108271#2953354, @kyulee wrote:

In D108271#2953310, @dblaikie wrote:

Perhaps the name of the function should have something to do with line tables, since this is only for use when generating line tables (& in non-line table situations the code should use the CU.getUniqueID directly, I think?)?

What about getDwarfCompileUnitIDForLineTable?

Sure, sounds good!

llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h

private:
   void recordSourceLine(unsigned Line, unsigned Col, const MDNode *Scope,
                         unsigned Flags);
 
   /// Populate LexicalScope entries with variables' info.
   void collectEntityInfo(DwarfCompileUnit &TheCU, const DISubprogram *SP,
                          DenseSet<InlinedEntity> &ProcessedVars);
 
   /// Build the location list for all DBG_VALUEs in the
-  /// function that describe the same variable. If the resulting 
+  /// function that describe the same variable. If the resulting
   /// list has only one entry that is valid for entire variable's
   /// scope return true.
   bool buildLocationList(SmallVectorImpl<DebugLocEntry> &DebugLoc,
                          const DbgValueHistoryMap::Entries &Entries);
 
   /// Collect variable information from the side table maintained by MF.
   void collectVariableInfoFromMFTable(DwarfCompileUnit &TheCU,
                                       DenseSet<InlinedEntity> &P);
 
   /// Emit the reference to the section.
   void emitSectionReference(const DwarfCompileUnit &CU);
 
 protected:
   /// Gather pre-function debug information.
   void beginFunctionImpl(const MachineFunction *MF) override;
 
   /// Gather and emit post-function debug information.
   void endFunctionImpl(const MachineFunction *MF) override;
 
+  /// Get Dwarf compile unit ID for line table.
+  unsigned getDwarfCompileUnitIDForLineTable(const DwarfCompileUnit &CU);
+
   void skippedNonDebugFunction() override;
 
 public:
   //===--------------------------------------------------------------------===//
   // Main entry points.
   //
   DwarfDebug(AsmPrinter *A);
 

llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp

void DwarfDebug::beginFunctionImpl(const MachineFunction *MF) {
 
   auto *SP = MF->getFunction().getSubprogram();
   assert(LScopes.empty() || SP == LScopes.getCurrentFunctionScope()->getScopeNode());
   if (SP->getUnit()->getEmissionKind() == DICompileUnit::NoDebug)
     return;
 
   DwarfCompileUnit &CU = getOrCreateDwarfCompileUnit(SP->getUnit());
 
+  Asm->OutStreamer->getContext().setDwarfCompileUnitID(
+      getDwarfCompileUnitIDForLineTable(CU));
+
+  // Record beginning of function.
+  PrologEndLoc = emitInitialLocDirective(
+      *MF, Asm->OutStreamer->getContext().getDwarfCompileUnitID());
+}
+
+unsigned
+DwarfDebug::getDwarfCompileUnitIDForLineTable(const DwarfCompileUnit &CU) {
   // Set DwarfDwarfCompileUnitID in MCContext to the Compile Unit this function
   // belongs to so that we add to the correct per-cu line table in the
   // non-asm case.
   if (Asm->OutStreamer->hasRawTextSupport())
     // Use a single line table if we are generating assembly.
-    Asm->OutStreamer->getContext().setDwarfCompileUnitID(0);
+    return 0;
   else
-    Asm->OutStreamer->getContext().setDwarfCompileUnitID(CU.getUniqueID());
-
-  // Record beginning of function.
-  PrologEndLoc = emitInitialLocDirective(
-      *MF, Asm->OutStreamer->getContext().getDwarfCompileUnitID());
+    return CU.getUniqueID();
 }
 
 void DwarfDebug::skippedNonDebugFunction() {
   // If we don't have a subprogram for this function then there will be a hole
   // in the range information. Keep note of this by setting the previously used
   // section to nullptr.
   PrevCU = nullptr;
   CurFn = nullptr;