Reland "[DwarfDebug] Dump call site debug info"

The build failure found after the rL365467 has been
resolved.

Differential Revision: https://reviews.llvm.org/D60716

llvm-svn: 367446

Author: djtodoro

llvm/docs/LangRef.rst

@@ -4769,6 +4769,10 @@ The current supported opcode vocabulary is limited:
   ``DW_OP_entry_value`` may also appear after the ``AsmPrinter`` pass when
   a call site parameter value (``DW_AT_call_site_parameter_value``)
   is represented as entry value of the parameter.
+- ``DW_OP_breg`` (or ``DW_OP_bregx``) represents a content on the provided
+  signed offset of the specified register. The opcode is only generated by the
+  ``AsmPrinter`` pass to describe call site parameter value which requires an
+  expression over two registers.
 
 DWARF specifies three kinds of simple location descriptions: Register, memory,
 and implicit location descriptions.  Note that a location description is

llvm/include/llvm/CodeGen/TargetInstrInfo.h

@@ -60,6 +60,8 @@ class TargetSubtargetInfo;
 
 template <class T> class SmallVectorImpl;
 
+using ParamLoadedValue = std::pair<const MachineOperand*, DIExpression*>;
+
 //---------------------------------------------------------------------------
 ///
 /// TargetInstrInfo - Interface to description of machine instruction set
@@ -1691,6 +1693,11 @@ class TargetInstrInfo : public MCInstrInfo {
     return false;
   }
 
+  /// Produce the expression describing the \p MI loading a value into
+  /// the parameter's forwarding register.
+  virtual Optional<ParamLoadedValue>
+  describeLoadedValue(const MachineInstr &MI) const;
+
 private:
   unsigned CallFrameSetupOpcode, CallFrameDestroyOpcode;
   unsigned CatchRetOpcode;

llvm/include/llvm/CodeGen/TargetRegisterInfo.h

@@ -535,6 +535,11 @@ class TargetRegisterInfo : public MCRegisterInfo {
     return false;
   }
 
+  /// This is a wrapper around getCallPreservedMask().
+  /// Return true if the register is preserved after the call.
+  virtual bool isCalleeSavedPhysReg(unsigned PhysReg,
+                                    const MachineFunction &MF) const;
+
   /// Prior to adding the live-out mask to a stackmap or patchpoint
   /// instruction, provide the target the opportunity to adjust it (mainly to
   /// remove pseudo-registers that should be ignored).

llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp

@@ -892,32 +892,106 @@ void DwarfCompileUnit::constructAbstractSubprogramScopeDIE(
     ContextCU->addDIEEntry(*AbsDef, dwarf::DW_AT_object_pointer, *ObjectPointer);
 }
 
-DIE &DwarfCompileUnit::constructCallSiteEntryDIE(DIE &ScopeDIE,
-                                                 const DISubprogram &CalleeSP,
-                                                 bool IsTail,
-                                                 const MCExpr *PCOffset) {
-  // Insert a call site entry DIE within ScopeDIE.
-  DIE &CallSiteDIE =
-      createAndAddDIE(dwarf::DW_TAG_call_site, ScopeDIE, nullptr);
+dwarf::Tag DwarfCompileUnit::getDwarf5OrGNUCallSiteTag(dwarf::Tag Tag) const {
+  bool ApplyGNUExtensions = DD->getDwarfVersion() == 4 && DD->tuneForGDB();
+  if (!ApplyGNUExtensions)
+    return Tag;
+  switch (Tag) {
+  case dwarf::DW_TAG_call_site:
+    return dwarf::DW_TAG_GNU_call_site;
+  case dwarf::DW_TAG_call_site_parameter:
+    return dwarf::DW_TAG_GNU_call_site_parameter;
+  default:
+    llvm_unreachable("unhandled call site tag");
+  }
+}
 
-  // For the purposes of showing tail call frames in backtraces, a key piece of
-  // information is DW_AT_call_origin, a pointer to the callee DIE.
-  DIE *CalleeDIE = getOrCreateSubprogramDIE(&CalleeSP);
-  assert(CalleeDIE && "Could not create DIE for call site entry origin");
-  addDIEEntry(CallSiteDIE, dwarf::DW_AT_call_origin, *CalleeDIE);
+dwarf::Attribute
+DwarfCompileUnit::getDwarf5OrGNUCallSiteAttr(dwarf::Attribute Attr) const {
+  bool ApplyGNUExtensions = DD->getDwarfVersion() == 4 && DD->tuneForGDB();
+  if (!ApplyGNUExtensions)
+    return Attr;
+  switch (Attr) {
+  case dwarf::DW_AT_call_all_calls:
+    return dwarf::DW_AT_GNU_all_call_sites;
+  case dwarf::DW_AT_call_target:
+    return dwarf::DW_AT_GNU_call_site_target;
+  case dwarf::DW_AT_call_origin:
+    return dwarf::DW_AT_abstract_origin;
+  case dwarf::DW_AT_call_pc:
+    return dwarf::DW_AT_low_pc;
+  case dwarf::DW_AT_call_value:
+    return dwarf::DW_AT_GNU_call_site_value;
+  case dwarf::DW_AT_call_tail_call:
+    return dwarf::DW_AT_GNU_tail_call;
+  default:
+    llvm_unreachable("unhandled call site attribute");
+  }
+}
 
-  if (IsTail) {
-    // Attach DW_AT_call_tail_call to tail calls for standards compliance.
-    addFlag(CallSiteDIE, dwarf::DW_AT_call_tail_call);
+DIE &DwarfCompileUnit::constructCallSiteEntryDIE(
+    DIE &ScopeDIE, const DISubprogram *CalleeSP, bool IsTail,
+    const MCSymbol *PCAddr, const MCExpr *PCOffset, unsigned CallReg) {
+  // Insert a call site entry DIE within ScopeDIE.
+  DIE &CallSiteDIE = createAndAddDIE(
+      getDwarf5OrGNUCallSiteTag(dwarf::DW_TAG_call_site), ScopeDIE, nullptr);
+
+  if (CallReg) {
+    // Indirect call.
+    addAddress(CallSiteDIE,
+               getDwarf5OrGNUCallSiteAttr(dwarf::DW_AT_call_target),
+               MachineLocation(CallReg));
   } else {
-    // Attach the return PC to allow the debugger to disambiguate call paths
-    // from one function to another.
+    DIE *CalleeDIE = getOrCreateSubprogramDIE(CalleeSP);
+    assert(CalleeDIE && "Could not create DIE for call site entry origin");
+    addDIEEntry(CallSiteDIE,
+                getDwarf5OrGNUCallSiteAttr(dwarf::DW_AT_call_origin),
+                *CalleeDIE);
+  }
+
+  if (IsTail)
+    // Attach DW_AT_call_tail_call to tail calls for standards compliance.
+    addFlag(CallSiteDIE,
+            getDwarf5OrGNUCallSiteAttr(dwarf::DW_AT_call_tail_call));
+
+  // Attach the return PC to allow the debugger to disambiguate call paths
+  // from one function to another.
+  if (DD->getDwarfVersion() == 4 && DD->tuneForGDB()) {
+    assert(PCAddr && "Missing PC information for a call");
+    addLabelAddress(CallSiteDIE, dwarf::DW_AT_low_pc, PCAddr);
+  } else if (!IsTail || DD->tuneForGDB()) {
     assert(PCOffset && "Missing return PC information for a call");
     addAddressExpr(CallSiteDIE, dwarf::DW_AT_call_return_pc, PCOffset);
   }
+
   return CallSiteDIE;
 }
 
+void DwarfCompileUnit::constructCallSiteParmEntryDIEs(
+    DIE &CallSiteDIE, SmallVector<DbgCallSiteParam, 4> &Params) {
+  for (const auto &Param : Params) {
+    unsigned Register = Param.getRegister();
+    auto CallSiteDieParam =
+        DIE::get(DIEValueAllocator,
+                 getDwarf5OrGNUCallSiteTag(dwarf::DW_TAG_call_site_parameter));
+    insertDIE(CallSiteDieParam);
+    addAddress(*CallSiteDieParam, dwarf::DW_AT_location,
+               MachineLocation(Register));
+
+    DIELoc *Loc = new (DIEValueAllocator) DIELoc;
+    DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
+    DwarfExpr.setCallSiteParamValueFlag();
+
+    DwarfDebug::emitDebugLocValue(*Asm, nullptr, Param.getValue(), DwarfExpr);
+
+    addBlock(*CallSiteDieParam,
+             getDwarf5OrGNUCallSiteAttr(dwarf::DW_AT_call_value),
+             DwarfExpr.finalize());
+
+    CallSiteDIE.addChild(CallSiteDieParam);
+  }
+}
+
 DIE *DwarfCompileUnit::constructImportedEntityDIE(
     const DIImportedEntity *Module) {
   DIE *IMDie = DIE::get(DIEValueAllocator, (dwarf::Tag)Module->getTag());

llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h

@@ -227,12 +227,33 @@ class DwarfCompileUnit final : public DwarfUnit {
 
   void constructAbstractSubprogramScopeDIE(LexicalScope *Scope);
 
+  /// This takes the official DWARF 5 tag and returns the appropriate
+  /// GNU tag if needed.
+  dwarf::Tag getDwarf5OrGNUCallSiteTag(dwarf::Tag Tag) const;
+  /// This takes the official DWARF 5 attribute and returns the appropriate
+  /// GNU attribute if needed.
+  dwarf::Attribute getDwarf5OrGNUCallSiteAttr(dwarf::Attribute Attr) const;
+
   /// Construct a call site entry DIE describing a call within \p Scope to a
-  /// callee described by \p CalleeSP. \p IsTail specifies whether the call is
-  /// a tail call. \p PCOffset must be non-zero for non-tail calls or be the
+  /// callee described by \p CalleeSP.
+  /// \p IsTail specifies whether the call is a tail call.
+  /// \p PCAddr (used for GDB + DWARF 4 tuning) points to the PC value after
+  /// the call instruction.
+  /// \p PCOffset (used for cases other than GDB + DWARF 4 tuning) must be
+  /// non-zero for non-tail calls (in the case of non-gdb tuning, since for
+  /// GDB + DWARF 5 tuning we still generate PC info for tail calls) or be the
   /// function-local offset to PC value after the call instruction.
-  DIE &constructCallSiteEntryDIE(DIE &ScopeDIE, const DISubprogram &CalleeSP,
-                                 bool IsTail, const MCExpr *PCOffset);
+  /// \p CallReg is a register location for an indirect call. For direct calls
+  /// the \p CallReg is set to 0.
+  DIE &constructCallSiteEntryDIE(DIE &ScopeDIE, const DISubprogram *CalleeSP,
+                                 bool IsTail, const MCSymbol *PCAddr,
+                                 const MCExpr *PCOffset, unsigned CallReg);
+  /// Construct call site parameter DIEs for the \p CallSiteDIE. The \p Params
+  /// were collected by the \ref collectCallSiteParameters.
+  /// Note: The order of parameters does not matter, since debuggers recognize
+  ///       call site parameters by the DW_AT_location attribute.
+  void constructCallSiteParmEntryDIEs(DIE &CallSiteDIE,
+                                      SmallVector<DbgCallSiteParam, 4> &Params);
 
   /// Construct import_module DIE.
   DIE *constructImportedEntityDIE(const DIImportedEntity *Module);