[DebugInfo] Fix emitting the DW_AT_location attribute for 64-bit DWARFv3 (7/19).

[ikudrin]

Summary

The patch uses a common method to determine the appropriate form for the value of the attribute.

[dblaikie]

Looks good

llvm/test/DebugInfo/X86/DW_AT_location-reference.ll

44

Should this be dumped in a different format/more digits to match the number of bytes in the field?

[ikudrin]

llvm/test/DebugInfo/X86/DW_AT_location-reference.ll

44

That is how DWARFLocationTable::dumpLocationList() dumps the offset. At that moment, the information about the form of the value is lost.

[ikudrin]

• Updated the test because the patch is being moved before fixing emitters for pre-v5 name lookup tables.

[dblaikie]

llvm/test/DebugInfo/X86/DW_AT_location-reference.ll

44

Fair enough, just a thought to consider/keep in mind at some point. Consistency in dumping seems important if we're going to use longer fields to indicate longer encodings. Only using that strategy sometimes seems like it could be more confusing than helpful.

llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp

void DwarfCompileUnit::addComplexAddress(const DbgVariable &DV, DIE &Die,
   if (DwarfExpr.TagOffset)
     addUInt(Die, dwarf::DW_AT_LLVM_tag_offset, dwarf::DW_FORM_data1,
             *DwarfExpr.TagOffset);
 }
 
 /// Add a Dwarf loclistptr attribute data and value.
 void DwarfCompileUnit::addLocationList(DIE &Die, dwarf::Attribute Attribute,
                                        unsigned Index) {
-  dwarf::Form Form = dwarf::DW_FORM_data4;
-  if (DD->getDwarfVersion() == 4)
-    Form =dwarf::DW_FORM_sec_offset;
-  if (DD->getDwarfVersion() >= 5)
-    Form =dwarf::DW_FORM_loclistx;
+  dwarf::Form Form = (DD->getDwarfVersion() >= 5)
+                         ? dwarf::DW_FORM_loclistx
+                         : DD->getDwarfSectionOffsetForm();
   Die.addValue(DIEValueAllocator, Attribute, Form, DIELocList(Index));
 }
 
 void DwarfCompileUnit::applyVariableAttributes(const DbgVariable &Var,
                                                DIE &VariableDie) {
   StringRef Name = Var.getName();
   if (!Name.empty())
     addString(VariableDie, dwarf::DW_AT_name, Name);

llvm/test/DebugInfo/X86/DW_AT_location-reference.ll

 ; RUN: llc -O1 -filetype=obj -mtriple=x86_64-apple-darwin < %s > %t
-; RUN: llvm-dwarfdump -v %t  | FileCheck %s
+; RUN: llvm-dwarfdump -v %t | FileCheck %s --check-prefixes=CHECK,DWARFv4
 ; RUN: llvm-objdump -r %t | FileCheck --check-prefix=DARWIN %s
+
 ; RUN: llc -O1 -filetype=obj -mtriple=x86_64-pc-linux-gnu < %s > %t
-; RUN: llvm-dwarfdump -v %t  | FileCheck %s
+; RUN: llvm-dwarfdump -v %t | FileCheck %s --check-prefixes=CHECK,DWARFv4
+; RUN: llvm-objdump -r %t | FileCheck --check-prefix=LINUX %s
+
+; RUN: llc -dwarf-version=3 -O1 -filetype=obj -mtriple=x86_64-pc-linux-gnu < %s > %t
+; RUN: llvm-dwarfdump -debug-info -v %t | FileCheck %s --check-prefixes=CHECK,DWARF32v3
+; RUN: llvm-objdump -r %t | FileCheck --check-prefix=LINUX %s
+
+; RUN: llc -dwarf64 -dwarf-version=3 -O1 -filetype=obj -mtriple=x86_64-pc-linux-gnu < %s > %t
+; RUN: llvm-dwarfdump -debug-info -v %t | FileCheck %s --check-prefixes=CHECK,DWARF64v3
 ; RUN: llvm-objdump -r %t | FileCheck --check-prefix=LINUX %s
 
 ; PR9493
 ; Adapted from the original test case in r127757.
 ; We use 'llc -O1' to induce variable 'x' to live in different locations.
 ; We don't actually care where 'x' lives, or what exact optimizations get
 ; used, as long as 'x' moves around we're fine.
 

 ;   x = 2;
 ;   while (x & 2) { x *= a; }
 ;   a = g(0, x);
 ; }
 
 ; // The 'x' variable and its symbol reference location
 ; CHECK: .debug_info contents:
 ; CHECK:      DW_TAG_variable
-; CHECK-NEXT:   DW_AT_location [DW_FORM_sec_offset] (0x00000000
+; DWARF32v3-NEXT: DW_AT_location [DW_FORM_data4] (0x00000000
+; DWARF64v3-NEXT: DW_AT_location [DW_FORM_data8] (0x00000000
+; DWARFv4-NEXT:   DW_AT_location [DW_FORM_sec_offset] (0x00000000
 ; Check that the location contains only 4 ranges.
 ; CHECK-NEXT:   [0x{{[0-9a-f]*}}, 0x{{[0-9a-f]*}})
 ; CHECK-NEXT:   [0x{{[0-9a-f]*}}, 0x{{[0-9a-f]*}})
 ; CHECK-NEXT:   [0x{{[0-9a-f]*}}, 0x{{[0-9a-f]*}})
 ; CHECK-NEXT:   [0x{{[0-9a-f]*}}, 0x{{[0-9a-f]*}}){{.*}})
 ; CHECK-NEXT:   DW_AT_name {{.*}} "x"
 ; CHECK-NEXT:   DW_AT_decl_file
 ; CHECK-NEXT:   DW_AT_decl_line