[Debug-Info] handle DW_CC_pass_by_value/DW_CC_pass_by_reference under strict DWARF.

[Esme]

Summary

When -strict-dwarf=true is specified, the calling convention info DW_CC_pass_by_value or DW_CC_pass_by_reference can only be generated at DWARF5.

[shchenz]

LGTM. Thanks for fixing this.

Please wait for some days to wait for @dblaikie or @aprantl comments if they have.

[dblaikie]

Looks alright. Test might be tidied up a bit I think.

llvm/test/DebugInfo/Generic/pass-by-value.ll

27

I'd probably relax this to: STRICT-NOT: DW_AT_calling_convention (& similarly below)

Or maybe even implicit-check-not=DW_AT_calling_convention in the FileCheck line above?

[Esme]

Address comments

[dblaikie]

Looks good, thanks!

llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp

case dwarf::DW_TAG_class_type: {
     if (auto *ContainingType = CTy->getVTableHolder())
       addDIEEntry(Buffer, dwarf::DW_AT_containing_type,
                   *getOrCreateTypeDIE(ContainingType));
 
     if (CTy->isObjcClassComplete())
       addFlag(Buffer, dwarf::DW_AT_APPLE_objc_complete_type);
 
     // Add the type's non-standard calling convention.
+    // DW_CC_pass_by_value/DW_CC_pass_by_reference are introduced in DWARF 5.
+    if (!Asm->TM.Options.DebugStrictDwarf || DD->getDwarfVersion() >= 5) {
       uint8_t CC = 0;
       if (CTy->isTypePassByValue())
         CC = dwarf::DW_CC_pass_by_value;
       else if (CTy->isTypePassByReference())
         CC = dwarf::DW_CC_pass_by_reference;
       if (CC)
         addUInt(Buffer, dwarf::DW_AT_calling_convention, dwarf::DW_FORM_data1,
                 CC);
+    }
     break;
   }
   default:
     break;
   }
 
   // Add name if not anonymous or intermediate type.
   if (!Name.empty())

llvm/test/DebugInfo/Generic/pass-by-value.ll

 ; RUN: %llc_dwarf -O0 -filetype=obj < %s | llvm-dwarfdump -debug-info - | FileCheck %s
+; RUN: %llc_dwarf -O0 -filetype=obj < %s -strict-dwarf=true | llvm-dwarfdump -debug-info - \
+; RUN:   | FileCheck %s --check-prefix=STRICT --implicit-check-not DW_AT_calling_convention
 ;
 ; // S is not trivially copyable.
 ; struct S {
 ;    ~S() {}
 ; };
 ;
 ; // T is a POD.
 ; struct T {
 ;    ~T() = default;
 ; };
 ;  
 ; S s;
 ; T t;
 ;
 ; CHECK: DW_TAG_structure_type
 ; CHECK-NEXT: DW_AT_calling_convention  (DW_CC_pass_by_reference)
 ; CHECK-NEXT: DW_AT_name  ("S")
 ;
 ; CHECK: DW_TAG_structure_type
 ; CHECK-NEXT: DW_AT_calling_convention  (DW_CC_pass_by_value)
 ; CHECK-NEXT: DW_AT_name  ("T")
+;
+; STRICT: DW_TAG_structure_type
+; STRICT-NEXT: DW_AT_name ("S")
+;
+; STRICT: DW_TAG_structure_type
+; STRICT-NEXT: DW_AT_name ("T")
 
 %struct.S = type { i8 }
 %struct.T = type { i8 }
 
 @s = global %struct.S zeroinitializer, align 1, !dbg !0
 @__dso_handle = external hidden global i8
 @t = global %struct.T zeroinitializer, align 1, !dbg !6