The issue is found when parsing the "hb_font_make_immutable" function:
0x00084270: DW_TAG_subprogram
DW_AT_low_pc (0x0000000000002fb0)
DW_AT_high_pc (0x0000000000002fe4)
DW_AT_frame_base (DW_OP_reg29 W29)
DW_AT_name ("hb_font_make_immutable")
DW_AT_decl_file (".harfbuzz/src/hb-font.cc")
DW_AT_decl_line (1514)
DW_AT_external (0x01)
DW_AT_APPLE_optimized (0x01)
0x0008428d: DW_TAG_formal_parameter
DW_AT_location (0x00008852
[0x0000000000002fb0, 0x0000000000002fc0): DW_OP_reg0 W0
[0x0000000000002fc0, 0x0000000000002fe0): DW_OP_reg19 W19)
DW_AT_name ("font")
DW_AT_decl_file (".harfbuzz/src/hb-font.cc")
DW_AT_decl_line (1514)
DW_AT_type (0x0008431c "hb_font_t*")
The parameter has type 0x0008431c:
0x0008431c: DW_TAG_pointer_type
DW_AT_type (0x00084322 "hb_font_t")
Which points to 0x00084322:
0x00084322: DW_TAG_typedef
DW_AT_type (0x00084202 "hb_font_t")
DW_AT_name ("hb_font_t")
DW_AT_decl_file (".harfbuzz/src/hb-font.h")
DW_AT_decl_line (40)
which points to:
0x00084202: DW_TAG_structure_type
DW_AT_calling_convention (DW_CC_pass_by_value)
DW_AT_name ("hb_font_t")
DW_AT_byte_size (0x68)
DW_AT_declaration (0x01)
Boom we crash when parsing the function type. This was compiled with a
derivative of clang version 6.0.0.
My attempt at a minimal test case was:
$ cat main.cpp
#include "ByValue.h"
void f(ByValueTD *arg) {}
int main() {
return 0;
}
$ cat ByValue.h
struct ByValue {
~ByValue() = default;
};
typedef ByValue ByValueTD;
The I try to compile with:
$ clang++ -g -O0 -std=gnu++11 -stdlib=libc++ -flimit-debug-info main.cpp
But the DWARF from more recent clangs will remove the DW_CC_pass_by_value from
the ByValue. See the DIE at 0x00000082 in the DWARF below, it doesn't contain
the "DW_AT_calling_convention (DW_CC_pass_by_value)" anymore.
0x0000000b: DW_TAG_compile_unit
DW_AT_producer ("Apple LLVM version 10.0.1
(clang-1001.0.46.4)")
DW_AT_language (DW_LANG_C_plus_plus)
DW_AT_name ("main.cpp")
DW_AT_stmt_list (0x00000000)
DW_AT_comp_dir ("/Users/gclayton/Documents/src/cc_calling")
DW_AT_low_pc (0x0000000100000f90)
DW_AT_high_pc (0x0000000100000faf)
0x0000002a: DW_TAG_subprogram
DW_AT_low_pc (0x0000000100000f90)
DW_AT_high_pc (0x0000000100000f9a)
DW_AT_frame_base (DW_OP_reg6 RBP)
DW_AT_linkage_name ("_Z1fP7ByValue")
DW_AT_name ("f")
DW_AT_decl_file
("/Users/gclayton/Documents/src/cc_calling/main.cpp")
DW_AT_decl_line (3)
DW_AT_external (true)
0x00000043: DW_TAG_formal_parameter
DW_AT_location (DW_OP_fbreg -8)
DW_AT_name ("arg")
DW_AT_decl_file
("/Users/gclayton/Documents/src/cc_calling/main.cpp")
DW_AT_decl_line (3)
DW_AT_type (0x0000000000000072 "ByValueTD*")
0x00000051: NULL
0x00000052: DW_TAG_subprogram
DW_AT_low_pc (0x0000000100000fa0)
DW_AT_high_pc (0x0000000100000faf)
DW_AT_frame_base (DW_OP_reg6 RBP)
DW_AT_name ("main")
DW_AT_decl_file
("/Users/gclayton/Documents/src/cc_calling/main.cpp")
DW_AT_decl_line (5)
DW_AT_type (0x000000000000006b "int")
DW_AT_external (true)
0x0000006b: DW_TAG_base_type
DW_AT_name ("int")
DW_AT_encoding (DW_ATE_signed)
DW_AT_byte_size (0x04)
0x00000072: DW_TAG_pointer_type
DW_AT_type (0x0000000000000077 "ByValueTD")
0x00000077: DW_TAG_typedef
DW_AT_type (0x0000000000000082 "ByValue")
DW_AT_name ("ByValueTD")
DW_AT_decl_file
("/Users/gclayton/Documents/src/cc_calling/./ByValue.h")
DW_AT_decl_line (4)
0x00000082: DW_TAG_structure_type
DW_AT_name ("ByValue")
DW_AT_declaration (true)
0x00000087: NULL
If we compile with -fno-limit-debug-info we get the "DW_AT_calling_convention
(DW_CC_pass_by_value)":
0x0000000b: DW_TAG_compile_unit
DW_AT_producer ("Apple LLVM version 10.0.1
(clang-1001.0.46.4)")
DW_AT_language (DW_LANG_C_plus_plus)
DW_AT_name ("main.cpp")
DW_AT_stmt_list (0x00000000)
DW_AT_comp_dir ("/Users/gclayton/Documents/src/cc_calling")
DW_AT_low_pc (0x0000000100000f90)
DW_AT_high_pc (0x0000000100000faf)
0x0000002a: DW_TAG_subprogram
DW_AT_low_pc (0x0000000100000f90)
DW_AT_high_pc (0x0000000100000f9a)
DW_AT_frame_base (DW_OP_reg6 RBP)
DW_AT_linkage_name ("_Z1fP7ByValue")
DW_AT_name ("f")
DW_AT_decl_file
("/Users/gclayton/Documents/src/cc_calling/main.cpp")
DW_AT_decl_line (3)
DW_AT_external (true)
0x00000043: DW_TAG_formal_parameter
DW_AT_location (DW_OP_fbreg -8)
DW_AT_name ("arg")
DW_AT_decl_file
("/Users/gclayton/Documents/src/cc_calling/main.cpp")
DW_AT_decl_line (3)
DW_AT_type (0x0000000000000072 "ByValueTD*")
0x00000051: NULL
0x00000052: DW_TAG_subprogram
DW_AT_low_pc (0x0000000100000fa0)
DW_AT_high_pc (0x0000000100000faf)
DW_AT_frame_base (DW_OP_reg6 RBP)
DW_AT_name ("main")
DW_AT_decl_file
("/Users/gclayton/Documents/src/cc_calling/main.cpp")
DW_AT_decl_line (5)
DW_AT_type (0x000000000000006b "int")
DW_AT_external (true)
0x0000006b: DW_TAG_base_type
DW_AT_name ("int")
DW_AT_encoding (DW_ATE_signed)
DW_AT_byte_size (0x04)
0x00000072: DW_TAG_pointer_type
DW_AT_type (0x0000000000000077 "ByValueTD")
0x00000077: DW_TAG_typedef
DW_AT_type (0x0000000000000082 "ByValue")
DW_AT_name ("ByValueTD")
DW_AT_decl_file
("/Users/gclayton/Documents/src/cc_calling/./ByValue.h")
DW_AT_decl_line (4)
0x00000082: DW_TAG_structure_type
DW_AT_calling_convention (DW_CC_pass_by_value)
DW_AT_name ("ByValue")
DW_AT_byte_size (0x01)
DW_AT_decl_file
("/Users/gclayton/Documents/src/cc_calling/./ByValue.h")
DW_AT_decl_line (1)
0x0000008b: DW_TAG_subprogram
DW_AT_name ("~ByValue")
DW_AT_decl_file
("/Users/gclayton/Documents/src/cc_calling/./ByValue.h")
DW_AT_decl_line (2)
DW_AT_declaration (true)
DW_AT_external (true)
0x00000092: DW_TAG_formal_parameter
DW_AT_type (0x0000000000000099 "ByValue*")
DW_AT_artificial (true)
0x00000097: NULL
0x00000098: NULL
0x00000099: DW_TAG_pointer_type
DW_AT_type (0x0000000000000082 "ByValue")
0x0000009e: NULL
> On Aug 4, 2019, at 11:28 AM, Saleem Abdulrasool <[email protected]> wrote:
>
> On Wed, Jul 31, 2019 at 11:29 AM Greg Clayton via lldb-commits
> <[email protected] <mailto:[email protected]>> wrote:
>
>
> > On Jul 31, 2019, at 10:57 AM, Raphael Isemann <[email protected]
> > <mailto:[email protected]>> wrote:
> >
> > It seems that patch is lacking a test (which doesn't seem too hard to
> > provide).
>
> I am not the original author of this patch that was causing the crash, just
> fixing a crash that was introduced by the patch.
>
> Perhaps we should identify the original change and revert that instead?
>
> I am all ears for anyone that can provide me with DWARF to help reproduce
> this scenario where we have a DW_CC_pass_by_value struct with no definition.
> Not sure how you would have a compiler that is passing a struct to a function
> as a parameter and yet does not emit debug info for that struct it is clearly
> using in the debug info.
>
> Was this something that you noticed by inspection? It doesn't sound like it,
> so we should be able to reduce something from what caused it to be triggered.
> lldb has been better about adding test coverage, and I think that we should
> be encouraging that. It really does help make it easier to make changes to
> the project where we can be sure that we don't cause regressions.
>
>
> >
> > Am Mi., 31. Juli 2019 um 18:24 Uhr schrieb Greg Clayton via
> > lldb-commits <[email protected]
> > <mailto:[email protected]>>:
> >>
> >> Author: gclayton
> >> Date: Wed Jul 31 09:24:55 2019
> >> New Revision: 367441
> >>
> >> URL: http://llvm.org/viewvc/llvm-project?rev=367441&view=rev
> >> <http://llvm.org/viewvc/llvm-project?rev=367441&view=rev>
> >> Log:
> >> Don't crash when pass by value struct has no definition.
> >>
> >>
> >> Modified:
> >> lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
> >>
> >> Modified:
> >> lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
> >> URL:
> >> http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp?rev=367441&r1=367440&r2=367441&view=diff
> >>
> >> <http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp?rev=367441&r1=367440&r2=367441&view=diff>
> >> ==============================================================================
> >> --- lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
> >> (original)
> >> +++ lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp Wed
> >> Jul 31 09:24:55 2019
> >> @@ -1010,7 +1010,7 @@ TypeSP DWARFASTParserClang::ParseTypeFro
> >> if (attrs.calling_convention == llvm::dwarf::DW_CC_pass_by_value) {
> >> clang::CXXRecordDecl *record_decl =
> >> m_ast.GetAsCXXRecordDecl(clang_type.GetOpaqueQualType());
> >> - if (record_decl) {
> >> + if (record_decl && record_decl->getDefinition()) {
> >> record_decl->setHasTrivialSpecialMemberForCall();
> >> }
> >> }
> >>
> >>
> >> _______________________________________________
> >> lldb-commits mailing list
> >> [email protected] <mailto:[email protected]>
> >> https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
> >> <https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits>
>
> _______________________________________________
> lldb-commits mailing list
> [email protected] <mailto:[email protected]>
> https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
> <https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits>
>
>
> --
> Saleem Abdulrasool
> compnerd (at) compnerd (dot) org
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