Author: David Spickett Date: 2022-10-27T08:51:07Z New Revision: c6e2de60423ae98b1a7a175bab98c3c3c578b284
URL: https://github.com/llvm/llvm-project/commit/c6e2de60423ae98b1a7a175bab98c3c3c578b284 DIFF: https://github.com/llvm/llvm-project/commit/c6e2de60423ae98b1a7a175bab98c3c3c578b284.diff LOG: [LLVM] Use DWARFv4 bitfields when tuning for GDB GDB implemented data_bit_offset in https://sourceware.org/bugzilla/show_bug.cgi?id=12616 which has been present since GDB 8.0. GCC started using it at GCC 11. Reviewed By: dblaikie Differential Revision: https://reviews.llvm.org/D135583 Added: Modified: clang/docs/ReleaseNotes.rst llvm/docs/ReleaseNotes.rst llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp llvm/test/DebugInfo/X86/bitfields-dwarf4.ll llvm/test/DebugInfo/X86/packed_bitfields.ll Removed: ################################################################################ diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index d73e58acbccd1..fa5154649095c 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -624,6 +624,13 @@ proposals are standardized and available in all major engines. DWARF Support in Clang ---------------------- +Previously when emitting DWARFv4 and tuning for GDB, Clang would use DWARF v2's +``DW_AT_bit_offset`` and ``DW_AT_data_member_location``. Clang now uses DWARF v4's +``DW_AT_data_bit_offset`` regardless of tuning. + +Support for ``DW_AT_data_bit_offset`` was added in GDB 8.0. For earlier versions, +you can use the ``-gdwarf-3`` option to emit compatible DWARF. + Arm and AArch64 Support in Clang -------------------------------- diff --git a/llvm/docs/ReleaseNotes.rst b/llvm/docs/ReleaseNotes.rst index dfdae3ca1dc2b..3918899d72229 100644 --- a/llvm/docs/ReleaseNotes.rst +++ b/llvm/docs/ReleaseNotes.rst @@ -177,7 +177,12 @@ Changes to the Metadata Info Changes to the Debug Info --------------------------------- -During this release ... +Previously when emitting DWARF v4 and tuning for GDB, llc would use DWARF v2's +``DW_AT_bit_offset`` and ``DW_AT_data_member_location``. llc now uses DWARF v4's +``DW_AT_data_bit_offset`` regardless of tuning. + +Support for ``DW_AT_data_bit_offset`` was added in GDB 8.0. For earlier versions, +you can use llc's ``-dwarf-version=3`` option to emit compatible DWARF. Changes to the LLVM tools --------------------------------- diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp index 54af144299077..d3e2befbd23e4 100644 --- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp +++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp @@ -428,8 +428,7 @@ DwarfDebug::DwarfDebug(AsmPrinter *A) // https://sourceware.org/bugzilla/show_bug.cgi?id=11616 UseGNUTLSOpcode = tuneForGDB() || DwarfVersion < 3; - // GDB does not fully support the DWARF 4 representation for bitfields. - UseDWARF2Bitfields = (DwarfVersion < 4) || tuneForGDB(); + UseDWARF2Bitfields = DwarfVersion < 4; // The DWARF v5 string offsets table has - possibly shared - contributions // from each compile and type unit each preceded by a header. The string diff --git a/llvm/test/DebugInfo/X86/bitfields-dwarf4.ll b/llvm/test/DebugInfo/X86/bitfields-dwarf4.ll index 018653751961a..23ddee459abbc 100644 --- a/llvm/test/DebugInfo/X86/bitfields-dwarf4.ll +++ b/llvm/test/DebugInfo/X86/bitfields-dwarf4.ll @@ -1,8 +1,9 @@ ; RUN: llc -mtriple x86_64-apple-macosx -O0 -filetype=obj -o - %s \ ; RUN: | llvm-dwarfdump -v -debug-info - | FileCheck %s ; RUN: llc -mtriple x86_64-gnu-linux -O0 -filetype=obj -o - %s \ -; RUN: | llvm-dwarfdump -v -debug-info - | FileCheck %s --check-prefix=LINUX -; LINUX-NOT: DW_AT_data_bit_offset +; RUN: | llvm-dwarfdump -v -debug-info - | FileCheck %s +; RUN: llc -mtriple x86_64-gnu-linux -O0 -debugger-tune=gdb -filetype=obj -o - %s \ +; RUN: | llvm-dwarfdump -v -debug-info - | FileCheck %s ; ; Generated from: ; #include <stdint.h> diff --git a/llvm/test/DebugInfo/X86/packed_bitfields.ll b/llvm/test/DebugInfo/X86/packed_bitfields.ll index c36df72439ebb..0e541f09d2270 100644 --- a/llvm/test/DebugInfo/X86/packed_bitfields.ll +++ b/llvm/test/DebugInfo/X86/packed_bitfields.ll @@ -1,7 +1,5 @@ ; RUN: llc -dwarf-version=2 -mtriple x86_64-apple-macosx -O0 -filetype=obj -o %t_2_le.o %s ; RUN: llvm-dwarfdump -v -debug-info %t_2_le.o | FileCheck %s -; RUN: llc -dwarf-version=4 -debugger-tune=gdb -mtriple x86_64-apple-macosx -O0 -filetype=obj -o %t_4_le.o %s -; RUN: llvm-dwarfdump -v -debug-info %t_4_le.o | FileCheck %s ; Produced at -O0 from: ; struct { _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
