mirror of
https://github.com/espressif/binutils-gdb.git
synced 2025-06-22 02:50:08 +08:00
b52c4ee466
Currently supported for x86_64 and aarch64 only. [PS: Currently, the compiler has not been adapted to generate ".cfi_sections" with ".sframe" in it. The newly added command line option of --gsframe provides an easy way to try out .sframe support in the toolchain.] gas interprets the CFI directives to generate DWARF-based .eh_frame info. These internal DWARF structures are now consumed by gen-sframe.[ch] sub-system to, in turn, create the SFrame unwind information. These internal DWARF structures are read-only for the purpose of SFrame unwind info generation. SFrame unwind info generation does not impact .eh_frame unwind info generation. Both .eh_frame and .sframe can co-exist in an ELF file, if so desired by the user. Recall that SFrame unwind information only contains the minimal necessary information to generate backtraces and does not provide information to recover all callee-saved registers. The reason being that callee-saved registers other than FP are not needed for stack unwinding, and hence are not included in the .sframe section. Consequently, gen-sframe.[ch] only needs to interpret a subset of DWARF opcodes in gas. More details follow. [Set 1, Interpreted] The following opcodes are interpreted: - DW_CFA_advance_loc - DW_CFA_def_cfa - DW_CFA_def_cfa_register - DW_CFA_def_cfa_offset - DW_CFA_offset - DW_CFA_remember_state - DW_CFA_restore_state - DW_CFA_restore [Set 2, Bypassed] The following opcodes are acknowledged but are not necessary for generating SFrame unwind info: - DW_CFA_undefined - DW_CFA_same_value Anything else apart from the two above-mentioned sets is skipped altogether. This means that any function containing a CFI directive not in Set 1 or Set 2 above, will not have any SFrame unwind information generated for them. Holes in instructions covered by FREs of a single FDE are not representable in the SFrame unwind format. As few examples, following opcodes are not processed for .sframe generation, and are skipped: - .cfi_personality* - .cfi_*lsda - .cfi_escape - .cfi_negate_ra_state - ... Not processing .cfi_escape, .cfi_negate_ra_state will cause SFrame unwind information to be absent for SFrame FDEs that contain these CFI directives, hence affecting the asynchronicity. x86-64 and aarch64 backends need to have a few new definitions and functions for .sframe generation. These provide gas with architecture specific information like the SP/FP/RA register numbers and an SFrame-specific ABI marker. Lastly, the patch also implements an optimization for size, where specific fragments containing SFrame FRE start address and SFrame FDE function are fixed up. This is similar to other similar optimizations in gas, where fragments are sized and fixed up when the associated symbols can be resolved. This optimization is controlled by a #define SFRAME_FRE_TYPE_SELECTION_OPT and should be easy to turn off if needed. The optimization is on by default for both x86_64 and aarch64. ChangeLog: * gas/Makefile.am: Include gen-sframe.c and sframe-opt.c. * gas/Makefile.in: Regenerated. * gas/as.h (enum _relax_state): Add new state rs_sframe. (sframe_estimate_size_before_relax): New function. (sframe_relax_frag): Likewise. (sframe_convert_frag): Likewise. * gas/config/tc-aarch64.c (aarch64_support_sframe_p): New definition. (aarch64_sframe_ra_tracking_p): Likewise. (aarch64_sframe_cfa_ra_offset): Likewise. (aarch64_sframe_get_abi_arch): Likewise. (md_begin): Set values of sp/fp/ra registers. * gas/config/tc-aarch64.h (aarch64_support_sframe_p): New declaration. (support_sframe_p): Likewise. (SFRAME_CFA_SP_REG): Likewise. (SFRAME_CFA_FP_REG): Likewise. (SFRAME_CFA_RA_REG): Likewise. (aarch64_sframe_ra_tracking_p): Likewise. (sframe_ra_tracking_p): Likewise. (aarch64_sframe_cfa_ra_offset): Likewise. (sframe_cfa_ra_offset): Likewise. (aarch64_sframe_get_abi_arch): Likewise. (sframe_get_abi_arch): Likewise. * gas/config/tc-i386.c (x86_support_sframe_p): New definition. (x86_sframe_ra_tracking_p): Likewise. (x86_sframe_cfa_ra_offset): Likewise. (x86_sframe_get_abi_arch): Likewise. * gas/config/tc-i386.h (x86_support_sframe_p): New declaration. (support_sframe_p): Likewise. (SFRAME_CFA_SP_REG): Likewise. (SFRAME_CFA_FP_REG): Likewise. (x86_sframe_ra_tracking_p): Likewise. (sframe_ra_tracking_p): Likewise. (x86_sframe_cfa_ra_offset): Likewise. (sframe_cfa_ra_offset): Likewise. (x86_sframe_get_abi_arch): Likewise. (sframe_get_abi_arch): Likewise. * gas/config/tc-xtensa.c (unrelaxed_frag_max_size): Add case for rs_sframe. * gas/doc/as.texi: Add .sframe to the documentation for .cfi_sections. * gas/dw2gencfi.c (cfi_finish): Create a .sframe section. * gas/dw2gencfi.h (CFI_EMIT_sframe): New definition. * gas/write.c (cvt_frag_to_fill): Handle rs_sframe. (relax_segment): Likewise. * gas/gen-sframe.c: New file. * gas/gen-sframe.h: New file. * gas/sframe-opt.c: New file.
README for GNU development tools This directory contains various GNU compilers, assemblers, linkers, debuggers, etc., plus their support routines, definitions, and documentation. If you are receiving this as part of a GDB release, see the file gdb/README. If with a binutils release, see binutils/README; if with a libg++ release, see libg++/README, etc. That'll give you info about this package -- supported targets, how to use it, how to report bugs, etc. It is now possible to automatically configure and build a variety of tools with one command. To build all of the tools contained herein, run the ``configure'' script here, e.g.: ./configure make To install them (by default in /usr/local/bin, /usr/local/lib, etc), then do: make install (If the configure script can't determine your type of computer, give it the name as an argument, for instance ``./configure sun4''. You can use the script ``config.sub'' to test whether a name is recognized; if it is, config.sub translates it to a triplet specifying CPU, vendor, and OS.) If you have more than one compiler on your system, it is often best to explicitly set CC in the environment before running configure, and to also set CC when running make. For example (assuming sh/bash/ksh): CC=gcc ./configure make A similar example using csh: setenv CC gcc ./configure make Much of the code and documentation enclosed is copyright by the Free Software Foundation, Inc. See the file COPYING or COPYING.LIB in the various directories, for a description of the GNU General Public License terms under which you can copy the files. REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info on where and how to report problems.