Matthieu Longo <matthieu.lo...@arm.com> writes: > Architecture-specific CFI directives are currently declared an processed > among others architecture-independent CFI directives in gcc/dwarf2* files. > This approach creates confusion, specifically in the case of DWARF > instructions in the vendor space and using the same instruction code. > Such a clash currently happen between DW_CFA_GNU_window_save (used on SPARC) > and DW_CFA_AARCH64_negate_ra_state (used on AArch64), and both having the > same instruction code 0x2d. Then AArch64 compilers generates a SPARC CFI > directive (.cfi_window_save) instead of .cfi_negate_ra_state, contrarily to > what is expected in [1].
The series LGTM, thanks. OK for trunk if there are no objections before Monday. Richard > 1. Rename REG_CFA_TOGGLE_RA_MANGLE to REG_CFA_NEGATE_RA_STATE > > This patch renames: > - dwarf2out_frame_debug_cfa_toggle_ra_mangle to > dwarf2out_frame_debug_cfa_negate_ra_state, > - REG_CFA_TOGGLE_RA_MANGLE to REG_CFA_NEGATE_RA_STATE, > as the naming was misleading. > The word "toggle" suggested a binary state, whereas this register stores the > mangling state (that can be more than 2 states) for the return address on > AArch64. > > 2. dwarf2: add hooks for architecture-specific CFIs > > This refactoring does not solve completely the problem, but improve the > situation by moving some of the processing of those directives (more > specifically their output in the assembly) to the backend via 2 target hooks: > - DW_CFI_OPRND1_DESC: parse the first operand of the directive (if any). > - OUTPUT_CFI_DIRECTIVE: output the CFI directive as a string. > Only AArch64's and SPARC's backend are impacted. > > 3. aarch64 testsuite: explain expectections for pr94515* > PR94515's tests in AArch64 G++ testsuite were lacking documentation. They are > now thoroughly documented. > > 4. dwarf2: store the RA state in CFI row > > On AArch64, the RA state informs the unwinder whether the return address is > mangled and how, or not. This information is encoded in a boolean in the CFI > row. This binary approach prevents from expressing more complex > configuration, as it is the case with PAuth_LR introduced in Armv9.5-A. > This patch addresses this limitation by replacing the boolean by an enum. > > > References: > [1] DWARF for the Arm 64-bit Architecture (AArch64) --> > https://github.com/ARM-software/abi-aa/blob/main/aadwarf64/aadwarf64.rst > > ### Diff between revisions 1 & 2 > > patch 1: no change. > patch 2: > - fix issue with default hook signature for new hooks. > - code style formatting. > - change targetm.dw_cfi_oprnd1_desc signature to match the one of > dw_cfi_oprnd2_desc. > patch 3: > - add comments suggested by Richard Sandiford in test case > gcc/testsuite/g++.target > /aarch64/pr94515-2.C. > patch 4: > - code style formatting. > > ## Testing > > Built for target aarch64-unknown-linux-gnu and ran GCC's & G++'s testsuites > for AArch64. > Built GCC stage 1 for target sparc64-unknown-linux-gnu. > > > Ok for master? I don't have commit access so I need someone to commit on my > behalf. > > Regards, > Matthieu. > > Matthieu Longo (4): > Rename REG_CFA_TOGGLE_RA_MANGLE to REG_CFA_NEGATE_RA_STATE > dwarf2: add hooks for architecture-specific CFIs > aarch64 testsuite: explain expectections for pr94515* tests > dwarf2: store the RA state in CFI row > > gcc/combine-stack-adj.cc | 2 +- > gcc/config/aarch64/aarch64.cc | 37 +++++++++++- > gcc/config/sparc/sparc.cc | 35 ++++++++++++ > gcc/coretypes.h | 6 ++ > gcc/doc/tm.texi | 16 +++++- > gcc/doc/tm.texi.in | 5 +- > gcc/dwarf2cfi.cc | 59 ++++++++++---------- > gcc/dwarf2out.cc | 13 +++-- > gcc/dwarf2out.h | 11 ++-- > gcc/hooks.cc | 14 +++++ > gcc/hooks.h | 3 + > gcc/reg-notes.def | 8 +-- > gcc/target.def | 20 +++++++ > gcc/testsuite/g++.target/aarch64/pr94515-1.C | 14 ++++- > gcc/testsuite/g++.target/aarch64/pr94515-2.C | 41 +++++++++++--- > include/dwarf2.h | 5 ++ > libffi/include/ffi_cfi.h | 2 + > libgcc/config/aarch64/aarch64-asm.h | 4 +- > libitm/config/aarch64/sjlj.S | 10 ++-- > 19 files changed, 239 insertions(+), 66 deletions(-)
