On Thu, Jan 23, 2025 at 2:23 PM Georg-Johann Lay <a...@gjlay.de> wrote: > > Hi, this is Ping #2 for a patch from 2024. > > It adds a new target hook that allows to output > assembly code for a VAR_DECL in a custom way. > > The default action is an obvious no-op, > i.e. assemble_variable() behaves like before.
I tried to understand the AVR part of the series - there I fail to see what exactly special handling "io" and friends requires and how that was made work with the TLS noswitch section. I do not think the sentence the middle-end doesn't allow custom NOSWITCH sections is correct (it would be a matter of exporting get_noswitch_section), but I also don't exactly see how "io" and friends require a NOSWITCH. The implementation of the new hook is basically a complete override of assemble_variable which IMO is bad style at least. The missing requirements for "io" and friends should instead be made available by other means (for example more targeted hooks). That said, I can see how the patch works and doesn't affect anything besides AVR. Richard. > This hook is needed in the avr backend to properly implement > some variable attributes. The avr part has already been approved. > > The patch is bootstrapped, and it tests without new regressions. > > Ok for trunk? > > Johann > > -- > > Original submission > https://gcc.gnu.org/pipermail/gcc-patches/2025-January/673459.html > > Ping #1 > https://gcc.gnu.org/pipermail/gcc-patches/2025-January/673459.html > > avr part and approval > https://gcc.gnu.org/pipermail/gcc-patches/2024-December/672051.html > https://gcc.gnu.org/pipermail/gcc-patches/2024-December/672084.html > > -- > > Add new target hook TARGET_ASM_VARIABLE. > > This patch adds a new target hook that allows the backend to asm output > a variable definition in its own way. This hook is needed because > varasm.cc imposes a very restrictive layout for all variable definitions > which will be basically ELF style (on ELF targets as least). To date, > there is no way for a backend to output a variable definition in a > different way. > This hook is required by the avr backend when it outputs definitions > for variables defined with the "io", "io_low" or "address" attribute that > don't follow ELF style. These attributes are basically symbol definitions > of the form > > .global var_io > var_io = 32 > > with some additional assertions. > > gcc/ > * target.def (TARGET_ASM_OUT) <variable>: Add new DEFHOOK. > * targhooks.cc (default_asm_out_variable): New function. > * targhooks.h (default_asm_out_variable): New prototype. > * doc/tm.texi.in (TARGET_ASM_VARIABLE): Place hook documentation. > * doc/tm.texi: Rebuild. > * varasm.cc (assemble_variable): Call targetm.asm_out.variable > in order to allow the backend to output a variable definition > in its own style.
