jyknight added a comment. In D110869#3295477 <https://reviews.llvm.org/D110869#3295477>, @nathanchance wrote:
> Rather interesting function to have problems with as a result of this patch > but it seems like this function is being used in a very specific way further > down the file with the `__PV_IS_CALLEE_SAVE` macro. AFAICT, `__PV_IS_CALLEE_SAVE` is just bogus. It appears to be used in order to promise that a given function preserves all GPR registers (including those registers that are normally caller-saved), as an optimized alternative to generating a wrapper for the function with `PC_CALLEE_SAVE_REGS_THUNK`, to save the extra registers. That would be fine if the functions it was making the promise about were written in asm, or the compiler was informed about the adjusted calling convention expectation... However, it's being applied to functions which are implemented in C with no special calling-convention attributes on them . That's a promise that simply cannot be upheld -- I mean, I guess it //happens// to work currently, but that's super-fragile. Also the whole mechanism (including the asm thunk) should be unnecessary in Clang, as it provides an attribute you can put on a function to use a calling convention that'll preserve all GPRs except r11. I imagine the call locations could easily be adjusted to avoid needing to have r11 preserved, if that's not already the case. https://clang.llvm.org/docs/AttributeReference.html#preserve-most Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D110869/new/ https://reviews.llvm.org/D110869 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
