The 06/05/2020 17:51, Szabolcs Nagy wrote:
> This is a big hammer fix for __builtin_return_address (PR target/94891)
> returning signed addresses (sometimes, depending on wether lr happens
> to be signed or not at the time of call which depends on optimizations),
> and similarly -pg may pass signed return address to _mcount
> (PR target/94791).
>
> At the time of return address expansion we don't know if it's signed or
> not so it is done unconditionally.
>
> I wonder if allocate_initial_value for the lr reg may solve this better
> such that get_hard_reg_initial_val just gives the right (unsigned) value?
>
> 2020-06-04 Szabolcs Nagy <szabolcs.n...@arm.com>
>
> * config/aarch64/aarch64-protos.h (aarch64_return_addr_rtx): Declare.
> * config/aarch64/aarch64.c (aarch64_return_addr_rtx): New.
> (aarch64_return_addr): Use aarch64_return_addr_rtx.
> * config/aarch64/aarch64.h (PROFILE_HOOK): Likewise.
ping.
(this fixes a correctness bug in pac-ret, tested with no regressions).
> ---
> gcc/config/aarch64/aarch64-protos.h | 1 +
> gcc/config/aarch64/aarch64.c | 20 +++++++++++++++++++-
> gcc/config/aarch64/aarch64.h | 2 +-
> 3 files changed, 21 insertions(+), 2 deletions(-)
>
> diff --git a/gcc/config/aarch64/aarch64-protos.h
> b/gcc/config/aarch64/aarch64-protos.h
> index 9e43adb7db0..723d9ba6ac6 100644
> --- a/gcc/config/aarch64/aarch64-protos.h
> +++ b/gcc/config/aarch64/aarch64-protos.h
> @@ -578,6 +578,7 @@ int aarch64_vec_fpconst_pow_of_2 (rtx);
> rtx aarch64_eh_return_handler_rtx (void);
> rtx aarch64_mask_from_zextract_ops (rtx, rtx);
> const char *aarch64_output_move_struct (rtx *operands);
> +rtx aarch64_return_addr_rtx (void);
> rtx aarch64_return_addr (int, rtx);
> rtx aarch64_simd_gen_const_vector_dup (machine_mode, HOST_WIDE_INT);
> bool aarch64_simd_mem_operand_p (rtx);
> diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
> index 6352d4ff78a..6a2f85c4af7 100644
> --- a/gcc/config/aarch64/aarch64.c
> +++ b/gcc/config/aarch64/aarch64.c
> @@ -10819,6 +10819,24 @@ aarch64_initial_elimination_offset (unsigned from,
> unsigned to)
> return cfun->machine->frame.frame_size;
> }
>
> +
> +/* Get return address without mangling. */
> +
> +rtx
> +aarch64_return_addr_rtx (void)
> +{
> + rtx val = get_hard_reg_initial_val (Pmode, LR_REGNUM);
> + /* Note: aarch64_return_address_signing_enabled only
> + works after cfun->machine->frame.laid_out is set,
> + so here we don't know if the return address will
> + be signed or not. */
> + rtx lr = gen_rtx_REG (Pmode, LR_REGNUM);
> + emit_move_insn (lr, val);
> + emit_insn (GEN_FCN (CODE_FOR_xpaclri) ());
> + return lr;
> +}
> +
> +
> /* Implement RETURN_ADDR_RTX. We do not support moving back to a
> previous frame. */
>
> @@ -10827,7 +10845,7 @@ aarch64_return_addr (int count, rtx frame
> ATTRIBUTE_UNUSED)
> {
> if (count != 0)
> return const0_rtx;
> - return get_hard_reg_initial_val (Pmode, LR_REGNUM);
> + return aarch64_return_addr_rtx ();
> }
>
>
> diff --git a/gcc/config/aarch64/aarch64.h b/gcc/config/aarch64/aarch64.h
> index 2be52fd4d73..f11941bbc86 100644
> --- a/gcc/config/aarch64/aarch64.h
> +++ b/gcc/config/aarch64/aarch64.h
> @@ -1112,7 +1112,7 @@ typedef struct
> #define PROFILE_HOOK(LABEL) \
> { \
> rtx fun, lr; \
> - lr = get_hard_reg_initial_val (Pmode, LR_REGNUM);
> \
> + lr = aarch64_return_addr_rtx (); \
> fun = gen_rtx_SYMBOL_REF (Pmode, MCOUNT_NAME); \
> emit_library_call (fun, LCT_NORMAL, VOIDmode, lr, Pmode);
> \
> }
> --
> 2.17.1
>
--
