ping?
On Tue, 29 Sep 2020 at 21:50, Christophe Lyon
<christophe.l...@linaro.org> wrote:
>
> When mi_delta is > 255 and -mpure-code is used, we cannot load delta
> from code memory (like we do without -mpure-code).
>
> This patch builds the value of mi_delta into r3 with a series of
> movs/adds/lsls.
>
> We also do some cleanup by not emitting the function address and delta
> via .word directives at the end of the thunk since we don't use them
> with -mpure-code.
>
> No need for new testcases, this bug was already identified by
> eg. pr46287-3.C
>
> 2020-09-29 Christophe Lyon <christophe.l...@linaro.org>
>
> gcc/
> * config/arm/arm.c (arm_thumb1_mi_thunk): Build mi_delta in r3 and
> do not emit function address and delta when -mpure-code is used.
>
> k# (use "git pull" to merge the remote branch into yours)
> ---
> gcc/config/arm/arm.c | 91
> +++++++++++++++++++++++++++++++++++++---------------
> 1 file changed, 66 insertions(+), 25 deletions(-)
>
> diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
> index ceeb91f..62abeb5 100644
> --- a/gcc/config/arm/arm.c
> +++ b/gcc/config/arm/arm.c
> @@ -28342,9 +28342,43 @@ arm_thumb1_mi_thunk (FILE *file, tree, HOST_WIDE_INT
> delta,
> {
> if (mi_delta > 255)
> {
> - fputs ("\tldr\tr3, ", file);
> - assemble_name (file, label);
> - fputs ("+4\n", file);
> + /* With -mpure-code, we cannot load delta from the constant
> + pool: we build it explicitly. */
> + if (target_pure_code)
> + {
> + bool mov_done_p = false;
> + int i;
> +
> + /* Emit upper 3 bytes if needed. */
> + for (i = 0; i < 3; i++)
> + {
> + int byte = (mi_delta >> (8 * (3 - i))) & 0xff;
> +
> + if (byte)
> + {
> + if (mov_done_p)
> + asm_fprintf (file, "\tadds\tr3, #%d\n", byte);
> + else
> + asm_fprintf (file, "\tmovs\tr3, #%d\n", byte);
> + mov_done_p = true;
> + }
> +
> + if (mov_done_p)
> + asm_fprintf (file, "\tlsls\tr3, #8\n");
> + }
> +
> + /* Emit lower byte if needed. */
> + if (!mov_done_p)
> + asm_fprintf (file, "\tmovs\tr3, #%d\n", mi_delta & 0xff);
> + else if (mi_delta & 0xff)
> + asm_fprintf (file, "\tadds\tr3, #%d\n", mi_delta & 0xff);
> + }
> + else
> + {
> + fputs ("\tldr\tr3, ", file);
> + assemble_name (file, label);
> + fputs ("+4\n", file);
> + }
> asm_fprintf (file, "\t%ss\t%r, %r, r3\n",
> mi_op, this_regno, this_regno);
> }
> @@ -28380,30 +28414,37 @@ arm_thumb1_mi_thunk (FILE *file, tree,
> HOST_WIDE_INT delta,
> fputs ("\tpop\t{r3}\n", file);
>
> fprintf (file, "\tbx\tr12\n");
> - ASM_OUTPUT_ALIGN (file, 2);
> - assemble_name (file, label);
> - fputs (":\n", file);
> - if (flag_pic)
> +
> + /* With -mpure-code, we don't need to emit literals for the
> + function address and delta since we emitted code to build
> + them. */
> + if (!target_pure_code)
> {
> - /* Output ".word .LTHUNKn-[3,7]-.LTHUNKPCn". */
> - rtx tem = XEXP (DECL_RTL (function), 0);
> - /* For TARGET_THUMB1_ONLY the thunk is in Thumb mode, so the PC
> - pipeline offset is four rather than eight. Adjust the offset
> - accordingly. */
> - tem = plus_constant (GET_MODE (tem), tem,
> - TARGET_THUMB1_ONLY ? -3 : -7);
> - tem = gen_rtx_MINUS (GET_MODE (tem),
> - tem,
> - gen_rtx_SYMBOL_REF (Pmode,
> - ggc_strdup (labelpc)));
> - assemble_integer (tem, 4, BITS_PER_WORD, 1);
> - }
> - else
> - /* Output ".word .LTHUNKn". */
> - assemble_integer (XEXP (DECL_RTL (function), 0), 4, BITS_PER_WORD, 1);
> + ASM_OUTPUT_ALIGN (file, 2);
> + assemble_name (file, label);
> + fputs (":\n", file);
> + if (flag_pic)
> + {
> + /* Output ".word .LTHUNKn-[3,7]-.LTHUNKPCn". */
> + rtx tem = XEXP (DECL_RTL (function), 0);
> + /* For TARGET_THUMB1_ONLY the thunk is in Thumb mode, so the PC
> + pipeline offset is four rather than eight. Adjust the offset
> + accordingly. */
> + tem = plus_constant (GET_MODE (tem), tem,
> + TARGET_THUMB1_ONLY ? -3 : -7);
> + tem = gen_rtx_MINUS (GET_MODE (tem),
> + tem,
> + gen_rtx_SYMBOL_REF (Pmode,
> + ggc_strdup (labelpc)));
> + assemble_integer (tem, 4, BITS_PER_WORD, 1);
> + }
> + else
> + /* Output ".word .LTHUNKn". */
> + assemble_integer (XEXP (DECL_RTL (function), 0), 4,
> BITS_PER_WORD, 1);
>
> - if (TARGET_THUMB1_ONLY && mi_delta > 255)
> - assemble_integer (GEN_INT(mi_delta), 4, BITS_PER_WORD, 1);
> + if (TARGET_THUMB1_ONLY && mi_delta > 255)
> + assemble_integer (GEN_INT(mi_delta), 4, BITS_PER_WORD, 1);
> + }
> }
> else
> {
> --
> 2.7.4
>
