[PATCH] Fix documentation of -mpoke-function-name ARM option

[PATCH] Fix documentation of -mpoke-function-name ARM option

[Jérémy Lefaure]

Hi!

Since in ARM state the value of PC is the address of the current
instruction plus 8 bytes, the code inspecting the value of PC stored at
FP + 0 should look at location PC - 16 : PC - 8 points to the stmfd
instruction, PC - 16 points two words before, where the top 8 bits are
set.

gcc/
2019-12-14  Jérémy Lefaure <jeremy@lefaure.fr>

	* config/arm/arm.c (-mpoke-function-name): Fix documentation in comment.
	* doc/invoke.texi (-mpoke-function-name): Fix documentation.

Index: gcc/config/arm/arm.c
===================================================================
--- gcc/config/arm/arm.c
+++ gcc/config/arm/arm.c
@@ -20738,9 +20738,9 @@ arm_asm_declare_function_name (FILE *file, const c
 
    When performing a stack backtrace, code can inspect the value
    of 'pc' stored at 'fp' + 0.  If the trace function then looks
-   at location pc - 12 and the top 8 bits are set, then we know
+   at location pc - 16 and the top 8 bits are set, then we know
    that there is a function name embedded immediately preceding this
-   location and has length ((pc[-3]) & 0xff000000).
+   location and has length ((pc[-4]) & 0xff000000).
 
    We assume that pc is declared as a pointer to an unsigned long.
 
Index: gcc/doc/invoke.texi
===================================================================
--- gcc/doc/invoke.texi
+++ gcc/doc/invoke.texi
@@ -18080,9 +18080,9 @@ preceding the function prologue.  The generated co
 
 When performing a stack backtrace, code can inspect the value of
 @code{pc} stored at @code{fp + 0}.  If the trace function then looks at
-location @code{pc - 12} and the top 8 bits are set, then we know that
+location @code{pc - 16} and the top 8 bits are set, then we know that
 there is a function name embedded immediately preceding this location
-and has length @code{((pc[-3]) & 0xff000000)}.
+and has length @code{((pc[-4]) & 0xff000000)}.
 
 @item -mthumb
 @itemx -marm

[PING][PATCH] Fix documentation of -mpoke-function-name ARM option

[Jérémy Lefaure]

Hello,

Ping for https://gcc.gnu.org/ml/gcc-patches/2019-12/msg01081.html.

Thank you,
Jérémy

On Sun, Dec 15, 2019 at 07:20:26PM +0100, Jérémy Lefaure wrote:
> Hi!
> 
> Since in ARM state the value of PC is the address of the current
> instruction plus 8 bytes, the code inspecting the value of PC stored at
> FP + 0 should look at location PC - 16 : PC - 8 points to the stmfd
> instruction, PC - 16 points two words before, where the top 8 bits are
> set.
> 
> gcc/
> 2019-12-14  Jérémy Lefaure <jeremy@lefaure.fr>
> 
> 	* config/arm/arm.c (-mpoke-function-name): Fix documentation in comment.
> 	* doc/invoke.texi (-mpoke-function-name): Fix documentation.
> 

[PING^2][PATCH] Fix documentation of -mpoke-function-name ARM option

[Jérémy Lefaure]

Hello,

Ping for https://gcc.gnu.org/ml/gcc-patches/2019-12/msg01081.html.

Thank you,
Jérémy

On Sun, Dec 15, 2019 at 07:20:26PM +0100, Jérémy Lefaure wrote:
> Hi!
> 
> Since in ARM state the value of PC is the address of the current
> instruction plus 8 bytes, the code inspecting the value of PC stored at
> FP + 0 should look at location PC - 16 : PC - 8 points to the stmfd
> instruction, PC - 16 points two words before, where the top 8 bits are
> set.
> 
> gcc/
> 2019-12-14  Jérémy Lefaure <jeremy@lefaure.fr>
> 
> 	* config/arm/arm.c (-mpoke-function-name): Fix documentation in comment.
> 	* doc/invoke.texi (-mpoke-function-name): Fix documentation.
> 

Re: [PING^2][PATCH] Fix documentation of -mpoke-function-name ARM option

[Sandra Loosemore]

On 2/20/20 3:08 PM, Jérémy Lefaure wrote:
> Hello,
> 
> Ping for https://gcc.gnu.org/ml/gcc-patches/2019-12/msg01081.html.
> 
> Thank you,
> Jérémy
> 
> On Sun, Dec 15, 2019 at 07:20:26PM +0100, Jérémy Lefaure wrote:
>> Hi!
>>
>> Since in ARM state the value of PC is the address of the current
>> instruction plus 8 bytes, the code inspecting the value of PC stored at
>> FP + 0 should look at location PC - 16 : PC - 8 points to the stmfd
>> instruction, PC - 16 points two words before, where the top 8 bits are
>> set.
>>
>> gcc/
>> 2019-12-14  Jérémy Lefaure <jeremy@lefaure.fr>
>>
>> 	* config/arm/arm.c (-mpoke-function-name): Fix documentation in comment.
>> 	* doc/invoke.texi (-mpoke-function-name): Fix documentation.
>>
> 

The patch looks OK to me from a documentation point of view, but I'm no 
expert about the technical correctness of the change.  Maybe an ARM 
maintainer can review this?

-Sandra

Re: [PING^2][PATCH] Fix documentation of -mpoke-function-name ARM option

[blatinox]

Hi Sandra,

On Mon, Feb 24, 2020 at 02:19:21PM -0700, Sandra Loosemore wrote:
> On 2/20/20 3:08 PM, Jérémy Lefaure wrote:
> > Hello,
> > 
> > Ping for https://gcc.gnu.org/ml/gcc-patches/2019-12/msg01081.html.
> > 
> > Thank you,
> > Jérémy
> > 
> > On Sun, Dec 15, 2019 at 07:20:26PM +0100, Jérémy Lefaure wrote:
> > > Hi!
> > > 
> > > Since in ARM state the value of PC is the address of the current
> > > instruction plus 8 bytes, the code inspecting the value of PC stored at
> > > FP + 0 should look at location PC - 16 : PC - 8 points to the stmfd
> > > instruction, PC - 16 points two words before, where the top 8 bits are
> > > set.
> > > 
> > > gcc/
> > > 2019-12-14  Jérémy Lefaure <jeremy@lefaure.fr>
> > > 
> > > 	* config/arm/arm.c (-mpoke-function-name): Fix documentation in comment.
> > > 	* doc/invoke.texi (-mpoke-function-name): Fix documentation.
> > > 
> > 
> 
> The patch looks OK to me from a documentation point of view, but I'm no
> expert about the technical correctness of the change.  Maybe an ARM
> maintainer can review this?
> 

Thank you for taking the time to review this patch.
I hope that an ARM maintainer will have time to review it too.


Thank you,
Jérémy