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 <jer...@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
