Are the global registers 5 and 6 really available for the operating
system or uses GCC or the linker them for a special purpose? Is it
possible to document this somewhere in to standard documentation and not
only in a header file?
gcc/ChangeLog
2014-03-08 Sebastian Huber <sebastian.hu...@embedded-brains.de>
* config/sparc/sparc.h: Mention global register 7 usage for TLS.
---
gcc/config/sparc/sparc.h | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/gcc/config/sparc/sparc.h b/gcc/config/sparc/sparc.h
index dd2b5ad..23c79fc 100644
--- a/gcc/config/sparc/sparc.h
+++ b/gcc/config/sparc/sparc.h
@@ -637,16 +637,17 @@ extern enum cmodel sparc_cmodel;
On non-v9 systems:
g1 is free to use as temporary.
- g2-g4 are reserved for applications. Gcc normally uses them as
+ g2-g4 are reserved for applications. GCC normally uses them as
temporaries, but this can be disabled via the -mno-app-regs option.
- g5 through g7 are reserved for the operating system.
+ g5 and g6 are reserved for the operating system.
+ g7 is used for thread-local storage (TLS) in the initial exec TLS model.
On v9 systems:
g1,g5 are free to use as temporaries, and are free to use between calls
if the call is to an external function via the PLT.
g4 is free to use as a temporary in the non-embedded case.
g4 is reserved in the embedded case.
- g2-g3 are reserved for applications. Gcc normally uses them as
+ g2-g3 are reserved for applications. GCC normally uses them as
temporaries, but this can be disabled via the -mno-app-regs option.
g6-g7 are reserved for the operating system (or application in
embedded case).
--
1.8.1.4
