Linker support for -freorder-functions?

[H. J. Lu]

On Thu, Aug 05, 2004 at 03:02:27PM -0700, Mike Stump wrote:
> On Aug 5, 2004, at 1:58 PM, H. J. Lu wrote:
> >But it is useless without linker support. Should linker group
> >text.hot/text.unlikely like
> >
> >*(.text.hot)
> >*(.text .stub${RELOCATING+ .text.* .gnu.linkonce.t.*})
> >KEEP (*(.text.*personality*))
> >*(.text.unlikely)
> 
> Seems almost reasonable from my humble perspective...  though, hot 
> would be all together in the .text.* area...  so, listing it first 
> isn't strictly necessary....  and, likewise, unlikely would tend to 
> group together as well, so strictly speaking, listing it last should 
> not be necessary...

I was wondering what the reasonable memory layout for this is. I
don't think you want .text.unlikely to be next to .text.hot.

> 
> The change might be wrong from a {non-,}RELOCATING perspective, a 
> script wizz should be able to offer advice...
> 
> >Also, should section names be .text.hot/.text.unlikely instead of
> >text.hot/text.unlikely?
> 
> Again, seems reasonable...

Here is a patch.


H.J.
---
2004-08-05  H.J. Lu  <hongjiu.lu@intel.com>

	* doc/invoke.text (freorder-functions): Add a leading `.' to
	"text.hot" and "text.unlikely" sections.

--- gcc/doc/invoke.texi.sec	2004-07-13 14:43:22.000000000 -0700
+++ gcc/doc/invoke.texi	2004-08-05 15:34:37.046887526 -0700
@@ -4198,8 +4198,8 @@ Enabled at levels @option{-O2}, @option{
 @opindex freorder-functions
 Reorder basic blocks in the compiled function in order to reduce number of
 taken branches and improve code locality. This is implemented by using special
-subsections @code{text.hot} for most frequently executed functions and
-@code{text.unlikely} for unlikely executed functions.  Reordering is done by
+subsections @code{.text.hot} for most frequently executed functions and
+@code{.text.unlikely} for unlikely executed functions.  Reordering is done by
 the linker so object file format must support named sections and linker must
 place them in a reasonable way.