Re: [PATCH 02/25] tracing: Improve "if" macro code generation

[Peter Zijlstra]

On Mon, Mar 18, 2019 at 06:37:20PM -0500, Josh Poimboeuf wrote:
> On Mon, Mar 18, 2019 at 04:38:42PM +0100, Peter Zijlstra wrote:
> > With CONFIG_PROFILE_ALL_BRANCHES, the "if" macro converts the
> > conditional to an array index.  This can cause GCC to create horrible
> > code.  When there are nested ifs, the generated code uses register
> > values to encode branching decisions.
> > 
> > Make it easier for GCC to optimize by keeping the conditional as a
> > conditional rather than converting it to an integer.  This shrinks the
> > generated code quite a bit, and also makes the code sane enough for
> > objtool to understand.
> > 
> > Cc: rostedt@xxxxxxxxxxx
> > Cc: valentin.schneider@xxxxxxx
> > Cc: luto@xxxxxxxxxxxxxx
> > Cc: brgerst@xxxxxxxxx
> > Cc: catalin.marinas@xxxxxxx
> > Cc: mingo@xxxxxxxxxx
> > Cc: dvlasenk@xxxxxxxxxx
> > Cc: will.deacon@xxxxxxx
> > Cc: julien.thierry@xxxxxxx
> > Cc: torvalds@xxxxxxxxxxxxxxxxxxxx
> > Cc: dvyukov@xxxxxxxxxx
> > Cc: bp@xxxxxxxxx
> > Cc: tglx@xxxxxxxxxxxxx
> > Cc: james.morse@xxxxxxx
> > Cc: luto@xxxxxxxxxx
> > Cc: hpa@xxxxxxxxx
> > Reported-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> > Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> > Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> > Link: https://lkml.kernel.org/r/20190307174802.46fmpysxyo35hh43@treble
> 
> Missing "From" me.

Right, sorry, quilt eats that and I sometimes forget to fix up :/