William Mahoney <wmahoney@xxxxxxxxxxxxxxxx> writes:
> I have some code that I have added to GCCs in the past for doing
> instrumentation at a basic block level. Recently I grabbed 4.5.1 and added
> in my changes.
>
> First, so you know:
>
> Target: x86_64-unknown-linux-gnu
> Configured with: /home/bmahoney/Projects/gcc-4.5.1/configure
> --disable-multilib --prefix=/home/bmahoney/Projects/native_451_out
> --enable-libjava --enable-languages=c,c++,java,fortran
>
> Now, I need to be aware of the live-in set for each block, so that I can
> save and restore the registers that are live around the instrumentation
> code that is inserted. In the past, looking at the live-in set for the
> basic block header has always worked but now I have something that is
> confusing. I put some debugging in to look at things at the RTL level and
> my debugging output (hopefully self-evident) is:
>
> Starting on basic block 12 it looks like it DOES have code
> global_live_at_start = 6 [bp] 7 [sp] 16 [argp] 20 [frame] 75
> global_live_at_end = 6 [bp] 7 [sp] 16 [argp] 20 [frame] 74
> Block after this one is block 13
> FIRST_PSEUDO_REGISTER = 53
> Here is the basic block before adding code:
> (note 170 70 71 [bb 12] NOTE_INSN_BASIC_BLOCK)
> (insn 71 170 190 (set (reg:DF 21 xmm0 [74])
> (float:DF (reg:DI 0 ax [75]))) play.cpp:91 219
> {*floatdidf2_sse_interunit}
> (nil))
>
> My pass is right after pass_convert_to_eh_region_ranges, so it is right at
> the end and should be past the hard register assignment.
>
> Finally my question. In the past, checking the register set from 0 to
> FIRST_PSEUDO_REGISTER has always worked because this should be the range
> of the hard registers. It certainly looks to me like 74 and 75 are above
> the range of the hard registers and thus would not really be "live" in
> that sense. I couldn't find the #define for FIRST_PSEUDO_REGISTER so I
> just printed it out, but on this hardware it is 53 as you can see.
>
> What am I missing here?
It's hard to answer without seeing your code. What are you doing to
fetch the global_live_at_start information? How are you printing it?
If you are running after pass_convert_to_eh_region_ranges then it sounds
like you are running after pass_free_cfg and that means that basic block
info is very dubious. Can you move your pass before pass_free_cfg?
Ian
