Hi! Apologies if this looks like a duplicate but my email did not show up
in the archive so I think it got lost.
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?
Thanks!
Bill Mahoney
U. Nebraska at Omaha
