https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92283
--- Comment #26 from Vladimir Makarov <vmakarov at gcc dot gnu.org> ---
I think I find the problem root. We have
********** Local #2: **********
Choosing alt 0 in insn 1804: (0) =v (1) %0 (2) vm (3) v
{*fma_fmadd_df}
Creating newreg=4707 from oldreg=1801, assigning class ALL_SSE_REGS to
r4707
Creating newreg=4708 from oldreg=1801, assigning class ALL_SSE_REGS to
r4708
Making reload reg 4708 for reg 1801 optional
1804: r4707:DF={r4707:DF*r4708:DF+r984:DF}
! REG_DEAD r1801:DF
REG_DEAD r984:DF
Inserting insn reload before:
10917: r4707:DF=r1801:DF
10919: r4708:DF=r1801:DF
Inserting insn reload after:
10918: r238:DF=r4707:DF
.........
Choosing alt 2 in insn 1814: (0) v (1) v (2) vm (3) 0
{*fma_fmadd_df}
Creating newreg=4709 from oldreg=1801, assigning class ALL_SSE_REGS to
r4709
Making reload reg 4709 for reg 1801 optional
1814: r244:DF={r1795:DF*r4709:DF+r1803:DF}
REG_DEAD r1801:DF
REG_DEAD r1803:DF
Inserting insn reload before:
10920: r4709:DF=r1801:DF
********** Inheritance #2: **********
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
Use smallest class of ALL_SSE_REGS and SSE_REGS
Creating newreg=4778 from oldreg=1801, assigning class ALL_SSE_REGS to
inheritance r4778
Original reg change 1801->4778 (bb177):
10920: r4709:DF=r4778:DF
Add inheritance<-original before:
10995: r4778:DF=r1801:DF
Inheritance reuse change 1801->4778 (bb177):
10019: r3911:DF=r4778:DF
REG_DEAD r4778:DF
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
Use smallest class of ALL_SSE_REGS and SSE_REGS
Creating newreg=4779 from oldreg=1801, assigning class ALL_SSE_REGS to
inheritance r4779
Original reg change 1801->4779 (bb177):
! 10919: r4708:DF=r4779:DF
Add inheritance<-original before:
10996: r4779:DF=r1801:DF
Inheritance reuse change 1801->4779 (bb177):
10995: r4778:DF=r4779:DF
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
********** Assignment #2: **********
Assigning to 4779 (cl=ALL_SSE_REGS, orig=1801, freq=18, tfirst=4707,
tfreq=36)...
Assigning to 4778 (cl=ALL_SSE_REGS, orig=1801, freq=18, tfirst=4707,
tfreq=36)...
Assigning to 4780 (cl=ALL_SSE_REGS, orig=1801, freq=18, tfirst=4707,
tfreq=36)...
Assign 26 to inheritance r4780 (freq=18)
Reassigning non-reload pseudos
Assign 4 to r237 (freq=26)
Assign 26 to inheritance r4778 (freq=18)
! Hard reg 26 is preferable by r4779 with profit 24
Assign 26 to inheritance r4779 (freq=18)
We assigned 26 for conflicting 4779 and 4707 because they have the same value
1802 (from r1801).
4707 got the same value as 1801 because LRA sees wrong (REG_DEAD r1801:DF) in
insn 1804. In most cases LRA uses live-ranges but in constraint sub-pass it
can use reg notes too.
Live ranges and reg notes should be synchronized but in this case we did not
update notes after
first inheritance sub-pass although there were some changes there too.
I working on a patch. If the tests are ok, I commit the patch today.
