https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69030
--- Comment #4 from Vladimir Makarov <vmakarov at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #3)
> Note, before *.ira the pseudo 93 set by the movsicc is actually used by
> another insn, but that is removed early in the ira pass during
> delete_trivially_dead_insns. But for some reason the if_then_else is not
> removed as trivially dead, and even if it would, nothing recomputes the lr
> problem (or is that live) that would adjust or reset the debug insns that
> are refering the pseudos that are not live anymore.
Jakub, you gave the right analysis. Thanks. We have the following code
situation (see below). Although fixing delete_trivially_dead_insns
will not fix the problem, as the troubled debug insn 24 from block
different from one of insn 121 still will stay. I am working on the
problem and hope to have a fix by Monday.
BB3:
17: {r138:SI=r138:SI^r91:SI;clobber flags:CC;}
REG_UNUSED flags:CC
Inserting insn reload before:
145: r138:SI=r90:SI
Inserting insn reload after:
146: r93:SI=r138:SI
18: debug_insn h=> 93
Creating newreg=139 from oldreg=114, assigning class AREG to r139
20: {r139:SI=udiv(r139:SI,r91:SI);r115:SI=umod(r139:SI,r91:SI);clobber
flags:CC;}
REG_UNUSED r115:SI
REG_UNUSED flags:CC
Inserting insn reload before:
147: r139:SI=r93:SI
Inserting insn reload after:
148: r114:SI=r139:SI
24: debug_insn h=> ...93
BB6:
Creating newreg=142 from oldreg=135, assigning class GENERAL_REGS to r142
Creating newreg=143 from oldreg=93, assigning class GENERAL_REGS to r143
Making reload reg 143 for reg 93 optional
121: r142:SI={(flags:CCZ==0)?r143:SI:r142:SI}
REG_DEAD r135:SI
REG_DEAD flags:CCZ
REG_UNUSED r93:SI
REG_EQUAL {(flags:CCZ==0)?r93:SI:0}
Inserting insn reload before:
152: r142:SI=r135:SI
153: r143:SI=r93:SI
---
BB6:
Insn 153: point = 25
Deleting dead insn 153
r93 is removed as live at bb6 start
---
BB3:
Creating newreg=147 from oldreg=93, assigning class GENERAL_REGS to
inheritance r147
Original reg change 93->147 (bb3):
146: r147:SI=r138:SI
REG_DEAD r138:SI
Add original<-inheritance after:
157: r93:SI=r147:SI
Inheritance reuse change 93->147 (bb3):
18: debug h => r147:SI
Inheritance reuse change 93->147 (bb3):
147: r139:SI=r147:SI
REG_DEAD r147:SI
Removing dead insn:
157: r93:SI=r147:SI
