[Bug rtl-optimization/99863] [10/11 Regression] wrong code with -O -fno-tree-forwprop -mno-sse2 since r10-7268-g529ea7d9596b26ba

["jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99863

--- Comment #12 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Ah, I see the actual problem.  replace_read checks the hard regs in the insn
sequence and compares them to the live hard regs at the point of the read_insn,
in the testcase insn 134 after the CC setter 6 and CC users 7 and 40.
CC is not live on the insn 134.
But we emit that sequence elsewhere:
2076          /* Insert this right before the store insn where it will be safe
2077             from later insns that might change it before the read.  */
2078          emit_insn_before (insns, store_insn->insn);
and store_insn->insn in this case is insn 19, which is in between insn 7 and
40, and CC is live there.
So, I think we need to do this live hard regs testing in record_store instead
or in addition to.
We already call get_stored_val there just for testing purposes and throw it
away afterwards.