https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96347
--- Comment #2 from Iain Buclaw <ibuclaw at gdcproject dot org> ---
Possibly some useful information for context.
At expand_expr_real_1 (expr.c:10567) there is the following expression.
---
MEM <int *> [(struct Darray *)&testYearsBC + 8B]
---
Lowered to RTL as
---
(plus:DI (unspec:DI [
(const_int 0 [0])
] UNSPEC_TP)
(const:DI (plus:DI (unspec:DI [
(symbol_ref:DI ("testYearsBC") [flags 0x2a] <var_decl
0x7ffff7fa2bd0 testYearsBC>)
] UNSPEC_NTPOFF)
(const_int 8 [0x8]))))
---
At break_out_memory_refs (explow.c:277) the rhs of the plus expression is
forced into a register.
---
(insn 18 17 0 (set (reg:DI 89)
(const:DI (plus:DI (unspec:DI [
(symbol_ref:DI ("testYearsBC") [flags 0x2a] <var_decl
0x7ffff7fa2bd0 testYearsBC>)
] UNSPEC_NTPOFF)
(const_int 8 [0x8])))) -1
(nil))
(mem/f/c:DI (plus:DI (unspec:DI [
(const_int 0 [0])
] UNSPEC_TP)
(reg:DI 89)) [1 MEM <int *> [(struct Darray *)&testYearsBC + 8B]+0 S8
A64])
---
And it is the second insn that reaches const_ok_for_output_1() at
mem_loc_descriptor (dwarf2out.c:15748)
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(note 133 132 163 3 (var_location year (mem:SI (mem/f/c:DI (plus:DI (unspec:DI
[
(const_int 0 [0])
] UNSPEC_TP)
(reg/f:DI 6 bp [90])) [1 MEM <int *> [(struct Darray *)&testYearsBC
+ 8B]+0 S8 A64]) [6 *rs$pt
r_5+0 S4 A32])) NOTE_INSN_VAR_LOCATION)
---
