https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119360
Bug ID: 119360
Summary: incomplete folding of initializers leads to dynamic
initialization
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: nathan at gcc dot gnu.org
Target Milestone: ---
Created attachment 60812
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=60812&action=edit
reproducer
compiling as
g++ -O2
results in static initialization and folding. Compilng as
g++ -O2 -DBUG
results in dynamic init for BAR, but static init for FOO:
_GLOBAL__sub_I__Z3foov:
movq $16, _ZL3BAR(%rip)
ret
_Z3foov:
movl 16, %eax
ret
_Z3barv:
movq _ZL3BAR(%rip), %rax
movl (%rax), %eax
ret
The problem is that we end up n initializer_constant_valid_p (varasm.cc), which
I think expects fully folded expressions. When analyzing BAR's initializer it
recurses into FOO's DECL_INITIAL, which is essentially (+ 16 (* 16 0)), and
because of the multiplier thinks it's not suitable for a constant init. For
some reason we don't make that mistake with FOO itself.
I suspect we need to store a more folded initializer in DECL_INITIAL?
The original code had the multiplier as 2, not zero BTW.
