https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100483
Bug ID: 100483
Summary: Extend -fno-semantic-interposition to global variables
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: i at maskray dot me
Target Milestone: ---
% cat a.c
int var;
int foo() { return var; }
(I implemented this for clang 11 x86)
% clang -fpic -fno-semantic-interposition -O2 -S a.c
% cat a.s
...
foo: # @foo
.Lfoo$local:
# %bb.0: # %entry
movl .Lvar$local(%rip), %eax
retq
...
var:
.Lvar$local:
.long 0 # 0x0
.size var, 4
# On x86-64, because of R_X86_64_REX_GOTPCRELX, it isn't too bad without the
optimization.
# This is more useful on other architectures without GOT optimization.
# With my clang patch https://reviews.llvm.org/D101873
% clang -target aarch64 -fpic -fno-semantic-interposition
-fno-asynchronous-unwind-tables -O2 -S a.c
% cat a.s
...
foo: // @foo
.Lfoo$local:
// %bb.0: // %entry
adrp x8, .Lvar$local
ldr w0, [x8, :lo12:.Lvar$local]
ret
