https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110516
Bug ID: 110516
Summary: core.volatile.volatileLoad is broken
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: d
Assignee: ibuclaw at gdcproject dot org
Reporter: witold.baryluk+gcc at gmail dot com
Target Milestone: ---
gcc 12.2.0 (from Debian stable) and gcc trunk 14.0.0 (in godbolt) tested.
core.volatile.volatileLoad simply does not work.
1) It merges loads.
2) It removes unused loads at -O1 and higher.
Example:
void actualRun(ubyte* ptr1) {
import core.volatile : volatileLoad;
volatileLoad(ptr1);
volatileLoad(ptr1);
volatileLoad(ptr1);
volatileLoad(ptr1);
}
Without optimisations:
void example.actualRun(ubyte*):
push rbp
mov rbp, rsp
mov QWORD PTR [rbp-8], rdi
nop
pop rbp
ret
Incorrect.
With optimisations:
void example.actualRun(ubyte*):
ret
Incorrect.
Expected:
void example.actualRun(ubyte*):
movzx eax, byte ptr [rdi]
movzx eax, byte ptr [rdi]
movzx eax, byte ptr [rdi]
movzx eax, byte ptr [rdi]
ret
dmd and ldc behave properly.
It looks like it never worked properly.
Would be good to have a test case for this, so it does not become a regression
later.
I did not test volatileStore, but I would not be surprised it is also broken.
