https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99748
Bug ID: 99748
Summary: MVE: Wrong code at -O0 with float to integer
conversion
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: acoplan at gcc dot gnu.org
Target Milestone: ---
GCC miscompiles the following testcase:
int main() {
float a = 1.0f;
return (int)a != 1;
}
with -march=armv8.1-m.main+mve -mfloat-abi=hard. The program should return 0
but returns 1 when compiled with these options. Looking at the generated code:
main:
@ args = 0, pretend = 0, frame = 8
@ frame_needed = 1, uses_anonymous_args = 0
push {r7, lr}
sub sp, sp, #8
add r7, sp, #0
mov r3, #1065353216
str r3, [r7, #4] @ float
vldr.32 s0, [r7, #4]
bl __aeabi_f2iz
mov r3, r0
cmp r3, #1
ite ne
movne r3, #1
moveq r3, #0
uxtb r3, r3
mov r0, r3
adds r7, r7, #8
mov sp, r7
@ sp needed
pop {r7, pc}
.size main, .-main
we use the aeabi_f2iz libcall to do the float to integer conversion, passing
the argument in the s0 (VFP) register. However, looking at the implementation
of aeabi_f2iz in libgcc/config/arm/ieee754-sf.S, the function appears to be
expecting its argument in the GPR r0. So we do the conversion on whatever
happens to be in r0 when the libcall is made.
