https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116149
Bug ID: 116149
Summary: RISC-V: Miscompile at -O3 with zvl256b
-mrvv-vector-bits=zvl
Product: gcc
Version: 15.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: patrick at rivosinc dot com
Target Milestone: ---
Testcase:
long a;
short b[60000];
short c[20];
int main() {
for (short d = 0; d < 20; d += 3) {
c[d] = 0;
for (int e = 0; e < 20; e += 2)
for (int f = 1; f < 20; f += 2)
a += (unsigned)b[f + e];
}
__builtin_printf("%lu\n", a);
}
Commands:
> /scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/bin/riscv64-unknown-linux-gnu-gcc
> -march=rv64gcv_zvl256b -O3 -mrvv-vector-bits=zvl red.c -o red.out
> QEMU_CPU=rv64,vlen=256,rvv_ta_all_1s=true,v=true,vext_spec=v1.0,zve32f=true,zve64f=true
> timeout --verbose -k 0.1 4
> /scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/bin/qemu-riscv64 red.out
18446744073709551613
> /scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/bin/riscv64-unknown-linux-gnu-gcc
> -march=rv64gcv_zvl256b -O2 -mrvv-vector-bits=zvl red.c -o red.out
> QEMU_CPU=rv64,vlen=256,rvv_ta_all_1s=true,v=true,vext_spec=v1.0,zve32f=true,zve64f=true
> timeout --verbose -k 0.1 4
> /scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/bin/qemu-riscv64 red.out
0
Still present when rvv_ta_all_1s=true is omitted.
Found via fuzzer
