[llvm-bugs] [Bug 149335] [RISC-V] Miscompile at -O[23]

[LLVM Bugs via llvm-bugs]

Issue	149335
Summary	[RISC-V] Miscompile at -O[23]
Labels	new issue
Assignees
Reporter	ewlu

    Testcase:
```c
unsigned short a[10];
void b(short c, short i[]) {
  for (short k = 1; k < 9; k += 2)
    a[k] = c ? i[k] : i[k + 1];
}
long long m;
short c;
short i[10];
void checksum() {
  for (int k = 0; k < 10; ++k)
    m ^= a[k] + (m < 6) + (m > 2);
}
int main() {
  for (int k = 0; k < 10; ++k)
    a[k] = 3;
  b(c, i);
 checksum();
  __builtin_printf("%llu\n", m);
}
```

Commands
```
# -O3
$ /scratch/ewlu/daily-upstream-build/build-gcv/bin/clang -march=rv64gcv -O3 red.c -o user-config.out -fsigned-char -fno-strict-aliasing -fwrapv 
$ QEMU_CPU=rv64,vlen=128,rvv_ta_all_1s=true,rvv_ma_all_1s=true,v=true,vext_spec=v1.0,zve32f=true,zve64f=true timeout --verbose -k 0.1 4 /scratch/ewlu/daily-upstream-build/build-gcv/bin/qemu-riscv64 user-config.out 1
65541

# -O2
$ /scratch/ewlu/daily-upstream-build/build-gcv/bin/clang -march=rv64gcv -O2 red.c -o user-config.out -fsigned-char -fno-strict-aliasing -fwrapv 
$ QEMU_CPU=rv64,vlen=128,rvv_ta_all_1s=true,rvv_ma_all_1s=true,v=true,vext_spec=v1.0,zve32f=true,zve64f=true timeout --verbose -k 0.1 4 /scratch/ewlu/daily-upstream-build/build-gcv/bin/qemu-riscv64 user-config.out 1
65541

# -O1
$ /scratch/ewlu/daily-upstream-build/build-gcv/bin/clang -march=rv64gcv -O1 red.c -o user-config.out -fsigned-char -fno-strict-aliasing -fwrapv 
$ QEMU_CPU=rv64,vlen=128,rvv_ta_all_1s=true,rvv_ma_all_1s=true,v=true,vext_spec=v1.0,zve32f=true,zve64f=true timeout --verbose -k 0.1 4 /scratch/ewlu/daily-upstream-build/build-gcv/bin/qemu-riscv64 user-config.out 1
0
```

Bisected to 60ad6e3fa45c03dc1fc7521ead7583a9a7d9fb61 as the first bad commit.

Found via fuzzer

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