weird fuzz bug

input.txt

24
46
40
41

linux results

$ ~/Dev/clang+llvm-3.2-x86-linux-ubuntu-12.04/bin/clang -O0 t245.c ; ./a.out 
res = 1146
$ ~/Dev/clang+llvm-3.2-x86-linux-ubuntu-12.04/bin/clang -O2 t245.c ; ./a.out 
res = 335544632
$ ~/Dev/emscripten/emcc -O2 t245.c --embed-file input.txt ; node a.out.js
res = 335544632

that is on linux. on mac, a report says clang -O2 gives the same
result as -O0, and only emcc -O2 is wrong. all tests are on
LLVM 3.2 release.

t245.c

//
//   t245.c
//   Generated by Moh's fuzzer on Fri Jun 21 22:42:39 2013
//
//   Intel Corporation
//

#include <stdio.h>

#define N 100
#define CS(a,n) checkSum((unsigned int*) a, n)
#define INIT(a,n,s) init((unsigned int*) a, n, s)

void init (unsigned int a[], unsigned int n, int seed)
{
    unsigned int j;

    for (j = 0; j < n; j++) {
        a[j] = ((j % 2 == 0) ? seed+j : seed-j) % 101;
    }
}

unsigned int checkSum (unsigned int a[], unsigned int n)
{
    unsigned int j, sum;

    sum = 0;
    for (j = 0; j < n; j++) {
        sum += ((j % 2 == 0) ? a[j] : -a[j]);
    }
    return sum;
}

int main()
{
    FILE* INPUT = fopen ("input.txt", "r");

    unsigned int ko=24, iq=46, k9=40, jm=41, res=31;

    unsigned int er[N];

    unsigned int *pm=&ko;

    INIT (er, N, 90);

    fscanf (INPUT, "%u %u %u %u", &ko, &iq, &k9, &jm);

    ko = -(er[96]);

    if (er[70] <= er[80]) {

        for (iq = 1; iq < 44; ++iq) {
        }

        *pm += *pm;
    }


    // Test Loop Fusion
    for (k9 = 2; k9 < 54; k9++) {
    }
    for (jm = 2; jm < 54; jm++) {

        // Test Pointer Intensiveness
        *pm = ko - k9;
        pm = &er[jm+1];
        *pm = er[jm-1];
        pm = &er[jm];
        *pm += er[jm+1];
        *pm += *pm;

    }


    res  = ko;
    res += CS (er, N);

    printf ("res = %u\n", res);

    return 0;
}