The current tests in iv-select-cmp.ll are not representative of clang

output of common real-world C programs, which are often written with i32

induction vars, as opposed to i64 induction vars. Hence, add five tests

corresponding to the following programs:

int test(int *a, int n) { int rdx = 331; for (int i = 0; i < n; i++) { if (a[i] > 3) rdx = i; } return rdx; } int test(int *a) { int rdx = 331; for (int i = 0; i < 20000; i++) { if (a[i] > 3) rdx = i; } return rdx; } int test(int *a, long n) { int rdx = 331; for (int i = 0; i < n; i++) { if (a[i] > 3) rdx = i; } return rdx; } int test(int *a, unsigned n) { int rdx = 331; for (int i = 0; i < n; i++) { if (a[i] > 3) rdx = i; } return rdx; } int test(int *a) { int rdx = 331; for (long i = INT_MIN - 1; i < UINT_MAX; i++) { if (a[i] > 3) rdx = i; } return rdx; }

The first two can theoretically be vectorized without a runtime-check,

while the third and fourth cannot. The fifth cannot be vectorized, even

with a runtime-check.

This issue was found while reviewing D150851.

nit: define i32 @select_icmp_const_truncated_iv(ptr nocapture readonly %a, i32 %n) {