opt-report-results.md

Notes:

All optimization reports were obtained using `icc -opt-report 3` 
with the default optimization level(2).

Case 1

for (i = 0; i < 10; i++) {
  c[i] = a[i] + b[i];
  a[i] = c[i] + b[i];
}

With instrumentation

• method being instrumented is inlined.
• instrumentation methods are being inlined to multiple levels.
• loop was not vectorized: nonstandard loop is not a vectorization candidate
• Forward substitution happened here. Probably in instrumentation functions.

Without instrumentation

• Loop was vectorized.
• No forward substitution
• Modification and Reference Analysis is different.

Conclusions:

• Optimizations Inhibited: Vectorization
• MOD-REF Analysis(Different) -> Interprocedural Analysis

---

Case 2:

for (i = 0; i < 10; i++) {
  c[i] = (a[i] + b[i]);
}

loop was not vectorized: nonstandard loop is not a vectorization candidate. Instrumentation methods are getting inlined.

Optimizations Inhibited: Vectorization. MODREF analysis is different.

---

case 3

for(int i=0; i<n; ++i)
  a[i] = b[0];

No vectorization in either case.

MODREF analysis different