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* [[Optimization Topics/Exercise 03|Exercises 03]] | * [[Optimization Topics/Exercise 03|Exercises 03]] | ||
* [[Optimization Topics/Exercise 04|Exercises 04]] | * [[Optimization Topics/Exercise 04|Exercises 04]] | ||
+ | * [[Optimization Topics/Exercise 05|Exercises 05]] | ||
+ | * [[Optimization Topics/Exercise 06|Exercises 06]] | ||
[[category:Compiladores]] | [[category:Compiladores]] | ||
[[category:Ensino]] | [[category:Ensino]] |
Instruction sequence where control flow starts at the first instruction and ends at the last, without jumps (except at the last instruction).
Transformations in a basic block maintain the block semantics (considered as an atomic entity).
Direct evaluation of expressions using only literal and known values:
int *x = (int *)malloc(1024 * 4); int y = 3; int z = 20 * y + 10;
Becomes:
int *x = (int *)malloc(4096); int y = 3; int z = 70;
Using temporary variables to store common results:
d = c * (a + b) e = (a + b) / 2
Becomes:
t = a + b d = c * t e = t / 2
for (i = 1; i < n; i++) a[i] = b[i] + 10;
Becomes:
for (i = 1; i < (n/4)*4; i+=4) { a[i] = b[i] + 10; a[i+1] = b[i+1] + 10; a[i+2] = b[i+2] + 10; a[i+3] = b[i+3] + 10; } // rest of the cycle for (; i < n; i++) a[i] = b[i] + 10;
for (i = 1; i < n; i++) { a[i] = b[i] + c * d; e = g[k]; }
Becomes:
t = c * d; for (i = 1; i < n; i++) { a[i] = b[i] + t; } e = g[k];
for (i = 1; i < n; i++) k = i * 4 + m;
Becomes:
k = m; for (i = 1; i < n; i++) k = k + 4;
xor eax,eax
instead of
mov 0,eax
x << 2 + x
instead of
x * 5
Reorder independent instructions in order to avoid register spilling.