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Examples of loop hoisting (LICM)
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#include <stddef.h> | |
// TODO(dannas): Find examples of loop hoisting. WIP | |
// https://godbolt.org/z/YWf5c7 | |
// baseline | |
void f1(int a[], size_t N) { | |
for (size_t i = 0; i < N; i++) { | |
a[i] = i; | |
} | |
} | |
// Mult strength-reduced to shift | |
void f2(int a[], size_t N) { | |
for (size_t i = 0; i < N; i++) { | |
a[i] = i*2; | |
} | |
} | |
// x is hoisted outside the loop | |
void f3(int a[], size_t N) { | |
for (size_t i = 0; i < N; i++) { | |
int x = N*N; | |
a[i] = x + i; | |
} | |
} | |
// N*N is hoisted outside the loop | |
void f4(int a[], size_t N) { | |
for (size_t i = 0; i < N*N; i++) { | |
a[i] = i; | |
} | |
} | |
// Was hoping for loop unswitching, but doesn't happen | |
void f5(int a[], size_t N, int x) { | |
for (size_t i = 0; i < N; i++) { | |
if (x) { | |
a[i] = i; | |
} | |
} | |
} |
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