CODEWITHSUNDEEP
gccmicro-optimization
user877329
user877329

Reputation: 6200

Does GCC have a conventional "likely" path

You can hint give GCC hints about the likelihood of a particular branch taken by using __builtin_expect. Without that, does it have any default assumptions. That is, will code like

if(error) { /*unlikely path*/ return FAILURE;}
return SUCCESS;

perform better/worse than

if(!error) {/*likely path*/ return SUCCESS;}
return FAILURE;

Upvotes: 1

Views: 46

Answers (1)

Thomas Lang
Thomas Lang

Reputation: 780

As any modern compiler, gcc will also perform code analysis. If the code analysis yields any useable / provable information, it chooses some optimization (cf. basic block reordering). gcc will at least perform static code analysis, while clang (maybe using extensions) will also analyze the execution flow graph.

Upvotes: 1

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