LLVM inliner not run at -O2

[lattner]

Bugzilla Link	2244
Resolution	FIXED
Resolved on	Apr 21, 2008 03:27
Version	2.2
OS	All

Extended Description

This trivial function isn't inlined at -O2:

void factorial(int a, int* b) {
*b = a + 1;
}
int main() {
int a = 4;
int b;
factorial(a,&b);
return b;
}

The reason is this code in llvm-backend.cpp:

if (optimize > 1) {
  if (flag_inline_trees > 1)                // respect -fno-inline-functions
    PM->add(createFunctionInliningPass());  // Inline small functions

At -O2, flag_inline_trees is equal to 1, so this is not run.

[llvmbot]

gcc runs pass_early_ipa_inline when

flag_inline_trees && flag_early_inlining

It runs pass_ipa_inline when

flag_inline_trees

So I think we should not pay any attention to the -O level
and just do the same.

[llvmbot]

Fixed here:
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20080421/061359.html