SimplfyLibCalls should inline calls to abs

[efriedma-quic]

Bugzilla Link	2337
Resolution	FIXED
Resolved on	Jun 09, 2008 03:28
Version	unspecified
OS	Linux
CC	@asl

Extended Description

Per description, SimplfyLibCalls should simplify calls to abs. This isn't necessary for llvm-gcc, but it is useful for compilers that aren't clever enough to fold calls to abs, like clang.

Simple testcase (in clang):
int a(int x) {return abs(x);}

This does bring up an interesting side-issue: can LLVM simplify calls to llabs? llabs, as far as I can tell, only became a reserved external identifier in C99.

[lattner]

I agree simplifylibcalls should do this. I'm fine with unconditionally doing llabs. If someone has a system where llabs isn't supported, they can come up with an approach to conditionalize it :)

[lattner]

Hrm. What should abs be inlined into? abs isn't inlined on darwin/x86, it is handled in the code generator.

[lattner]

Nevermind, I was thinking of fabs, not abs.

[lattner]

Implemented, patch here:
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20080609/063514.html