pow is transformed to exp2 if the target doesn't have exp2

[llvmbot]

Bugzilla Link	8943
Resolution	WORKSFORME
Resolved on	Mar 03, 2014 04:45
Version	trunk
OS	Windows NT
Blocks	#7187
Reporter	LLVM Bugzilla Contributor
CC	@AaronBallman,@lattner

Extended Description

I got undefined reference to `exp2' from this line of code:

r->f = a->f * pow(2., n.f);

exp2 doesn't seem to be in the C89 standard, so this transformation is a bug most likely.

[lattner]

Whether the compiler is run in gnu89 mode or not doesn't matter here. This is only a bug if the target doesn't have the exp2 function.

[lattner]

BTW, exp2 is C99.

[lattner]

We have a new TargetLibraryInfo interface which is designed to solve this sort of thing, if you're interested.

[AaronBallman]

I can't seem to reproduce on ToT, but may be testing something different than you -- is this still an issue? If so, can you attach some steps to reproduce?

[AaronBallman]

Still appears to be working on ToT, and no new steps to reproduce in past three months.

[llvmbot]

I just tried with:
clang version 3.5 (202644)
Target: i686-pc-mingw32
Thread model: posix

And got:

base/applications/calc/CMakeFiles/calc.dir/rpn.c.obj: In function rpn_shl_f': e:/reactos/base/applications/calc/rpn.c:177: undefined reference to exp2'

http://git.reactos.org/?p=reactos.git;a=blob;f=reactos/base/applications/calc/rpn.c;h=ccbf171ba772eb8467739917363ac0e940d6d050;hb=HEAD#l177

[lattner]

mentioned in issue llvm/llvm-bugzilla-archive#9315