[llvm-commits] [llvm] r165367 - /llvm/trunk/lib/Analysis/InlineCost.cpp

[Nick Lewycky]

Bob Wilson wrote:
> Author: bwilson
> Date: Sat Oct  6 20:11:19 2012
> New Revision: 165367
>
> URL: http://llvm.org/viewvc/llvm-project?rev=165367&view=rev
> Log:
> Make sure always-inline functions get inlined.<rdar://problem/12423986>
>
> Without this change, when the estimated cost for inlining a function with
> an "alwaysinline" attribute was lower than the inlining threshold, the
> getInlineCost function was returning that estimated cost rather than the
> special InlineCost::AlwaysInlineCost value. That is fine in the normal
> inlining case, but it can fail when the inliner considers the opportunity
> cost of inlining into an internal or linkonce-odr function. It may decide
> not to inline the always-inline function in that case. The fix here is just
> to make getInlineCost always return the special value for always-inline
> functions. I ran into this building clang with libc++. Tablegen failed to
> link because of an always-inline function that was not inlined. I have been
> unable to reduce the testcase down to a reasonable size.

I don't think this patch is correct. There's an -always-inline pass 
which shouldn't reach this code in InlineCost at all. Why didn't that 
kick in?

Nick

> Modified:
>      llvm/trunk/lib/Analysis/InlineCost.cpp
>
> Modified: llvm/trunk/lib/Analysis/InlineCost.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/InlineCost.cpp?rev=165367&r1=165366&r2=165367&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Analysis/InlineCost.cpp (original)
> +++ llvm/trunk/lib/Analysis/InlineCost.cpp Sat Oct  6 20:11:19 2012
> @@ -142,6 +142,7 @@
>
>     int getThreshold() { return Threshold; }
>     int getCost() { return Cost; }
> +  bool isAlwaysInline() { return AlwaysInline; }
>
>     // Keep a bunch of stats about the cost savings found so we can print them
>     // out when debugging.
> @@ -1057,7 +1058,8 @@
>     // Check if there was a reason to force inlining or no inlining.
>     if (!ShouldInline&&  CA.getCost()<  CA.getThreshold())
>       return InlineCost::getNever();
> -  if (ShouldInline&&  CA.getCost()>= CA.getThreshold())
> +  if (ShouldInline&&  (CA.isAlwaysInline() ||
> +                       CA.getCost()>= CA.getThreshold()))
>       return InlineCost::getAlways();
>
>     return llvm::InlineCost::get(CA.getCost(), CA.getThreshold());
>
>
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