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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165367 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bob Wilson 2012-10-07 01:11:19 +00:00
parent af63f0b6dc
commit c38b636e6e

View File

@ -142,6 +142,7 @@ public:
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 @@ InlineCost InlineCostAnalyzer::getInlineCost(CallSite CS, Function *Callee,
// 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());