Reintroduce the InlineHint function attribute.
This time it's for real! I am going to hook this up in the frontends as well.
The inliner has some experimental heuristics for dealing with the inline hint.
When given a -respect-inlinehint option, functions marked with the inline
keyword are given a threshold just above the default for -O3.
We need some experiments to determine if that is the right thing to do.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95466 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/IPO/Inliner.cpp b/lib/Transforms/IPO/Inliner.cpp
index 55cc536..97e2f06 100644
--- a/lib/Transforms/IPO/Inliner.cpp
+++ b/lib/Transforms/IPO/Inliner.cpp
@@ -41,6 +41,16 @@
InlineLimit("inline-threshold", cl::Hidden, cl::init(225), cl::ZeroOrMore,
cl::desc("Control the amount of inlining to perform (default = 225)"));
+static cl::opt<bool>
+RespectHint("respect-inlinehint", cl::Hidden,
+ cl::desc("Respect the inlinehint attribute"));
+
+// Threshold to use when inlinehint is given.
+const int HintThreshold = 300;
+
+// Threshold to use when optsize is specified (and there is no -inline-limit).
+const int OptSizeThreshold = 75;
+
Inliner::Inliner(void *ID)
: CallGraphSCCPass(ID), InlineThreshold(InlineLimit) {}
@@ -172,13 +182,21 @@
return true;
}
-unsigned Inliner::getInlineThreshold(Function* Caller) const {
+unsigned Inliner::getInlineThreshold(CallSite CS) const {
+ // Listen to inlinehint when -respect-inlinehint is given.
+ Function *Callee = CS.getCalledFunction();
+ if (RespectHint && Callee && !Callee->isDeclaration() &&
+ Callee->hasFnAttr(Attribute::InlineHint))
+ return HintThreshold;
+
+ // Listen to optsize when -inline-limit is not given.
+ Function *Caller = CS.getCaller();
if (Caller && !Caller->isDeclaration() &&
Caller->hasFnAttr(Attribute::OptimizeForSize) &&
InlineLimit.getNumOccurrences() == 0)
- return 75;
- else
- return InlineThreshold;
+ return OptSizeThreshold;
+
+ return InlineThreshold;
}
/// shouldInline - Return true if the inliner should attempt to inline
@@ -200,7 +218,7 @@
int Cost = IC.getValue();
Function *Caller = CS.getCaller();
- int CurrentThreshold = getInlineThreshold(Caller);
+ int CurrentThreshold = getInlineThreshold(CS);
float FudgeFactor = getInlineFudgeFactor(CS);
if (Cost >= (int)(CurrentThreshold * FudgeFactor)) {
DEBUG(dbgs() << " NOT Inlining: cost=" << Cost
@@ -236,8 +254,7 @@
outerCallsFound = true;
int Cost2 = IC2.getValue();
- Function *Caller2 = CS2.getCaller();
- int CurrentThreshold2 = getInlineThreshold(Caller2);
+ int CurrentThreshold2 = getInlineThreshold(CS2);
float FudgeFactor2 = getInlineFudgeFactor(CS2);
if (Cost2 >= (int)(CurrentThreshold2 * FudgeFactor2))