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/AsmParser/LLLexer.cpp b/lib/AsmParser/LLLexer.cpp
index 2a926d2..8ad658d 100644
--- a/lib/AsmParser/LLLexer.cpp
+++ b/lib/AsmParser/LLLexer.cpp
@@ -558,6 +558,7 @@
KEYWORD(readnone);
KEYWORD(readonly);
+ KEYWORD(inlinehint);
KEYWORD(noinline);
KEYWORD(alwaysinline);
KEYWORD(optsize);
diff --git a/lib/AsmParser/LLParser.cpp b/lib/AsmParser/LLParser.cpp
index ed74301..5dd6569 100644
--- a/lib/AsmParser/LLParser.cpp
+++ b/lib/AsmParser/LLParser.cpp
@@ -947,6 +947,7 @@
case lltok::kw_noinline: Attrs |= Attribute::NoInline; break;
case lltok::kw_readnone: Attrs |= Attribute::ReadNone; break;
case lltok::kw_readonly: Attrs |= Attribute::ReadOnly; break;
+ case lltok::kw_inlinehint: Attrs |= Attribute::InlineHint; break;
case lltok::kw_alwaysinline: Attrs |= Attribute::AlwaysInline; break;
case lltok::kw_optsize: Attrs |= Attribute::OptimizeForSize; break;
case lltok::kw_ssp: Attrs |= Attribute::StackProtect; break;
diff --git a/lib/AsmParser/LLToken.h b/lib/AsmParser/LLToken.h
index 80eb194..7f1807c 100644
--- a/lib/AsmParser/LLToken.h
+++ b/lib/AsmParser/LLToken.h
@@ -85,6 +85,7 @@
kw_readnone,
kw_readonly,
+ kw_inlinehint,
kw_noinline,
kw_alwaysinline,
kw_optsize,
diff --git a/lib/Target/CppBackend/CPPBackend.cpp b/lib/Target/CppBackend/CPPBackend.cpp
index 4f3f004..3dd8ca7 100644
--- a/lib/Target/CppBackend/CPPBackend.cpp
+++ b/lib/Target/CppBackend/CPPBackend.cpp
@@ -470,6 +470,7 @@
HANDLE_ATTR(Nest);
HANDLE_ATTR(ReadNone);
HANDLE_ATTR(ReadOnly);
+ HANDLE_ATTR(InlineHint);
HANDLE_ATTR(NoInline);
HANDLE_ATTR(AlwaysInline);
HANDLE_ATTR(OptimizeForSize);
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))
diff --git a/lib/VMCore/Attributes.cpp b/lib/VMCore/Attributes.cpp
index 65155f1..a371c6f 100644
--- a/lib/VMCore/Attributes.cpp
+++ b/lib/VMCore/Attributes.cpp
@@ -56,6 +56,8 @@
Result += "optsize ";
if (Attrs & Attribute::NoInline)
Result += "noinline ";
+ if (Attrs & Attribute::InlineHint)
+ Result += "inlinehint ";
if (Attrs & Attribute::AlwaysInline)
Result += "alwaysinline ";
if (Attrs & Attribute::StackProtect)