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/bindings/ocaml/llvm/llvm.ml b/bindings/ocaml/llvm/llvm.ml
index 4539098..7e4acbf 100644
--- a/bindings/ocaml/llvm/llvm.ml
+++ b/bindings/ocaml/llvm/llvm.ml
@@ -93,6 +93,7 @@
| Noredzone
| Noimplicitfloat
| Naked
+ | Inlinehint
end
module Icmp = struct
diff --git a/bindings/ocaml/llvm/llvm.mli b/bindings/ocaml/llvm/llvm.mli
index 719df43..bcdcb2c 100644
--- a/bindings/ocaml/llvm/llvm.mli
+++ b/bindings/ocaml/llvm/llvm.mli
@@ -143,6 +143,7 @@
| Noredzone
| Noimplicitfloat
| Naked
+ | Inlinehint
end
(** The predicate for an integer comparison ([icmp]) instruction.
diff --git a/docs/LangRef.html b/docs/LangRef.html
index c028f6b..fed2f80 100644
--- a/docs/LangRef.html
+++ b/docs/LangRef.html
@@ -1083,6 +1083,11 @@
function into callers whenever possible, ignoring any active inlining size
threshold for this caller.</dd>
+ <dt><tt><b>inlinehint</b></tt></dt>
+ <dd>This attribute indicates that the source code contained a hint that inlining
+ this function is desirable (such as the "inline" keyword in C/C++). It
+ is just a hint; it imposes no requirements on the inliner.</dd>
+
<dt><tt><b>noinline</b></tt></dt>
<dd>This attribute indicates that the inliner should never inline this
function in any situation. This attribute may not be used together with
diff --git a/include/llvm-c/Core.h b/include/llvm-c/Core.h
index 674dde5..98358fe 100644
--- a/include/llvm-c/Core.h
+++ b/include/llvm-c/Core.h
@@ -118,7 +118,8 @@
LLVMNoCaptureAttribute = 1<<21,
LLVMNoRedZoneAttribute = 1<<22,
LLVMNoImplicitFloatAttribute = 1<<23,
- LLVMNakedAttribute = 1<<24
+ LLVMNakedAttribute = 1<<24,
+ LLVMInlineHintAttribute = 1<<25
} LLVMAttribute;
typedef enum {
diff --git a/include/llvm/Attributes.h b/include/llvm/Attributes.h
index 7fa5d4a..068f81f 100644
--- a/include/llvm/Attributes.h
+++ b/include/llvm/Attributes.h
@@ -58,6 +58,8 @@
const Attributes NoImplicitFloat = 1<<23; /// disable implicit floating point
/// instructions.
const Attributes Naked = 1<<24; ///< Naked function
+const Attributes InlineHint = 1<<25; ///< source said inlining was
+ ///desirable
/// @brief Attributes that only apply to function parameters.
const Attributes ParameterOnly = ByVal | Nest | StructRet | NoCapture;
@@ -66,7 +68,7 @@
/// be used on return values or function parameters.
const Attributes FunctionOnly = NoReturn | NoUnwind | ReadNone | ReadOnly |
NoInline | AlwaysInline | OptimizeForSize | StackProtect | StackProtectReq |
- NoRedZone | NoImplicitFloat | Naked;
+ NoRedZone | NoImplicitFloat | Naked | InlineHint;
/// @brief Parameter attributes that do not apply to vararg call arguments.
const Attributes VarArgsIncompatible = StructRet;
diff --git a/include/llvm/Transforms/IPO/InlinerPass.h b/include/llvm/Transforms/IPO/InlinerPass.h
index dc5e644..30ece0e 100644
--- a/include/llvm/Transforms/IPO/InlinerPass.h
+++ b/include/llvm/Transforms/IPO/InlinerPass.h
@@ -52,10 +52,11 @@
unsigned getInlineThreshold() const { return InlineThreshold; }
/// Calculate the inline threshold for given Caller. This threshold is lower
- /// if Caller is marked with OptimizeForSize and -inline-threshold is not
- /// given on the comand line.
+ /// if the caller is marked with OptimizeForSize and -inline-threshold is not
+ /// given on the comand line. It is higher if the callee is marked with the
+ /// inlinehint attribute.
///
- unsigned getInlineThreshold(Function* Caller) const;
+ unsigned getInlineThreshold(CallSite CS) const;
/// getInlineCost - This method must be implemented by the subclass to
/// determine the cost of inlining the specified call site. If the cost
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)
diff --git a/utils/llvm.grm b/utils/llvm.grm
index 4499d4b..86a707a 100644
--- a/utils/llvm.grm
+++ b/utils/llvm.grm
@@ -161,6 +161,7 @@
| signext
| readnone
| readonly
+ | inlinehint
| noinline
| alwaysinline
| optsize
diff --git a/utils/vim/llvm.vim b/utils/vim/llvm.vim
index 48a4c68..6e4a207 100644
--- a/utils/vim/llvm.vim
+++ b/utils/vim/llvm.vim
@@ -51,7 +51,7 @@
syn keyword llvmKeyword x86_stdcallcc x86_fastcallcc
syn keyword llvmKeyword signext zeroext inreg sret nounwind noreturn
syn keyword llvmKeyword nocapture byval nest readnone readonly noalias
-syn keyword llvmKeyword noinline alwaysinline optsize ssp sspreq
+syn keyword llvmKeyword inlinehint noinline alwaysinline optsize ssp sspreq
syn keyword llvmKeyword noredzone noimplicitfloat naked
syn keyword llvmKeyword module asm align tail to
syn keyword llvmKeyword addrspace section alias sideeffect c gc