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Make Argument::getArgNo() constant time, not O(#args)

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getArgNo is actually hot in LLVM, because its how we check for
attributes on arguments:
  bool Argument::hasNonNullAttr() const {
    if (!getType()->isPointerTy()) return false;
    if (getParent()->getAttributes().
          hasAttribute(getArgNo()+1, Attribute::NonNull))
      return true;

It actually shows up as the 23rd hottest leaf function in a 13s sample
of LTO of llc.

This grows Argument by four bytes, but I have another pending patch to
shrink it by removing its ilist_node base.

Reviewed By: chandlerc

Subscribers: inglorion, llvm-commits, mehdi_amini

Differential Revision: https://reviews.llvm.org/D31057

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@298003 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Reid Kleckner 2017-03-16 22:25:45 +00:00
parent 7762f59a0d
commit 36d60de9d6
2 changed files with 8 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
include/llvm/IR/Argument.h
View File

@ -32,6 +32,7 @@ template <typename NodeTy> class SymbolTableListTraits;
class Argument : public Value, public ilist_node<Argument> {
virtual void anchor();
Function *Parent;
unsigned ArgNo;
friend class SymbolTableListTraits<Argument>;
void setParent(Function *parent);
@ -39,7 +40,8 @@ class Argument : public Value, public ilist_node<Argument> {
public:
/// If \p F is specified, the argument is inserted at the end of the argument
/// list for \p F.
explicit Argument(Type *Ty, const Twine &Name = "", Function *F = nullptr);
explicit Argument(Type *Ty, const Twine &Name = "", Function *F = nullptr,
unsigned ArgNo = 0);
inline const Function *getParent() const { return Parent; }
inline Function *getParent() { return Parent; }
@ -47,7 +49,7 @@ public:
/// Return the index of this formal argument in its containing function.
///
/// For example in "void foo(int a, float b)" a is 0 and b is 1.
unsigned getArgNo() const;
unsigned getArgNo() const { return ArgNo; }
/// Return true if this argument has the nonnull attribute. Also returns true
/// if at least one byte is known to be dereferenceable and the pointer is in

19
lib/IR/Function.cpp
View File

@ -39,8 +39,8 @@ template class llvm::SymbolTableListTraits<BasicBlock>;
void Argument::anchor() { }
Argument::Argument(Type *Ty, const Twine &Name, Function *Par)
: Value(Ty, Value::ArgumentVal) {
Argument::Argument(Type *Ty, const Twine &Name, Function *Par, unsigned ArgNo)
: Value(Ty, Value::ArgumentVal), ArgNo(ArgNo) {
Parent = nullptr;
if (Par)
@ -52,18 +52,6 @@ void Argument::setParent(Function *parent) {
Parent = parent;
}
unsigned Argument::getArgNo() const {
const Function *F = getParent();
assert(F && "Argument is not in a function");
Function::const_arg_iterator AI = F->arg_begin();
unsigned ArgIdx = 0;
for (; &*AI != this; ++AI)
++ArgIdx;
return ArgIdx;
}
bool Argument::hasNonNullAttr() const {
if (!getType()->isPointerTy()) return false;
if (getParent()->getAttributes().
@ -244,7 +232,8 @@ void Function::BuildLazyArguments() const {
for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i) {
assert(!FT->getParamType(i)->isVoidTy() &&
"Cannot have void typed arguments!");
ArgumentList.push_back(new Argument(FT->getParamType(i)));
ArgumentList.push_back(
new Argument(FT->getParamType(i), "", nullptr, i));
}
// Clear the lazy arguments bit.