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IRGen: Steal single-Swift-refcounted partial_apply argument as context.

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If a partial application's context consists of a sole Swift-refcounted argument, we don't need an additional box; we can just adopt the argument as the function context. This nicely handles the common case of a class method being partially applied on its "self".

Swift SVN r9298
This commit is contained in:
Joe Groff
2013-10-14 00:23:18 +00:00
parent a288f160ba
commit a818f6f23b
2 changed files with 74 additions and 2 deletions
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48
lib/IRGen/GenFunc.cpp
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@@ -1847,11 +1847,39 @@ void irgen::emitFunctionPartialApplication(IRGenFunction &IGF,
SILType substType,
SILType outType,
Explosion &out) {
// If we have a single Swift-refcounted context value, we can adopt it
// directly as our closure context without creating a box and thunk.
enum HasSingleSwiftRefcountedContext { Maybe, Yes, No }
hasSingleSwiftRefcountedContext = Maybe;
// Collect the type infos for the context types.
// FIXME: Keep LValueTypes out of this.
SmallVector<const TypeInfo *, 4> argTypeInfos;
for (SILType argType : argTypes) {
argTypeInfos.push_back(&IGF.getTypeInfo(argType.getSwiftType()));
auto &ti = IGF.getTypeInfo(argType.getSwiftType());
argTypeInfos.push_back(&ti);
// Update the single-swift-refcounted check, unless we already ruled that
// out.
if (hasSingleSwiftRefcountedContext == No)
continue;
// Empty values don't matter.
auto schema = ti.getSchema(out.getKind());
if (schema.size() == 0)
continue;
// Adding nonempty values when we already have a single refcounted pointer
// ruins it.
if (hasSingleSwiftRefcountedContext == Yes) {
hasSingleSwiftRefcountedContext = No;
continue;
}
if (ti.isSingleRetainablePointer(ResilienceScope::Local))
hasSingleSwiftRefcountedContext = Yes;
else
hasSingleSwiftRefcountedContext = No;
}
// Include the context pointer, if any, in the function arguments.
@@ -1859,6 +1887,10 @@ void irgen::emitFunctionPartialApplication(IRGenFunction &IGF,
args.add(fnContext);
argTypeInfos.push_back(
&IGF.IGM.getTypeInfo(IGF.IGM.Context.TheObjectPointerType));
// If this is the only context argument we end up with, we can just share
// it.
if (args.size() == 1)
hasSingleSwiftRefcountedContext = Yes;
}
// Collect the polymorphic arguments.
@@ -1886,7 +1918,19 @@ void irgen::emitFunctionPartialApplication(IRGenFunction &IGF,
} else {
assert(subs.empty() && "substitutions for non-polymorphic function?!");
}
// If we have a single refcounted pointer context (and no polymorphic args
// to capture), skip building the box and thunk and just take the pointer as
// context.
if (args.size() == 1 && hasSingleSwiftRefcountedContext == Yes) {
fnPtr = IGF.Builder.CreateBitCast(fnPtr, IGF.IGM.Int8PtrTy);
out.add(fnPtr);
llvm::Value *ctx = args.claimNext();
ctx = IGF.Builder.CreateBitCast(ctx, IGF.IGM.RefCountedPtrTy);
out.add(ctx);
return;
}
// If the function pointer is dynamic, include it in the context.
auto staticFn = dyn_cast<llvm::Function>(fnPtr);
if (!staticFn) {