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Merge pull request #23907 from slavapestov/noescape-parameter-call-restriction

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Re-implement "no-escape parameter call restriction" as SIL pass
This commit is contained in:
Slava Pestov
2019-04-09 19:38:31 -04:00
committed by GitHub
parent 5577ec9d4f e2cb0572fe
commit d82b88cd82
7 changed files with 115 additions and 145 deletions
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102
lib/Sema/MiscDiagnostics.cpp
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@@ -179,10 +179,6 @@ static void diagSyntacticUseRestrictions(TypeChecker &TC, const Expr *E,
ConcreteDeclRef callee;
if (auto *calleeDRE = dyn_cast<DeclRefExpr>(base)) {
// This only cares about declarations of noescape function type.
auto AFT = calleeDRE->getType()->getAs<FunctionType>();
if (AFT && AFT->isNoEscape())
checkNoEscapeParameterCall(Call);
checkForSuspiciousBitCasts(calleeDRE, Call);
callee = calleeDRE->getDeclRef();
@@ -416,104 +412,6 @@ static void diagSyntacticUseRestrictions(TypeChecker &TC, const Expr *E,
TC.diagnose(E->getStartLoc(), diag::value_of_module_type);
}
class NoEscapeArgument {
llvm::PointerIntPair<ParamDecl*, 1, bool> ParamAndIsCapture;
public:
NoEscapeArgument() {}
NoEscapeArgument(ParamDecl *param, bool isCapture)
: ParamAndIsCapture(param, isCapture) {
assert(param);
}
explicit operator bool() const {
return ParamAndIsCapture.getPointer() != nullptr;
}
ParamDecl *getDecl() const { return ParamAndIsCapture.getPointer(); }
bool isDeclACapture() const { return ParamAndIsCapture.getInt(); }
static NoEscapeArgument find(TypeChecker &tc, ValueDecl *decl,
bool isCapture) {
if (auto param = dyn_cast<ParamDecl>(decl)) {
if (auto fnType =
param->getInterfaceType()->getAs<AnyFunctionType>()) {
if (fnType->isNoEscape())
return { param, isCapture };
}
return {};
}
if (auto fn = dyn_cast<AbstractFunctionDecl>(decl)) {
if (fn->getDeclContext()->isLocalContext()) {
return findInCaptures(tc, fn);
}
return {};
}
// FIXME: captures of computed local vars? Can these be non-escaping?
return {};
}
static NoEscapeArgument findInCaptures(TypeChecker &tc,
AnyFunctionRef fn) {
// Ensure we have accurate capture information for the function.
tc.computeCaptures(fn);
for (const auto &capture : fn.getCaptureInfo().getCaptures()) {
if (capture.isDynamicSelfMetadata()) continue;
if (auto param = find(tc, capture.getDecl(), true))
return param;
}
return {};
}
};
/// Enforce the exclusivity rule against calling a non-escaping
/// function parameter with another non-escaping function parameter
/// as an argument.
void checkNoEscapeParameterCall(ApplyExpr *apply) {
NoEscapeArgument noescapeArgument;
Expr *problematicArg = nullptr;
visitArguments(apply, [&](unsigned argIndex, Expr *arg) {
// Just find the first problematic argument.
if (noescapeArgument) return;
// Remember the expression which used the argument.
problematicArg = arg;
// Look through the same set of nodes that we look through when
// checking for no-escape functions.
arg = lookThroughArgument(arg);
// If the argument isn't noescape, ignore it.
auto fnType = arg->getType()->getAs<AnyFunctionType>();
if (!fnType || !fnType->isNoEscape())
return;
// Okay, it should be a closure or a decl ref.
if (auto declRef = dyn_cast<DeclRefExpr>(arg)) {
noescapeArgument =
NoEscapeArgument::find(TC, declRef->getDecl(), false);
} else if (auto closure = dyn_cast<AbstractClosureExpr>(arg)) {
noescapeArgument =
NoEscapeArgument::findInCaptures(TC, closure);
} else {
// This can happen with withoutActuallyEscaping.
assert(isa<OpaqueValueExpr>(arg) &&
"unexpected expression yielding noescape closure");
}
});
if (!noescapeArgument) return;
TC.diagnose(apply->getLoc(),
diag::err_noescape_param_call,
noescapeArgument.getDecl()->getName(),
noescapeArgument.isDeclACapture())
.highlight(problematicArg->getSourceRange());
}
// Diagnose metatype values that don't appear as part of a property,
// method, or constructor reference.
void checkUseOfMetaTypeName(Expr *E) {