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eaf90dff38
Adds sections `__TEXT,__swift_as_entry`, and `__TEXT,__swift_as_ret` that contain relative pointers to async functlets modelling async function entries, and function returns, respectively. Emission of the sections can be trigger with the frontend option `-Xfrontend -enable-async-frame-push-pop-metadata`. This is done by: * IRGen adding a `async_entry` function attribute to async functions. * LLVM's coroutine splitting identifying continuation funclets that model the return from an async function call by adding the function attribute `async_ret`. (see #llvm-project/pull/9204) * An LLVM pass that keys off these two function attribute and emits the metadata into the above mention sections. rdar://134460666
91 lines
2.9 KiB
C++
91 lines
2.9 KiB
C++
//===--- LLVMEmitAsyncEntryReturnMetadata.cpp - Async function metadata ---===//
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//
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#include "swift/LLVMPasses/Passes.h"
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#include "llvm/Pass.h"
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#include "llvm/IR/Constants.h"
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#include "llvm/Transforms/Utils/ModuleUtils.h"
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using namespace llvm;
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using namespace swift;
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#define DEBUG_TYPE "swift-async-return"
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PreservedAnalyses AsyncEntryReturnMetadataPass::run(Module &M,
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ModuleAnalysisManager &AM) {
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bool changed = false;
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SmallVector<llvm::Function *, 16> asyncEntries;
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SmallVector<llvm::Function *, 16> asyncReturns;
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for (auto &F : M) {
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if (F.isDeclaration())
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continue;
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if (F.hasFnAttribute("async_entry"))
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asyncEntries.push_back(&F);
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if (F.hasFnAttribute("async_ret"))
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asyncReturns.push_back(&F);
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}
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auto &ctxt = M.getContext();
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auto int32Ty = llvm::Type::getInt32Ty(ctxt);
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auto sizeTy = M.getDataLayout().getIntPtrType(ctxt, /*addrspace*/ 0);
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auto addSection = [&] (const char * sectionName, const char *globalName,
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SmallVectorImpl<llvm::Function *> & entries) {
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if (entries.empty())
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return;
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auto intArrayTy = llvm::ArrayType::get(int32Ty, entries.size());
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auto global =
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new llvm::GlobalVariable(M, intArrayTy, true,
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llvm::GlobalValue::InternalLinkage,
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nullptr, /*init*/ globalName,
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nullptr, /*insertBefore*/
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llvm::GlobalValue::NotThreadLocal,
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0/*address space*/);
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global->setAlignment(Align(4));
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global->setSection(sectionName);
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size_t index = 0;
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SmallVector<llvm::Constant*, 16> offsets;
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for (auto *fn : entries) {
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llvm::Constant *indices[] = { llvm::ConstantInt::get(int32Ty, 0),
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llvm::ConstantInt::get(int32Ty, index)};
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++index;
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llvm::Constant *base = llvm::ConstantExpr::getInBoundsGetElementPtr(
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intArrayTy, global, indices);
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base = llvm::ConstantExpr::getPtrToInt(base, sizeTy);
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auto *target = llvm::ConstantExpr::getPtrToInt(fn, sizeTy);
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llvm::Constant *offset = llvm::ConstantExpr::getSub(target, base);
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if (sizeTy != int32Ty) {
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offset = llvm::ConstantExpr::getTrunc(offset, int32Ty);
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}
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offsets.push_back(offset);
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}
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auto constant = llvm::ConstantArray::get(intArrayTy, offsets);
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global->setInitializer(constant);
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appendToUsed(M, global);
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llvm::GlobalVariable::SanitizerMetadata Meta;
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Meta.IsDynInit = false;
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Meta.NoAddress = true;
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global->setSanitizerMetadata(Meta);
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changed = true;
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};
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addSection("__TEXT,__swift_as_entry, coalesced, no_dead_strip",
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"__swift_async_entry_functlets",
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asyncEntries);
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addSection("__TEXT,__swift_as_ret, coalesced, no_dead_strip",
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"__swift_async_ret_functlets",
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asyncReturns);
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if (!changed)
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return PreservedAnalyses::all();
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return PreservedAnalyses::none();
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}
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