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e84c42802f
If we have a nobuiltin function, we can't assume we know anything about the implementation. I noticed this when tracing through a log from an in the wild miscompile (https://github.com/emscripten-core/emscripten/issues/9443) triggered after 8666463. We were incorrectly assuming that a custom allocator could not free. (It's not clear yet this is the only problem in said issue.) I also noticed something similiar mentioned in the commit message of ab243e when scrolling back through history. Through, from what I can tell, that commit fixed symptom not root cause. The interface we have for library function detection is extremely error prone, but given the interaction between ``nobuiltin`` decls and ``builtin`` callsites, it's really hard to imagine something much cleaner. I may iterate on that, but it'll be invasive enough I didn't want to hold an obvious functional fix on it.
93 lines
3.3 KiB
C++
93 lines
3.3 KiB
C++
//===- InferFunctionAttrs.cpp - Infer implicit function attributes --------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/IPO/InferFunctionAttrs.h"
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#include "llvm/Analysis/TargetLibraryInfo.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/LLVMContext.h"
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#include "llvm/IR/Module.h"
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#include "llvm/InitializePasses.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/Transforms/Utils/BuildLibCalls.h"
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#include "llvm/Transforms/Utils/Local.h"
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using namespace llvm;
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#define DEBUG_TYPE "inferattrs"
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static bool inferAllPrototypeAttributes(
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Module &M, function_ref<TargetLibraryInfo &(Function &)> GetTLI) {
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bool Changed = false;
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for (Function &F : M.functions())
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// We only infer things using the prototype and the name; we don't need
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// definitions. This ensures libfuncs are annotated and also allows our
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// CGSCC inference to avoid needing to duplicate the inference from other
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// attribute logic on all calls to declarations (as declarations aren't
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// explicitly visited by CGSCC passes in the new pass manager.)
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if (F.isDeclaration() && !F.hasOptNone()) {
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if (!F.hasFnAttribute(Attribute::NoBuiltin))
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Changed |= inferLibFuncAttributes(F, GetTLI(F));
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Changed |= inferAttributesFromOthers(F);
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}
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return Changed;
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}
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PreservedAnalyses InferFunctionAttrsPass::run(Module &M,
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ModuleAnalysisManager &AM) {
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FunctionAnalysisManager &FAM =
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AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
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auto GetTLI = [&FAM](Function &F) -> TargetLibraryInfo & {
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return FAM.getResult<TargetLibraryAnalysis>(F);
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};
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if (!inferAllPrototypeAttributes(M, GetTLI))
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// If we didn't infer anything, preserve all analyses.
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return PreservedAnalyses::all();
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// Otherwise, we may have changed fundamental function attributes, so clear
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// out all the passes.
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return PreservedAnalyses::none();
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}
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namespace {
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struct InferFunctionAttrsLegacyPass : public ModulePass {
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static char ID; // Pass identification, replacement for typeid
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InferFunctionAttrsLegacyPass() : ModulePass(ID) {
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initializeInferFunctionAttrsLegacyPassPass(
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*PassRegistry::getPassRegistry());
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}
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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AU.addRequired<TargetLibraryInfoWrapperPass>();
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}
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bool runOnModule(Module &M) override {
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if (skipModule(M))
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return false;
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auto GetTLI = [this](Function &F) -> TargetLibraryInfo & {
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return this->getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F);
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};
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return inferAllPrototypeAttributes(M, GetTLI);
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}
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};
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}
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char InferFunctionAttrsLegacyPass::ID = 0;
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INITIALIZE_PASS_BEGIN(InferFunctionAttrsLegacyPass, "inferattrs",
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"Infer set function attributes", false, false)
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INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
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INITIALIZE_PASS_END(InferFunctionAttrsLegacyPass, "inferattrs",
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"Infer set function attributes", false, false)
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Pass *llvm::createInferFunctionAttrsLegacyPass() {
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return new InferFunctionAttrsLegacyPass();
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}
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