#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/StringSwitch.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/BasicAliasAnalysis.h"
STATISTIC(NumNoAlias, "Number of function returns marked noalias");
STATISTIC(NumNonNullReturn, "Number of function returns marked nonnull");
STATISTIC(NumAnnotated, "Number of attributes added to library functions");
+STATISTIC(NumNoRecurse, "Number of functions marked as norecurse");
+
+static cl::list<std::string>
+ForceAttributes("force-attribute", cl::Hidden,
+ cl::desc("Add an attribute to a function. This should be a "
+ "pair of 'function-name:attribute-name', for "
+ "example -force-add-attribute=foo:noinline. This "
+ "option can be specified multiple times."));
namespace {
typedef SmallSetVector<Function *, 8> SCCNodeSet;
}
bool runOnSCC(CallGraphSCC &SCC) override;
-
+ bool doInitialization(CallGraph &CG) override {
+ Revisit.clear();
+ return false;
+ }
+ bool doFinalization(CallGraph &CG) override;
+
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesCFG();
AU.addRequired<AssumptionCacheTracker>();
private:
TargetLibraryInfo *TLI;
+ SmallVector<WeakVH,16> Revisit;
};
}
for (CallSite::arg_iterator CI = CS.arg_begin(), CE = CS.arg_end();
CI != CE; ++CI) {
Value *Arg = *CI;
- if (!Arg->getType()->isPointerTy())
+ if (!Arg->getType()->isPtrOrPtrVectorTy())
continue;
AAMDNodes AAInfo;
unsigned UseIndex =
std::distance(const_cast<const Use *>(CS.arg_begin()), U);
- assert(UseIndex < CS.arg_size() && "Non-argument use?");
+ assert(UseIndex < CS.data_operands_size() &&
+ "Indirect function calls should have been filtered above!");
+
+ if (UseIndex >= CS.getNumArgOperands()) {
+ // Data operand, but not a argument operand -- must be a bundle operand
+ assert(CS.hasOperandBundles() && "Must be!");
+
+ // CaptureTracking told us that we're being captured by an operand bundle
+ // use. In this case it does not matter if the callee is within our SCC
+ // or not -- we've been captured in some unknown way, and we have to be
+ // conservative.
+ Captured = true;
+ return true;
+ }
+
if (UseIndex >= F->arg_size()) {
assert(F->isVarArg() && "More params than args in non-varargs call");
Captured = true;
return true;
}
- Uses.push_back(std::next(F->arg_begin(), UseIndex));
+ Uses.push_back(&*std::next(F->arg_begin(), UseIndex));
return false;
}
while (!Worklist.empty()) {
Use *U = Worklist.pop_back_val();
Instruction *I = cast<Instruction>(U->getUser());
- Value *V = U->get();
switch (I->getOpcode()) {
case Instruction::BitCast:
return Attribute::None;
}
- Function::arg_iterator AI = F->arg_begin(), AE = F->arg_end();
- CallSite::arg_iterator B = CS.arg_begin(), E = CS.arg_end();
- for (CallSite::arg_iterator A = B; A != E; ++A, ++AI) {
- if (A->get() == V) {
- if (AI == AE) {
- assert(F->isVarArg() &&
- "More params than args in non-varargs call.");
- return Attribute::None;
- }
- Captures &= !CS.doesNotCapture(A - B);
- if (SCCNodes.count(&*AI))
- continue;
- if (!CS.onlyReadsMemory() && !CS.onlyReadsMemory(A - B))
- return Attribute::None;
- if (!CS.doesNotAccessMemory(A - B))
- IsRead = true;
- }
+ // Note: the callee and the two successor blocks *follow* the argument
+ // operands. This means there is no need to adjust UseIndex to account
+ // for these.
+
+ unsigned UseIndex = std::distance(CS.arg_begin(), U);
+
+ // U cannot be the callee operand use: since we're exploring the
+ // transitive uses of an Argument, having such a use be a callee would
+ // imply the CallSite is an indirect call or invoke; and we'd take the
+ // early exit above.
+ assert(UseIndex < CS.data_operands_size() &&
+ "Data operand use expected!");
+
+ bool IsOperandBundleUse = UseIndex >= CS.getNumArgOperands();
+
+ if (UseIndex >= F->arg_size() && !IsOperandBundleUse) {
+ assert(F->isVarArg() && "More params than args in non-varargs call");
+ return Attribute::None;
+ }
+
+ Captures &= !CS.doesNotCapture(UseIndex);
+
+ // Since the optimizer (by design) cannot see the data flow corresponding
+ // to a operand bundle use, these cannot participate in the optimistic SCC
+ // analysis. Instead, we model the operand bundle uses as arguments in
+ // call to a function external to the SCC.
+ if (!SCCNodes.count(&*std::next(F->arg_begin(), UseIndex)) ||
+ IsOperandBundleUse) {
+
+ // The accessors used on CallSite here do the right thing for calls and
+ // invokes with operand bundles.
+
+ if (!CS.onlyReadsMemory() && !CS.onlyReadsMemory(UseIndex))
+ return Attribute::None;
+ if (!CS.doesNotAccessMemory(UseIndex))
+ IsRead = true;
}
+
AddUsersToWorklistIfCapturing();
break;
}
}
}
+static bool setDoesNotRecurse(Function &F) {
+ if (F.doesNotRecurse())
+ return false;
+ F.setDoesNotRecurse();
+ ++NumNoRecurse;
+ return true;
+}
+
/// Analyze the name and prototype of the given function and set any applicable
/// attributes.
///
return true;
}
+static bool addNoRecurseAttrs(const CallGraphSCC &SCC,
+ SmallVectorImpl<WeakVH> &Revisit) {
+ // Try and identify functions that do not recurse.
+
+ // If the SCC contains multiple nodes we know for sure there is recursion.
+ if (!SCC.isSingular())
+ return false;
+
+ const CallGraphNode *CGN = *SCC.begin();
+ Function *F = CGN->getFunction();
+ if (!F || F->isDeclaration() || F->doesNotRecurse())
+ return false;
+
+ // If all of the calls in F are identifiable and are to norecurse functions, F
+ // is norecurse. This check also detects self-recursion as F is not currently
+ // marked norecurse, so any called from F to F will not be marked norecurse.
+ if (std::all_of(CGN->begin(), CGN->end(),
+ [](const CallGraphNode::CallRecord &CR) {
+ Function *F = CR.second->getFunction();
+ return F && F->doesNotRecurse();
+ }))
+ // Function calls a potentially recursive function.
+ return setDoesNotRecurse(*F);
+
+ // We know that F is not obviously recursive, but we haven't been able to
+ // prove that it doesn't actually recurse. Add it to the Revisit list to try
+ // again top-down later.
+ Revisit.push_back(F);
+ return false;
+}
+
+static bool addNoRecurseAttrsTopDownOnly(Function *F) {
+ // If F is internal and all uses are in norecurse functions, then F is also
+ // norecurse.
+ if (F->doesNotRecurse())
+ return false;
+ if (F->hasInternalLinkage()) {
+ for (auto *U : F->users())
+ if (auto *I = dyn_cast<Instruction>(U)) {
+ if (!I->getParent()->getParent()->doesNotRecurse())
+ return false;
+ } else {
+ return false;
+ }
+ return setDoesNotRecurse(*F);
+ }
+ return false;
+}
+
+static Attribute::AttrKind parseAttrKind(StringRef Kind) {
+ return StringSwitch<Attribute::AttrKind>(Kind)
+ .Case("alwaysinline", Attribute::AlwaysInline)
+ .Case("builtin", Attribute::Builtin)
+ .Case("cold", Attribute::Cold)
+ .Case("convergent", Attribute::Convergent)
+ .Case("inlinehint", Attribute::InlineHint)
+ .Case("jumptable", Attribute::JumpTable)
+ .Case("minsize", Attribute::MinSize)
+ .Case("naked", Attribute::Naked)
+ .Case("nobuiltin", Attribute::NoBuiltin)
+ .Case("noduplicate", Attribute::NoDuplicate)
+ .Case("noimplicitfloat", Attribute::NoImplicitFloat)
+ .Case("noinline", Attribute::NoInline)
+ .Case("nonlazybind", Attribute::NonLazyBind)
+ .Case("noredzone", Attribute::NoRedZone)
+ .Case("noreturn", Attribute::NoReturn)
+ .Case("norecurse", Attribute::NoRecurse)
+ .Case("nounwind", Attribute::NoUnwind)
+ .Case("optnone", Attribute::OptimizeNone)
+ .Case("optsize", Attribute::OptimizeForSize)
+ .Case("readnone", Attribute::ReadNone)
+ .Case("readonly", Attribute::ReadOnly)
+ .Case("argmemonly", Attribute::ArgMemOnly)
+ .Case("returns_twice", Attribute::ReturnsTwice)
+ .Case("safestack", Attribute::SafeStack)
+ .Case("sanitize_address", Attribute::SanitizeAddress)
+ .Case("sanitize_memory", Attribute::SanitizeMemory)
+ .Case("sanitize_thread", Attribute::SanitizeThread)
+ .Case("ssp", Attribute::StackProtect)
+ .Case("sspreq", Attribute::StackProtectReq)
+ .Case("sspstrong", Attribute::StackProtectStrong)
+ .Case("uwtable", Attribute::UWTable)
+ .Default(Attribute::None);
+}
+
+/// If F has any forced attributes given on the command line, add them.
+static bool addForcedAttributes(Function *F) {
+ bool Changed = false;
+ for (auto &S : ForceAttributes) {
+ auto KV = StringRef(S).split(':');
+ if (KV.first != F->getName())
+ continue;
+
+ auto Kind = parseAttrKind(KV.second);
+ if (Kind == Attribute::None) {
+ DEBUG(dbgs() << "ForcedAttribute: " << KV.second
+ << " unknown or not handled!\n");
+ continue;
+ }
+ if (F->hasFnAttribute(Kind))
+ continue;
+ Changed = true;
+ F->addFnAttr(Kind);
+ }
+ return Changed;
+}
+
bool FunctionAttrs::runOnSCC(CallGraphSCC &SCC) {
TLI = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
bool Changed = false;
if (F->isDeclaration())
Changed |= inferPrototypeAttributes(*F, *TLI);
+ Changed |= addForcedAttributes(F);
SCCNodes.insert(F);
}
Changed |= addNoAliasAttrs(SCCNodes);
Changed |= addNonNullAttrs(SCCNodes, *TLI);
}
+
+ Changed |= addNoRecurseAttrs(SCC, Revisit);
+ return Changed;
+}
+bool FunctionAttrs::doFinalization(CallGraph &CG) {
+ bool Changed = false;
+ // When iterating over SCCs we visit functions in a bottom-up fashion. Some of
+ // the rules we have for identifying norecurse functions work best with a
+ // top-down walk, so look again at all the functions we previously marked as
+ // worth revisiting, in top-down order.
+ for (auto &F : reverse(Revisit))
+ if (F)
+ Changed |= addNoRecurseAttrsTopDownOnly(cast<Function>((Value*)F));
return Changed;
}
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