r206681 - Thread Safety Analysis: Convert to minimal SSA.
Delesley Hutchins
delesley at google.com
Wed Apr 23 11:16:15 PDT 2014
I need to make a ThreadSafetyTIL.cpp, and move some of this stuff
there. Future patch.
-DeLesley
On Wed, Apr 23, 2014 at 7:27 AM, Aaron Ballman <aaron at aaronballman.com> wrote:
> On Fri, Apr 18, 2014 at 11:54 PM, DeLesley Hutchins <delesley at google.com> wrote:
>> Author: delesley
>> Date: Fri Apr 18 22:54:41 2014
>> New Revision: 206681
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=206681&view=rev
>> Log:
>> Thread Safety Analysis: Convert to minimal SSA.
>>
>> Modified:
>> cfe/trunk/include/clang/Analysis/Analyses/ThreadSafetyCommon.h
>> cfe/trunk/include/clang/Analysis/Analyses/ThreadSafetyTIL.h
>> cfe/trunk/include/clang/Analysis/Analyses/ThreadSafetyTraverse.h
>> cfe/trunk/lib/Analysis/ThreadSafetyCommon.cpp
>>
>> Modified: cfe/trunk/include/clang/Analysis/Analyses/ThreadSafetyCommon.h
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Analysis/Analyses/ThreadSafetyCommon.h?rev=206681&r1=206680&r2=206681&view=diff
>> ==============================================================================
>> --- cfe/trunk/include/clang/Analysis/Analyses/ThreadSafetyCommon.h (original)
>> +++ cfe/trunk/include/clang/Analysis/Analyses/ThreadSafetyCommon.h Fri Apr 18 22:54:41 2014
>> @@ -365,6 +365,7 @@ private:
>> LVarDefinitionMap CurrentLVarMap;
>> std::vector<til::Variable*> CurrentArguments;
>> std::vector<til::Variable*> CurrentInstructions;
>> + std::vector<til::Variable*> IncompleteArgs;
>> til::BasicBlock *CurrentBB;
>> BlockInfo *CurrentBlockInfo;
>> };
>>
>> Modified: cfe/trunk/include/clang/Analysis/Analyses/ThreadSafetyTIL.h
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Analysis/Analyses/ThreadSafetyTIL.h?rev=206681&r1=206680&r2=206681&view=diff
>> ==============================================================================
>> --- cfe/trunk/include/clang/Analysis/Analyses/ThreadSafetyTIL.h (original)
>> +++ cfe/trunk/include/clang/Analysis/Analyses/ThreadSafetyTIL.h Fri Apr 18 22:54:41 2014
>> @@ -162,7 +162,7 @@ private:
>>
>> // Contains various helper functions for SExprs.
>> namespace ThreadSafetyTIL {
>> - inline bool isTrivial(SExpr *E) {
>> + inline bool isTrivial(const SExpr *E) {
>> unsigned Op = E->opcode();
>> return Op == COP_Variable || Op == COP_Literal || Op == COP_LiteralPtr;
>> }
>> @@ -209,6 +209,7 @@ public:
>>
>> // Returns the definition (for let vars) or type (for parameter & self vars)
>> SExpr *definition() { return Definition.get(); }
>> + const SExpr *definition() const { return Definition.get(); }
>>
>> void attachVar() const { ++NumUses; }
>> void detachVar() const { assert(NumUses > 0); --NumUses; }
>> @@ -1107,6 +1108,15 @@ public:
>> // TODO: change to SExprRef
>> typedef SimpleArray<SExpr *> ValArray;
>>
>> + // In minimal SSA form, all Phi nodes are MultiVal.
>> + // During conversion to SSA, incomplete Phi nodes may be introduced, which
>> + // are later determined to be SingleVal.
>> + enum Status {
>> + PH_MultiVal = 0, // Phi node has multiple distinct values. (Normal)
>> + PH_SingleVal, // Phi node has one distinct value, and can be eliminated
>> + PH_Incomplete // Phi node is incomplete
>> + };
>> +
>> static bool classof(const SExpr *E) { return E->opcode() == COP_Phi; }
>>
>> Phi(MemRegionRef A, unsigned Nvals) : SExpr(COP_Phi), Values(A, Nvals) {}
>> @@ -1116,14 +1126,8 @@ public:
>> const ValArray &values() const { return Values; }
>> ValArray &values() { return Values; }
>>
>> - // Incomplete phi nodes are constructed during SSA conversion, and
>> - // may not be necessary.
>> - bool incomplete() const { return Flags == 1; }
>> -
>> - void setIncomplete(bool b) {
>> - if (b) Flags = 1;
>> - else Flags = 0;
>> - }
>> + Status status() const { return static_cast<Status>(Flags); }
>> + void setStatus(Status s) { Flags = s; }
>>
>> template <class V> typename V::R_SExpr traverse(V &Visitor) {
>> typename V::template Container<typename V::R_SExpr> Nvs(Visitor,
>> @@ -1222,6 +1226,12 @@ private:
>> };
>>
>>
>> +SExpr *getCanonicalVal(SExpr *E);
>
> This function is declared in TheadSafetyTIL.h but defined in
> ThreadSafetyCommon.cpp; should it instead be declared in
> ThreadSafetyCommon.h?
>
>> +void simplifyIncompleteArg(Variable *V, til::Phi *Ph);
>
> This function is only used in ThreadSafetyCommon.cpp; should it be a
> static function in that file instead, or are you intending to use it
> outside of that file soon?
>
>> +
>> +
>> +
>> +
>> } // end namespace til
>> } // end namespace threadSafety
>> } // end namespace clang
>>
>> Modified: cfe/trunk/include/clang/Analysis/Analyses/ThreadSafetyTraverse.h
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Analysis/Analyses/ThreadSafetyTraverse.h?rev=206681&r1=206680&r2=206681&view=diff
>> ==============================================================================
>> --- cfe/trunk/include/clang/Analysis/Analyses/ThreadSafetyTraverse.h (original)
>> +++ cfe/trunk/include/clang/Analysis/Analyses/ThreadSafetyTraverse.h Fri Apr 18 22:54:41 2014
>> @@ -505,16 +505,42 @@ protected:
>> }
>>
>> void printLiteral(Literal *E, StreamType &SS) {
>> - // TODO: actually pretty print the literal.
>> - SS << "#lit";
>> + const clang::Expr *CE = E->clangExpr();
>> + switch (CE->getStmtClass()) {
>> + case Stmt::IntegerLiteralClass:
>> + SS << cast<IntegerLiteral>(CE)->getValue().toString(10, true);
>> + return;
>> + case Stmt::StringLiteralClass:
>> + SS << "\"" << cast<StringLiteral>(CE)->getString() << "\"";
>> + return;
>> + case Stmt::CharacterLiteralClass:
>> + case Stmt::CXXNullPtrLiteralExprClass:
>> + case Stmt::GNUNullExprClass:
>> + case Stmt::CXXBoolLiteralExprClass:
>> + case Stmt::FloatingLiteralClass:
>> + case Stmt::ImaginaryLiteralClass:
>> + case Stmt::ObjCStringLiteralClass:
>> + default:
>> + SS << "#lit";
>> + return;
>> + }
>> }
>>
>> void printLiteralPtr(LiteralPtr *E, StreamType &SS) {
>> SS << E->clangDecl()->getNameAsString();
>> }
>>
>> - void printVariable(Variable *E, StreamType &SS) {
>> + void printVariable(Variable *E, StreamType &SS, bool IsVarDecl = false) {
>> SS << E->name() << E->getBlockID() << "_" << E->getID();
>> + if (IsVarDecl)
>> + return;
>> +
>> + SExpr *V = getCanonicalVal(E);
>> + if (V != E) {
>> + SS << "{";
>> + printSExpr(V, SS, Prec_MAX);
>> + SS << "}";
>> + }
>> }
>>
>> void printFunction(Function *E, StreamType &SS, unsigned sugared = 0) {
>> @@ -528,7 +554,7 @@ protected:
>> SS << ", "; // Curried functions
>> break;
>> }
>> - self()->printVariable(E->variableDecl(), SS);
>> + self()->printVariable(E->variableDecl(), SS, true);
>> SS << ": ";
>> self()->printSExpr(E->variableDecl()->definition(), SS, Prec_MAX);
>>
>> @@ -541,7 +567,7 @@ protected:
>>
>> void printSFunction(SFunction *E, StreamType &SS) {
>> SS << "@";
>> - self()->printVariable(E->variableDecl(), SS);
>> + self()->printVariable(E->variableDecl(), SS, true);
>> SS << " ";
>> self()->printSExpr(E->body(), SS, Prec_Decl);
>> }
>> @@ -632,7 +658,7 @@ protected:
>> newline(SS);
>> for (auto A : BBI->arguments()) {
>> SS << "let ";
>> - self()->printVariable(A, SS);
>> + self()->printVariable(A, SS, true);
>> SS << " = ";
>> self()->printSExpr(A->definition(), SS, Prec_MAX);
>> SS << ";";
>> @@ -641,7 +667,7 @@ protected:
>> for (auto I : BBI->instructions()) {
>> if (I->definition()->opcode() != COP_Store) {
>> SS << "let ";
>> - self()->printVariable(I, SS);
>> + self()->printVariable(I, SS, true);
>> SS << " = ";
>> }
>> self()->printSExpr(I->definition(), SS, Prec_MAX);
>> @@ -663,11 +689,16 @@ protected:
>> void printPhi(Phi *E, StreamType &SS) {
>> SS << "phi(";
>> unsigned i = 0;
>> - for (auto V : E->values()) {
>> - if (i > 0)
>> - SS << ", ";
>> - self()->printSExpr(V, SS, Prec_MAX);
>> - ++i;
>> + if (E->status() == Phi::PH_SingleVal) {
>> + self()->printSExpr(E->values()[0], SS, Prec_MAX);
>> + }
>> + else {
>> + for (auto V : E->values()) {
>> + if (i > 0)
>> + SS << ", ";
>> + self()->printSExpr(V, SS, Prec_MAX);
>> + ++i;
>> + }
>> }
>> SS << ")";
>> }
>>
>> Modified: cfe/trunk/lib/Analysis/ThreadSafetyCommon.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Analysis/ThreadSafetyCommon.cpp?rev=206681&r1=206680&r2=206681&view=diff
>> ==============================================================================
>> --- cfe/trunk/lib/Analysis/ThreadSafetyCommon.cpp (original)
>> +++ cfe/trunk/lib/Analysis/ThreadSafetyCommon.cpp Fri Apr 18 22:54:41 2014
>> @@ -36,6 +36,65 @@
>> namespace clang {
>> namespace threadSafety {
>>
>> +namespace til {
>> +
>> +// If E is a variable, then trace back through any aliases or redundant
>> +// Phi nodes to find the canonical definition.
>> +SExpr *getCanonicalVal(SExpr *E) {
>> + while (auto *V = dyn_cast<Variable>(E)) {
>> + SExpr *D;
>> + do {
>> + if (V->kind() != Variable::VK_Let)
>> + return V;
>> + D = V->definition();
>> + if (auto *V2 = dyn_cast<Variable>(D)) {
>> + V = V2;
>> + continue;
>> + }
>> + } while(false);
>> +
>> + if (ThreadSafetyTIL::isTrivial(D))
>> + return D;
>> +
>> + if (Phi *Ph = dyn_cast<Phi>(D)) {
>> + if (Ph->status() == Phi::PH_Incomplete)
>> + simplifyIncompleteArg(V, Ph);
>> +
>> + if (Ph->status() == Phi::PH_SingleVal) {
>> + E = Ph->values()[0];
>> + continue;
>> + }
>> + }
>> + return V;
>> + }
>> + return E;
>> +}
>> +
>> +
>> +// Trace the arguments of an incomplete Phi node to see if they have the same
>> +// canonical definition. If so, mark the Phi node as redundant.
>> +// getCanonicalVal() will recursively call simplifyIncompletePhi().
>> +void simplifyIncompleteArg(Variable *V, til::Phi *Ph) {
>> + assert(!Ph && Ph->status() == Phi::PH_Incomplete);
>> +
>> + // eliminate infinite recursion -- assume that this node is not redundant.
>> + Ph->setStatus(Phi::PH_MultiVal);
>> +
>> + SExpr *E0 = getCanonicalVal(Ph->values()[0]);
>> + for (unsigned i=1, n=Ph->values().size(); i<n; ++i) {
>> + SExpr *Ei = getCanonicalVal(Ph->values()[i]);
>> + if (Ei == V)
>> + continue; // Recursive reference to itself. Don't count.
>> + if (Ei != E0) {
>> + return; // Status is already set to MultiVal.
>> + }
>> + }
>> + Ph->setStatus(Phi::PH_SingleVal);
>> +}
>> +
>> +} // end namespace til
>> +
>> +
>> typedef SExprBuilder::CallingContext CallingContext;
>>
>>
>> @@ -416,19 +475,6 @@ til::SExpr *SExprBuilder::updateVarDecl(
>> }
>>
>>
>> -// Return true if the given expression represents a possibly unnecessary
>> -// variable: i.e. a variable that references a Phi node that may be removed.
>> -inline bool isIncompleteVar(til::SExpr *E) {
>> - if (!E)
>> - return true; // Null values are used on unknown backedges.
>> - if (til::Variable *V = dyn_cast<til::Variable>(E)) {
>> - if (til::Phi *Ph = dyn_cast<til::Phi>(V->definition()))
>> - return Ph->incomplete();
>> - }
>> - return false;
>> -}
>> -
>> -
>> // Make a Phi node in the current block for the i^th variable in CurrentVarMap.
>> // If E != null, sets Phi[CurrentBlockInfo->ArgIndex] = E.
>> // If E == null, this is a backedge and will be set later.
>> @@ -444,8 +490,6 @@ void SExprBuilder::makePhiNodeVar(unsign
>> assert(Ph && "Expecting Phi node.");
>> if (E)
>> Ph->values()[ArgIndex] = E;
>> - if (!Ph->incomplete() && isIncompleteVar(E))
>> - Ph->setIncomplete(true);
>> return;
>> }
>>
>> @@ -457,12 +501,16 @@ void SExprBuilder::makePhiNodeVar(unsign
>> Ph->values()[PIdx] = CurrentLVarMap[i].second;
>> if (E)
>> Ph->values()[ArgIndex] = E;
>> - if (isIncompleteVar(E))
>> - Ph->setIncomplete(true);
>> + if (!E) {
>> + // This is a non-minimal SSA node, which may be removed later.
>> + Ph->setStatus(til::Phi::PH_Incomplete);
>> + }
>>
>> // Add Phi node to current block, and update CurrentLVarMap[i]
>> auto *Var = new (Arena) til::Variable(Ph, CurrentLVarMap[i].first);
>> CurrentArguments.push_back(Var);
>> + if (Ph->status() == til::Phi::PH_Incomplete)
>> + IncompleteArgs.push_back(Var);
>>
>> CurrentLVarMap.makeWritable();
>> CurrentLVarMap.elem(i).second = Var;
>> @@ -680,8 +728,15 @@ void SExprBuilder::exitCFGBlock(const CF
>>
>>
>> void SExprBuilder::exitCFG(const CFGBlock *Last) {
>> + for (auto *V : IncompleteArgs) {
>> + til::Phi *Ph = dyn_cast<til::Phi>(V->definition());
>> + if (Ph && Ph->status() == til::Phi::PH_Incomplete)
>> + simplifyIncompleteArg(V, Ph);
>> + }
>> +
>> CurrentArguments.clear();
>> CurrentInstructions.clear();
>> + IncompleteArgs.clear();
>> }
>>
>>
>>
>>
>> _______________________________________________
>> cfe-commits mailing list
>> cfe-commits at cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
>
> ~Aaron
--
DeLesley Hutchins | Software Engineer | delesley at google.com | 505-206-0315
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