Split out the generation of indices for locals and registers

Change-Id: I0e98ccba9ae3026cd8bfdc4cae100f280b5aa22c
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

5 files changed, 51 insertions, 32 deletions

diff --git a/src/qml/compiler/qv4codegen.cpp b/src/qml/compiler/qv4codegen.cpp
index 6a409edc58..d0b84c7463 100644
--- a/src/qml/compiler/qv4codegen.cpp
+++ b/src/qml/compiler/qv4codegen.cpp
@@ -2318,6 +2318,7 @@ int Codegen::defineFunction(const QString &name, AST::Node *ast,
         returnAddress = bytecodeGenerator->newRegister();
     qSwap(_returnAddress, returnAddress);
 
+    RegisterScope registerScope(this);
     _context->emitHeaderBytecode(this);
 
     for (const Context::Member &member : qAsConst(_context->members)) {
@@ -2328,9 +2329,10 @@ int Codegen::defineFunction(const QString &name, AST::Node *ast,
             if (! _context->parent) {
                 Reference::fromName(this, member.function->name.toString()).storeConsumeAccumulator();
             } else {
-                Q_ASSERT(member.index >= 0);
-                Reference local = member.canEscape ? Reference::fromScopedLocal(this, member.index, 0)
-                                                   : Reference::fromStackSlot(this, member.index, true);
+                int idx = member.index;
+                Q_ASSERT(idx >= 0);
+                Reference local = member.canEscape ? Reference::fromScopedLocal(this, idx, 0)
+                                                   : Reference::fromStackSlot(this, idx, true);
                 local.storeConsumeAccumulator();
             }
         }
@@ -2380,11 +2382,11 @@ int Codegen::defineFunction(const QString &name, AST::Node *ast,
     }
 
     bytecodeGenerator->finalize(_context);
-    _context->registerCount = bytecodeGenerator->registerCount();
+    _context->registerCountInFunction = bytecodeGenerator->registerCount();
     static const bool showCode = qEnvironmentVariableIsSet("QV4_SHOW_BYTECODE");
     if (showCode) {
         qDebug() << "=== Bytecode for" << _context->name << "strict mode" << _context->isStrict
-                 << "register count" << _context->registerCount;
+                 << "register count" << _context->registerCountInFunction;
         QV4::Moth::dumpBytecode(_context->code, _context->locals.size(), _context->arguments.size(),
                                 _context->line, _context->lineNumberMapping);
         qDebug();
diff --git a/src/qml/compiler/qv4compiler.cpp b/src/qml/compiler/qv4compiler.cpp
index d870c34101..d9f37b542f 100644
--- a/src/qml/compiler/qv4compiler.cpp
+++ b/src/qml/compiler/qv4compiler.cpp
@@ -329,7 +329,7 @@ void QV4::Compiler::JSUnitGenerator::writeFunction(char *f, QV4::Compiler::Conte
     currentOffset += function->nLineNumbers * sizeof(CompiledData::CodeOffsetToLine);
 
 
-    function->nRegisters = irFunction->registerCount;
+    function->nRegisters = irFunction->registerCountInFunction;
 
     function->nDependingIdObjects = 0;
     function->nDependingContextProperties = 0;
diff --git a/src/qml/compiler/qv4compilercontext.cpp b/src/qml/compiler/qv4compilercontext.cpp
index 1c583b5cf2..e2e978be7c 100644
--- a/src/qml/compiler/qv4compilercontext.cpp
+++ b/src/qml/compiler/qv4compilercontext.cpp
@@ -163,10 +163,12 @@ Context::ResolvedName Context::resolveName(const QString &name)
 
 void Context::emitHeaderBytecode(Codegen *codegen)
 {
+
     using Instruction = Moth::Instruction;
     Moth::BytecodeGenerator *bytecodeGenerator = codegen->generator();
 
-    bool allVarsEscape = hasWith || hasTry || hasDirectEval;
+    setupFunctionIndices(bytecodeGenerator);
+
     if (requiresExecutionContext ||
         type == ContextType::Binding) { // we don't really need this for bindings, but we do for signal handlers, and we don't know if the code is a signal handler or not.
         Instruction::CreateCallContext createContext;
@@ -181,26 +183,14 @@ void Context::emitHeaderBytecode(Codegen *codegen)
     // variables in global code are properties of the global context object, not locals as with other functions.
     if (type == ContextType::Function || type == ContextType::Binding) {
         for (Context::MemberMap::iterator it = members.begin(), end = members.end(); it != end; ++it) {
-            const QString &local = it.key();
-            if (allVarsEscape)
-                it->canEscape = true;
-            if (it->canEscape) {
-                it->index = locals.size();
-                locals.append(local);
-                if (it->type == Context::ThisFunctionName) {
-                    // move the name from the stack to the call context
-                    Instruction::LoadReg load;
-                    load.reg = CallData::Function;
-                    bytecodeGenerator->addInstruction(load);
-                    Instruction::StoreLocal store;
-                    store.index = it->index;
-                    bytecodeGenerator->addInstruction(store);
-                }
-            } else {
-                if (it->type == Context::ThisFunctionName)
-                    it->index = CallData::Function;
-                else
-                    it->index = bytecodeGenerator->newRegister();
+            if (it->canEscape && it->type == Context::ThisFunctionName) {
+                // move the function from the stack to the call context
+                Instruction::LoadReg load;
+                load.reg = CallData::Function;
+                bytecodeGenerator->addInstruction(load);
+                Instruction::StoreLocal store;
+                store.index = it->index;
+                bytecodeGenerator->addInstruction(store);
             }
         }
     } else {
@@ -226,4 +216,27 @@ void Context::emitHeaderBytecode(Codegen *codegen)
     }
 }
 
+void Context::setupFunctionIndices(Moth::BytecodeGenerator *bytecodeGenerator)
+{
+    Q_ASSERT(locals.size() == 0);
+    Q_ASSERT(nRegisters == 0);
+    registerOffset = bytecodeGenerator->registerCount();
+
+    if (type == ContextType::Function || type == ContextType::Binding) {
+        for (Context::MemberMap::iterator it = members.begin(), end = members.end(); it != end; ++it) {
+            const QString &local = it.key();
+            if (it->canEscape) {
+                it->index = locals.size();
+                locals.append(local);
+            } else {
+                if (it->type == Context::ThisFunctionName)
+                    it->index = CallData::Function;
+                else
+                    it->index = bytecodeGenerator->newRegister();
+            }
+        }
+    }
+    nRegisters = bytecodeGenerator->registerCount() - registerOffset;
+}
+
 QT_END_NAMESPACE
diff --git a/src/qml/compiler/qv4compilercontext_p.h b/src/qml/compiler/qv4compilercontext_p.h
index 1047af973d..65091bb67e 100644
--- a/src/qml/compiler/qv4compilercontext_p.h
+++ b/src/qml/compiler/qv4compilercontext_p.h
@@ -105,7 +105,7 @@ struct Context {
     QString name;
     int line = 0;
     int column = 0;
-    int registerCount = 0;
+    int registerCountInFunction = 0;
     int functionIndex = -1;
 
     enum MemberType {
@@ -139,6 +139,8 @@ struct Context {
     QVector<CompiledData::CodeOffsetToLine> lineNumberMapping;
 
     int maxNumberOfArguments = 0;
+    int nRegisters = 0;
+    int registerOffset = -1;
     bool hasDirectEval = false;
     bool hasNestedFunctions = false;
     bool isStrict = false;
@@ -283,6 +285,7 @@ struct Context {
     };
     ResolvedName resolveName(const QString &name);
     void emitHeaderBytecode(Compiler::Codegen *codegen);
+    void setupFunctionIndices(Moth::BytecodeGenerator *bytecodeGenerator);
 };
 
 
diff --git a/src/qml/compiler/qv4compilerscanfunctions.cpp b/src/qml/compiler/qv4compilerscanfunctions.cpp
index 0feba7bb61..4fa35f3adb 100644
--- a/src/qml/compiler/qv4compilerscanfunctions.cpp
+++ b/src/qml/compiler/qv4compilerscanfunctions.cpp
@@ -502,9 +502,6 @@ void ScanFunctions::calcEscapingVariables()
         if (allVarsEscape) {
             c->requiresExecutionContext = true;
             c->argumentsCanEscape = true;
-            for (auto &m : c->members) {
-                m.canEscape = true;
-            }
         }
         // ### for now until we have lexically scoped vars that'll require it
         if (c->type == ContextType::Global)
@@ -522,13 +519,17 @@ void ScanFunctions::calcEscapingVariables()
                 c->requiresExecutionContext = true;
             }
         }
+        if (allVarsEscape) {
+            for (auto &m : c->members)
+                m.canEscape = true;
+        }
     }
 
     static const bool showEscapingVars = qEnvironmentVariableIsSet("QV4_SHOW_ESCAPING_VARS");
     if (showEscapingVars) {
         qDebug() << "==== escaping variables ====";
         for (Context *c : qAsConst(m->contextMap)) {
-            qDebug() << "Context" << c->name << ":";
+            qDebug() << "Context" << c << c->name << ":";
             if (c->argumentsCanEscape)
                 qDebug() << "    Arguments escape";
             for (auto it = c->members.constBegin(); it != c->members.constEnd(); ++it) {