Be less eager to optimize constant conditions in loops

It still requires more work to actually detect the scope in which
variables are set, but this at least solves the immediate problem I had.

diff --git a/source/programcompiler.cpp b/source/programcompiler.cpp
index 1c84a96dc925f18095368d63aa13aaaf19a7d88d..1a3cd34fae5067201f81dabf8ffcdf76121b0d59 100644 (file)
--- a/source/programcompiler.cpp
+++ b/source/programcompiler.cpp
@@ -1200,12 +1200,14 @@ void ProgramCompiler::FunctionInliner::visit(Return &ret)
 
 ProgramCompiler::ExpressionEvaluator::ExpressionEvaluator():
        variable_values(0),
+       const_only(false),
        result(0.0f),
        result_valid(false)
 { }
 
-ProgramCompiler::ExpressionEvaluator::ExpressionEvaluator(const ValueMap &v):
-       variable_values(&v),
+ProgramCompiler::ExpressionEvaluator::ExpressionEvaluator(const ValueMap *v, bool c):
+       variable_values(v),
+       const_only(c),
        result(0.0f),
        result_valid(false)
 { }
@@ -1230,6 +1232,8 @@ void ProgramCompiler::ExpressionEvaluator::visit(VariableReference &var)
 {
        if(!var.declaration)
                return;
+       if(const_only && !var.declaration->constant)
+               return;
 
        if(variable_values)
        {
@@ -1289,7 +1293,8 @@ void ProgramCompiler::ExpressionEvaluator::visit(BinaryExpression &binary)
 
 
 ProgramCompiler::ConstantConditionEliminator::ConstantConditionEliminator():
-       scope_level(0)
+       scope_level(0),
+       in_loop(false)
 { }
 
 void ProgramCompiler::ConstantConditionEliminator::visit(Block &block)
@@ -1314,7 +1319,7 @@ void ProgramCompiler::ConstantConditionEliminator::visit(VariableDeclaration &va
 
 void ProgramCompiler::ConstantConditionEliminator::visit(Conditional &cond)
 {
-       ExpressionEvaluator eval(variable_values);
+       ExpressionEvaluator eval(&variable_values, in_loop);
        cond.condition->visit(eval);
        if(eval.result_valid)
                flatten_block(eval.result ? cond.body : cond.else_body);
@@ -1324,9 +1329,10 @@ void ProgramCompiler::ConstantConditionEliminator::visit(Conditional &cond)
 
 void ProgramCompiler::ConstantConditionEliminator::visit(Iteration &iter)
 {
+       // XXX Should this not visit init_statement first?
        if(iter.condition)
        {
-               ExpressionEvaluator eval;
+               ExpressionEvaluator eval(0, in_loop);
                iter.condition->visit(eval);
                if(eval.result_valid && !eval.result)
                {
@@ -1335,6 +1341,7 @@ void ProgramCompiler::ConstantConditionEliminator::visit(Iteration &iter)
                }
        }
 
+       SetFlag set_loop(in_loop);
        TraversingVisitor::visit(iter);
 }
 

diff --git a/source/programcompiler.h b/source/programcompiler.h
index 56bf1d538fc1be3069f1ed816547fbbc20638585..d8b2608afe9b885a5e5b376761b80f1bed0d02c7 100644 (file)
--- a/source/programcompiler.h
+++ b/source/programcompiler.h
@@ -225,11 +225,12 @@ private:
                typedef std::map<ProgramSyntax::VariableDeclaration *, ProgramSyntax::Expression *> ValueMap;
 
                const ValueMap *variable_values;
+               bool const_only;
                float result;
                bool result_valid;
 
                ExpressionEvaluator();
-               ExpressionEvaluator(const ValueMap &);
+               ExpressionEvaluator(const ValueMap *, bool);
 
                using ProgramSyntax::NodeVisitor::visit;
                virtual void visit(ProgramSyntax::Literal &);
@@ -242,6 +243,7 @@ private:
        struct ConstantConditionEliminator: BlockModifier
        {
                unsigned scope_level;
+               bool in_loop;
                ExpressionEvaluator::ValueMap variable_values;
 
                ConstantConditionEliminator();