Changeset f9ad69d for src/GenPoly/GenPoly.cpp

Timestamp:

Aug 14, 2024, 1:12:18 PM (2 months ago)

Author:

Michael Brooks <mlbrooks@…>

Branches:

master

Children:

2f31773

Parents:

1a2ba84

Message:

Fix #175

File:

• src/GenPoly/GenPoly.cpp (modified) (4 diffs)

src/GenPoly/GenPoly.cpp

@@ -27 +27 @@
 #include "AST/Type.hpp"
 #include "AST/TypeSubstitution.hpp"
+#include "Common/Eval.hpp"                // for eval
 #include "GenPoly/ErasableScopedMap.hpp"  // for ErasableScopedMap<>::const_...
 #include "ResolvExpr/Typeops.hpp"         // for flatten
@@ -243 +244 @@
 } // namespace
 
+// This function, and its helpers following, have logic duplicated from
+// unification.  The difference in context is that unification applies where
+// the types "must" match, while this variation applies to arbitrary type
+// pairs, when an optimization could apply if they happen to match.  This
+// variation does not bind type variables.  The helper functions support
+// the case for matching ArrayType.
+bool typesPolyCompatible( ast::Type const * lhs, ast::Type const * rhs );
+
+static bool exprsPolyCompatibleByStaticValue(
+                const ast::Expr * e1, const ast::Expr * e2 ) {
+        Evaluation r1 = eval(e1);
+        Evaluation r2 = eval(e2);
+
+        if ( !r1.hasKnownValue ) return false;
+        if ( !r2.hasKnownValue ) return false;
+
+        if ( r1.knownValue != r2.knownValue ) return false;
+
+        return true;
+}
+
+static bool exprsPolyCompatible( ast::Expr const * lhs,
+                ast::Expr const * rhs ) {
+        type_index const lid = typeid(*lhs);
+        type_index const rid = typeid(*rhs);
+        if ( lid != rid ) return false;
+
+        if ( exprsPolyCompatibleByStaticValue( lhs, rhs ) ) return true;
+
+        if ( type_index(typeid(ast::CastExpr)) == lid ) {
+                ast::CastExpr const * l = as<ast::CastExpr>(lhs);
+                ast::CastExpr const * r = as<ast::CastExpr>(rhs);
+
+                // inspect casts' target types
+                if ( !typesPolyCompatible(
+                        l->result, r->result ) ) return false;
+
+                // inspect casts' inner expressions
+                return exprsPolyCompatible( l->arg, r->arg );
+
+        } else if ( type_index(typeid(ast::VariableExpr)) == lid ) {
+                ast::VariableExpr const * l = as<ast::VariableExpr>(lhs);
+                ast::VariableExpr const * r = as<ast::VariableExpr>(rhs);
+
+                assert(l->var);
+                assert(r->var);
+
+                // conservative: variable exprs match if their declarations are
+                // represented by the same C++ AST object
+                return (l->var == r->var);
+
+        } else if ( type_index(typeid(ast::SizeofExpr)) == lid ) {
+                ast::SizeofExpr const * l = as<ast::SizeofExpr>(lhs);
+                ast::SizeofExpr const * r = as<ast::SizeofExpr>(rhs);
+
+                assert((l->type != nullptr) ^ (l->expr != nullptr));
+                assert((r->type != nullptr) ^ (r->expr != nullptr));
+                if ( !(l->type && r->type) ) return false;
+
+                // mutual recursion with type poly compatibility
+                return typesPolyCompatible( l->type, r->type );
+
+        } else {
+                // All other forms compare on static value only, done earlier
+                return false;
+        }
+}
+
 bool typesPolyCompatible( ast::Type const * lhs, ast::Type const * rhs ) {
         type_index const lid = typeid(*lhs);
@@ -256 +325 @@
 
         // So remaining types can be examined case by case.
-        // Recurse through type structure (conditions borrowed from Unify.cpp).
+        // Recurse through type structure (conditions duplicated from Unify.cpp).
 
         if ( type_index(typeid(ast::BasicType)) == lid ) {
@@ -280 +349 @@
                 ast::ArrayType const * r = as<ast::ArrayType>(rhs);
 
-                if ( l->isVarLen ) {
-                        if ( !r->isVarLen ) return false;
-                } else {
-                        if ( r->isVarLen ) return false;
-
-                        auto lc = l->dimension.as<ast::ConstantExpr>();
-                        auto rc = r->dimension.as<ast::ConstantExpr>();
-                        if ( lc && rc && lc->intValue() != rc->intValue() ) {
+                if ( l->isVarLen != r->isVarLen ) return false;
+                if ( (l->dimension != nullptr) != (r->dimension != nullptr) )
+                        return false;
+
+                if ( l->dimension ) {
+                        assert( r->dimension );
+                        // mutual recursion with expression poly compatibility
+                        if ( !exprsPolyCompatible(l->dimension, r->dimension) )
                                 return false;
-                        }
                 }