Fix code generation where & is used on an rvalue

Added a daeExpReturnLValue function to Susan which converts an rvalue to
an lvalue when the code requires it. Can also be used when you want to
cache the expression and use its value twice (without evaluating the
expression twice).

This fixes ticket:4212.

Author: sjoelund

Compiler/Template/CodegenCFunctions.tpl

@@ -4352,6 +4352,18 @@ end getTempDeclMatchOutputName;
   else error(sourceInfo(), 'Unknown expression: <%ExpressionDumpTpl.dumpExp(exp,"\"")%>')
 end daeExp;
 
+/* public */ template daeExpAsLValue(Exp exp, Context context, Text &preExp, Text &varDecls, Text &auxFunction)
+ "Generates code for an expression. Makes sure that the output is an lvalue (so you can take the address of it)."
+::=
+  let res1 = daeExp(exp, context, &preExp, &varDecls, &auxFunction)
+  if isCIdentifier(res1)
+    then res1
+  else
+    let tmp = tempDecl(expTypeFromExpArrayIf(exp),&varDecls)
+    let &preExp += '<%tmp%> = <%res1%>;<%\n%>'
+    tmp
+end daeExpAsLValue;
+
 
 template daeExternalCExp(Exp exp, Context context, Text &preExp, Text &varDecls, Text &auxFunction)
   "Like daeExp, but also converts the type to external C"
@@ -5750,20 +5762,20 @@ template daeExpCall(Exp call, Context context, Text &preExp, Text &varDecls, Tex
 
   case CALL(path=IDENT(name="max"), attr=CALL_ATTR(ty = ty), expLst={array}) then
     let expVar = daeExp(array, context, &preExp, &varDecls, &auxFunction)
-    let arr_tp_str = '<%expTypeArray(ty)%>'
+    let arr_tp_str = expTypeArray(ty)
     let tvar = tempDecl(expTypeModelica(ty), &varDecls)
     let &preExp += '<%tvar%> = max_<%arr_tp_str%>(<%expVar%>);<%\n%>'
     tvar
 
   case CALL(path=IDENT(name="min"), attr=CALL_ATTR(ty = ty), expLst={array}) then
     let expVar = daeExp(array, context, &preExp, &varDecls, &auxFunction)
-    let arr_tp_str = '<%expTypeArray(ty)%>'
+    let arr_tp_str = expTypeArray(ty)
     let tvar = tempDecl(expTypeModelica(ty), &varDecls)
     let &preExp += '<%tvar%> = min_<%arr_tp_str%>(<%expVar%>);<%\n%>'
     tvar
 
   case CALL(path=IDENT(name="fill"), expLst=val::dims, attr=CALL_ATTR(ty = ty)) then
-    let valExp = daeExp(val, context, &preExp, &varDecls, &auxFunction)
+    let valExp = daeExpAsLValue(val, context, &preExp, &varDecls, &auxFunction)
     let dimsExp = (dims |> dim =>
       daeExp(dim, context, &preExp, &varDecls, &auxFunction) ;separator=", ")
     let ty_str = expTypeArray(ty)
@@ -5776,7 +5788,7 @@ template daeExpCall(Exp call, Context context, Text &preExp, Text &varDecls, Tex
     let tvarc = tempDecl("int", &varDecls)
     let tvardata = tempDecl("void *", &varDecls)
     let nElts = tempDecl("int", &varDecls)
-    let val = daeExp(exp, context, &preExp, &varDecls, &auxFunction)
+    let val = daeExpAsLValue(exp, context, &preExp, &varDecls, &auxFunction)
     let szElt = 'sizeof(<%expTypeModelica(ty)%>)'
     let dims =
       (getDimensionSizes(Expression.typeof(exp)) |> sz hasindex ix fromindex 1 =>
@@ -5802,51 +5814,51 @@ simple_alloc_1d_base_array(&<%tvar%>, <%nElts%>, <%tvardata%>);
   case CALL(path=IDENT(name="cat"), expLst=dim::arrays, attr=CALL_ATTR(ty = ty)) then
     let dim_exp = daeExp(dim, context, &preExp, &varDecls, &auxFunction)
     let arrays_exp = (arrays |> array =>
-      daeExp(array, context, &preExp, &varDecls, &auxFunction) ;separator=", &")
+      daeExpAsLValue(array, context, &preExp, &varDecls, &auxFunction) ;separator=", &")
     let ty_str = expTypeArray(ty)
     let tvar = tempDecl(ty_str, &varDecls)
     let &preExp += 'cat_alloc_<%ty_str%>(<%dim_exp%>, &<%tvar%>, <%listLength(arrays)%>, &<%arrays_exp%>);<%\n%>'
     tvar
 
   case CALL(path=IDENT(name="promote"), expLst={A, n}) then
-    let var1 = daeExp(A, context, &preExp, &varDecls, &auxFunction)
+    let var1 = daeExpAsLValue(A, context, &preExp, &varDecls, &auxFunction)
     let var2 = daeExp(n, context, &preExp, &varDecls, &auxFunction)
     let arr_tp_str = '<%expTypeFromExpArray(A)%>'
     let tvar = tempDecl(arr_tp_str, &varDecls)
     let &preExp += 'promote_alloc_<%arr_tp_str%>(&<%var1%>, <%var2%>, &<%tvar%>);<%\n%>'
     tvar
 
   case CALL(path=IDENT(name="transpose"), expLst={A}) then
-    let var1 = daeExp(A, context, &preExp, &varDecls, &auxFunction)
+    let var1 = daeExpAsLValue(A, context, &preExp, &varDecls, &auxFunction)
     let arr_tp_str = '<%expTypeFromExpArray(A)%>'
     let tvar = tempDecl(arr_tp_str, &varDecls)
     let &preExp += 'transpose_alloc_<%arr_tp_str%>(&<%var1%>, &<%tvar%>);<%\n%>'
     tvar
 
   case CALL(path=IDENT(name="symmetric"), expLst={A}) then
-    let var1 = daeExp(A, context, &preExp, &varDecls, &auxFunction)
+    let var1 = daeExpAsLValue(A, context, &preExp, &varDecls, &auxFunction)
     let arr_tp_str = '<%expTypeFromExpArray(A)%>'
     let tvar = tempDecl(arr_tp_str, &varDecls)
     let &preExp += 'symmetric_<%arr_tp_str%>(&<%var1%>, &<%tvar%>);<%\n%>'
     tvar
 
   case CALL(path=IDENT(name="skew"), expLst={A}) then
-    let var1 = daeExp(A, context, &preExp, &varDecls, &auxFunction)
+    let var1 = daeExpAsLValue(A, context, &preExp, &varDecls, &auxFunction)
     let arr_tp_str = '<%expTypeFromExpArray(A)%>'
     let tvar = tempDecl(arr_tp_str, &varDecls)
     let &preExp += 'skew_<%arr_tp_str%>(&<%var1%>, &<%tvar%>);<%\n%>'
     tvar
 
   case CALL(path=IDENT(name="cross"), expLst={v1, v2}) then
-    let var1 = daeExp(v1, context, &preExp, &varDecls, &auxFunction)
-    let var2 = daeExp(v2, context, &preExp, &varDecls, &auxFunction)
+    let var1 = daeExpAsLValue(v1, context, &preExp, &varDecls, &auxFunction)
+    let var2 = daeExpAsLValue(v2, context, &preExp, &varDecls, &auxFunction)
     let arr_tp_str = expTypeFromExpArray(v1)
     let tvar = tempDecl(arr_tp_str, &varDecls)
     let &preExp += 'cross_alloc_<%arr_tp_str%>(&<%var1%>, &<%var2%>, &<%tvar%>);<%\n%>'
     tvar
 
   case CALL(path=IDENT(name="identity"), expLst={A}) then
-    let var1 = daeExp(A, context, &preExp, &varDecls, &auxFunction)
+    let var1 = daeExpAsLValue(A, context, &preExp, &varDecls, &auxFunction)
     let arr_tp_str = expTypeFromExpArray(A)
     let tvar = tempDecl(arr_tp_str, &varDecls)
     let &preExp += 'identity_alloc_<%arr_tp_str%>(<%var1%>, &<%tvar%>);<%\n%>'
@@ -5856,7 +5868,7 @@ simple_alloc_1d_base_array(&<%tvar%>, <%nElts%>, <%tvardata%>);
     let arr_tp_str = expTypeFromExpArray(A)
     let tvar = tempDecl(arr_tp_str, &varDecls)
     let params = (A.array |> e =>
-      '<%daeExp(e, context, &preExp, &varDecls, &auxFunction)%>'
+      daeExp(e, context, &preExp, &varDecls, &auxFunction)
     ;separator=", ")
     let &preExp += 'diagonal_alloc_<%arr_tp_str%>(&<%tvar%>, <%listLength(A.array)%>, <%params%>);<%\n%>'
     tvar

Compiler/Util/Util.mo

@@ -1711,7 +1711,7 @@ public function isCIdentifier
 protected
   Integer i;
 algorithm
-  (i,_) := System.regex(str, "^[][_A-Za-z0-9]*$", 0, true, false);
+  (i,_) := System.regex(str, "^[_A-Za-z][_A-Za-z0-9]*$", 0, true, false);
   b := i == 1;
 end isCIdentifier;