From 19f18d65222d3f33c80ef658517bcb738c142491 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?R=C3=BCdiger=20Franke?= <rdgfranke@gmail.com>
Date: Tue, 20 Nov 2018 16:04:49 +0100
Subject: [PATCH] [BE] Improve inlining and solution of array equations

Belonging to [master]:
  - OpenModelica/OMCompiler#2793
  - OpenModelica/OpenModelica-testsuite#1079
---
 Compiler/BackEnd/BackendInline.mo       | 7 ++++++-
 Compiler/BackEnd/Differentiate.mo       | 3 ++-
 Compiler/FrontEnd/ExpressionSimplify.mo | 7 +++++++
 3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/Compiler/BackEnd/BackendInline.mo b/Compiler/BackEnd/BackendInline.mo
index 69d0b3a19f..e9c1828d7f 100644
--- a/Compiler/BackEnd/BackendInline.mo
+++ b/Compiler/BackEnd/BackendInline.mo
@@ -210,8 +210,13 @@ algorithm
         (e1_1,source,b1,_) = Inline.inlineExp(e1,fns,source);
         (e2_1,source,b2,_) = Inline.inlineExp(e2,fns,source);
         true = b1 or b2;
+        eqn = match (e1_1, e2_1)
+          case (DAE.ARRAY(array = {e1}), DAE.ARRAY(array = {e2}))
+          then BackendDAE.EQUATION(e1,e2,source,attr); // flatten if size==1
+          else BackendDAE.ARRAY_EQUATION(dimSize,e1_1,e2_1,source,attr);
+        end match;
       then
-        (BackendDAE.ARRAY_EQUATION(dimSize,e1_1,e2_1,source,attr),true);
+        (eqn, true);
 
     case(BackendDAE.FOR_EQUATION(e, e1, e2, eqn, source, attr), _)
       equation
diff --git a/Compiler/BackEnd/Differentiate.mo b/Compiler/BackEnd/Differentiate.mo
index a256614b99..0ff23ef7fa 100644
--- a/Compiler/BackEnd/Differentiate.mo
+++ b/Compiler/BackEnd/Differentiate.mo
@@ -1056,6 +1056,7 @@ algorithm
     // case for arrays
     case ((e as DAE.CREF(ty = DAE.T_ARRAY())), _, _, diffType, _) guard ( match diffType case BackendDAE.GENERIC_GRADIENT() then false; else true; end match )
       equation
+        true = Flags.isSet(Flags.NF_SCALARIZE); // only expand if scalarize
         (e1,true) = Expression.extendArrExp(e,false);
         (res, outFunctionTree) = differentiateExp(e1, inDiffwrtCref, inInputData, inDiffType, inFunctionTree, maxIter);
       then
@@ -1070,7 +1071,7 @@ algorithm
     case (DAE.CREF(componentRef = cr, ty = tp), _, _, _, _)
       equation
         true = ComponentReference.crefEqual(cr, inDiffwrtCref);
-        one = Expression.makeConstOne(tp);
+        (one,_) = Expression.makeOneExpression(Expression.arrayDimension(tp));
       then
         (one, inFunctionTree);
 
diff --git a/Compiler/FrontEnd/ExpressionSimplify.mo b/Compiler/FrontEnd/ExpressionSimplify.mo
index 9172a21307..40185abcb6 100644
--- a/Compiler/FrontEnd/ExpressionSimplify.mo
+++ b/Compiler/FrontEnd/ExpressionSimplify.mo
@@ -2397,6 +2397,13 @@ algorithm
       then
         exp;
 
+    // Scalar product of any expression with zeros
+    case (_, _)
+      equation
+        true = Expression.isZero(inVector1) or Expression.isZero(inVector2);
+      then
+        Expression.makeConstZero(DAE.T_REAL_DEFAULT);
+
   end match;
 end simplifyScalarProduct;