+ tfornode.simply which removes for loops being never executed

* handle function results correctly in life dfa
* handle for loops with at least one iteration better in life dfa
o resolves #8151

git-svn-id: trunk@11624 -

.gitattributes

@@ -8111,6 +8111,8 @@ tests/webtbf/tw11295b.pp svneol=native#text/plain
 tests/webtbf/tw1157a.pp svneol=native#text/plain
 tests/webtbf/tw11619b.pp svneol=native#text/plain
 tests/webtbf/tw11632.pp svneol=native#text/plain
+tests/webtbf/tw11846.pp svneol=native#text/plain
+tests/webtbf/tw11846c.pp svneol=native#text/plain
 tests/webtbf/tw11848a.pp svneol=native#text/plain
 tests/webtbf/tw11849a.pp svneol=native#text/plain
 tests/webtbf/tw11862a.pp svneol=native#text/plain
@@ -8300,6 +8302,8 @@ tests/webtbf/tw8150c.pp svneol=native#text/plain
 tests/webtbf/tw8150e.pp svneol=native#text/plain
 tests/webtbf/tw8150f.pp svneol=native#text/plain
 tests/webtbf/tw8150g.pp svneol=native#text/plain
+tests/webtbf/tw8151b.pp svneol=native#text/plain
+tests/webtbf/tw8151c.pp svneol=native#text/plain
 tests/webtbf/tw8264a.pp svneol=native#text/plain
 tests/webtbf/tw8398.pp svneol=native#text/plain
 tests/webtbf/tw8451.pp svneol=native#text/plain
@@ -8549,7 +8553,8 @@ tests/webtbs/tw1157.pp svneol=native#text/plain
 tests/webtbs/tw1157b.pp svneol=native#text/plain
 tests/webtbs/tw11619.pp svneol=native#text/plain
 tests/webtbs/tw1181.pp svneol=native#text/plain
-tests/webtbs/tw11846.pp svneol=native#text/plain
+tests/webtbs/tw11846a.pp svneol=native#text/plain
+tests/webtbs/tw11846b.pp svneol=native#text/plain
 tests/webtbs/tw11848.pp svneol=native#text/plain
 tests/webtbs/tw11849.pp svneol=native#text/plain
 tests/webtbs/tw11852.pp svneol=native#text/plain
@@ -9315,6 +9320,7 @@ tests/webtbs/tw8145.pp svneol=native#text/plain
 tests/webtbs/tw8148.pp svneol=native#text/plain
 tests/webtbs/tw8150a.pp svneol=native#text/plain
 tests/webtbs/tw8150d.pp svneol=native#text/plain
+tests/webtbs/tw8151a.pp svneol=native#text/plain
 tests/webtbs/tw8153.pp svneol=native#text/plain
 tests/webtbs/tw8153a.pp svneol=native#text/plain
 tests/webtbs/tw8155.pp svneol=native#text/plain

compiler/nflw.pas

@@ -101,6 +101,7 @@ interface
           procedure loop_var_access(not_type:Tnotification_flag;symbol:Tsym);
           function pass_typecheck:tnode;override;
           function pass_1 : tnode;override;
+          function simplify : tnode;override;
        end;
        tfornodeclass = class of tfornode;
 
@@ -764,6 +765,26 @@ implementation
       Tabstractvarsym(symbol).unregister_notification(loopvar_notid);
     end;
 
+
+    function tfornode.simplify : tnode;
+      begin
+        result:=nil;
+        if (t1.nodetype=ordconstn) and
+           (right.nodetype=ordconstn) and
+           (
+            (
+             (lnf_backward in loopflags) and
+             (tordconstnode(right).value<tordconstnode(t1).value)
+            ) or
+            (
+              not(lnf_backward in loopflags) and
+              (tordconstnode(right).value>tordconstnode(t1).value)
+            )
+           ) then
+        result:=cnothingnode.create;
+      end;
+
+
     function tfornode.pass_typecheck:tnode;
       var
         unrollres : tnode;

compiler/optdfa.pas

@@ -204,8 +204,20 @@ unit optdfa;
               end
             else
               begin
-                l:=n.optinfo^.use;
-                DFASetIncludeSet(l,n.optinfo^.life);
+                { last node, not exit or raise node and function? }
+                if assigned(resultnode) and
+                  not(node.nodetype in [raisen,exitn]) then
+                  begin
+                    { if yes, result lifes }
+                    DFASetDiff(l,resultnode.optinfo^.life,n.optinfo^.def);
+                    DFASetIncludeSet(l,n.optinfo^.use);
+                    DFASetIncludeSet(l,n.optinfo^.life);
+                  end
+                else
+                  begin
+                    l:=n.optinfo^.use;
+                    DFASetIncludeSet(l,n.optinfo^.life);
+                  end;
               end;
             updatelifeinfo(n,l);
           end;
@@ -275,7 +287,9 @@ unit optdfa;
                   t1: to
                   t2: body
                 }
-                calclife(node);
+                { take care of the sucessor if it's possible that we don't have one execution of the body }
+                if not((tfornode(node).right.nodetype=ordconstn) and (tfornode(node).t1.nodetype=ordconstn)) then
+                  calclife(node);
                 node.allocoptinfo;
                 if not(assigned(node.optinfo^.def)) and
                    not(assigned(node.optinfo^.use)) then
@@ -287,9 +301,11 @@ unit optdfa;
                     foreachnodestatic(pm_postprocess,tfornode(node).right,@AddDefUse,@dfainfo);
                     foreachnodestatic(pm_postprocess,tfornode(node).t1,@AddDefUse,@dfainfo);
                   end;
-                calclife(node);
+                { take care of the sucessor if it's possible that we don't have one execution of the body }
+                if not((tfornode(node).right.nodetype=ordconstn) and (tfornode(node).t1.nodetype=ordconstn)) then
+                  calclife(node);
 
-                { create life the body }
+                { create life for the body }
                 CreateInfo(tfornode(node).t2);
 
                 { update for node }
@@ -360,7 +376,12 @@ unit optdfa;
                   DFASetIncludeSet(l,tifnode(node).t1.optinfo^.life)
                 else
                   if assigned(node.successor) then
-                    DFASetIncludeSet(l,node.successor.optinfo^.life);
+                    DFASetIncludeSet(l,node.successor.optinfo^.life)
+                  { last node and function? }
+                else
+                  if assigned(resultnode) then
+                    DFASetIncludeSet(l,resultnode.optinfo^.life);
+
                 { add use info from the cond. expression }
                 DFASetIncludeSet(l,tifnode(node).optinfo^.use);
                 { finally, update the life info of the node }
@@ -397,7 +418,11 @@ unit optdfa;
                   DFASetIncludeSet(l,tcasenode(node).elseblock.optinfo^.life)
                 else
                   if assigned(node.successor) then
-                    DFASetIncludeSet(l,node.successor.optinfo^.life);
+                    DFASetIncludeSet(l,node.successor.optinfo^.life)
+                  { last node and function? }
+                else
+                  if assigned(resultnode) then
+                    DFASetIncludeSet(l,resultnode.optinfo^.life);
 
                 { add use info from the "case" expression }
                 DFASetIncludeSet(l,tcasenode(node).optinfo^.use);
@@ -502,6 +527,7 @@ unit optdfa;
             dfarec.def:[email protected]^.def;
             dfarec.map:=map;
             AddDefUse(resultnode,@dfarec);
+            resultnode.optinfo^.life:=resultnode.optinfo^.use;
           end
         else
           resultnode:=nil;
@@ -530,40 +556,13 @@ unit optdfa;
 
 
     procedure TDFABuilder.createdfainfo(node : tnode);
-    {
-      var
-        lastnode : tnode;
-        fakeexitnode : texitnode;
-    }
       begin
         if not(assigned(nodemap)) then
           nodemap:=TIndexedNodeSet.Create;
         { add controll flow information }
         SetNodeSucessors(node);
-     {
-        { create an exit node for functions to get
-          the function result at the end handled properly }
-        if not(is_void(current_procinfo.procdef.returndef)) and
-          not(current_procinfo.procdef.proctypeoption=potype_constructor) then
-          begin
-            lastnode:=node;
-            while assigned(lastnode.successor) do
-              lastnode:=lastnode.successor;
-            fakeexitnode:=cexitnode.create(nil);
-            lastnode.successor:=fakeexitnode;
-          end
-        else
-           fakeexitnode:=nil;
-     }
         { now, collect life information }
         CreateLifeInfo(node,nodemap);
-     {
-        if assigned(fakeexitnode) then
-          begin
-            lastnode.successor.free;
-            lastnode.successor:=nil;
-          end;
-     }
       end;
 
 

tests/webtbf/tw11846.pp

@@ -0,0 +1,14 @@
+{ %OPT=-Sew -Oodfa }
+{ %NORUN }
+{ %fail }
+{$mode objfpc}
+function Test(a: integer): boolean;
+var
+  i: Integer;
+begin
+  for i:=1 to a do
+    Result:=true;
+end;
+
+begin
+end.

tests/webtbf/tw11846c.pp

@@ -0,0 +1,14 @@
+{ %OPT=-Sew -Oodfa }
+{ %NORUN }
+{ %fail }
+{$mode objfpc}
+function Test(a: integer): boolean;
+var
+  i: Integer;
+begin
+  for i:=2 to 1 do
+    Result:=true;
+end;
+
+begin
+end.

tests/webtbf/tw8151b.pp

@@ -0,0 +1,21 @@
+{ %opt=-Oodfa -Sew }                                                                                                                                         program FunctionResultAnalysisWrong;
+{ %fail }
+{$IFDEF FPC}
+  {$mode delphi}
+{$ENDIF}
+
+uses
+  SysUtils;
+
+var
+  I : longint;
+
+function Test3: Integer;
+begin
+  if i > 0 then
+    raise Exception.Create('')
+end; {SHOULD generate "Warning: Function result does not seem to be set", and does in both delphi and FPC}
+
+begin
+  i:=1;
+end.

tests/webtbf/tw8151c.pp

@@ -0,0 +1,22 @@
+{ %opt=-Oodfa -Sew }                                                                                                                                         program FunctionResultAnalysisWrong;
+{ %fail }
+{$IFDEF FPC}
+  {$mode delphi}
+{$ENDIF}
+
+uses
+  SysUtils;
+
+var
+  I : longint;
+
+function Test5: Integer;
+begin
+  if i > 0 then
+    Result := 0;
+end; {SHOULD generate "Warning: Function result does not seem to be set", does in delphi, not in FPC }
+
+
+begin
+  i:=1;
+end.

tests/webtbs/tw11846b.pp

@@ -0,0 +1,14 @@
+{ %OPT=-Sew -Oodfa }
+{ %NORUN }
+{$mode objfpc}
+function Test(a: integer): boolean;
+var
+  i: Integer;
+begin
+  for i:=2 to 1 do
+    Result:=true;
+  Result:=true;
+end;
+
+begin
+end.

tests/webtbs/tw8151a.pp

@@ -0,0 +1,36 @@
+{ %opt=-Oodfa -Sew }                                                                                                                                         program FunctionResultAnalysisWrong;
+{ %norun }
+{$IFDEF FPC}
+  {$mode delphi}
+{$ENDIF}
+
+uses
+  SysUtils;
+
+var
+  I : longint;
+
+function Test1: Integer;
+begin
+  raise Exception.Create('');
+end; {should NOT generate "Warning: Function result does not seem to be set" (doesn't in delphi, does in FPC) }
+
+function Test2: Integer;
+begin
+  if i > 0 then
+    raise Exception.Create('')
+  else
+    raise Exception.Create('');
+end; {should NOT generate "Warning: Function result does not seem to be set" (doesn't in delphi, does in FPC) }
+
+function Test4: Integer;
+begin
+  if i > 0 then
+    raise Exception.Create('')
+  else
+    Result := 0;
+end; {should NOT generate "Warning: Function result does not seem to be set" (doesn't in delphi and FPC) }
+
+begin
+  i:=1;
+end.