From 80b96c1147382c1b7f29ad7eda1889f793b34c88 Mon Sep 17 00:00:00 2001
From: Stephen Heumann <stephenheumann@gmail.com>
Date: Fri, 14 Sep 2018 19:16:50 -0500
Subject: [PATCH] Ensure % with negative operands is not mis-optimized in
 intermediate code.

This will not be triggered in most cases, but might be if one of the operand expressions was itself subject to optimization.
---
 DAG.pas | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/DAG.pas b/DAG.pas
index 1325de9..901b49b 100644
--- a/DAG.pas
+++ b/DAG.pas
@@ -1625,7 +1625,7 @@ case op^.opcode of			{check for optimizations of this node}
    pc_mdl: begin			{pc_mdl}
       if op^.right^.opcode = pc_ldc then 
          if op^.left^.opcode = pc_ldc then 
-            if op^.right^.lval <> 0 then begin
+            if (op^.left^.lval >= 0) and (op^.right^.lval > 0) then begin
                op^.left^.lval := op^.left^.lval mod op^.right^.lval;
                opv := op^.left;
                end; {if}
@@ -1634,7 +1634,7 @@ case op^.opcode of			{check for optimizations of this node}
    pc_mod: begin			{pc_mod}
       if op^.right^.opcode = pc_ldc then 
          if op^.left^.opcode = pc_ldc then 
-            if op^.right^.q <> 0 then begin
+            if (op^.left^.q >= 0) and (op^.right^.q > 0) then begin
                op^.left^.q := op^.left^.q mod op^.right^.q;
                opv := op^.left;
                end; {if}