* avoid overflow during register allocation

git-svn-id: https://svn.freepascal.org/svn/fpc/trunk@49285 3ad0048d-3df7-0310-abae-a5850022a9f2

1 files changed, 8 insertions, 4 deletions

diff --git a/compiler/rgobj.pas b/compiler/rgobj.pas
index b4ad622ae1..b0d344f5ae 100644
--- a/compiler/rgobj.pas
+++ b/compiler/rgobj.pas
@@ -2846,8 +2846,10 @@ unit rgobj;
                     set weigth of the newly allocated register higher than the old one,
                     so it will selected for spilling with a lower priority than
                     the original one, this prevents an endless spilling loop if orgreg
-                    is short living, see e.g. tw25164.pp }
-                  add_reg_instruction(instr,loadreg,reginfo[orgreg].weight+1);
+                    is short living, see e.g. tw25164.pp
+
+                    the min trick is needed to avoid an overflow in case weight=high(weight which might happen }
+                  add_reg_instruction(instr,loadreg,min(high(reginfo[orgreg].weight)-1,reginfo[orgreg].weight)+1);
                   ungetregisterinline(list,loadreg);
                 end;
             end;
@@ -2878,8 +2880,10 @@ unit rgobj;
                     set weigth of the newly allocated register higher than the old one,
                     so it will selected for spilling with a lower priority than
                     the original one, this prevents an endless spilling loop if orgreg
-                    is short living, see e.g. tw25164.pp }
-                  add_reg_instruction(instr,storereg,reginfo[orgreg].weight+1);
+                    is short living, see e.g. tw25164.pp
+
+                    the min trick is needed to avoid an overflow in case weight=high(weight which might happen }
+                  add_reg_instruction(instr,storereg,min(high(reginfo[orgreg].weight)-1,reginfo[orgreg].weight)+1);
                 end;
             end;