Re: [Patch, IRA] Fix a function accessing beyond end-of-array

[Hari Sandanagobalane]

On 11/05/11 19:32, Vladimir Makarov wrote:
On 05/11/2011 10:07 AM, Hari Sandanagobalane wrote:
Hello,
I discussed this problem with Vlad in
http://gcc.gnu.org/ml/gcc/2011-05/msg00131.html. I propose the
following patch to fix it. Okay to commit?
Revised the ChangeLog.

Thanks
Hari

ChangeLog:
         * ira.c (clarify_prohibited_class_mode_regs): Prevent the
function from accessing beyond the end of REGNO_REG_CLASS array by
stopping the loop early.

Patch:
Index: gcc/ira.c
===================================================================
--- gcc/ira.c   (revision 173654)
+++ gcc/ira.c   (working copy)
@@ -1422,6 +1422,12 @@
            if (TEST_HARD_REG_BIT
(ira_prohibited_class_mode_regs[cl][j], hard_regno))
              continue;
            nregs = hard_regno_nregs[hard_regno][j];
+          if (hard_regno + nregs>= FIRST_PSEUDO_REGISTER)

I think it should be '>' not'>='

Vlad,

The REGNO_REG_CLASS is generally an array of size FIRST_PSEUDO_REGISTER. 
So, the indexes go from 0 to FIRST_PSEUDO_REGISTER-1. I think the ">=" 
condition is fine in that case. Do you agree?

Cheers
Hari


With this change, the patch is ok.  Thanks for the patch.

+            {
+              SET_HARD_REG_BIT (ira_prohibited_class_mode_regs[cl][j],
+                                hard_regno);
+               continue;
+            }
            pclass = ira_pressure_class_translate[REGNO_REG_CLASS
(hard_regno)];
            for (nregs-- ;nregs>= 0; nregs--)
              if (((enum reg_class) pclass