We recently applied patches up through September 2020 to our Enterprise COBOL
V6.2 compiler. Prior to this we had patches through September 2019. This
appears to have changed how some code is generate, even though the compiler
options have not changed.
Take the following example:
01 ipt.
05 as-char pic xx.
88 as-char-10 value '10'.
05 as-nums redefines as-char
pic 99.
88 as-num-10 value 10.
Code checking the as-num-10 condition is generating the following code with the
"current" patch level:
COBOL V6.2 NUMPROC(NOPFD) ZONEDATA(MIG)
000021: 002200 if as-num-10
0001C8 F211 D138 9018 000021 PACK 312(2,R13),24(2,R9) #
AS-NUMS
0001CE F911 D138 31EC 000021 CP 312(2,R13),492(2,R3) #
+492
0001D4 A764 0016 000021 JNE L0006
This causes a situation where if "as-nums" is not a valid zoned-decimal field
it's causing a data exception (S0C7) on the CP instruction.
While acknowledging that the code is "bad", or the data is bad (depending on
how you look at it), we're still wondering what changed with the recent patches.
While I can't (easily) recover the compiler to the previous level, I did test
with our COBOL V5.2 compiler, which is out of service and did not receive any
recent patches. The same code compiles to this:
COBOL V5.2 NUMPROC(NOPFD) ZONEDATA(MIG)
000021: 002200 if as-num-10
00019E E300 8028 0095 000021 LLH R0,40(,R8) #
AS-NUMS
0001A4 C00D FFFF F0F0 000021 OILF R0,X'FFFFF0F0'
0001AA A70E F1F0 000021 CHI R0,0xf1f0
0001AE A764 000C 000021 JNE L0007
My guess is that prior to the patches COBOL V6.2 would have done something
similar. As you can see, it's using a CHI instead of a CP, and thus no S0C7.
It seems like V6.2 should not have changed its behavior in this regard.
Thoughts? Is this a new "bug" in COBOL V6.2?
Frank
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