What’s C.E.E.1 and which function is this address in?

I had an abend in a module created from C programs, and wanted to know which function had the problem.

In the old days, each function had an eye-catcher and a compile date at the top of each function, so it was easy to scroll upwards towards the start of the dump until you came across the eye-catcher.

And then we had XPLINK… I think the XP link stands for eXtra Performance. The output of the C compiler changed to make it the code more efficient, especially with Java functions. For example:

• before XPLINK, a call to a function would save all of the registers, update the save area chain – call the module… return and restore the registers afterwards. Some functions were as simple as set this value to 0 – and the overhead of the call was many times the cost of the instructions. The overhead was reduced by only saving what needed to be saved, and passing more parameters in registers.
• by moving constant data, such as character strings, out of the mainline instructions, meant that sometimes fewer pages were needed for instructions – and so fewer pages were needed in the hardware instruction cache, and so may be faster. Moving the function name and compile time into the “data page” and so into the data cache, was part of this.

The function name etc is available – just not in an obvious place.

What does the code look like?

Meta data is stored in Program Prolog Areas (PPAs)

In the listing, at the start of each XPLINK function is “C.E.E.1”

00000E70    00C300C5 00C500F1 00000080 000000A0a *.C.E.E.1.....

At offset 00000080 from 00000E70 is a block of storage (PPA1) which identifies this function.

0006D8  02           =AL1(2)            Version 
0006D9  CE           =AL1(206)          CEL signature 
...
0006F0  0003         AL2(3),C'pit' 
0006F8  FFFFF9C0     =F'-1600'          Offset to Entry Point Marker 

• At offset 0 is 0x02… so you know you are in the right control block
• At offset 2 is 0xCE
• At offset 10 is the code length
• At offset 18 is 2 bytes of length, followed by the function name, possibly with up to 3 bytes of padding to align the next field on a 4 byte work boundary.
• (Sometimes,) after this, the offset will vary because the name length is variable, is a field like 0XFF… such as FFFFFA60. This is – 0x5a0 (-1440). The address of this section (the 0x02) minus this value gets you to the C.E.E.1. This does not always seem to work!

The start of the function “pit” is at x6d8 – 1600 = x6d8 -x640 = x98

At this address in the listing was

                                *  void pit() 
000098  00C300C5 DC   =F'12779717'       XPLink entrypoint marker 
00009C  00C500F1 DC   =F'12910833' 
0000A0  00000640 DC   =F'1600' 
0000A4  00000080 DC   =F'128' 
0000A8  pit      DS       0D 
        * Start of executable code
0000A8  9049  4780   STM      r4,r9,1920(r4) .....

Note the value’s 1600 and -1600 tie up.

So not too difficult to find the name of the function.