Hi.

Does a comprehensive list of the optimizations the enterprise PL/I compiler for z/OS will perform on PL/I code exist?

I have looked in the language reference as well as multiple data sheets, the programming guide, and release notes for different compiler versions; the best I could find was a presentation that states that the compiler will do loop unrolling.

So I know one optimization now, but there must be others. Any pointers are much appreciated.

Chapter 17 of the Programming Guide, "Improving Performance", gives details of optimisations

and ways of improving performace.

I was thinking more along the lines of knowing the compiler's internals, i.e.:

• Does it perform loop unrolling? (I have seen somewhere that it does)
• Does it perform tail call optimization for tail recursive procedures?
• etc.

What I would like to know is more detailed than what the programming guide provides.

The back-end of the PL/I for Windows compiler contains text

|SUMMARY REPORT:            %5.1fs                    100.0%                   |
|DETAILED REPORT:
|(%4d)       %5.1fs                     %4.1f%%
|       |             |                   |
(Inlining)                  %6d
Initialization
Termination
Translate
Build Procedure
Process WCode
Transform #1
Inlining
Transform #2
OTHER (Build)
Optimizer
DFG
CFG Build
SSA Build
Shadows
Value Numbers
Const Prop
Copy Prop
Dead Store
ForwardStore
If Conversion
RCE
Global CSE
Checking SSA
OTHER (DFG)
Walk
Global Walk
Local Walk
Late Opts
Rerun Walk
OTHER (Walk)
CSE
Loop
Loop Build
Invariant
Induction
Unrolling
Reg Assign
OTHER (Loop)
Transform LLI
Adjust Trees
OTHER (Opt)
Traverse Trees
Fix Instructions
Peephole Opt
Scheduling #1
Register Assign
Prologue/Epilogue
Value Tracking #1
Scheduling #2
Value Tracking #2
Emit Binary/Asm
OTHER (Translate)

that, when emitted, seems to produce a report on the optimizations performed. It may very well be the case that the z/OS compiler is capable of producing a similar report. As far as the Windows compiler is concerned, the way of producing this report isn't documented anywhere.