Agreed, it is truly a strange construct, but unless the algorithm that uses the
construct is available it is unreasonable to speculate.
For my part, I cannot think of a suitable reason to use that construct.
Peter
From: IBM Mainframe Assembler List <ASSEMBLER-LIST@LISTSERV.UGA.EDU> On Behalf
Of John Ganci
Sent: Wednesday, September 3, 2025 12:34 PM
To: ASSEMBLER-LIST@LISTSERV.UGA.EDU
Subject: Question about HLASM complex relocatable expressions
Why would anyone use the definition of ADDR2 shown below?
Why the question arose follows.
A recent problem reported to the z390 project (Don Higgins' z390 assembler
project) about an invalid displacement generated in the "L 3,ADDR3" instruction
shown below. The problem boiled down to a z390 error processing the statement
"ADDR2 DC A(DWD+DWD)", which does contain a complex relocatable expression.
Sample source provided by the user reporting the problem follows.
CPXRELEX CSECT
USING CPXRELEX,15
L 1,ADDR1
L 2,ADDR2
L 3,ADDR3
BR 14
ORG CPXRELEX+X'100'
DWD DS D
ADDR1 DC A(DWD)
ADDR2 DC A(DWD+DWD) Complex relocatable expression
ADDR3 DC A(DWD+1)
END
HLASM correctly assembles the sample source.
Running the program on z/OS, with the "BR 14" replaced by "DC H'0'", shows (in
the summary dump) registers 1, 2, and 3 set correctly (R1 contains the address
of DWD, R2 = 2 * R1, and R3 = R1 + 1).
The problem has been fixed in z390.
Thanks for any insight.
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