HP MLIB User's Guide Vol. 1 7th Ed.

Chapter 1 Introduction to VECLIB 15

Accessing VECLIB

This ﬁle includes both entry points xerbla and xerbla_, and xerbla_ conﬂicts

with your XERBLA subroutine.

Use one of the following workarounds on PA-RISC if you are compiling your

own Fortran version of XERBLA:

• Compile your XERBLA with +noppu. This implies that you also compile any

of your program that calls XERBLA with +noppu, and that you apply this

rule recursively.

• Use f90 ALIAS directives:

% !$HP$ ALIAS xerbla='xerbla'

This prevents the compiler from postpending the underbar onto the entry

point and external references for XERBLA.

This problem is not conﬁned to the XERBLA subroutine. It occurs on PA-RISC

when the following conditions are met:

• Any subprogram with the same name as a user-visible MLIB subprogram is

compiled in your program with +ppu

• Another MLIB subprogram used by your program also calls that

subprogram

Furthermore, the reverse can occur in the PA-RISC 32-bit libraries if you

compile with the +ppu compiler option.

Itanium processors

If you compile on Itanium using the compiler option +noppu your xerbla.o

object has an entry point xerbla (without the postpended underbar). However

the Itanium MLIB libraries were compiled with +ppu option (following the

default behavior described in Table 1-1) and the entry points without underbars

were added as synonyms to the entry points with underbars. Hence the various

MLIB Fortran source subprograms that call XERBLA reference them as

xerbla_. Therefore, your xerbla (without the postpended underbar) does not

satisfy the Fortran calls to XERBLA, so the linker accesses xerbla.o from the

library. This ﬁle contains both entry points xerbla and xerbla_, and xerbla

conﬂicts with your XERBLA subroutine.

Moreover, the various MLIB C source subprograms that call XERBLA still

reference them as xerbla (without the postpended underbar). It means that

both xerbla and xerbla_ entry points must be provided in your xerbla.o.

Use one of the following workarounds on Itanium if you are compiling your own

Fortran version of XERBLA:

• Compile your Fortran source for XERBLA with +noppu and provide both

xerbla and xerbla_ entry points: