F90 Compiler Backend Problem

[david maynard_1]

When recompiling a small block of FORTRAN 90 code that has not changed in a long time, the HP F90 compiler, v3.2.2, seems to parse the source code OK (no compile errors generated) but then generates a fatal "ASM_BACKEND" error during code generation. Could someone explain just what the compiler is trying to tell me. I've included the command line inputs and response below.

Also, is it possible to actually write source code that parses successful but fails to compile ? Seems to me, that either the compiler front-end source code parser is ignoring a fatal source code error or the back-end code generator is failing to assemble valid source code. Have I encountered a compiler bug ?



Command line compile results:

/opt/fortran90/bin/f90 -c initv.f
initv.f
external subroutine INITV

93 Lines Compiled
ASM_BACKEND fatal error: symbol `$.smcrt_@0000000000000044' already defined
f90: error 213: Errors detected.

Compiler info:

HP F90 v3.2.2
HP-UX f90 B.11.11.99.05 PHSS_37536 / B.11.23.37 PHSS_37537 / B.11.31.05 PHSS_37538 (Itanium(R)-based host and target) Mon Nov 26 16:39:03 2007 IST

Machine & OS info:

HP-UX sbhs905 B.11.23 U ia64 0368276839 unlimited-user license
model ia64 hp server rx4640

[Dennis Handly]

>Could someone explain just what the compiler is trying to tell me.

The part of the backend that generates the object file is noticing that there are two symbols of the same name. Typically this is a frontend bug.

There was a recent optimizer bug like this when doing procedure splitting for nested functions but you aren't optimizing and using PBO.

>is it possible to actually write source code that parses successful but fails to compile?

Sure, that backend is awfully picky. :-)
But the backend can have optimizer errors, especially since it is much more complicated than the frontend.

>that either the compiler front-end source code parser is ignoring a fatal source code error

Besides parsing, there is also semantic processing and code generation, this is where the error occur.

>or the back-end code generator is failing to assemble valid source code.

You're confused, there is no assembler here. You're thinking of a foreign devil compiler.

>Have I encountered a compiler bug?

Most likely. As you said, if it was your problem, the frontend should produce an error message.
You should contact the Response Center and report this bug.

[Chandra Reddy]

It is defect in the compiler(backend).
-Chandra