I tried to build fastdebug VM (most hard to compile due to
using -O4 with -g).

I set next variable:

jano% setenv ENFORCE_COMPILER_REV 5.6
jano% setenv ENFORCE_C_COMPILER_REV 5.6
setenv PATH /java/devtools/sparc/SUNWspro/SOS9/bin:$PATH

And I fixed (5074634) src/share/vm/oops/methodDataOop.hpp to avoid the warning
"line 28: Warning: Types cannot be declared in anonymous union."

After this I succesfully build debug and fastdebug VMs.
Unfortunately fastdebug VM crashed:

% /export/home2/work/j2sdk1.5.0_sparc/bin/java -server -version
#
# An unexpected error has been detected by HotSpot Virtual Machine:
#
# SIGBUS (0xa) at pc=0xfda85ecc, pid=16341, tid=1
#
...
Current thread is 1
Dumping core ...
Abort
% hs_err hs_err_pid16353.log|c++filt
Instructions: (pc=0xfda85ecc)
0xfda85ebc: e0 07 00 02 f8 07 00 01 de 5c 20 00 f8 25 e0 00
0xfda85ecc: de 75 e0 38 da 5c 20 08 da 75 e0 40 d8 5c 20 10
;; 00000000fda85ebc e0 07 00 02 f8 07 00 01 de 5c 20 00 f8 25 e0 00
;; ---------------
;; 00000000fda85ecc de 75 e0 38 unknown
;; 00000000fda85ed0 da 5c 20 08 unknown
;; 00000000fda85ed4 da 75 e0 40 unknown
;; 00000000fda85ed8 d8 5c 20 10 unknown
Stack: [0xffb80000,0xffc00000), sp=0xffbf7f40, free space=479k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0x285ecc] ;; Node*CallNode::match(const ProjNode*,const Matcher*)+0xa0
V [libjvm.so+0x8ae7d0] ;; Node*Matcher::xform(Node*,int)+0x42c