Just realized that some of the compiler option tests for 5.7 belong to 5.8 as well, so it should have been 5.7 or newer:

j2se/make/common/Defs-solaris.gmk:

  ifeq ($(COMPILER_REV), 5.7)
    # Do NOT use the frame pointer register as a general purpose opt register
    CFLAGS_REQUIRED_i586 += -xregs=no%frameptr
    CFLAGS_REQUIRED_amd64 += -xregs=no%frameptr
    # We MUST allow data alignment of 4 for sparc (sparcv9 is ok at 8s)
    CFLAGS_REQUIRED_sparc += -xmemalign=4s
  endif

NOTE: This is for sparc (v8 or 32bit) only, NOT FOR SPARCV9!

The hotspot and other workspaces look ok, this is the only problem I saw.

I think this needs to be 5.7 or greater, e.g. something like

ifeq ($(shell $(EXPR) $(COMPILER_REV) \> 5.6), 1)

See 6238560 for why this needs to be 4s (abi issue for jni libraries).
There is also a use of -xmemalign=8s with CC_HIGHEST_OPT, which is the default anyway on sparcv9, but using this on sparcv8 might be an issue. Needs investigation.