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midRTL - virtualization
- From: Jan Hubicka <jh at suse dot cz>
- To: gcc-pdo at atrey dot karlin dot mff dot cuni dot cz, law at cygnus dot com, gcc at gcc dot gnu dot org
- Date: Tue, 5 Feb 2002 19:42:29 +0100
- Subject: midRTL - virtualization
I've done basics of virtualization and I would like to outlilne my approach
here so you can object and bring more ideas. The point of virutalization
is to allow multiple machine descriptions in the single compiler. I want
to use it for midRTL/real MD file, but in theory later we may want to use
it to allow multiple MDs to be compiled into single binarry, even when I
am not completely sure how fruitfull that trick can be.
1) Most of gen* programs now accepts -p switch that specify prefix
to avoid C namespace collision. I want to keep insn-output/insn-emit/insn-recog
separate file, but all of these reffers functions from each other, so I need
to distinguish them.
I now have insn-output/midinsn-output and same for recog, emit, opinit
all do use mid_ prefix.
2) I've removed the prototype for gen_* functions from insn-flags.h and created
insn-protos.h. In longer term we will want to remove gen_* references from compiler.
Since dozen of md files do use them, I now include insn-protos from insn-flags,
but use midinsn-protos only from midinsn-output that needs prototypes to
I don't want to update all the md files right now on the branch that may live
for a while, but I will do that incrementally as cleanups to the mainline.
3) I've reworked the CODE_FOR to be variables. I have codes.h that lits all
known insn names I want CODE_FOR_*. I've created new insn-defcodes to define
the variables and insn-initcodes to set the proper numbers to them. When
named pattern is missing or condition is false, it is initialized to CODE_FOR_nothing.
(insn_code is now enum containing only CODE_FOR_nothing initialized to INT_MAX).
This basically eliminate need for HAVE_* macros.
I can now bootstrap comiler that switch the MD files in the middle of compilation
so it basically works. I've hit problem on i386 that use dozen of CODE_FOR_*
valies for SSE builtins generation. I don't think it is good idea and it will
not work for midRTL, so it may be nice if we defined the named pattern
for vectorized code generation - this is way to go anyway.
As this is independent issue, may I hope that someone else will care that
while I am concentrating on the midRTL? I hope to implement the current plans
to working prototype in about one week and then we need to address these issues.
I will now cleanup my changes and prepare patch I will commit to branch
sometime tomorrow or day later, as it is relativly huge beast.