RE: [Open64-devel] addr_saved & addr_passed.

[Chan, S. C <sun...@in...>]

I can give definitive answer for question #2 and #3. For #1, either =
Raymond, Shin or Wilson could give you more definitive answer.
For #2, register is considered a hint by this compiler. I.e. it was =
ignored since it's believed that GRA can do a better job of it. This has =
been the view consistently held even back at Mips days with the ucode =
compiler.
For #3, the code should be in wn_lower.cxx
Sun

-----Original Message-----
From: Peng Zhao [mailto:pen...@cs...]
Sent: Wednesday, February 12, 2003 4:37 PM
To: open64
Subject: [Open64-devel] addr_saved & addr_passed.


Hi,

1.	I want to know when my optimization happens in the earlier phase=20
of BE, should I update some properties of STs that I manipulated. E.g. =
If=20
some symbols are passed to another new function by address, should I=20
modify their flags with addr_saved or addr_passed?

	The reason I asked about it is that I am afraid that later phases=20
will need these flags set correctly to work properly. Or they will=20
re-calculate these information by themselves thus I donot need to worry=20
about it.

=09
2. 	How the register variables are handled in a compiler? I noticed=20
that even a variable is declared as register, in WHIRL three, its =
Storage=20
class is not register. I.e. you cannot tell whether the variable is=20
register variable or not from the whirl symbol table.
	How I can tell that a symbol is register variable in whirl=20
representation?=20

	Does the declaration of a variable as register variable only take=20
effect in register allocation?=20

	What will happen when a register variable's address is taken or=20
passed to another PU? I can see a warning message spit out during the =
FE.=20
Will it cause the "register" lose the meaning? or the variable still=20
occupy a register and its memory location will contains some old values=20
that causes passing its memory address meaningless?


3. 	I noticed that there is someting mentioned in the ORC2.0 slides.=20
It is about switch-case optimization, which says "hoist most frequent=20
cases outside of switch case". However, I cannot find related codes. Can =

somebody give me a pointer?=20



4. 	I am also interested in implementing something that is machine=20
specific, e.g. I make some code that goto the caller's label or =
rewinding=20
2 or more levels of stack (i.e. directly return to the caller's caller).
Can somebody give me some idea about that?

	Thanks.

					Peng


--=20
                         	            |    |    |
Peng Zhao   pen...@cs...	   )_)  )_)  )_)
http://www.cs.ualberta.ca/~pengzhao       )___))___))___)
Phone: 1-780-492-3725	    		 )____)____)_____)\\
Fax:   1-780-492-1071	            ________|____|____|____\\\__
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