|PRE and CISC firstname.lastname@example.org (shrey) (2008-01-17)|
|Re: PRE and CISC email@example.com (2008-01-18)|
|Date:||Thu, 17 Jan 2008 21:22:34 -0800 (PST)|
|Keywords:||registers, optimize, question|
|Posted-Date:||18 Jan 2008 00:50:02 EST|
I am wondering how compilers with aggressive PRE work for CISC
compilers. CISC instruction sets provide addressing modes where the
variable can be in symbolic form residing in memory. for example
add a, b, c - Registers need not be allocated.
Since PRE aims at trying to promote candidates into pseudo registers,
the subsequent passes may not have the opportunity to realize the
addressing mode (lets assume the addressing mode is sometimes
beneficial over using registers)
Two questions if somebody can help me find answers:
1. Are there any PRE algorithms that are aware of such addressing
2. if not, how else can the subsequent passes recover so that they can
use these addressing modes?
Any pointers ?
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