IR Transformations
Thu, 15 Apr 1993 17:42:49 GMT

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IR Transformations (1993-04-15)
Re: IR Transformations donawa@bluebeard.CS.McGill.CA (1993-04-21)
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Newsgroups: comp.compilers
Keywords: optimize, question
Organization: Compilers Central
Date: Thu, 15 Apr 1993 17:42:49 GMT

Could anyone give me pointers to papers on the subject of IR
transformations to suit code generation?

More specificaly, suppose we want to generate code for x = 2 * a; The
problem is how to know, at the IR level (before code is generated), that
the above expression can be rewritten as x = a + a (assuming + is cheaper
than *). The problem is that the above transformation may be context
dependent and not always desirable. In other words, sometimes 2*a may be
covered cheaper than a+a, e.g. by a shift left, which some processors
accomplish for free, bundled in a previous instruction.

Thanks for any help

Jim Yu

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