b1b737ed6c
Enable this in CS for PowerPC; disable it for all other machines. PowerPC has no remainder instruction; the back end uses division to compute remainder. If CS finds both a / b and a % b, then CS now rewrites a % b as a - b * (a / b) and computes a / b only once. This removes an extra division in the PowerPC code, so it saves both time and space. I have not considered whether to enable this optimization for other machines. It might be less useful in machines with a remainder instruction. Also, if a % b occurs before a / b, the EM code gets a DUP. PowerPC ncg handles this DUP well; other back ends might not.
26 lines
736 B
C
26 lines
736 B
C
/* $Id$ */
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/*
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* (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
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* See the copyright notice in the ACK home directory, in the file "Copyright".
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*/
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void cs_machinit(void *vp); /* (FILE *f)
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* Read phase-specific information from f.
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*/
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bool may_become_aar(avail_p avp);
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/*
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* Return whether a LAR/SAR may become
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* an AAR LOI/STI.
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*/
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bool may_become_dv(void); /*
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* Return whether an RMI/RMU may become
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* a DVI/DVU: a % b = a - (a / b * b).
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*/
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bool desirable(avail_p avp); /*
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* Return whether it is desirable to eliminate
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* the recurrences of the expression in avp.
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* At the same time delete the recurrences
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* for which it is not allowed.
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*/
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