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Re: On -ftrapv vs. libcalls...

From: James E Wilson <wilson at specifixinc dot com>
To: Zdenek Dvorak <rakdver at atrey dot karlin dot mff dot cuni dot cz>
Cc: gcc at gcc dot gnu dot org
Date: Tue, 31 Aug 2004 11:55:50 -0700
Subject: Re: On -ftrapv vs. libcalls...
References: <200408221254.28457.stevenb@suse.de> <20040831135711.GA19870@atrey.karlin.mff.cuni.cz>

Zdenek Dvorak wrote:

What I do not understand is why it is legal to turn the libcall back
into MULT.

Because there is a REG_EQUAL note that claims the mulvdi3 result is exactly equivalent to an ordinary multiply. If it isn't exactly the same as an ordinary multiply, then the REG_EQUAL note should not be there. Or else the REG_EQUAL note should be changed to be accurate, but that would probably require creating a new RTL operator, e.g. multv. -- Jim Wilson, GNU Tools Support, http://www.SpecifixInc.com

References:
- On -ftrapv vs. libcalls...
  - From: Steven Bosscher
- Re: On -ftrapv vs. libcalls...
  - From: Zdenek Dvorak

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