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Re: [PATCH] Document arithmetic overflow semantics

From: Andrew Haley <aph at redhat dot com>
To: Roger Sayle <roger at www dot eyesopen dot com>
Cc: Richard Henderson <rth at redhat dot com>, gcc-patches at gcc dot gnu dot org,<gcc at gcc dot gnu dot org>
Date: Thu, 13 Feb 2003 18:33:15 +0000 (GMT)
Subject: Re: [PATCH] Document arithmetic overflow semantics
References: <20030213175851.GC12198@redhat.com><Pine.LNX.4.44.0302131030430.9292-100000@www.eyesopen.com>

Roger Sayle writes:
 > 
 > 
 > Do you believe the Java front-end is currently incorrect to use
 > PLUS_EXPR to represent signed addition?

It probably is.  

Java requires strict 32-bit two's complement arithmetic for its ints,
and PLUS_EXPR isn't guaranteed to do that.  We could, of course,
generate something like

   uint((ulong)a + (ulong)b)

which would be well defined. 

Andrew.

References:
- Re: [PATCH] Document arithmetic overflow semantics
  - From: Richard Henderson
- Re: [PATCH] Document arithmetic overflow semantics
  - From: Roger Sayle

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