Ada front-end depends on signed overflow

[Dave Korn]

----Original Message----
>From: Paul Schlie
>Sent: 08 June 2005 15:53

>> From: Robert Dewar

>> There is nothing imprecise about IEEE floating-point operations
> 
> - agreed, however nor is it mandated by most language specifications,
>   so seemingly irrelevant.

I refer you to "Annex F (normative) IEC 60559 floating-point arithmetic" of the C language spec.  "Normative" implies a mandate, does it not?

F.1 Introduction
1 This annex specifies C language support for the IEC 60559 floating-point standard. The IEC 60559 floating-point standard is specifically Binary floating-point arithmetic for microprocessor systems, second edition (IEC 60559:1989), previously designated IEC 559:1989 and as IEEE Standard for Binary Floating-Point Arithmetic (ANSI/IEEE 754−1985). IEEE Standard for Radix-Independent Floating-Point Arithmetic (ANSI/IEEE 854−1987) generalizes the binary standard to remove dependencies on radix and word length. IEC 60559 generally refers to the floating-point standard, as in IEC 60559 operation, IEC 60559 format, etc. An implementation that defines
__STDC_IEC_559__ conforms to the specifications in this annex. Where a binding between the C language and IEC 60559 is indicated, the IEC 60559-specified behavior is adopted by reference, unless stated otherwise.

> - as above (actually most, if inclusive of all processors in production,
>   don't directly implement fully compliant IEEE FP math, although many
>   closely approximate it, or simply provide no FP support at all; 

  Pretty much every single ix86 and rs6000, and many m68 arch CPUs provide last-bit-exact IEEE implementations in hardware these days.  Your statement is simply factually incorrect.


    cheers,
      DaveK
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