Re: Avoid treating the stack as an array [Re: "Back & Forth" is back!]

Paul Rubin <no.email@nospam.invalid> writes:

mhx@iae.nl (mhx) writes:

This appears not to be a good idea.  The root cause is piling up too
many items on the F-stack (exceeding the hardware FPU stack limits).

>
I wonder if any Forth compilers use SSE instead of the x86 FPU stack.

Gforth 0.7.9_20240821
[...]
see f+
Code f+ 
55AF6580BDC1:   add     rbx,$08
55AF6580BDC5:   mov     rax,r12
55AF6580BDC8:   lea     r12,$08[r12]
55AF6580BDCD:   addsd   xmm15,$08[rax]
55AF6580BDD3:   mov     rax,[rbx]
55AF6580BDD6:   jmp     eax

VFX Forth 64 5.11 RC2 [build 0112] 2021-05-02 for Linux x64
[...]
see f+
F+
( 004C4100    F2450F584500 )          ADDSD   XMM8, [R13]
( 004C4106    4983C508 )              ADD     R13, # 08
( 004C410A    C3 )                    RET/NEXT
( 11 bytes, 3 instructions )

But:

VFX Forth 64 5.43 [build 0199] 2023-11-09 for Linux x64
[...]
see f+
F+
( 00505620    DEC1 )                  FADDP   ST(1), ST
( 00505622    C3 )                    RET/NEXT
( 3 bytes, 2 instructions )

The customers of VFX preferred the 80-bit floats.

- anton
--
M. Anton Ertl  http://www.complang.tuwien.ac.at/anton/home.html
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