* Mistake in GNU AS of IA-32 for the result about half-precision floating-point value
@ 2023-02-12 13:51 anix
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From: anix @ 2023-02-12 13:51 UTC (permalink / raw)
To: bug-gdb
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dear:
I found one mistake in GNU AS of IA-32 for the result about half-precision floating-point value.
as the following, including source code and gdb result:
# The source code convert between single-precision floating-point(32-bit) and half-precision floating-point (16-bit).
.section .data
m32fp: .float 142, 580, 36832, 65504
half: .short 0x5870, 0x6080, 0x787f, 0x7bff
h1: .short 0, 0 ,0, 0
m1: .float 0, 0, 0, 0
.section .text
.globl _start
_start:
nop
movaps m32fp, %xmm0
vcvtps2ph $0, %xmm0, h1 #imm8=$0; h1 {m64}
vcvtph2ps h1, %xmm1
movups %xmm1, m1
next: movl $1, %eax
movl $0, %ebx
int $0x80
# the source code end here.
# results under GNU Debugger (gdb)
(gdb) x/4fw &m32fp
0x804a000: 142 580 36832 65504
(gdb) x/4fw &m1
0x804a020: 142 580 36832 65504
(gdb) x/4fh &half
0x804a010: 22640 24704 30847 31743
(gdb) x/4fh &h1
0x804a018: 22640 24712 30847 31743
(gdb) x/4xw &m32fp
0x804a000: 0x430e0000 0x44110000 0x470fe000 0x477fe000
(gdb) x/4xw &m1
0x804a020: 0x430e0000 0x44110000 0x470fe000 0x477fe000
(gdb) x/4xh &half
0x804a010: 0x5870 0x6080 0x787f 0x7bff
(gdb) x/4xh &h1
0x804a018: 0x5870 0x6088 0x787f 0x7bff
# the results of half-precision data (half, h1) by gdb are mistakes, or instruct me
# All above under IA-32 , OS is centos (32-bit), GNU as and gdb are also 32-bit.
hope your return.
thank you very much!
Niu wensheng
2023.02.12
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2023-02-12 13:51 Mistake in GNU AS of IA-32 for the result about half-precision floating-point value anix
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