Gabriel F. T. Gomes 4d98ace9de powerpc: Restrict xssqrtqp operands to Vector Registers (bug 21941)
POWER ISA 3.0 introduces the xssqrtqp instructions, which expects
operands to be in Vector Registers (Altivec/VMX), even though this
instruction belongs to the Vector-Scalar Instruction Set.

In GCC's Extended Assembly for POWER, the 'wq' register constraint is
provided for use with IEEE 754 128-bit floating-point values.  However,
this constraint does not limit the register allocation to Vector
Registers (Altivec/VMX) and could assign a Vector-Scalar Register (VSX)
to the operands of the instruction.

This patch changes the register constraint used in sqrtf128 from 'wq' to
'v', in order to request a Vector Register (Altivec/VMX) for use with
the xssqrtqp instruction.

Tested for powerpc64le and --with-cpu=power9.

	[BZ #21941]
	* sysdeps/powerpc/fpu/math_private.h (__ieee754_sqrtf128): Since
	xssqrtqp requires operands to be in Vector Registers
	(Altivec/VMX), replace the register constraint 'wq' with 'v'.
	* sysdeps/powerpc/powerpc64le/power9/fpu/e_sqrtf128.c
	(__ieee754_sqrtf128): Likewise.
2017-08-10 16:10:21 -03:00

37 lines
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C

/* POWER9 sqrt for _Float128
Return sqrt(a)
Copyright (C) 2017 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
In addition to the permissions in the GNU Lesser General Public
License, the Free Software Foundation gives you unlimited
permission to link the compiled version of this file into
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The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
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You should have received a copy of the GNU Lesser General Public
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<http://www.gnu.org/licenses/>. */
__float128
__ieee754_sqrtf128 (__float128 a)
{
__float128 z;
asm ("xssqrtqp %0,%1" : "=v" (z) : "v" (a));
return z;
}
strong_alias (__ieee754_sqrtf128, __sqrtf128_finite)