chebyshev.cpp

// chebyshev.cpp

#include <stdio.h>
#include <math.h>

static float chebyshev(int n, float x)
{
	float a = 1.0f, b = x;
	x += x;
	while (n--) {
		float t = b;
		b = x * b - a;
		a = t;
	}
	return a;
}

int main()
{
	char line[80];
	gets(line);
	float x = float(atof(line));
	float r = chebyshev(10, x);
	printf("%f\n", r);
	return 0;
}

// chebyshev.s (generated by clang++ chebyshev.cpp -O3 -march=native -S)

	.def	 _main;
	.scl	2;
	.type	32;
	.endef
	.section	.rdata,"r"
	.align	4
LCPI0_0:                                # constant pool float
	.long	3212836864              # float -1.000000e+000
	.text
	.globl	_main
	.align	16, 0x90
_main:                                  # @main
# BB#0:
	pushl	%ebp
	movl	%esp, %ebp
	pushl	%esi
	subl	$100, %esp
	leal	-84(%ebp), %esi
	movl	%esi, (%esp)
	calll	_gets
	movl	%esi, (%esp)
	calll	_atof
	fstps	-88(%ebp)
	movss	-88(%ebp), %xmm0
	movaps	%xmm0, %xmm1
	addss	%xmm1, %xmm1
	movaps	%xmm1, %xmm2
	mulss	%xmm0, %xmm2
	addss	LCPI0_0, %xmm2
	movaps	%xmm1, %xmm3
	mulss	%xmm2, %xmm3
	subss	%xmm0, %xmm3
	movaps	%xmm1, %xmm0
	mulss	%xmm3, %xmm0
	subss	%xmm2, %xmm0
	movaps	%xmm1, %xmm2
	mulss	%xmm0, %xmm2
	subss	%xmm3, %xmm2
	movaps	%xmm1, %xmm3
	mulss	%xmm2, %xmm3
	subss	%xmm0, %xmm3
	movaps	%xmm1, %xmm0
	mulss	%xmm3, %xmm0
	subss	%xmm2, %xmm0
	movaps	%xmm1, %xmm2
	mulss	%xmm0, %xmm2
	subss	%xmm3, %xmm2
	movaps	%xmm1, %xmm3
	mulss	%xmm2, %xmm3
	subss	%xmm0, %xmm3
	mulss	%xmm1, %xmm3
	subss	%xmm2, %xmm3
	cvtss2sd	%xmm3, %xmm0
	movsd	%xmm0, 4(%esp)
	movl	$L_.str, (%esp)
	calll	_printf
	xorl	%eax, %eax
	addl	$100, %esp
	popl	%esi
	popl	%ebp
	ret

	.data
L_.str:                                 # @.str
	.asciz	 "%f\n"


	.globl	__fltused