/*
 * gcc -c fpcontract.c -O2 -march=haswell -std=c99 && objdump -dr fpcontract.o
 *
 * good (except -stdc=c99 ignores #pragma STDC FP_CONTRACT ON):
 *
 *	fpcontract.o:     file format elf64-x86-64
 *
 *
 *	Disassembly of section .text:
 *
 *	0000000000000000 <my_fma>:
 *	   0:	c5 f3 59 ca          	vmulsd %xmm2,%xmm1,%xmm1
 *	   4:	c5 f3 58 c0          	vaddsd %xmm0,%xmm1,%xmm0
 *	   8:	c3                   	retq   
 *
 * gcc -c fpcontract.c -O2 -march=haswell && objdump -dr fpcontract.o
 *
 * bad:
 *
 *	fpcontract.o:     file format elf64-x86-64
 *
 *
 *	Disassembly of section .text:
 *
 *	0000000000000000 <my_fma>:
 *	   0:	c4 e2 f1 b9 c2       	vfmadd231sd %xmm2,%xmm1,%xmm0
 *	   5:	c3                   	retq   
 */

#pragma STDC FP_CONTRACT OFF

double
my_fma(double a, double x, double y)
{
	return a + x*y;
}