epsilon1.c running 
no store double deps=2.220446e-16 
forced store double deps=2.220446e-16 
the difference is because of more precision when kept in registers

no store float eps=2.220446e-16 
forced store float eps=1.192093e-07 
the difference is because of more precision when kept in registers

Now float eps, note double when kept in registers 
eps=2^-1= 5.960464e-08, (1+eps)-1= 0.000000e+00 
eps=2^-2= 2.980232e-08, (1+eps)-1= 0.000000e+00 
eps=2^-3= 1.490116e-08, (1+eps)-1= 0.000000e+00 
eps=2^-4= 7.450581e-09, (1+eps)-1= 0.000000e+00 
eps=2^-5= 3.725290e-09, (1+eps)-1= 0.000000e+00 
eps=2^-6= 1.862645e-09, (1+eps)-1= 0.000000e+00 
eps=2^-7= 9.313226e-10, (1+eps)-1= 0.000000e+00 
eps=2^-8= 4.656613e-10, (1+eps)-1= 0.000000e+00 
eps=2^-9= 2.328306e-10, (1+eps)-1= 0.000000e+00 
eps=2^-10= 1.164153e-10, (1+eps)-1= 0.000000e+00 
eps=2^-11= 5.820766e-11, (1+eps)-1= 0.000000e+00 
eps=2^-12= 2.910383e-11, (1+eps)-1= 0.000000e+00 
eps=2^-13= 1.455192e-11, (1+eps)-1= 0.000000e+00 
eps=2^-14= 7.275958e-12, (1+eps)-1= 0.000000e+00 
eps=2^-15= 3.637979e-12, (1+eps)-1= 0.000000e+00 
eps=2^-16= 1.818989e-12, (1+eps)-1= 0.000000e+00 
eps=2^-17= 9.094947e-13, (1+eps)-1= 0.000000e+00 
eps=2^-18= 4.547474e-13, (1+eps)-1= 0.000000e+00 
eps=2^-19= 2.273737e-13, (1+eps)-1= 0.000000e+00 
eps=2^-20= 1.136868e-13, (1+eps)-1= 0.000000e+00 
eps=2^-21= 5.684342e-14, (1+eps)-1= 0.000000e+00 
eps=2^-22= 2.842171e-14, (1+eps)-1= 0.000000e+00 
eps=2^-23= 1.421085e-14, (1+eps)-1= 0.000000e+00 
eps=2^-24= 7.105427e-15, (1+eps)-1= 0.000000e+00 
eps=2^-25= 3.552714e-15, (1+eps)-1= 0.000000e+00 
eps=2^-26= 1.776357e-15, (1+eps)-1= 0.000000e+00 
eps=2^-27= 8.881784e-16, (1+eps)-1= 0.000000e+00 
eps=2^-28= 4.440892e-16, (1+eps)-1= 0.000000e+00 
eps=2^-29= 2.220446e-16, (1+eps)-1= 0.000000e+00 
eps=2^-30= 1.110223e-16, (1+eps)-1= 0.000000e+00 
eps=2^-31= 5.551115e-17, (1+eps)-1= 0.000000e+00 
eps=2^-32= 2.775558e-17, (1+eps)-1= 0.000000e+00 
eps=2^-33= 1.387779e-17, (1+eps)-1= 0.000000e+00 
eps=2^-34= 6.938894e-18, (1+eps)-1= 0.000000e+00 
eps=2^-35= 3.469447e-18, (1+eps)-1= 0.000000e+00 
eps=2^-36= 1.734723e-18, (1+eps)-1= 0.000000e+00 
eps=2^-37= 8.673617e-19, (1+eps)-1= 0.000000e+00 
eps=2^-38= 4.336809e-19, (1+eps)-1= 0.000000e+00 
eps=2^-39= 2.168404e-19, (1+eps)-1= 0.000000e+00 
eps=2^-40= 1.084202e-19, (1+eps)-1= 0.000000e+00 
eps=2^-41= 5.421011e-20, (1+eps)-1= 0.000000e+00 
eps=2^-42= 2.710505e-20, (1+eps)-1= 0.000000e+00 

force store, break optimization 
eps=2^-1= 5.000000e-01, (1+eps)-1= 5.000000e-01 
eps=2^-2= 2.500000e-01, (1+eps)-1= 2.500000e-01 
eps=2^-3= 1.250000e-01, (1+eps)-1= 1.250000e-01 
eps=2^-4= 6.250000e-02, (1+eps)-1= 6.250000e-02 
eps=2^-5= 3.125000e-02, (1+eps)-1= 3.125000e-02 
eps=2^-6= 1.562500e-02, (1+eps)-1= 1.562500e-02 
eps=2^-7= 7.812500e-03, (1+eps)-1= 7.812500e-03 
eps=2^-8= 3.906250e-03, (1+eps)-1= 3.906250e-03 
eps=2^-9= 1.953125e-03, (1+eps)-1= 1.953125e-03 
eps=2^-10= 9.765625e-04, (1+eps)-1= 9.765625e-04 
eps=2^-11= 4.882812e-04, (1+eps)-1= 4.882812e-04 
eps=2^-12= 2.441406e-04, (1+eps)-1= 2.441406e-04 
eps=2^-13= 1.220703e-04, (1+eps)-1= 1.220703e-04 
eps=2^-14= 6.103516e-05, (1+eps)-1= 6.103516e-05 
eps=2^-15= 3.051758e-05, (1+eps)-1= 3.051758e-05 
eps=2^-16= 1.525879e-05, (1+eps)-1= 1.525879e-05 
eps=2^-17= 7.629395e-06, (1+eps)-1= 7.629395e-06 
eps=2^-18= 3.814697e-06, (1+eps)-1= 3.814697e-06 
eps=2^-19= 1.907349e-06, (1+eps)-1= 1.907349e-06 
eps=2^-20= 9.536743e-07, (1+eps)-1= 9.536743e-07 
eps=2^-21= 4.768372e-07, (1+eps)-1= 4.768372e-07 
eps=2^-22= 2.384186e-07, (1+eps)-1= 2.384186e-07 
eps=2^-23= 1.192093e-07, (1+eps)-1= 1.192093e-07 
eps=2^-24= 5.960464e-08, (1+eps)-1= 0.000000e+00 
eps=2^-25= 2.980232e-08, (1+eps)-1= 0.000000e+00 

end epsilon1.c