C# - Inconsistent math operation result on 32-bit and 64-bit

Question

Consider the following code:

double v1 = double.MaxValue;
double r = Math.Sqrt(v1 * v1);

r = double.MaxValue on 32-bit machine r = Infinity

Answer 1

I tried this in x86 and x64 in debug and release mode:

x86 debug:   Double.MaxValue
x64 debug:   Infinity
x86 release: Infinity
x64 release: Infinity

So, it seems that it's only in debug mode that you get that result.

Not sure why there is a difference, though, the x86 code in debug mode:

            double r = Math.Sqrt(v1 * v1);
00025bda  fld         qword ptr [ebp-44h] 
00025bdd  fmul        st,st(0) 
00025bdf  fsqrt            
00025be1  fstp        qword ptr [ebp-5Ch] 
00025be4  fld         qword ptr [ebp-5Ch] 
00025be7  fstp        qword ptr [ebp-4Ch] 

is the same as the code in release mode:

            double r = Math.Sqrt(v1 * v1);
00000027  fld         qword ptr [ebp-8] 
0000002a  fmul        st,st(0) 
0000002c  fsqrt            
0000002e  fstp        qword ptr [ebp-18h] 
00000031  fld         qword ptr [ebp-18h] 
00000034  fstp        qword ptr [ebp-10h]