Context:
http://forum.dlang.org/post/[email protected]
--- prints 1 ---
void main(string[] args)
{
import std.stdio;
import core.stdc.fenv;
fesetround(FE_UPWARD);
writefln("%.32g", 1.0f + float.min_normal);
}
---
--- prints 1.00000011920928955078125 ---
void main(string[] args)
{
import std.stdio;
import core.stdc.fenv;
fesetround(FE_UPWARD);
float x = 1.0f;
x += float.min_normal;
writefln("%.32g", x);
}
---
Considering the floating point operations have a runtime
component, it seems to me that constant folding is not allowed to
occur in the first example. For example, it does not occur in the
following C++ snippet:
---
#include <limits>
#include <cstdio>
#include <cfenv>
int main(int, char**) {
std::fesetround(FE_UPWARD);
printf("%.32g\n", std::numeric_limits<float>::denorm_min() +
1.0f);
return 0;
}
---
Thoughts?
