https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70523
Bug ID: 70523
Summary: Inconsistent casting of floats to unsigned short
Product: gcc
Version: 4.8.4
Status: UNCONFIRMED
Severity: minor
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: sergey.s at samsung dot com
Target Milestone: ---
Created attachment 38171
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=38171&action=edit
Test program
Casting of float expression to unsigned short gives different result when cast
is performed via intermediate variable. Specifically:
#include <stdio.h>
int main()
{
float f = 1.7857142687f;
printf("%.10f\n", f);
unsigned short b = 28;
unsigned short a = (unsigned short)(b * f);
printf("%u\n", a);
float temp = b * f;
a = (unsigned short)temp;
printf("%u\n", a);
return 0;
}
Output:
1.7857142687
49
50
Reproduced only for 32-bit compilation.
On 64-bit compilers both outputs are 50.
Optimization level shall be default.
If optimization level is -O2 or higher both outputs are 50.
Similar to bug 47297, but here value of float expression is well within range
of unsigned short, so behaviour should be defined.
