FIX: Incorrect Optimization of Left Shift Operator

SYMPTOMS

Optimization of the left shift operator may generate incorrect code in loop operations when compiled with global optimizations on. In the code sample below, the "for" loop incorrectly evaluates the "count" variable. The resultant code causes the loop to execute only once with the following output:

   #pragma optimize ("g", off)
				

/*
* Compile options needed: /Og
*/ 

#include <stdio.h>

void main( void )
{
    unsigned count;
     for ( count = 0 ; count < 4 ; count++ )
         printf(" %X \n", count << 30);
}