Is reading an indeterminate value undefined behavior?

Question

The question arose in the comments of an answer to the question Is C/C++ bool type always guaranteed to be 0 or 1 when typecast\'ed to int?

The code in question allo

Answer 1

The fact that reading an Indeterminate Value generally results in Undefined Behavior is not merely a "theoretical" issue. Even for types where all possible bit patterns have defined values, it should not be considered "surprising" for indeterminate values to behave in ways which differ from Unspecified values. For example, if *p holds Indeterminate Value, and x is not used anywhere except as shown, the code:

uint32_t x,y,z;
...
x = *p;
if (condition1) y=x;
... code that "shouldn't" affect *p if its value is defined
if (condition2) z=x;

could be rewritten as:

if (condition1) y=*p;
... code that "shouldn't" affect *p if its value is defined
if (condition2) z=*p;

If the value of *p is Indeterminate, a compiler would not be forbidden from having the code between the two "if" statements modify its value. For example, if the storage occupied by *p was occupied by a "float" before it freed and re-malloc'ed, the compiler might write that "float" value between the two "if" statements above.