conditional vs operator?

In the GCC (version 4.8.2) manual, the following is stated:

-ftree-loop-if-convert-stores:
Attempt to also if-convert conditional jumps containing memory writes. This transformation can be unsafe for multi-threaded programs as it transforms conditional memory writes into unconditional memory writes. For example,

   for (i = 0; i < N; i++)
      if (cond)
        A[i] = expr;

is transformed to

   for (i = 0; i < N; i++)
       A[i] = cond ? expr : A[i];

potentially producing data races.

I wonder, however, if there is a performance gain by using the operator? versus the if statement.

• In the first piece of code, A[i] is set to expr only if the condition is met. If it is not met, then the code inside the statement is skipped.
• In the second one, A[i] seems to be written regardless of the condition; the condition only affects the value it is set to.

By using operator?, we are also doing a check; however, we are adding some overhead in the case that the condition is not met. Have I missed something?