programming language that does not inhibit further optimization by gcc

[Albert Abramson <abramson dot albert at gmail dot com>]

I have been looking everywhere online and talking to other coders at
every opportunity about this, but cannot find a complete answer.
Different languages have different obstacles to complete optimization.
 Software developers often have to drop down into non-portable
Assembly because they can't get the performance or small size of
hand-optimized Assembly for their particular platform.

The C language has the alias issue that limits the hoisting of loads.
Unless the programmer specifies that two arrays will never overlap
using the 'restrict' keyword, the compiler may not be able to handle
operations on arrays efficiently because of the unlikely event that
the arrays could overlap.  Most/all languages also demand the
appearance of serialization of instructions and memory operations, as
well as extreme correctness in even the most unlikely circumstances,
even where the programmer may not need them.

Is there a language out there (similar to Fortran or a dialect of C)
that doesn't inhibit the compiler from taking advantage of every
optimization possible?  Is there some way to provide a C/C++ compiler
with extra information about variables and programs so that it can
maximize performance or minimize size?  For example:

int age = 21;    //[0, 150)  setting maximum limits, compiler could use byte int
int outsideTemp = 20;    //[-273, 80]
float ERA = 297;           //[0, 1000, 3]   [min, max, digits of
accuracy needed]

Better yet, allow some easier way of spawning multiple threads without
have to learn all of the Boost libraries, OpenCL, or OpenGL.  In other
words, is there yet a language that is designed only for performance
that places no limits on compiler optimizations?  Is there a language
that allows the compiler to pack struct variables in tighter by
reorganizing those values, etc?

If not, is it possible to put together some dialect of C/C++ that
replaces Assembly outright?

-- 
Max Abramson
“In the end, more than freedom, they wanted security. They wanted a
comfortable life, and they lost it all – security, comfort, and
freedom. When the Athenians finally wanted not to give to society but
for society to give to them, when the freedom they wished for most was
freedom from responsibility, then Athens ceased to be free and was
never free again.” --Sir Edward Gibbon