How well does the Visual C++ 2008/2010 compiler optimize?

Question

Im just wondering how good the MSVC++ Compiler can optimize code(with Code examples) or what he can't optimize and why.

For example i used the SSE-intrinsics with something like this(var is an __m128 value)(it was for an frustrum-culling test):

if( var.m128_f32[0] > 0.0f && var.m128_f32[1] > 0.0f && var.m128_f32[2] > 0.0f && var.m128_f32[3] > 0.0f ) {
    ...
}

As i took a look at the asm-output i saw that it did compile to an ugly very jumpy version (and i know that the CPU's just hate tight jumps) and i know also that i can optimize it with the SSE4.1 PTEST instruction, but why did the compiler not do it(even if the compiler writers defined the PTEST intrinsic, so they knew the instruction)?

What optimizations can't it do too (until now).

Does this imply that im with the todays technology forced to use intrinsics and inline ASM and linked ASM functions and will compilers ever find such things(i don't think so)?

Where can i read more about how good the MSVC++ compiler optimizes?

(Edit 1): I used the SSE2 switch and FP:fast switch

Answer 1

You might want to try Intel's ICC compiler - it generates a lot better code than Visual C++, especially for SSE code. You can get a free 30 day evaluation license from intel.com.

Answer 2

You can activate asm view of the compiled code and see yourself what is generated.

Answer 3

Check the presentation at http://lambda-the-ultimate.org/node/3674

Summary: Compilers generally do lots of amazing tricks now, even things that doesn't seem to be generally related to imperative programming, like tail-call optimization. MSVC++ is not the best, still it seems pretty good.

Answer 4

The default for the compiler is set to generate code that wil run on a 'lowest common denominator' CPU - ie one without SSE 4.1 instructions.

You can change that by targetting later CPUs only in the build options.

That said, the MS compiler is traditionally 'not the best' when it comes to SSE optimisation. I'm not even sure if it supports SSE 4 at all. That link gives good credit to GCC for SSE optimisation:

As a side note about GCC’s near perfection in code generation – I was quite surprised seeing it surpass even Intel’s own compiler

Perhaps you need to change compiler!