-opt

Specifies code optimization options to apply to object code.

  -optkeyword [,...]

  

The keyword arguments are:

off | none

Suppresses all optimizations. This is the default.

  on

  

Same as -opt level=2

  all | full

  

Same as -opt speed,level=4,intrinsics,noframe

  l[evel]=num

  

Sets a specific optimization level. The options for num are:

• 0 - Global register allocation only for temporary values. Equivalent to #pragma optimization_level 0.
• 1 - Adds dead code elimination, branch and arithmetic optimizations, expression simplification, and peephole optimization. Equivalent to #pragma optimization_level 1.
• 2 - Adds common subexpression elimination, copy and expression propagation, stack frame compression, stack alignment, and fast floating-point to integer conversions. Equivalent to: #pragma optimization_level 2.
• 3 - Adds dead store elimination, live range splitting, loop-invariant code motion, strength reduction, loop transformations, loop unrolling (with -opt speed only), loop vectorization, lifetime-based register allocation, and instruction scheduling. Equivalent to optimization_level 3.
• 4 - Like level 3, but with more comprehensive optimizations from levels 1 and 2. Equivalent to #pragma optimization_level 4.

For num options 0 through 4 inclusive, the default is 0.

  [no]space

  

Optimizes object code for size. Equivalent to #pragma optimize_for_size on.

  [no]speed

  

Optimizes object code for speed. Equivalent to #pragma optimize_for_size off.

  [no]cse | [no]commonsubs

  

Common subexpression elimination. Equivalent to #pragma opt_common_subs.

  [no]deadcode

  

Removes dead code. Equivalent to #pragma opt_dead_code.

  [no]deadstore

  

Removes dead assignments. Equivalent to #pragma opt_dead_assignments.

  [no]lifetimes

  

Computes variable lifetimes. Equivalent to #pragma opt_lifetimes.

  [no]loop[invariants]

  

Removes loop invariants. Equivalent to #pragma opt_loop_invariants.

  [no]prop[agation]

  

Propagation of constant and copy assignments. Equivalent to #pragma opt_propagation.

  [no]strength 

  

Strength reduction. Reducing multiplication by an array index variable to addition. Equivalent to #pragma opt_strength_reduction.

  [no]dead

  

Same as -opt [no]deadcode and [no]deadstore. Equivalent to #pragma opt_dead_code on|off and #pragma opt_dead_assignments.

  display | dump

  

Displays complete list of active optimizations.