DSC Compiler > Optimization

Use this panel to control compiler optimizations. The compiler's optimizer can apply any of its optimizations in either global or non-global optimization mode. You can apply global optimization at the end of the development cycle, after compiling and optimizing all source files individually or in groups.

The following table lists and describes the compiler optimization options for DSC.

Table 1. Tool Settings - DSC Compiler > Optimization
Option Description
Optimization Level (-opt) Specify the optimizations that you want the compiler to apply to the generated object code: 0-Disable optimizations. This setting is equivalent to specifying the -O0 command-line option. The compiler generates unoptimized, linear assembly-language code. 1-The compiler performs all target-independent (that is, non-parallelized) optimizations, such as function inlining. This setting is equivalent to specifying the -O1 command-line option. The compiler omits all target-specific optimizations and generates linear assembly-language code. 2-The compiler performs all optimizations (both target-independent and target-specific). This setting is equivalent to specifying the -O2 command-line option. The compiler outputs optimized, non-linear, parallelized assembly-language code. 3-The compiler performs all the level 2 optimizations, then the low-level optimizer performs global-algorithm register allocation. This setting is equivalent to specifying the -O3 command-line option. At this optimization level, the compiler generates code that is usually faster than the code generated from level 2 optimizations. 4- The compiler performs all the level 3 optimizations. This setting is equivalent to specifying the -O4 command-line option. At this level, the compiler adds repeated subexpression elimination and loop-invariant code motion.
Speed Vs Size Use to specify an Optimization Level greater than 0.
  • Speed-The compiler optimizes object code at the specified Optimization Level such that the resulting binary file has a faster execution speed, as opposed to a smaller executable code size.
  • Size-The compiler optimizes object code at the specified Optimization Level such that the resulting binary file has a smaller executable code size, as opposed to a faster execution speed. This setting is equivalent to specifying the -Os command-line option.
Inter-Procedural Analysis Control whether the compiler views single or multiple source files at compile time.
  • Off-Compiler compiles one file at a time. The functions are displayed in order as they appear in the source file. An object file is created for each source.
  • File-The compiler sees all the functions and data in a translation unit (source file) before code or data is generated. This allows inlining of functions that may not have been possible in -ipa off mode.
  • Program-The compiler sees all the source files of a project before code and data are generated. This allows for cross-module optimizations, including inlining.
  • Program-Final-The compiler sees all the source files of a project before code and data are generated. The object files are passed explicitly to the linker.
Inline Level Enables inline expansion. If there is a #pragma INLINE before a function definition, all calls of this function are replaced by the code of this function, if possible. Using the -Oi=c0 option switches off inlining. Functions marked with the #pragma INLINE are still inlined. To disable inlining, use the -Oi=OFF option.
  • Smart- Inlines function declared with the inline qualifier
  • Off- No functions are inlined.
Auto Inline Inlines small function even if they are not declared with the inline qualifier
Bottom-up Inlining Check to control the bottom-up function inlining method. When active, the compiler inlines function code starting with the last function in the chain of functions calls, to the first one.