This KB article is applicable to ElectricAccelerator v7.0 and later.
Overview
ElectricAccelerator includes a dependency optimization feature to improve performance. By learning which dependencies are actually needed for a build, Accelerator can use that information to improve performance in subsequent builds.
When dependency optimization is enabled, emake maintains a dependency information file for each makefile. If a build's dependencies have not changed from its previous build, emake can use that stored dependency information file for subsequent builds.
Enabling dependency optimization
You must first run a "learning" build with the dependency optimization feature enabled. To enable dependency optimization, set the following: --emake-optimize-deps=1
For the learning build, (because there is no stored dependency information file for that specific makefile), the argument only saves a new result. For subsequent builds, the argument enables the reuse of stored dependency information and saves a new file as appropriate. If you do not specify --emake-optimize-deps=1, then dependency information is not saved or accessed.
Note: It is recommended that you turn on --emake-autodepend=1 to ensure accurate incremental builds.
The following table describes dependency optimization-related options.
| eMake Option | Description |
|---|---|
| --emake-assetdir=<path> | Use the specified directory for assets such as saved dependency information. The default directory is .emake. This option also affects parse avoidance. |
| --emake-optimize-deps=<0/1> | Use the saved dependency information file for a makefile when dependencies are the same and save new dependency information when appropriate. |
Dependency optimization file location and naming
Dependency information files are saved in the working directory where emake was invoked under <assetdir>/deps. (The default asset directory is .emake.)
The file is named from the md5 hash of the root-relative path of the "main" makefile for the make instance that the dependency information file belongs to.
Examples
- If your emake root is /tmp/src, and your makefile is /tmp/src/Makefile, then the dependency information file is named after the md5 hash of the string "Makefile".
- If your root is /tmp/src and your makefile is /tmp/src/foo/Makefile, the file is named after the md5 hash of the string "foo/Makefile".
Limitations
- Dependency optimization is not supported when using NMAKE (or Visual Studio/devenv) emulation.
Applies to
- Product versions: 7.0 and later
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