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[K/N] Update documentation on building and using LLVM

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This commit is contained in:
Sergey Bogolepov
2022-04-18 18:15:41 +03:00
committed by Space
parent 404cc54bd4
commit 21399b4edd
4 changed files with 27 additions and 73 deletions
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kotlin-native/HACKING.md
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@@ -367,22 +367,15 @@ instead of provided one.
### Using different LLVM distributions as part of Kotlin/Native compilation pipeline.
`llvmHome.<HOST_NAME>` variable in `<distribution_location>/konan/konan.properties` controls
which LLVM distribution Kotlin/Native will use in its compilation pipeline.
You can replace its value with either `$llvm.<HOST_NAME>.{dev, user}` to use one of predefined distributions
or pass an absolute to your own distribution.
Don't forget to set `llvmVersion.<HOST_NAME>` to the version of your LLVM distribution.
#### Example. Using LLVM from an absolute path.
Assuming LLVM distribution is installed at `/usr` path, one can specify a path to it
with the `-Xoverride-konan-properties` option:
```
konanc main.kt -Xoverride-konan-properties=llvmHome.linux_x64=/usr
```
`-Xllvm-variant` compiler option allows to choose which LLVM distribution should be used during compilation.
The following values are supported:
* `user` — The compiler downloads (if necessary) and uses small LLVM distribution that contains only necessary tools. This is what compiler does by default.
* `dev` — The compiler downloads (if necessary) and uses large LLVM distribution that contains additional development tools like `llvm-nm`, `opt`, etc.
* `<absolute path>` — Use local distribution of LLVM.
### Playing with compilation pipeline.
Following compiler phases control different parts of LLVM pipeline:
The following compiler phases control different parts of LLVM pipeline:
1. `LinkBitcodeDependencies`. Linkage of produced bitcode with runtime and some other dependencies.
2. `BitcodeOptimization`. Running LLVM optimization pipeline.
3. `ObjectFiles`. Compilation of bitcode with Clang.
@@ -400,20 +393,16 @@ Please note:
3. Use `clang -cc1 -help` to see a list of available options.
Another useful compiler option is `-Xtemporary-files-dir=<PATH>` which allows
to specify a directory for intermediate compiler artifacts like bitcode and object files.
specifying a directory for intermediate compiler artifacts like bitcode and object files.
For example, it allows to store LLVM IR after a particular compiler phase.
#### Example 1. Bitcode right after IR to Bitcode translation.
```shell script
konanc main.kt -produce bitcode -o bitcode.bc
konanc main.kt -Xsave-llvm-ir-after=BitcodeOptimization -Xtemporary-files-dir=<PATH>
```
#### Example 2. Bitcode after LLVM optimizations.
```shell script
konanc main.kt -Xtemporary-files-dir=<PATH> -o <OUTPUT_NAME>
```
`<PATH>/<OUTPUT_NAME>.kt.bc` will contain bitcode after LLVM optimization pipeline.
`<PATH>/out.BitcodeOptimization.ll` will contain LLVM IR after LLVM optimization pipeline.
#### Example 3. Replace predefined LLVM pipeline with Clang options.
#### Example: replace predefined LLVM pipeline with Clang options.
```shell script
CLANG_FLAGS="clangFlags.macos_x64=-cc1 -emit-obj;clangNooptFlags.macos_x64=-O2"
konanc main.kt -Xdisable-phases=BitcodeOptimization -Xoverride-konan-properties="$CLANG_FLAGS"