updated readme

README.md

@@ -28,6 +28,7 @@ Once a DVF is published, any user can choose to trust the signer of that DVF and
    - [Update DVF](#update-dvf)
    - [Check Bytecode](#check-bytecode)
    - [Handle errors](#handle-errors)
+   - [Use Build Cache](#use-build-cache)
 
 6. [Advanced Usage](#advanced-usage)
 
@@ -190,6 +191,12 @@ If the Hardhat project does not store its compilation artifacts in the default d
 dv init --project <PROJECT_PATH> --address <ADDRESS> --contractname <NAME> --env hardhat --artifacts <ARTIFACTS> new.dvf.json
 ```
 
+If you have to use an external build-info (i.e., you don't want `dv` to build the project), you can specify the path to the build-info directory with `--buildcache`:
+
+```
+dv init --project <PROJECT_PATH> --address <ADDRESS> --contractname <NAME> --buildcache <PATH_TO_BUILD_INFO> new.dvf.json
+```
+
 In many cases, deployments are not completed in one block as parameters may be set in subsequent transactions. To receive the storage at a later block (and emitted events up to that block), you can pass the desired block number with `--initblock`:
 
 ```
@@ -339,7 +346,7 @@ dv bytecode-check --project <PROJECT_PATH> --address <ADDRESS> --contractname <N
 
 Please note that `<B>` must be equal to or larger than the deployment block of the contract.
 
-### Handle errors
+### Handle Errors
 
 If something goes wrong during a run of `dv`, you can add the `--verbose` option to get additional information:
 
@@ -357,6 +364,33 @@ Please refer to section [Common Problems](#common-problems) for help with unders
 
 If your problem cannot be solved by yourself or if you have found a bug (e.g., `dv` crashed), please refer to section [Getting Help](#getting-help).
 
+### Use Build Cache
+
+By default `dv` compiles the full project every time you run the `init` or `bytecode-check` commands.
+
+You can pass an external build-info path (containing the compiler output) to `dv` using the `--buildcache` flag. This can be used to:
+
+1. Circumvent the internal project compilation in case of issues.
+2. Skip subsequent compilations if you want to create DVFs for multiple contracts in a large project.
+
+For the second case, you can use the `generate-build-cache` command to generate a persisted build-info path that can be passed to `--buildcache`:
+
+```
+dv generate-build-cache --project <PROJECT_PATH>
+```
+
+You can also use the command for hardhat projects using `--env`:
+
+```
+dv generate-build-cache --project <PROJECT_PATH> --env hardhat
+```
+
+If the Hardhat project does not store its compilation artifacts in the default directory, you can pass the correct directory with `--artifacts`:
+
+```
+dv generate-build-cache --project <PROJECT_PATH> --env hardhat --artifacts <ARTIFACTS>
+```
+
 ## Advanced Usage
 
 Not all projects can be easily validated by validating single contracts. If the smart contracts in the project you are validating have dependencies to other contracts that are security relevant, please refer to this section.