Updated the documentation for -XX:+MergeCompilerOptions

#1392

Updated the topic for clarity.

Closes #1392
Signed-off-by: Sreekala Gopakumar [email protected]

docs/xxmergecompileroptions.md

@@ -36,11 +36,19 @@ This option enables or disables the merging of multiple `-Xjit` or `-Xaot` optio
 
 ## Explanation
 
- By default, if you specify `-Xjit` option (or `-Xaot` option) multiple times, only the last option takes effect. Therefore, on adding an `-Xjit` option, the resultant behavior might not be as expected, if any instance of this option already exists. It is time-consuming to find the existing instances and try combining them manually so that the system behaves as required.
+By default, if you specify `-Xjit` option (or `-Xaot` option) multiple times, only the last option takes effect. Therefore, on adding an `-Xjit` option, the resultant behavior might not be as expected, if any instance of this option already exists. It is time-consuming to find the existing instances and try combining them manually so that the system behaves as required.
 
- You can use the `-XX:+MergeCompilerOptions` option to merge all the existing instances of the `-Xjit` options logically. To retain the default behavior, whereby only the last option takes effect, you can use the `-XX:-MergeCompilerOptions` option.
+You can use the `-XX:+MergeCompilerOptions` option to merge all the existing instances of the `-Xjit` options (or `-Xaot` options) logically. To retain the default behavior, whereby only the last option takes effect, you can use the `-XX:-MergeCompilerOptions` option.
 
- If both `-Xjit` and `-Xaot` options exist and you use the `-XX:+MergeCompilerOptions` option, then multiple `-Xjit` options are merged into a single `-Xjit` option and multiple `-Xaot` options are merged into a single `-Xaot` option.
+If both `-Xjit` and `-Xaot` options exist and you use the `-XX:+MergeCompilerOptions` option, then multiple `-Xjit` options are merged into a single `-Xjit` option and multiple `-Xaot` options are merged into a single `-Xaot` option.
+
+Typically, `-Xjit` and `-Xaot` options are ignored if these options are followed by `-Xint` or `-Xnojit` or `-Xnoaot` options:
+
+- `-Xint` option overrides any `-Xjit` and `-Xaot` options
+- `-Xnojit` option overrides `-Xjit` options
+- `-Xnoaot` option overrides `-Xaot` options
+
+However, with `-XX:+MergeCompilerOptions` all `-Xjit` and `-Xaot` options are merged, even if those options are followed by `-Xint`, `-Xnojit`, or `-Xnoaot` options. At least one `-Xjit` or `-Xaot` option must be specified after these options.
 
 ## Examples
 
@@ -90,7 +98,24 @@ java -XX:+MergeCompilerOptions -XX:-MergeCompilerOptions -Xshareclasses:none '-X
 ```
 java -XX:-MergeCompilerOptions -XX:+MergeCompilerOptions -Xshareclasses:none '-Xjit:verbose={compilePerformance},vlog=vlog' -Xjit:version -version
 ```
-`-Xjit` options that are applied - `{compilePerformance}`,`vlog=vlog`,`version`
+`-Xjit` options that are applied - `verbose={compilePerformance}`,`vlog=vlog`,`version`
+
+### `-Xnojit`, `-Xnoaot`, or `-Xint` options with and without `-XX:+MergeCompilerOptions`
+
+```
+java -Xshareclasses:none -Xjit:version -Xnojit -version
+```
+No `-Xjit` option is applied
+
+```
+java -XX:+MergeCompilerOptions -Xshareclasses:none -Xjit:verbose={compilePerformance} -Xjit:vlog=vlog -Xint -Xjit:version -version
+```
+`-Xjit` options that are applied - `verbose={compilePerformance}`,`vlog=vlog`,`version`
+
+```
+java -XX:+MergeCompilerOptions -Xshareclasses:none -Xjit:version -Xnojit -version
+```
+No `-Xjit` option is applied because no `-Xjit` option is specified after the `-Xnojit` option
 
 ## See also