451e853e51
Previously we had an individiaul global array of implied extensions for each extension that needed it. This allowed each array to have a different length. Then we had a sorted table that stored pointers and size for the indivual arrays keyed by the extension name. This patch changes the sorted table to use multiple rows if multiple extensions are implied. We use equal_range instead of lower_bound to find all the rows that apply to a given extension. The CombineIntoExts array was also modified to store only the extension name that need to be combined. This extension name is looked up in the implied table to find all the extensions it depends on.
LLVM TableGen
The purpose of TableGen is to generate complex output files based on information from source files that are significantly easier to code than the output files would be, and also easier to maintain and modify over time.
The information is coded in a declarative style involving classes and records, which are then processed by TableGen.
class Hello <string _msg> {
string msg = !strconcat("Hello ", _msg);
}
def HelloWorld: Hello<"world!"> {}
------------- Classes -----------------
class Hello<string Hello:_msg = ?> {
string msg = !strconcat("Hello ", Hello:_msg);
}
------------- Defs -----------------
def HelloWorld { // Hello
string msg = "Hello world!";
}
Try this example on Compiler Explorer.
The internalized records are passed on to various backends, which extract information from a subset of the records and generate one or more output files.
These output files are typically .inc files for C++, but may be any type of file that the backend developer needs.
Resources for learning the language:
- TableGen Overview
- Programmer's reference guide
- Tutorial
- Tools for Learning LLVM TableGen
- Lessons in TableGen (video), slides
- Improving Your TableGen Descriptions (video), slides
Writing TableGen backends:
- TableGen Backend Developer's Guide
- How to write a TableGen backend (video), slides, also available as a notebook.
TableGen in MLIR:
Useful tools: