Commits on Oct 18, 2023

1. Add a custom lowering of vaarg for xtensa. …

   LLVM does not include an implementation of the va_arg instruction for
   Xtensa. From what I understand, this is a conscious decision and
   instead language frontends are encouraged to implement it themselves.
   The rationale seems to be that loading values correctly requires
   language and ABI-specific knowledge that LLVM lacks.
   
   This is true of most architectures, and rustc already provides
   implementation for a number of them. This commit extends the support to
   include Xtensa.
   
   See https://lists.llvm.org/pipermail/llvm-dev/2017-August/116337.html
   for some discussion on the topic.
   
   Unfortunately there does not seem to be a reference document for the
   semantics of the va_list and va_arg on Xtensa. The most reliable source
   is the GCC implementation, which this commit tries to follow. Clang also
   provides its own compatible implementation.
   
   This was tested for all the types that rustc allows in variadics.

   

   plietar committed Oct 18, 2023
   Configuration menu

   • View commit details
   • Copy full SHA for 1860557
   • Browse repository at this point

   Copy the full SHA

   1860557 View commit details

   Browse the repository at this point in the history