[llvm-dev] RFC: Adding Register Calling Convention Support

Ben Simhon, Oren via llvm-dev llvm-dev at lists.llvm.org
Thu Sep 22 00:07:37 PDT 2016

Hi All,

The Register Calling Convention (RegCall) was introduced by Intel to optimize parameter transfer on function call.
This calling convention ensures that as many values as possible are passed or returned in registers.

To use RegCall, place the keyword before a function declaration. For example:
__regcall int foo (int i, int j); // Windows OS
__attribute__((regcall)) foo (int I, int j); // Linux OS and Mac OS X)

The calling convention is described in more details here:

We are adding support for RegCall calling convention for Clang and LLVM IR.
The first step will include the implementation for LLVM IR.

I will appreciate your comments.


Intel Israel (74) Limited

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