Summary:
(1) Function descriptor on AIX
On AIX, a called routine may have 2 distinct symbols associated with it:
* A function descriptor (Name)
* A function entry point (.Name)
The descriptor structure on AIX is the same as those in the ELF V1 ABI:
* The address of the entry point of the function.
* The TOC base address for the function.
* The environment pointer.
The descriptor symbol uses the same name as the source level function in C.
The function entry point is analogous to the symbol we would generate for a
function in a non-descriptor-based ABI, except that it is renamed by
prepending a ".".
Which symbol gets referenced depends on the context:
* Taking the address of the function references the descriptor symbol.
* Calling the function references the entry point symbol.
(2) Speaking of implementation on AIX, for direct function call target, we
create proper MCSymbol SDNode(e.g . ".foo") while constructing SDAG to
replace original TargetGlobalAddress SDNode. Then down the path, we can
take advantage of this MCSymbol.
Patch by: Xiangling_L
Reviewed by: sfertile, hubert.reinterpretcast, jasonliu, syzaara
Differential Revision: https://reviews.llvm.org/D62532
llvm-svn: 362735
Summary:
This patch implements SDAG call lowering on AIX for functions
which only have parameters that could fit into GPRs.
Reviewers: hubert.reinterpretcast, syzaara
Differential Revision: https://reviews.llvm.org/D62823
llvm-svn: 362708
Jason Liu