The current PIC model for WebAssembly is more like ELF in that it
allows symbol interposition.
This means that more functions end up being addressed via the GOT
and fewer directly added to the wasm table.
One effect is a reduction in the number of wasm table entries similar
to the previous attempt in https://reviews.llvm.org/D61539 which was
reverted.
Differential Revision: https://reviews.llvm.org/D61772
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@360402 91177308-0d34-0410-b5e6-96231b3b80d8
My understanding is that once BuildMI has been called we can't fallback
to SelectionDAG.
This change moves the fallback for when getRegForValue() fails for
that target of an indirect call. This was failing in -fPIC mode when
the callee is GlobalValue.
Add a test case that tickles this.
Differential Revision: https://reviews.llvm.org/D60908
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@358793 91177308-0d34-0410-b5e6-96231b3b80d8
This change implements lowering of references global symbols in PIC
mode.
This change implements lowering of global references in PIC mode using a
new @GOT reference type. @GOT references can be used with function or
data symbol names combined with the get_global instruction. In this case
the linker will insert the wasm global that stores the address of the
symbol (either in memory for data symbols or in the wasm table for
function symbols).
For now I'm continuing to use the R_WASM_GLOBAL_INDEX_LEB relocation
type for this type of reference which means that this relocation type
can refer to either a global or a function or data symbol. We could
choose to introduce specific relocation types for GOT entries in the
future. See the current dynamic linking proposal:
https://github.com/WebAssembly/tool-conventions/blob/master/DynamicLinking.md
Differential Revision: https://reviews.llvm.org/D54647
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@357022 91177308-0d34-0410-b5e6-96231b3b80d8
Dan Gohman