A linker optimization is available on PowerPC for GOT indirect PCRelative loads.
The idea is that we can mark a usual GOT indirect load:
pld 3, vec@got@pcrel(0), 1
lwa 3, 4(3)
With a relocation to say that if we don't need to go through the GOT we can let
the linker further optimize this and replace a load with a nop.
pld 3, vec@got@pcrel(0), 1
.Lpcrel1:
.reloc .Lpcrel1-8,R_PPC64_PCREL_OPT,.-(.Lpcrel1-8)
lwa 3, 4(3)
This patch adds the logic that allows the compiler to add the R_PPC64_PCREL_OPT.
Reviewers: nemanjai, lei, hfinkel, sfertile, efriedma, tstellar, grosbach
Reviewed By: nemanjai
Differential Revision: https://reviews.llvm.org/D79864
We should not be adding the relocation addend to the instruction encoding.
This patch removes that and sets those bits to zero.
Differential Revision: https://reviews.llvm.org/D81082
This is an optimization that applies to global addresses and
allows for the following transformation:
Convert this:
paddi r3, 0, symbol@PCREL, 1
ld r4, 8(r3)
To this:
pld r4, symbol@PCREL+8(0), 1
An instruction is saved and the linker can do the addition when
the symbol is resolved.
Differential Revision: https://reviews.llvm.org/D76160
Stefan Pintilie