The primary ISA-independent justification for using PC-relative
addressing is that it makes code position-independent and therefore
allows sharing of .text pages between processes.
When not sharing .text pages, we can use absolute relocations instead,
which will possibly prevent a bubble introduced by s_getpc_b64.
Co-authored-by: Thomas Symalla <thomas.symalla@amd.com>
Since d6de1e1a71406c75a4ea4d5a2fe84289f07ea3a1, no attributes is quivalent to
setting attribute to false.
This is a preliminary commit for https://reviews.llvm.org/D99080
As we don't sort local symbols, don't sort non-local symbols. This makes
non-local symbols appear in their register order, which matches GNU as. The
register order is nice in that you can write tests with interleaved CHECK
prefixes, e.g.
```
// CHECK: something about foo
.globl foo
foo:
// CHECK: something about bar
.globl bar
bar:
```
With the lexicographical order, the user needs to place lexicographical smallest
symbol first or keep CHECK prefixes in one place.
Summary:
The symbols use the processor-specific SHN_AMDGPU_LDS section index
introduced with a previous change. The linker is then expected to resolve
relocations, which are also emitted.
Initially disabled for HSA and PAL environments until they have caught up
in terms of linker and runtime loader.
Some notes:
- The llvm.amdgcn.groupstaticsize intrinsics can no longer be lowered
to a constant at compile times, which means some tests can no longer
be applied.
The current "solution" is a terrible hack, but the intrinsic isn't
used by Mesa, so we can keep it for now.
- We no longer know the full LDS size per kernel at compile time, which
means that we can no longer generate a relevant error message at
compile time. It would be possible to add a check for the size of
individual variables, but ultimately the linker will have to perform
the final check.
Change-Id: If66dbf33fccfbf3609aefefa2558ac0850d42275
Reviewers: arsenm, rampitec, t-tye, b-sumner, jsjodin
Subscribers: qcolombet, kzhuravl, jvesely, wdng, yaxunl, dstuttard, tpr, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D61494
llvm-svn: 364297
