If a local_unnamed_addr attribute is attached to a global, the address
is known to be insignificant within the module. It is distinct from the
existing unnamed_addr attribute in that it only describes a local property
of the module rather than a global property of the symbol.
This attribute is intended to be used by the code generator and LTO to allow
the linker to decide whether the global needs to be in the symbol table. It is
possible to exclude a global from the symbol table if three things are true:
- This attribute is present on every instance of the global (which means that
the normal rule that the global must have a unique address can be broken without
being observable by the program by performing comparisons against the global's
address)
- The global has linkonce_odr linkage (which means that each linkage unit must have
its own copy of the global if it requires one, and the copy in each linkage unit
must be the same)
- It is a constant or a function (which means that the program cannot observe that
the unique-address rule has been broken by writing to the global)
Although this attribute could in principle be computed from the module
contents, LTO clients (i.e. linkers) will normally need to be able to compute
this property as part of symbol resolution, and it would be inefficient to
materialize every module just to compute it.
See:
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20160509/356401.htmlhttp://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20160516/356738.html
for earlier discussion.
Part of the fix for PR27553.
Differential Revision: http://reviews.llvm.org/D20348
llvm-svn: 272709
This was assuming it could use all memory before, which is
a bad decision because it restricts occupancy.
By default, only try to use enough space that could reduce
occupancy to 7, an arbitrarily chosen limit.
Based on the exist LDS usage, try to round up to the limit
in the current tier instead of further hurting occupancy.
This isn't ideal, because it doesn't accurately know how much
space is going to be used for alignment padding.
llvm-svn: 269708
The promote alloca pass would attempt to promote an alloca with
a select, icmp, or phi user, even though the other operand was
from a non-promotable source, producing a select on two different
pointer types.
Only do this if we know that both operands derive from the same
alloca. In the future we should be able to relax this to an alloca
which will also be promoted.
llvm-svn: 269265
The canonical form for allocas is a single allocation of the array type.
In case we see a non-canonical array alloca, make sure we aren't
replacing this with an array N times smaller.
llvm-svn: 267916
Summary:
For GL_ARB_compute_shader we need to support workgroup sizes of at least 1024. However, if we want to allow large workgroup sizes, we may need to use less registers, as we have to run more waves per SIMD.
This patch adds an attribute to specify the maximum work group size the compiled program needs to support. It defaults, to 256, as that has no wave restrictions.
Reducing the number of registers available is done similarly to how the registers were reserved for chips with the sgpr init bug.
Reviewers: mareko, arsenm, tstellarAMD, nhaehnle
Subscribers: FireBurn, kerberizer, llvm-commits, arsenm
Differential Revision: http://reviews.llvm.org/D18340
Patch By: Bas Nieuwenhuizen
llvm-svn: 266337
Frontend authors are strongly encouraged to keep allocas
in the entry block, so don't bother visiting every instruction
in the other blocks of the function.
llvm-svn: 263206
If we can't assume the pointer value isn't within the bounds
of the object, it seems risky to try to replace the pointer
calculations.
llvm-svn: 259573
When promoting allocas to LDS, we know we are indexing
into a specific area just created, and the calculation
will also never overflow.
Also emit some of the muls as nsw nuw, because instcombine
infers this already from the range metadata. I think
putting this on the other adds and muls might be OK too,
but I'm not 100% sure.
llvm-svn: 259545
The AMDGPUPromoteAlloca pass was emitting the read.local.size
calls, which with HSA was incorrectly selected to reading from
the offset mesa uses off of the kernarg pointer.
Error on intrinsics which aren't supported by HSA, and start
emitting the correct IR to read the workgroup size
out of the dispatch pointer.
Also initialize the pass so it can be tested with opt, and
start moving towards not depending on the subtarget as an
argument.
Start emitting errors for the intrinsics not handled with HSA.
llvm-svn: 259297
The promote alloca pass didn't handle these intrinsics and crashed.
These intrinsics should accept any address space, but for now just
erase them to avoid breaking.
llvm-svn: 258537
Note, this was reviewed (and more details are in) http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20151109/312083.html
These intrinsics currently have an explicit alignment argument which is
required to be a constant integer. It represents the alignment of the
source and dest, and so must be the minimum of those.
This change allows source and dest to each have their own alignments
by using the alignment attribute on their arguments. The alignment
argument itself is removed.
There are a few places in the code for which the code needs to be
checked by an expert as to whether using only src/dest alignment is
safe. For those places, they currently take the minimum of src/dest
alignments which matches the current behaviour.
For example, code which used to read:
call void @llvm.memcpy.p0i8.p0i8.i32(i8* %dest, i8* %src, i32 500, i32 8, i1 false)
will now read:
call void @llvm.memcpy.p0i8.p0i8.i32(i8* align 8 %dest, i8* align 8 %src, i32 500, i1 false)
For out of tree owners, I was able to strip alignment from calls using sed by replacing:
(call.*llvm\.memset.*)i32\ [0-9]*\,\ i1 false\)
with:
$1i1 false)
and similarly for memmove and memcpy.
I then added back in alignment to test cases which needed it.
A similar commit will be made to clang which actually has many differences in alignment as now
IRBuilder can generate different source/dest alignments on calls.
In IRBuilder itself, a new argument was added. Instead of calling:
CreateMemCpy(Dst, Src, getInt64(Size), DstAlign, /* isVolatile */ false)
you now call
CreateMemCpy(Dst, Src, getInt64(Size), DstAlign, SrcAlign, /* isVolatile */ false)
There is a temporary class (IntegerAlignment) which takes the source alignment and rejects
implicit conversion from bool. This is to prevent isVolatile here from passing its default
parameter to the source alignment.
Note, changes in future can now be made to codegen. I didn't change anything here, but this
change should enable better memcpy code sequences.
Reviewed by Hal Finkel.
llvm-svn: 253511
One of the changes in lib/Target/AMDGPU/AMDGPUMCInstLower.cpp was a new
one. Previously, bundle iterators and single-instruction iterators
could be compared to each other (comparing on underlying pointers).
I changed a comparison from using `MBB->end()` to using
`MBB->instr_end()`, since both end iterators should point at the some
place anyway.
I don't think the implicit conversion between the two iterator types is
a good idea since it's fairly easy to accidentally compare to the wrong
thing (they aren't always end iterators). Otherwise I would have just
added the conversion.
Even with that, no there should be functionality change here.
llvm-svn: 250218
If the pointer is the store's value operand, this would produce
a broken module. Make sure the use is actually for the pointer operand.
llvm-svn: 243462
