Add to the VOP patterns to recognise when or/xor/and are masking only
the most significant bit of i32/v2i32/i64 and replace with the appropriate source modifier.
The last parameter of these functions used to be `Signed`, and it looks
like a few calls weren't updated when that was changed to `FlatVariant`.
Effectively, the functions were called with `FlatVariant=SALU` due to
integer promotions, which doesn't make any sense.
These instructions return a 64-bit result and a 1-bit carry, unlike
smul_lohi and umul_lohi which return a pair of 32-bit results.
This does not appear to make any difference in practice because the DAG
types are not used for anything before these nodes are converted to
MachineInstrs.
APInt will fail when given a negative offset. SelectScratchSVAddr
utilizes this function and can be given a negative offset as well, so
this change modifies it to use APSInt instead.
SDNode::use_iterator now returns an SDUse& when dereferenced.
SDNode::user_iterator returns SDNode*. SDNode::use_begin/use_end/uses
work on use_iterator. SDNode::user_begin/user_end/users work on
user_iterator.
We can now write range based for loops using SDUse& and SDNode::uses().
I've converted many of these in this patch. I didn't update loops that
have additional variables updated in their for statement.
Some loops use SDNode::use_iterator::getOperandNo() which also prevents
using range based for loops. I plan to move this into SDUse in a follow
up patch.
Create signed constant using getSignedConstant(), to avoid future
assertion failures when we disable implicit truncation in getConstant().
This also touches some generic legalization code, which apparently only
AMDGPU tests.
This was a bit annoying because these introduce a new special case
encoding usage. op_sel is repurposed as a subset of dpp controls,
and is eligible for VOP3->VOP1 shrinking. For some reason fi also
uses an enum value, so we need to convert the raw boolean to 1 instead
of -1.
The 2 registers are swapped, so this has 2 defs. Ideally the builtin
would return a pair, but that's difficult so return a vector instead.
This would make a hypothetical builtin that supports v2f16 directly
uglier.
It is not correct to lower "x&(-1>>(32-y))" to "bfe x, 0, y". When y
equals 32, "-1" is not shifted, so x&(-1>>(32-32) is still x, but "bfe
x, 0, 32" is 0. However, if we know y is at most of 5 bits (< 32), we
can still do the pattern matching.
Based on the suggestion from
https://github.com/llvm/llvm-project/pull/115543, we should not do the
pattern matching from x << (32-y) >> (32-y) to "bfe x, 0, y" at all.
This reverts commits a2bacf8ab58af4c1a0247026ea131443d6066602 and
bdf8e308b7.
This reverts commit
7792b4ae79.
The problem was a conflict with
e55d6f5ea2
"[AMDGPU] Simplify and improve codegen for llvm.amdgcn.set.inactive
(https://github.com/llvm/llvm-project/pull/107889)"
which changed the syntax of V_SET_INACTIVE (and thus made my MIR test
crash).
...if only we had a merge queue.
Reverts llvm/llvm-project#108173
si-init-whole-wave.mir crashes on some buildbots (although it passed
both locally with sanitizers enabled and in pre-merge tests).
Investigating.
This intrinsic is meant to be used in functions that have a "tail" that
needs to be run with all the lanes enabled. The "tail" may contain
complex control flow that makes it unsuitable for the use of the
existing WWM intrinsics. Instead, we will pretend that the function
starts with all the lanes enabled, then branches into the actual body of
the function for the lanes that were meant to run it, and then finally
all the lanes will rejoin and run the tail.
As such, the intrinsic will return the EXEC mask for the body of the
function, and is meant to be used only as part of a very limited pattern
(for now only in amdgpu_cs_chain functions):
```
entry:
%func_exec = call i1 @llvm.amdgcn.init.whole.wave()
br i1 %func_exec, label %func, label %tail
func:
; ... stuff that should run with the actual EXEC mask
br label %tail
tail:
; ... stuff that runs with all the lanes enabled;
; can contain more than one basic block
```
It's an error to use the result of this intrinsic for anything
other than a branch (but unfortunately checking that in the verifier is
non-trivial because SIAnnotateControlFlow will introduce an amdgcn.if
between the intrinsic and the branch).
The intrinsic is lowered to a SI_INIT_WHOLE_WAVE pseudo, which for now
is expanded in si-wqm (which is where SI_INIT_EXEC is handled too);
however the information that the function was conceptually started in
whole wave mode is stored in the machine function info
(hasInitWholeWave). This will be useful in prolog epilog insertion,
where we can skip saving the inactive lanes for CSRs (since if the
function started with all the lanes active, then there are no inactive
lanes to preserve).
This was much more difficult than I anticipated. The pass is
not in a good state, with poor test coverage. The legacy PM
does seem to be relying on maintaining the map state between
different SCCs, which seems bad. The pass is going out of its
way to avoid putting the attributes it introduces onto non-callee
functions. If it just added them, we could use them directly
instead of relying on the map, I would think.
The NewPM path uses a ModulePass; I'm not sure if we should be
using CGSCC here but there seems to be some missing infrastructure
to support backend defined ones.
For unbuffered smem loads, it is illegal for the immediate offset to be
negative if the resulting IOFFSET + (SGPR[Offset] or M0 or zero) is
negative.
New PR of https://github.com/llvm/llvm-project/pull/79553.
