This value had the default value of 4 which caused branch relaxation to fail.
Review: Ulrich Weigand
Differential Revision: https://reviews.llvm.org/D90065
It's currently ambiguous in IR whether the source language explicitly
did not want a stack a stack protector (in C, via function attribute
no_stack_protector) or doesn't care for any given function.
It's common for code that manipulates the stack via inline assembly or
that has to set up its own stack canary (such as the Linux kernel) would
like to avoid stack protectors in certain functions. In this case, we've
been bitten by numerous bugs where a callee with a stack protector is
inlined into an __attribute__((__no_stack_protector__)) caller, which
generally breaks the caller's assumptions about not having a stack
protector. LTO exacerbates the issue.
While developers can avoid this by putting all no_stack_protector
functions in one translation unit together and compiling those with
-fno-stack-protector, it's generally not very ergonomic or as
ergonomic as a function attribute, and still doesn't work for LTO. See also:
https://lore.kernel.org/linux-pm/20200915172658.1432732-1-rkir@google.com/https://lore.kernel.org/lkml/20200918201436.2932360-30-samitolvanen@google.com/T/#u
Typically, when inlining a callee into a caller, the caller will be
upgraded in its level of stack protection (see adjustCallerSSPLevel()).
By adding an explicit attribute in the IR when the function attribute is
used in the source language, we can now identify such cases and prevent
inlining. Block inlining when the callee and caller differ in the case that one
contains `nossp` when the other has `ssp`, `sspstrong`, or `sspreq`.
Fixes pr/47479.
Reviewed By: void
Differential Revision: https://reviews.llvm.org/D87956
There are two optimizations here:
1. Consider the following code:
FCMPSrr %0, %1, implicit-def $nzcv
%sel1:gpr32 = CSELWr %_, %_, 12, implicit $nzcv
%sub:gpr32 = SUBSWrr %_, %_, implicit-def $nzcv
FCMPSrr %0, %1, implicit-def $nzcv
%sel2:gpr32 = CSELWr %_, %_, 12, implicit $nzcv
This kind of code where we have 2 FCMPs each feeding a CSEL can happen
when we have a single IR fcmp being used by two selects. During selection,
to ensure that there can be no clobbering of nzcv between the fcmp and the
csel, we have to generate an fcmp immediately before each csel is
selected.
However, often we can essentially CSE these together later in MachineCSE.
This doesn't work though if there are unrelated flag-setting instructions
in between the two FCMPs. In this case, the SUBS defines NZCV
but it doesn't have any users, being overwritten by the second FCMP.
Our solution here is to try to convert flag setting operations between
a interval of identical FCMPs, so that CSE will be able to eliminate one.
2. SelectionDAG imported patterns for arithmetic ops currently select the
flag-setting ops for CSE reasons, and add the implicit-def $nzcv operand
to those instructions. However if those impdef operands are not marked as
dead, the peephole optimizations are not able to optimize them into non-flag
setting variants. The optimization here is to find these dead imp-defs and
mark them as such.
This pass is only enabled when optimizations are enabled.
Differential Revision: https://reviews.llvm.org/D89415
Immediate must be in an integer range [0,255] for umin/umax instruction.
Extend pattern matching helper SelectSVEArithImm() to take in value type
bitwidth when checking immediate value is in range or not.
Reviewed By: sdesmalen
Differential Revision: https://reviews.llvm.org/D89831
In this patch, Predicates fix added for the following:
* disable prefix-instrs will disable pcrelative-memops
* set two predicates PairedVectorMemops and PrefixInstrs for PLXVP/PSTXVP definitions
Differential Revision: https://reviews.llvm.org/D89727
Reviewed by: amyk, steven.zhang
Move the code which adjusts the immediate/predicate on a G_ICMP to
AArch64PostLegalizerLowering.
This
- Reduces the number of places we need to test for optimized compares in the
selector. We know that the compare should have been simplified by the time it
hits the selector, so we can avoid testing this in selects, brconds, etc.
- Allows us to potentially fold more compares (previously, this optimization
was only done after calling `tryFoldCompare`, this may allow us to hit some more
TST cases)
- Simplifies the selection code in `emitIntegerCompare` significantly; we can
just use an emitSUBS function.
- Allows us to avoid checking that the predicate has been updated after
`emitIntegerCompare`.
Also add a utility header file for things that may be useful in the selector
and various combiners. No need for an implementation file at this point, since
it's just one constexpr function for now. I've run into a couple cases where
having one of these would be handy, so might as well add it here. There are
a couple functions in the selector that can probably be factored out into
here.
Differential Revision: https://reviews.llvm.org/D89823
There are a lot of combines in AArch64PostLegalizerCombiner which exist to
facilitate instruction matching in the selector. (E.g. matching for G_ZIP and
other shuffle vector pseudos)
It still makes sense to select these instructions at -O0.
Matching earlier in a combiner can reduce complexity in the selector
significantly. For example, a good portion of our selection code for compares
would be a lot easier to represent in a combine.
This patch moves matching combines into a "AArch64PostLegalizerLowering"
combiner which runs at all optimization levels.
Also, while we're here, improve the documentation for the
AArch64PostLegalizerCombiner, and fix up the filepath in its file comment.
And also add a 'r' which somehow got dropped from a bunch of function names.
https://reviews.llvm.org/D89820
This commit marks i16 MULH as expand in AMDGPU backend,
which is necessary after the refactoring in D80485.
Differential Revision: https://reviews.llvm.org/D89965
If the end instruction of the scheduling region was a DBG_VALUE, the
uses of the debug instruction were tracked as if they were real
uses. This would then hit the deadDefHasNoUse assertion in
addVRegDefDeps if the only use was the debug instruction.
There are bunch of optimization opportunities right now in the vector
popcnt code gen when doing simple less-than/greater-than comparisons, so
let's examine them all to ensure that things don't regress as different
scenarios are fixed. We can always delete some later once some fixes are
made.
Please note: the new files were auto-generated. If people want, I can
commit the short C code that printed out the various combinations.
Some of our conversion algorithms produce -0.0 when converting unsigned i64 to double when the rounding mode is round toward negative. This switches them to other algorithms that don't have this problem. Since it is undefined behavior to change rounding mode with the non-strict nodes, this patch only changes the behavior for strict nodes.
There are still problems with unsigned i32 conversions too which I'll try to fix in another patch.
Fixes part of PR47393
Reviewed By: efriedma
Differential Revision: https://reviews.llvm.org/D87115
1. Fixed liveness issue with implicit kills.
2. Fixed potential problem with an indirect mov.
Fixes: SWDEV-256848
Differential Revision: https://reviews.llvm.org/D89599
Fixes being overly conservative with the register counts in called
functions. This should try to do a conservative range merge, but for
now just clone.
Also fix not being able to functionally run the pass standalone.
For historical reasons, the R6 register is a callee-saved argument
register. This means that if it is used to pass an argument to a function
that does not clobber it, it is live throughout the function.
This patch makes sure that in this special case any kill flags of it are
removed.
Review: Ulrich Weigand, Eli Friedman
Differential Revision: https://reviews.llvm.org/D89451
Updates an optimization that relies on boolean contents being either 0
or 1 to properly check for this before triggering.
The following:
(X & 8) != 0 --> (X & 8) >> 3
Produces unexpected results when a boolean 'true' value is represented
by negative one.
Patch by Erik Hogeman.
Differential Revision: https://reviews.llvm.org/D89390
This adds a test covering an issue in bit comparison folding. The
issue will be addressed in the subsequent commit.
Patch by Erik Hogeman.
Differential Revision: https://reviews.llvm.org/D89390
Passes that are run after the post-RA scheduler may insert instructions like
waitcnt which eliminate the need for certain noops. After this patch the
scheduler is still aware of possible latency from hazards but noops will
not be inserted until the dedicated hazard recognizer pass is run.
Depends on D89753.
Reviewed By: foad
Differential Revision: https://reviews.llvm.org/D89754
If a target can encode multiple wait-states into a noop allow emitting such
instructions directly.
Reviewed By: rampitec, dmgreen
Differential Revision: https://reviews.llvm.org/D89753
Change waitcnt insertion to check the memory operand tokens to see if
flat memory operations access VMEM in the same way it does to check if
accessing LDS. This avoids adding waitcnt for counters for address
spaces that are not accessed.
In addition, only generate the pessimistic waitcnt 0 if a flat memory
operation appears to access both VMEM and LDS.
This benefits flat memory operations that explicitly specify the
address space as GLOBAL or LOCAL.
Differential Revision: https://reviews.llvm.org/D89618
- In general, a generic point may alias to pointers in all other address
spaces. However, for certain cases enforced by the programming model,
we may found a generic point won't alias to pointers to local objects.
* When a generic pointer is loaded from the constant address space, it
could only be a pointer to the GLOBAL or CONSTANT address space.
Thus, it won't alias to pointers to the PRIVATE or LOCAL address
space.
* When a generic pointer is passed as a kernel argument, it also could
only be a pointer to the GLOBAL or CONSTANT address space. Thus, it
also won't alias to pointers to the PRIVATE or LOCAL address space.
Differential Revision: https://reviews.llvm.org/D89525
Remove immediate operand from SI_ELSE which indicates if EXEC has
been modified. Instead always emit code that handles EXEC and
remove unnecessary instructions during pre-RA optimisation.
This facilitates passes (i.e. SIWholeQuadMode) adding exec mask
manipulation post control flow lowering, and pre control flow
lower passes do not need to be aware of SI_ELSE handling.
Reviewed By: nhaehnle
Differential Revision: https://reviews.llvm.org/D89644
D70365 allows us to make attributes default. This is a follow up to
actually make nosync, nofree and willreturn default. The approach we
chose, for now, is to opt-in to default attributes to avoid introducing
problems to target specific intrinsics. Intrinsics with default
attributes can be created using `DefaultAttrsIntrinsic` class.
This reverts commit 38f625d0d1.
This commit contains some holes in its logic and has been causing
issues since it was commited. The idea sounds OK but some cases were not
handled correctly. Instead of trying to fix that up later it is probably
simpler to revert it and work to reimplement it in a more reliable way.
From LangRef, FMF contract should not enable reassociating to form
arbitrary contractions. So it should not help rearrange nodes like
(fma (fmul x, c1), c2, y) into (fma x, c1*c2, y).
Reviewed By: spatel
Differential Revision: https://reviews.llvm.org/D89527
extract_vector_elt will turn type vxi1 into i8, which triggers the assertion fail.
Since we don't really handle vxi1 cases in below code, we can just return from here.
Reviewed By: RKSimon
Differential Revision: https://reviews.llvm.org/D89096
Summary:
Initializer merging generates pretty inefficient code for large allocas
that also happens to trigger an exponential algorithm somewhere in
Machine Instruction Scheduler. See https://bugs.llvm.org/show_bug.cgi?id=47867.
This change adds an upper limit for the alloca size. The default limit
is selected such that worst case size of memtag-generated code is
similar to non-memtag (but because of the ISA quirks, this case is
realized at the different value of alloca size, ex. memset inlining
triggers at sizes below 512, but stack tagging instructions are 2x
shorter, so limit is approx. 256).
We could try harder to emit more compact code with initializer merging,
but that would only affect large, sparsely initialized allocas, and
those are doing fine already.
Reviewers: vitalybuka, pcc
Subscribers: llvm-commits
This enables these transforms for vectors:
(ctpop x) u< 2 -> (x & x-1) == 0
(ctpop x) u> 1 -> (x & x-1) != 0
(ctpop x) == 1 --> (x != 0) && ((x & x-1) == 0)
(ctpop x) != 1 --> (x == 0) || ((x & x-1) != 0)
All enabled if CTPOP isn't Legal. This differs from the scalar
behavior where the first two are done unconditionally and the
last two are done if CTPOP isn't Legal or Custom. The Legal
check produced better results for vectors based on X86's
custom handling. Might be worth re-visiting scalars here.
I disabled the looking through truncate for vectors. The
code that creates new setcc can use the same result VT as the
original setcc even if we truncated the input. That may work
work for most scalars, but definitely wouldn't work for vectors
unless it was a vector of i1.
Fixes or at least improves PR47825
Reviewed By: spatel
Differential Revision: https://reviews.llvm.org/D89346
We have pseudo instructions we use for bitcasts between these types.
We have them in the load folding table, but not the store folding
table. This adds them there so they can be used for stack spills.
I added an exact size check so that we don't fold when the stack slot
is larger than the GPR. Otherwise the upper bits in the stack slot
would be garbage. That would be fine for Eli's test case in PR47874,
but I'm not sure its safe in general.
A step towards fixing PR47874. Next steps are to change the ADDSSrr_Int
pseudo instructions to use FR32 as the second source register class
instead of VR128. That will keep the coalescer from promoting the
register class of the bitcast instruction which will make the stack
slot 4 bytes instead of 16 bytes.
Reviewed By: RKSimon
Differential Revision: https://reviews.llvm.org/D89656
Benjamin Kramer