Rename hasCMPXCHG16B() to canUseCMPXCHG16B() to make it less like other
feature functions. Add a similar canUseCMPXCHG8B() that aliases
hasCX8() to keep similar naming.
Differential Revision: https://reviews.llvm.org/D121978
-Rename Mode*Bit to Is*Bit to match X86Subtarget.
-Rename FeatureLAHFSAHF to FeatureLAFHSAFH64 to match X86Subtarget.
-Use consistent capitalization
Reviewed By: skan
Differential Revision: https://reviews.llvm.org/D121975
Discussed extensively on D98232. The functionality introduced in D35816
never worked correctly. In D98232, it was fixed, but, as it was
introducing a large compile-time regression, and the value of the
original patch was called into doubt, we disabled it by default
everywhere. A year later, it appears that caused no grief, so it seems
safe to remove the disabled code.
This should be accompanied by re-opening bug 26810.
Differential Revision: https://reviews.llvm.org/D121128
This is effectively inverting the transform added with D116804
because the downside of the false dependency of something like
"sbb %eax, %eax" is much greater than the upside of eliminating
a zeroing instruction on (all?) Intel CPUs.
Differential Revision: https://reviews.llvm.org/D118843
Replace X86ProcFamilyEnum::IntelSLM enum with a TuningUseSLMArithCosts flag instead, matching what we already do for Goldmont.
This just leaves X86ProcFamilyEnum::IntelAtom to replace with general Tuning/Feature flags and we can finally get rid of the old X86ProcFamilyEnum enum.
Differential Revision: https://reviews.llvm.org/D112079
The feature tells the backend to allow tags in the upper bits of global
variable addresses. These tags will be ignored by upcoming CPUs with
the Intel LAM feature but may be used in instrumentation passes (e.g.,
HWASan).
This patch implements the feature by using @GOTPCREL relocations instead
of direct references to the locally defined global. Thus the full
tagged address can be loaded by a single instruction:
movq global@GOTPCREL(%rip), %rax
Reviewed By: eugenis
Differential Revision: https://reviews.llvm.org/D111343
When back-deploying Swift async code we can't always toggle the flag showing an
extended frame is present because it will confuse unwinders on systems released
before this feature. So in cases where the code might run there, we `or` in a
mask provided by the runtime (as an absolute symbol) telling us whether the
unwinders can cope.
When deploying only for newer OSs, we can still hard-code the bit-set for
greater efficiency.
d8faf03807 implemented general-regs-only for X86 by disabling all features
with vector instructions. But the CRC32 instruction in SSE4.2 ISA, which uses
only GPRs, also becomes unavailable. This patch adds a CRC32 feature for this
instruction and allows it to be used with general-regs-only.
Reviewed By: pengfei
Differential Revision: https://reviews.llvm.org/D105462
So far, support for x86_64-linux-gnux32 has been handled by explicit
comparisons of Triple.getEnvironment() to GNUX32. This worked as long as
x86_64-linux-gnux32 was the only X32 environment to worry about, but we
now have x86_64-linux-muslx32 as well. To support this, this change adds
an isX32() function and uses it. It replaces all checks for GNUX32 or
MuslX32 by isX32(), except for the following:
- Triple::isGNUEnvironment() and Triple::isMusl() are supposed to treat
GNUX32 and MuslX32 differently.
- computeTargetTriple() needs to be able to transform triples to add or
remove X32 from the environment and needs to map GNU to GNUX32, and
Musl to MuslX32.
- getMultiarchTriple() completely lacks any Musl support and retains the
explicit check for GNUX32 as it can only return x86_64-linux-gnux32.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D103777
Currently, X86 backend only has a global one-size-fits-all `FeatureFastVariableShuffle` feature,
which controls profitability of both the cross-lane and per-lane variable shuffles.
I guess, this has been fine so far.
But at least on AMD Zen 3, while per-line variable shuffles (e.g. `VPSHUFB`)
are as fast as as shuffles with fixed/immediate mask,
while lane-crossing shuffles, e.g. `VPERMPS` is performing worse.
So to get the benefits of variable-mask shuffles, but not the drawbacks of lane-crossing shuffles,
as suggested by @RKSimon, split the feature flag into two.
Differential Revision: https://reviews.llvm.org/D103274
Swift's new concurrency features are going to require guaranteed tail calls so
that they don't consume excessive amounts of stack space. This would normally
mean "tailcc", but there are also Swift-specific ABI desires that don't
naturally go along with "tailcc" so this adds another calling convention that's
the combination of "swiftcc" and "tailcc".
Support is added for AArch64 and X86 for now.
Currently we model i16 bswap as very high cost (`10`),
which doesn't seem right, with all other being at `1`.
Regardless of `MOVBE`, i16 reg-reg bswap is lowered into
(an extending move plus) rot-by-8:
https://godbolt.org/z/8jrq7fMTj
I think it should at worst have throughput of `1`:
Since i32/i64 already have cost of `1`,
`MOVBE` doesn't improve their costs any further.
BUT, `MOVBE` must have at least a single memory operand,
with other being a register. Which means, if we have
a bswap of load, iff load has a single use,
we'll fold bswap into load.
Likewise, if we have store of a bswap, iff bswap
has a single use, we'll fold bswap into store.
So i think we should treat such a bswap as free,
unless of course we know that for the particular CPU
they are performing badly.
Reviewed By: RKSimon
Differential Revision: https://reviews.llvm.org/D101924
The main part of the patch is the change in RegAllocGreedy.cpp: Q.collectInterferringVregs()
needs to be called before iterating the interfering live ranges.
The rest of the patch offers support that is the case: instead of clearing the query's
InterferingVRegs field, we invalidate it. The clearing happens when the live reg matrix
is invalidated (existing triggering mechanism).
Without the change in RegAllocGreedy.cpp, the compiler ices.
This patch should make it more easily discoverable by developers that
collectInterferringVregs needs to be called before iterating.
I will follow up with a subsequent patch to improve the usability and maintainability of Query.
Differential Revision: https://reviews.llvm.org/D98232
This patch implements amx programming model that discussed in llvm-dev
(http://lists.llvm.org/pipermail/llvm-dev/2020-August/144302.html).
Thank Hal for the good suggestion in the RA. The fast RA is not in the patch yet.
This patch implemeted 7 components.
1. The c interface to end user.
2. The AMX intrinsics in LLVM IR.
3. Transform load/store <256 x i32> to AMX intrinsics or split the
type into two <128 x i32>.
4. The Lowering from AMX intrinsics to AMX pseudo instruction.
5. Insert psuedo ldtilecfg and build the def-use between ldtilecfg to amx
intruction.
6. The register allocation for tile register.
7. Morph AMX pseudo instruction to AMX real instruction.
Change-Id: I935e1080916ffcb72af54c2c83faa8b2e97d5cb0
Differential Revision: https://reviews.llvm.org/D87981
This patch mainly made the following changes:
1. Support AVX-VNNI instructions;
2. Introduce ExplicitVEXPrefix flag so that vpdpbusd/vpdpbusds/vpdpbusds/vpdpbusds instructions only use vex-encoding when user explicity add {vex} prefix.
Differential Revision: https://reviews.llvm.org/D89105
Key Locker provides a mechanism to encrypt and decrypt data with an AES key without having access
to the raw key value by converting AES keys into “handles”. These handles can be used to perform the
same encryption and decryption operations as the original AES keys, but they only work on the current
system and only until they are revoked. If software revokes Key Locker handles (e.g., on a reboot),
then any previous handles can no longer be used.
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D88398
This patch implements initial backend support for a -mtune CPU controlled by a "tune-cpu" function attribute. If the attribute is not present X86 will use the resolved CPU from target-cpu attribute or command line.
This patch adds MC layer support a tune CPU. Each CPU now has two sets of features stored in their GenSubtargetInfo.inc tables . These features lists are passed separately to the Processor and ProcessorModel classes in tablegen. The tune list defaults to an empty list to avoid changes to non-X86. This annoyingly increases the size of static tables on all target as we now store 24 more bytes per CPU. I haven't quantified the overall impact, but I can if we're concerned.
One new test is added to X86 to show a few tuning features with mismatched tune-cpu and target-cpu/target-feature attributes to demonstrate independent control. Another new test is added to demonstrate that the scheduler model follows the tune CPU.
I have not added a -mtune to llc/opt or MC layer command line yet. With no attributes we'll just use the -mcpu for both. MC layer tools will always follow the normal CPU for tuning.
Differential Revision: https://reviews.llvm.org/D85165
As briefly discussed in IRC with @craig.topper,
the pass is disabled basically since it's original introduction (nov 2018)
due to known correctness issues (miscompilations),
and there hasn't been much work done to fix that.
While i won't promise that i will "fix" the pass,
i have looked at it previously, and i'm sure i won't try to fix it
if that requires actually fixing this existing code.
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D84775
These cost methods don't make much sense in X86Subtarget. Make
them methods in X86's TTI and move the feature checks from the
X86Subtarget constructor into these methods.
Reviewed By: RKSimon
Differential Revision: https://reviews.llvm.org/D84594
Remove mode flags from constructor and remove calls to
ToggleFeature for the mode bits.
By adding them to the feature string we handle initializing the
mode member variables in X86Subtarget and the feature bits in
MCSubtargetInfo in one shot.
We deprecated mpx feature in 10.0. I left this feature flag
in case someone still had IR files containing the feature
in a target-feature attribute. At the time I think I thought it
would fail the test if the feature couldn't be found. Further
review suggests that at worst it prints a message to
stderr about ignoring the feature.
SAHF/LAHF instructions are always available in 32-bit mode. Early
64-bit capable CPUs made the undefined opcodes in 64-bit mode. This
was changed on later CPUs.
We have a feature flag to control our usage of these instructions.
This feature flag is hooked up to a clang command line option
-msahf/-mno-sahf specifically to give control of the 64-bit mode
behavior.
In the backend X86Subtarget constructor we were explicitly forcing
+sahf into the feature flag string if we were not compiling for
64-bit mode. This was intended to make the predicates always allow
the instructions outside of 64-bit mode. Unfortunately, the way
it was placed into the string allowed -mno-sahf from clang to disable
SAHF instructions in 32-bit mode. This causes an assertion to fire
if you compile a floating point comparison with something like
"-march=pentium -mno-sahf" as our floating point comparison
handling on CPUs that don't support FCOMI/FUCOMI instructions
requires SAHF.
To fix this, this commit restricts the feature flag to only apply to
64-bit mode by ignoring the flag outside 64-bit mode in
X86Subtarget::hasLAHFSAHF(). This way we don't need to mess with
the feature string at all.
This patch creates a clang flag to enable SESES. This flag also ensures that
lvi-cfi is on when using seses via clang.
SESES should use lvi-cfi to mitigate returns and indirect branches.
The flag to enable the SESES functionality only without lvi-cfi is now
-x86-seses-enable-without-lvi-cfi to warn users part of the mitigation is not
enabled if they use this flag. This is useful in case folks want to see the
cost of SESES separate from the LVI-CFI.
Reviewed By: sconstab
Differential Revision: https://reviews.llvm.org/D79910
The PREFETCHW instruction was originally part of the 3DNow. But
it was given its own CPUID bit on later CPUs just before 3DNow
was deprecated.
We were setting the -mprfchw flag if -m3dnow was passed or the CPU
supported 3dnow unless -mno-prfchw was passed. But -march=native
on a CPU without the PRFCHW CPUID bit set will pass -mno-prfchw.
So -march=k8 will behave differently than -march=native on a K8
for example.
So remove this implicit setting from the frontend and instead
enable the backend to use PREFETCHW if 3dnow OR prfchw is enabled.
Also enable PRFCHW flag on amdfam10/barcelona which seems to be
where this CPUID bit was introduced. That CPU also supported
3dnow.
The PREFETCHW instruction was originally part of the 3DNow. But
it was given its own CPUID bit on later CPUs just before 3DNow
was deprecated.
We were setting the -mprfchw flag if -m3dnow was passed or the CPU
supported 3dnow unless -mno-prfchw was passed. But -march=native
on a CPU without the PRFCHW CPUID bit set will pass -mno-prfchw.
So -march=k8 will behave differently than -march=native on a K8
for example.
So remove this implicit setting from the frontend and instead
enable the backend to use PREFETCHW if 3dnow OR prfchw is enabled.
Also enable PRFCHW flag on amdfam10/barcelona which seems to be
where this CPUID bit was introduced. That CPU also supported
3dnow.
Replace with forward declaration and move dependency down to source files that actually need it.
Both TargetLowering.h and TargetMachine.h are 2 of the most expensive headers (top 10) in the ClangBuildAnalyzer report when building llc.
Adds a new data structure, ImmutableGraph, and uses RDF to find LVI gadgets and add them to a MachineGadgetGraph.
More specifically, a new X86 machine pass finds Load Value Injection (LVI) gadgets consisting of a load from memory (i.e., SOURCE), and any operation that may transmit the value loaded from memory over a covert channel, or use the value loaded from memory to determine a branch/call target (i.e., SINK).
Also adds a new target feature to X86: +lvi-load-hardening
The feature can be added via the clang CLI using -mlvi-hardening.
Differential Revision: https://reviews.llvm.org/D75936
Paul Robinson