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this metadata
Sometimes an developer would like to have more control over cmov vs branch. We have unpredictable metadata in LLVM IR, but currently it is ignored by X86 backend. Propagate this metadata and avoid cmov->branch conversion in X86CmovConversion for cmov with this metadata.
Example:
```
int MaxIndex(int n, int *a) {
int t = 0;
for (int i = 1; i < n; i++) {
// cmov is converted to branch by X86CmovConversion
if (a[i] > a[t]) t = i;
}
return t;
}
int MaxIndex2(int n, int *a) {
int t = 0;
for (int i = 1; i < n; i++) {
// cmov is preserved
if (__builtin_unpredictable(a[i] > a[t])) t = i;
}
return t;
}
```
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D118118
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This commit implements the serialization and deserialization of the Machine
Function's EntryValueObjects.
Depends on D149879, D149778
Differential Revision: https://reviews.llvm.org/D149880
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MachineFunction keeps a table of variables whose addresses never change
throughout the function. Today, the only kinds of locations it can
handle are stack slots.
However, we could expand this for variables whose address is derived
from the value a register had upon function entry. One case where this
happens is with variables alive across coroutine funclets: these can
be placed in a coroutine frame object whose pointer is placed in a
register that is an argument to coroutine funclets.
```
define @foo(ptr %frame_ptr) {
dbg.declare(%frame_ptr, !some_var,
!DIExpression(EntryValue, <ptr_arithmetic>))
```
This is a patch in a series that aims to improve the debug information
generated by the CoroSplit pass in the context of `swiftasync`
arguments. Variables stored in the coroutine frame _must_ be described
the entry_value of the ABI-defined register containing a pointer to the
coroutine frame. Since these variables have a single location throughout
their lifetime, they are candidates for being stored in the
MachineFunction table.
Differential Revision: https://reviews.llvm.org/D149879
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This is rework of;
- D30046 (LLT)
Since I have introduced `llvm-min-tblgen` as D146352, `llvm-tblgen`
may depend on `CodeGen`.
`LowLevlType.h` originally belonged to `CodeGen`. Almost all userse are
still under `CodeGen` or `Target`. I think `CodeGen` is the right place
to put `LowLevelType.h`.
`MachineValueType.h` may be moved as well. (later, D149024)
I have made many modules depend on `CodeGen`. It is consistent but
inefficient. It will be split out later, D148769
Besides, I had to isolate MVT and LLT in modmap, since
`llvm::PredicateInfo` clashes between `TableGen/CodeGenSchedule.h`
and `Transforms/Utils/PredicateInfo.h`.
(I think better to introduce namespace llvm::TableGen)
Depends on D145937, D146352, and D148768.
Differential Revision: https://reviews.llvm.org/D148767
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We add a field `IsOutlined` to indicate whether a MachineFunction
is outlined and set it true for outlined functions in MachineOutliner.
Reviewed By: paquette
Differential Revision: https://reviews.llvm.org/D146191
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Add a flag state (and a MIR key) to MachineFunctions indicating whether they
contain instruction referencing debug-info or not. Whether DBG_VALUEs or
DBG_INSTR_REFs are used needs to be determined by LiveDebugValues at least, and
using the current optimisation level as a proxy is proving unreliable.
Test updates are purely adding the flag to tests, in a couple of cases it
involves separating out VarLocBasedLDV/InstrRefBasedLDV tests into separate
files, as they can no longer share the same input.
Differential Revision: https://reviews.llvm.org/D141387
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This patch makes two notable changes to the MIR debug info representation,
which result in different MIR output but identical final DWARF output (NFC
w.r.t. the full compilation). The two changes are:
* The introduction of a new MachineOperand type, MO_DbgInstrRef, which
consists of two unsigned numbers that are used to index an instruction
and an output operand within that instruction, having a meaning
identical to first two operands of the current DBG_INSTR_REF
instruction. This operand is only used in DBG_INSTR_REF (see below).
* A change in syntax for the DBG_INSTR_REF instruction, shuffling the
operands to make it resemble DBG_VALUE_LIST instead of DBG_VALUE,
and replacing the first two operands with a single MO_DbgInstrRef-type
operand.
This patch is the first of a set that will allow DBG_INSTR_REF
instructions to refer to multiple machine locations in the same manner
as DBG_VALUE_LIST.
Reviewed By: jmorse
Differential Revision: https://reviews.llvm.org/D129372
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object
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D139451
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Adds support for printing and parsing PC sections metadata in MIR.
Reviewed By: arsenm
Differential Revision: https://reviews.llvm.org/D133785
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The KCFI sanitizer, enabled with `-fsanitize=kcfi`, implements a
forward-edge control flow integrity scheme for indirect calls. It
uses a !kcfi_type metadata node to attach a type identifier for each
function and injects verification code before indirect calls.
Unlike the current CFI schemes implemented in LLVM, KCFI does not
require LTO, does not alter function references to point to a jump
table, and never breaks function address equality. KCFI is intended
to be used in low-level code, such as operating system kernels,
where the existing schemes can cause undue complications because
of the aforementioned properties. However, unlike the existing
schemes, KCFI is limited to validating only function pointers and is
not compatible with executable-only memory.
KCFI does not provide runtime support, but always traps when a
type mismatch is encountered. Users of the scheme are expected
to handle the trap. With `-fsanitize=kcfi`, Clang emits a `kcfi`
operand bundle to indirect calls, and LLVM lowers this to a
known architecture-specific sequence of instructions for each
callsite to make runtime patching easier for users who require this
functionality.
A KCFI type identifier is a 32-bit constant produced by taking the
lower half of xxHash64 from a C++ mangled typename. If a program
contains indirect calls to assembly functions, they must be
manually annotated with the expected type identifiers to prevent
errors. To make this easier, Clang generates a weak SHN_ABS
`__kcfi_typeid_<function>` symbol for each address-taken function
declaration, which can be used to annotate functions in assembly
as long as at least one C translation unit linked into the program
takes the function address. For example on AArch64, we might have
the following code:
```
.c:
int f(void);
int (*p)(void) = f;
p();
.s:
.4byte __kcfi_typeid_f
.global f
f:
...
```
Note that X86 uses a different preamble format for compatibility
with Linux kernel tooling. See the comments in
`X86AsmPrinter::emitKCFITypeId` for details.
As users of KCFI may need to locate trap locations for binary
validation and error handling, LLVM can additionally emit the
locations of traps to a `.kcfi_traps` section.
Similarly to other sanitizers, KCFI checking can be disabled for a
function with a `no_sanitize("kcfi")` function attribute.
Relands 67504c95494ff05be2a613129110c9bcf17f6c13 with a fix for
32-bit builds.
Reviewed By: nickdesaulniers, kees, joaomoreira, MaskRay
Differential Revision: https://reviews.llvm.org/D119296
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This reverts commit 67504c95494ff05be2a613129110c9bcf17f6c13 as using
PointerEmbeddedInt to store 32 bits breaks 32-bit arm builds.
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The KCFI sanitizer, enabled with `-fsanitize=kcfi`, implements a
forward-edge control flow integrity scheme for indirect calls. It
uses a !kcfi_type metadata node to attach a type identifier for each
function and injects verification code before indirect calls.
Unlike the current CFI schemes implemented in LLVM, KCFI does not
require LTO, does not alter function references to point to a jump
table, and never breaks function address equality. KCFI is intended
to be used in low-level code, such as operating system kernels,
where the existing schemes can cause undue complications because
of the aforementioned properties. However, unlike the existing
schemes, KCFI is limited to validating only function pointers and is
not compatible with executable-only memory.
KCFI does not provide runtime support, but always traps when a
type mismatch is encountered. Users of the scheme are expected
to handle the trap. With `-fsanitize=kcfi`, Clang emits a `kcfi`
operand bundle to indirect calls, and LLVM lowers this to a
known architecture-specific sequence of instructions for each
callsite to make runtime patching easier for users who require this
functionality.
A KCFI type identifier is a 32-bit constant produced by taking the
lower half of xxHash64 from a C++ mangled typename. If a program
contains indirect calls to assembly functions, they must be
manually annotated with the expected type identifiers to prevent
errors. To make this easier, Clang generates a weak SHN_ABS
`__kcfi_typeid_<function>` symbol for each address-taken function
declaration, which can be used to annotate functions in assembly
as long as at least one C translation unit linked into the program
takes the function address. For example on AArch64, we might have
the following code:
```
.c:
int f(void);
int (*p)(void) = f;
p();
.s:
.4byte __kcfi_typeid_f
.global f
f:
...
```
Note that X86 uses a different preamble format for compatibility
with Linux kernel tooling. See the comments in
`X86AsmPrinter::emitKCFITypeId` for details.
As users of KCFI may need to locate trap locations for binary
validation and error handling, LLVM can additionally emit the
locations of traps to a `.kcfi_traps` section.
Similarly to other sanitizers, KCFI checking can be disabled for a
function with a `no_sanitize("kcfi")` function attribute.
Reviewed By: nickdesaulniers, kees, joaomoreira, MaskRay
Differential Revision: https://reviews.llvm.org/D119296
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With C++17 there is no Clang pedantic warning or MSVC C5051.
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Use the query that doesn't assert if TracksLiveness isn't set, which
needs to always be available. We also need to start printing liveins
regardless of TracksLiveness.
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This is a (fixed) recommit of https://reviews.llvm.org/D121169
after: 1061034926
before: 1063332844
Discourse thread: https://discourse.llvm.org/t/include-what-you-use-include-cleanup
Differential Revision: https://reviews.llvm.org/D121681
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This reverts commit 7f230feeeac8a67b335f52bd2e900a05c6098f20.
Breaks CodeGenCUDA/link-device-bitcode.cu in check-clang,
and many LLVM tests, see comments on https://reviews.llvm.org/D121169
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after: 1061034926
before: 1063332844
Differential Revision: https://reviews.llvm.org/D121169
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This wraps up from D119053. The 2 headers are moved as described,
fixed file headers and include guards, updated all files where the old
paths were detected (simple grep through the repo), and `clang-format`-ed it all.
Differential Revision: https://reviews.llvm.org/D119876
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Expanding on D109750.
Since `DBG_VALUE` instructions have final register validity determined in
`LDVImpl::handleDebugValue`, there is no apparent reason to immediately prune
unused register operands as their defs are erased. Consequently, this renders
`MachineInstr::eraseFromParentAndMarkDBGValuesForRemoval` moot; gaining a
substantial performance improvement.
The only necessary changes involve making relevant passes consider invalid
DBG_VALUE vregs uses as valid.
Reviewed By: MatzeB
Differential Revision: https://reviews.llvm.org/D112852
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TargetPassConfig::addPass takes a "bool verifyAfter" argument which lets
you skip machine verification after a particular pass. Unfortunately
this is used in generic code in TargetPassConfig itself to skip
verification after a generic pass, only because some previous target-
specific pass damaged the MIR on that specific target. This is bad
because problems in one target cause lack of verification for all
targets.
This patch replaces that mechanism with a new MachineFunction property
called "FailsVerification" which can be set by (usually target-specific)
passes that are known to introduce problems. Later passes can reset it
again if they are known to clean up the previous problems.
Differential Revision: https://reviews.llvm.org/D111397
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We keep a record of substitutions between debug value numbers post-isel,
however we never actually look them up until the end of compilation. As a
result, there's nothing gained by the collection being a std::map. This
patch downgrades it to being a vector, that's then sorted at the end of
compilation in LiveDebugValues.
Differential Revision: https://reviews.llvm.org/D105029
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Very late in compilation, backends like X86 will perform optimisations like
this:
$cx = MOV16rm $rax, ...
->
$rcx = MOV64rm $rax, ...
Widening the load from 16 bits to 64 bits. SEeing how the lower 16 bits
remain the same, this doesn't affect execution. However, any debug
instruction reference to the defined operand now refers to a 64 bit value,
nto a 16 bit one, which might be unexpected. Elsewhere in codegen, there's
often this pattern:
CALL64pcrel32 @foo, implicit-def $rax
%0:gr64 = COPY $rax
%1:gr32 = COPY %0.sub_32bit
Where we want to refer to the definition of $eax by the call, but don't
want to refer the copies (they don't define values in the way
LiveDebugValues sees it). To solve this, add a subregister field to the
existing "substitutions" facility, so that we can describe a field within
a larger value definition. I would imagine that this would be used most
often when a value is widened, and we need to refer to the original,
narrower definition.
Differential Revision: https://reviews.llvm.org/D88891
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- Distinct metadata needs generating in the codegen to attach correct
AAInfo on the loads/stores after lowering, merging, and other relevant
transformations.
- This patch adds 'MachhineModuleSlotTracker' to help assign slot
numbers to these newly generated unnamed metadata nodes.
- To help 'MachhineModuleSlotTracker' track machine metadata, the
original 'SlotTracker' is rebased from 'AbstractSlotTrackerStorage',
which provides basic interfaces to create/retrive metadata slots. In
addition, once LLVM IR is processsed, additional hooks are also
introduced to help collect machine metadata and assign them slot
numbers.
- Finally, if there is any such machine metadata, 'MIRPrinter' outputs
an additional 'machineMetadataNodes' field containing all the
definition of those nodes.
Reviewed By: arsenm
Differential Revision: https://reviews.llvm.org/D103205
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The MIRParser expects unnamed stack entries to have empty names ('').
In case of unnamed alloca instructions, the MIRPrinter would output
'<unnamed alloca>', which caused the MIRParser to reject the generated
code.
Reviewed By: arsenm
Differential Revision: https://reviews.llvm.org/D93685
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Fixes: SWDEV-256460
Reviewed By: arsenm
Differential Revision: https://reviews.llvm.org/D90239
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Add a table recording "substitutions" between pairs of <instruction,
operand> numbers, from old pairs to new pairs. Post-isel optimizations are
able to record the outcome of an optimization in this way. For example, if
there were a divide instruction that generated the quotient and remainder,
and it were replaced by one that only generated the quotient:
$rax, $rcx = DIV-AND-REMAINDER $rdx, $rsi, debug-instr-num 1
DBG_INSTR_REF 1, 0
DBG_INSTR_REF 1, 1
Became:
$rax = DIV $rdx, $rsi, debug-instr-num 2
DBG_INSTR_REF 1, 0
DBG_INSTR_REF 1, 1
We could enter a substitution from <1, 0> to <2, 0>, and no substitution
for <1, 1> as it's no longer generated.
This approach means that if an instruction or value is deleted once we've
left SSA form, all variables that used the value implicitly become
"optimized out", something that isn't true of the current DBG_VALUE
approach.
Differential Revision: https://reviews.llvm.org/D85749
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This patch defines the MIR format for debug instruction references: it's an
integer trailing an instruction, marked out by "debug-instr-number", much
like how "debug-location" identifies the DebugLoc metadata of an
instruction. The instruction number is stored directly in a MachineInstr.
Actually referring to an instruction comes in a later patch, but is done
using one of these instruction numbers.
I've added a round-trip test and two verifier checks: that we don't label
meta-instructions as generating values, and that there are no duplicates.
Differential Revision: https://reviews.llvm.org/D85746
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Common up some existing MBB name printing logic into a single place.
Note that basic block dumping now prints the same set of attributes as
the MIRPrinter.
Change-Id: I8f022bbd922e831bc96d63143d7472c03282530b
Differential Revision: https://reviews.llvm.org/D83253
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Let the codegen recognized the nomerge attribute and disable branch folding when the attribute is given
Differential Revision: https://reviews.llvm.org/D79537
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This reverts commit e38018b80d8e60206268740c688236734dea7b86.
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- Need to skip the assignment of `ID`, which is used to index that two
object arrays.
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Summary:
The INLINEASM MIR instructions use immediate operands to encode the values of some operands.
The MachineInstr pretty printer function already handles those operands and prints human readable annotations instead of the immediates. This patch adds similar annotations to the output of the MIRPrinter, however uses the new MIROperandComment feature.
Reviewers: SjoerdMeijer, arsenm, efriedma
Reviewed By: arsenm
Subscribers: qcolombet, sdardis, jvesely, wdng, nhaehnle, hiraditya, jrtc27, atanasyan, kerbowa, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D78088
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the same section.
Differential Revision: https://reviews.llvm.org/D76954
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This reverts commit 0d4ec16d3db3a92514e14101f635e8536c208c4f Because
tests were not added to the commit.
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in the same section.
This allows specifying BasicBlock clusters like the following example:
!foo
!!0 1 2
!!4
This places basic blocks 0, 1, and 2 in one section in this order, and
places basic block #4 in a single section of its own.
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Summary:
In lieu of a proper pass that strips debug info, add a way
to omit debug-locations from the MIR output so that
instructions with MMO's continue to match CHECK's when
mir-debugify is used
Reviewers: aprantl, bogner, vsk
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D77575
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Summary:
Although it may look like non NFC it is. especially the MIRParser may set `0` to the MachineFrameInfo and MachineFunction, but they all deal with `Align` internally and assume that `0` means `1`.
https://github.com/llvm/llvm-project/blob/93fc0ba145c2f9619d3174c95cacda5d4a0a2815/llvm/include/llvm/CodeGen/MachineFrameInfo.h#L483
This is patch is part of a series to introduce an Alignment type.
See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html
See this patch for the introduction of the type: https://reviews.llvm.org/D64790
Reviewers: courbet
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D77203
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Otherwise, the Win64 unwinder considers direct branches to such empty
trailing BBs to be a branch out of the function. It treats such a branch
as a tail call, which can only be part of an epilogue. If the unwinder
misclassifies such a branch as part of the epilogue, it will fail to
unwind the stack further. This can lead to bad stack traces, or failure
to handle exceptions properly. This is described in
https://llvm.org/PR45064#c4, and by the comment at the top of the
X86AvoidTrailingCallPass.cpp file.
It should be safe to insert int3 for such blocks. An empty trailing BB
that reaches this pass is pretty much guaranteed to be unreachable. If
a program executed such a block, it would fall off the end of the
function.
Most of the complexity in this patch comes from threading through the
"EHFuncletEntry" boolean on the MIRParser and registering the pass so we
can stop and start codegen around it. I used an MIR test because we
should teach LLVM to optimize away these branches as a follow-up.
Reviewed By: hans
Differential Revision: https://reviews.llvm.org/D76531
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Summary:
This is patch is part of a series to introduce an Alignment type.
See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html
See this patch for the introduction of the type: https://reviews.llvm.org/D64790
Reviewers: courbet
Subscribers: jholewinski, arsenm, dschuff, jyknight, sdardis, nemanjai, jvesely, nhaehnle, sbc100, jgravelle-google, hiraditya, aheejin, kbarton, fedor.sergeev, asb, rbar, johnrusso, simoncook, sabuasal, niosHD, jrtc27, MaskRay, zzheng, edward-jones, atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, PkmX, jocewei, Jim, lenary, s.egerton, pzheng, sameer.abuasal, apazos, luismarques, kerbowa, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D76348
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This is the second patch in a series of patches to enable basic block
sections support.
This patch adds support for:
* Creating direct jumps at the end of basic blocks that have fall
through instructions.
* New pass, bbsections-prepare, that analyzes placement of basic blocks
in sections.
* Actual placing of a basic block in a unique section with special
handling of exception handling blocks.
* Supports placing a subset of basic blocks in a unique section.
* Support for MIR serialization and deserialization with basic block
sections.
Parent patch : D68063
Differential Revision: https://reviews.llvm.org/D73674
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This adds infrastructure to print and parse MIR MachineOperand comments.
The motivation for the ARM backend is to print condition code names instead of
magic constants that are difficult to read (for human beings). For example,
instead of this:
dead renamable $r2, $cpsr = tEOR killed renamable $r2, renamable $r1, 14, $noreg
t2Bcc %bb.4, 0, killed $cpsr
we now print this:
dead renamable $r2, $cpsr = tEOR killed renamable $r2, renamable $r1, 14 /* CC::always */, $noreg
t2Bcc %bb.4, 0 /* CC:eq */, killed $cpsr
This shows that MachineOperand comments are enclosed between /* and */. In this
example, the EOR instruction is not conditionally executed (i.e. it is "always
executed"), which is encoded by the 14 immediate machine operand. Thus, now
this machine operand has /* CC::always */ as a comment. The 0 on the next
conditional branch instruction represents the equal condition code, thus now
this operand has /* CC:eq */ as a comment.
As it is a comment, the MI lexer/parser completely ignores it. The benefit is
that this keeps the change in the lexer extremely minimal and no target
specific parsing needs to be done. The changes on the MIPrinter side are also
minimal, as there is only one target hooks that is used to create the machine
operand comments.
Differential Revision: https://reviews.llvm.org/D74306
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This is how it should've been and brings it more in line with
std::string_view. There should be no functional change here.
This is mostly mechanical from a custom clang-tidy check, with a lot of
manual fixups. It uncovers a lot of minor inefficiencies.
This doesn't actually modify StringRef yet, I'll do that in a follow-up.
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Summary:
This is a follow up on https://reviews.llvm.org/D71473#inline-647262.
There's a caveat here that `Align(1)` relies on the compiler understanding of `Log2_64` implementation to produce good code. One could use `Align()` as a replacement but I believe it is less clear that the alignment is one in that case.
Reviewers: xbolva00, courbet, bollu
Subscribers: arsenm, dylanmckay, sdardis, nemanjai, jvesely, nhaehnle, hiraditya, kbarton, jrtc27, atanasyan, jsji, Jim, kerbowa, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D73099
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In D71841 we inverted the sense of the SDNode-level flag to ensure all nodes
default to potentially raising FP exceptions unless otherwise specified --
i.e. if we forget to propagate the flag somewhere, the effect is now only
lost performance, not incorrect code.
However, the related flag at the MI level still defaults to nodes not raising
FP exceptions unless otherwise specified. To be fully on the (conservatively)
safe side, we should invert that flag as well.
This patch does so by replacing MIFlag::FPExcept with MIFlag::NoFPExcept.
(Note that this does also introduce an incompatible change in the MIR format.)
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D72466
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Summary:
Move MIR formatter pointer from TargetMachine to TargetInstrInfo to
avoid cyclic dependency between target & codegen.
Reviewers: dsanders, bkramer, arsenm
Subscribers: wdng, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D72485
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There was an unguarded dereference of MF in a function that permitted
nullptr. Fixed
This reverts commit 71d64f72f934631aa2f12b9542c23f74f256f494.
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