85 Commits

Author SHA1 Message Date
Frederik Harwath
6962cf1700
Rename ExpandLargeFpConvertPass to ExpandFpPass (#131128)
This is meant as a preparation for PR #130988 "[AMDGPU] Implement IR
expansion for frem instruction" which implements the expansion of
another instruction in this pass. The more general name seems more
appropriate given this change and quite reasonable even without it.
2025-03-14 13:11:45 +01:00
Florian Mayer
514580b438
[MTE] Apply alignment / size in AsmPrinter rather than IR (#111918)
This makes sure no optimizations are applied that assume the
bigger alignment or size, which could be incorrect if we link
together with non-instrumented code.
2024-12-17 00:47:02 -08:00
Florian Mayer
ddaf2e2d29
[HWASan] add OptimizationRemark for alloca safety (#105872) 2024-08-29 20:50:51 -07:00
Stephen Tozer
3d08ade7bd
[ExtendLifetimes] Implement llvm.fake.use to extend variable lifetimes (#86149)
This patch is part of a set of patches that add an `-fextend-lifetimes`
flag to clang, which extends the lifetimes of local variables and
parameters for improved debuggability. In addition to that flag, the
patch series adds a pragma to selectively disable `-fextend-lifetimes`,
and an `-fextend-this-ptr` flag which functions as `-fextend-lifetimes`
for this pointers only. All changes and tests in these patches were
written by Wolfgang Pieb (@wolfy1961), while Stephen Tozer (@SLTozer)
has handled review and merging. The extend lifetimes flag is intended to
eventually be set on by `-Og`, as discussed in the RFC
here:

https://discourse.llvm.org/t/rfc-redefine-og-o1-and-add-a-new-level-of-og/72850

This patch implements a new intrinsic instruction in LLVM,
`llvm.fake.use` in IR and `FAKE_USE` in MIR, that takes a single operand
and has no effect other than "using" its operand, to ensure that its
operand remains live until after the fake use. This patch does not emit
fake uses anywhere; the next patch in this sequence causes them to be
emitted from the clang frontend, such that for each variable (or this) a
fake.use operand is inserted at the end of that variable's scope, using
that variable's value. This patch covers everything post-frontend, which
is largely just the basic plumbing for a new intrinsic/instruction,
along with a few steps to preserve the fake uses through optimizations
(such as moving them ahead of a tail call or translating them through
SROA).

Co-authored-by: Stephen Tozer <stephen.tozer@sony.com>
2024-08-29 17:53:32 +01:00
Alexis Engelke
fa92d51f9e
[VP] Merge ExpandVP pass into PreISelIntrinsicLowering (#101652)
Similar to #97727; avoid an extra pass over the entire IR by performing
the lowering as part of the pre-isel-intrinsic-lowering pass.
2024-08-06 09:27:59 +02:00
Alexis Engelke
b5fc083dc3
[CodeGen] Merge lowerConstantIntrinsics into pre-isel lowering (#97727)
Currently, the LowerConstantIntrinsics pass does an RPO traversal of
every function... only to find that many functions don't have constant
intrinsics (is.constant, objectsize). In the CodeGen pipeline, there is
already a pre-isel intrinsic lowering pass, which iterates over
intrinsic declarations and lowers all users. Call
lowerConstantIntrinsics from this pass to avoid the extra iteration over
the entire IR and the RPO traversal.
2024-08-01 17:44:32 +02:00
Anatoly Trosinenko
cc53b953ac
[AArch64] When hardening against SLS, only create called thunks (#97472)
In preparation for implementing hardening of BLRA* instructions,
restrict thunk function generation to only the thunks being actually
called from any function. As described in the existing comments,
emitting all possible thunks for BLRAA and BLRAB instructions would mean
adding about 1800 functions in total, most of which are likely not to be
called.

This commit merges AArch64SLSHardening class into SLSBLRThunkInserter,
so thunks can be created as needed while rewriting a machine function.
The usages of TII, TRI and ST fields of AArch64SLSHardening class are
replaced with requesting them in-place, as ThunkInserter assumes
multiple "entry points" in contrast to the only runOnMachineFunction
method of AArch64SLSHardening.

The runOnMachineFunction method essentially replaces pre-existing
insertThunks implementation as there is no more need to insert all
possible thunks unconditionally. Instead, thunks are created on first
use from inside of insertThunks method.
2024-07-05 13:12:09 +03:00
Egor Pasko
cab81dd038
[EntryExitInstrumenter] Move passes out of clang into LLVM default pipelines (#92171)
Move EntryExitInstrumenter(PostInlining=true) to as late as possible and
EntryExitInstrumenter(PostInlining=false) to an early pre-inlining stage
(but skip for ThinLTO post-link).

This should fix the issues reported in
https://github.com/rust-lang/rust/issues/92109 and
https://github.com/llvm/llvm-project/issues/52853. These are caused
by https://reviews.llvm.org/D97608.
2024-05-31 12:48:45 -07:00
Nikita Popov
1579e9ca9c Revert "Run ObjCContractPass in Default Codegen Pipeline (#92331)"
This reverts commit 8cc8e5d6c6ac9bfc888f3449f7e424678deae8c2.
This reverts commit dae55c89835347a353619f506ee5c8f8a2c136a7.

Causes major compile-time regressions for unoptimized builds.
2024-05-24 08:14:26 +02:00
Nuri Amari
8cc8e5d6c6
Run ObjCContractPass in Default Codegen Pipeline (#92331)
Prior to this patch, when using -fthinlto-index= the ObjCARCContractPass isn't run prior to CodeGen, and instruction selection fails on IR containing arc intrinsics. This patch is motivated by that usecase.

The pass was previously added in various places codegen is performed. This patch adds the pass to the default codegen pipepline, makes sure it bails immediately if no arc intrinsics are found, and removes the adhoc scheduling of the pass. 

Co-authored-by: Nuri Amari <nuriamari@fb.com>
2024-05-23 10:04:55 -07:00
ostannard
503c55e170
[AArch64] Move SLS later in pass pipeline (#84210)
Currently, the SLS hardening pass is run before the machine outliner,
which means that the outliner creates new functions and calls which do
not have the SLS hardening applied.

The fix for this is to move the SLS passes to after the outliner, as has
recently been done for the return address signing pass.

This also avoids a bug where the SLS outliner emits code with
instructions after a return, which the outliner doesn't correctly
handle.
2024-03-07 09:28:49 +00:00
Oliver Stannard
339faffd05 Revert "[AArch64] Move SLS later in pass pipeline"
The (MF.size() == 0) assertis is triggering when building at -O0.
Reverting this while I work out what is going wrong.

This reverts commit 7e8eccd990d37d2771ca5ad7a84f54c3cfc4a5e1.
2023-10-26 09:50:13 +01:00
Oliver Stannard
7e8eccd990 [AArch64] Move SLS later in pass pipeline
Currently, the SLS hardening pass is run before the machine outliner,
which means that the outliner creates new functions and calls which do
not have the SLS hardening applied.

The fix for this is to move the SLS passes to after the outliner, as has
recently been done for the return address signing pass.

This also avoids a bug where the SLS outliner emits code with
instructions after a return, which the outliner doesn't correctly
handle.

Reviewed By: kristof.beyls

Differential Revision: https://reviews.llvm.org/D158511
2023-10-25 10:45:12 +01:00
Anatoly Trosinenko
eb02ee44d3 [AArch64] Move PAuth codegen down the machine pipeline
To simplify handling PAuth in the machine outliner, introduce a
separate AArch64PointerAuth pass that is executed after both
Prologue/Epilogue Inserter and Machine Outliner passes.

After moving to AArch64PointerAuth, signLR and authenticateLR are
not used outside of their class anymore, so make them private and
simplify accordingly.

The new pass is added via AArch64PassConfig::addPostBBSections(),
so that it can change the code size before branch relaxation occurs.
AArch64BranchTargets is placed there too, so it can take into account
any PACI(A|B)SP instructions and not excessively add BTIs at the start
of functions.

Reviewed By: tmatheson

Differential Revision: https://reviews.llvm.org/D159357
2023-09-22 14:49:14 +03:00
Daniel Hoekwater
0315fca912 [AArch64] Move branch relaxation after bbsection assignment
Because branch relaxation needs to factor in if branches target
a block in the same section or a different one, it needs to run
after the Basic Block Sections / Machine Function Splitting passes.

Because Jump table compression relies on block offsets remaining
fixed after the table is compressed, we must also move the JT
compression pass.

The only tests affected are ones enforcing just the ordering and
the a few that have basic block ids changed because RenumberBlocks
hasn't run yet.

Differential Revision: https://reviews.llvm.org/D153829
2023-07-21 20:24:52 +00:00
Amara Emerson
1e2f87868f [AArch64][GlobalISel] Move the localizer to run before the legalizer, and always localize globals.
Our strategy for localizing globals in the entry block breaks down when we have
large functions with high register pressure, using lots of globals. When this
happens, our heuristics say that globals with many uses should not be localized,
leading us to cause excessive spills and stack usage. These situations are also
exacerbated by LTO which tends to generate large functions.

For now, moving to a strategy that's simpler and more akin to SelectionDAG
fixes these issues and makes our codegen more similar. This has an overall
neutral effect on size on CTMark, while showing slight improvements with -Os -flto
on benchmarks. For low level firmware software though we see big improvements.

The reason this is neutral, and not an improvement, is because we give up the
gains from CSE'ing globals in cases where we low register pressure. I think
this can be addressed in future with some better heuristics.

Differential Revision: https://reviews.llvm.org/D147484
2023-04-03 20:41:54 -07:00
Nick Desaulniers
a3a84c9e25 [llvm] add CallBrPrepare pass to pipelines
Capstone of
https://discourse.llvm.org/t/rfc-syncing-asm-goto-with-outputs-with-gcc/65453/8

Clang changes are still necessary to enable the use of outputs along
indirect edges of asm goto statements.

Link: https://github.com/llvm/llvm-project/issues/53562

Reviewed By: void

Differential Revision: https://reviews.llvm.org/D140180
2023-02-16 17:58:34 -08:00
Mitch Phillips
486729ce06 Re-land: [MTE] Add AArch64GlobalsTagging Pass
Adds an IR pass for -fsanitize=memtag-globals. This pass goes over the
tag-capable global variables, and replaces them with a tagged global
variable of the same contents. This new global variable will have its
size and alignment adjusted if neccesary so that they're both a multiple
of the tag granule size (16 bytes).

Global merge must also be suppressed for tagged globals, as each global
variable must have a unique tag. This can possibly be relaxed in future;
globals that are identical in size, alignment, and content can possibly
be merged. The major problem comes from tail- or head-merging, which if
left unchecked, could have partially-overlapping global variables with
different memory tags, leading to crashes at runtime.

Reviewed By: fmayer, eugenis

Differential Revision: https://reviews.llvm.org/D133392
2023-01-31 13:03:37 -08:00
Mitch Phillips
15e33c699c Revert "[MTE] Add AArch64GlobalsTagging Pass"
This reverts commit 4edfcff71e150770675a19576f698c7bbe788ee2.

Broke the non-aarch64-containing target builds.
https://reviews.llvm.org/D133392 has more context.
2023-01-31 12:25:58 -08:00
Mitch Phillips
4edfcff71e [MTE] Add AArch64GlobalsTagging Pass
Adds an IR pass for -fsanitize=memtag-globals. This pass goes over the
tag-capable global variables, and replaces them with a tagged global
variable of the same contents. This new global variable will have its
size and alignment adjusted if neccesary so that they're both a multiple
of the tag granule size (16 bytes).

Global merge must also be suppressed for tagged globals, as each global
variable must have a unique tag. This can possibly be relaxed in future;
globals that are identical in size, alignment, and content can possibly
be merged. The major problem comes from tail- or head-merging, which if
left unchecked, could have partially-overlapping global variables with
different memory tags, leading to crashes at runtime.

Reviewed By: fmayer, eugenis

Differential Revision: https://reviews.llvm.org/D133392
2023-01-31 09:24:18 -08:00
OCHyams
99c12afeb4 [Assignment Tracking] Fix tests for buildbot failure (2)
Follow-up for 4ece50737d5385fb80cfa23f5297d1111f8eed39 (D142027).

Assignment Tracking Analysis now always runs and is skipped internally if
assignment tracking is disabled. Update these tests to expect to see the
pass run.

Buildbot failure: https://lab.llvm.org/buildbot/#/builders/57/builds/24094
2023-01-20 15:58:35 +00:00
Paul Kirth
557a5bc336 [codegen] Add StackFrameLayoutAnalysisPass
Issue #58168 describes the difficulty diagnosing stack size issues
identified by -Wframe-larger-than. For simple code, its easy to
understand the stack layout and where space is being allocated, but in
more complex programs, where code may be heavily inlined, unrolled, and
have duplicated code paths, it is no longer easy to manually inspect the
source program and understand where stack space can be attributed.

This patch implements a machine function pass that emits remarks with a
textual representation of stack slots, and also outputs any available
debug information to map source variables to those slots.

The new behavior can be used by adding `-Rpass-analysis=stack-frame-layout`
to the compiler invocation. Like other remarks the diagnostic
information can be saved to a file in a machine readable format by
adding -fsave-optimzation-record.

Fixes: #58168

Reviewed By: nickdesaulniers, thegameg

Differential Revision: https://reviews.llvm.org/D135488
2023-01-19 01:51:14 +00:00
Paul Kirth
fdc0bf6adc Revert "[codegen] Add StackFrameLayoutAnalysisPass"
This breaks on some AArch64 bots

This reverts commit 0a652c540556a118bbd9386ed3ab7fd9e60a9754.
2023-01-13 22:59:36 +00:00
Paul Kirth
0a652c5405 [codegen] Add StackFrameLayoutAnalysisPass
Issue #58168 describes the difficulty diagnosing stack size issues
identified by -Wframe-larger-than. For simple code, its easy to
understand the stack layout and where space is being allocated, but in
more complex programs, where code may be heavily inlined, unrolled, and
have duplicated code paths, it is no longer easy to manually inspect the
source program and understand where stack space can be attributed.

This patch implements a machine function pass that emits remarks with a
textual representation of stack slots, and also outputs any available
debug information to map source variables to those slots.

The new behavior can be used by adding `-Rpass-analysis=stack-frame-layout`
to the compiler invocation. Like other remarks the diagnostic
information can be saved to a file in a machine readable format by
adding -fsave-optimzation-record.

Fixes: #58168

Reviewed By: nickdesaulniers, thegameg

Differential Revision: https://reviews.llvm.org/D135488
2023-01-13 20:52:48 +00:00
Dmitry Vyukov
dbe8c2c316 Use-after-return sanitizer binary metadata
Currently per-function metadata consists of:
(start-pc, size, features)

This adds a new UAR feature and if it's set an additional element:
(start-pc, size, features, stack-args-size)

Reviewed By: melver

Differential Revision: https://reviews.llvm.org/D136078
2022-12-05 14:40:31 +01:00
Freddy Ye
89f36dd8f3 [X86] Add ExpandLargeFpConvert Pass and enable for X86
As stated in
https://discourse.llvm.org/t/rfc-llc-add-expandlargeintfpconvert-pass-for-fp-int-conversion-of-large-bitint/65528,
this implementation is very similar to ExpandLargeDivRem, which expands
‘fptoui .. to’, ‘fptosi .. to’, ‘uitofp .. to’, ‘sitofp .. to’ instructions
with a bitwidth above a threshold into auto-generated functions. This is
useful for targets like x86_64 that cannot lower fp convertions with more
than 128 bits. The expanded nodes are referring from the IR generated by
`compiler-rt/lib/builtins/floattidf.c`, `compiler-rt/lib/builtins/fixdfti.c`,
and etc.

Corner cases:
1. For fp16: as there is no related builtins added in compliler-rt. So I
mainly utilized the fp32 <-> fp16 lib calls to implement.
2. For fp80: as this pass is soft fp emulation and no fp80 instructions can
help in this problem. I recommend users to deprecate this usage. For now, the
implementation uses fp128 as the temporary conversion type and inserts
fptrunc/ext at top/end of the function.
3. For bf16: as clang FE currently doesn't support bf16 algorithm operations
(convert to int, float, +, -, *, ...), this patch doesn't consider bf16 for
now.
4. For unsigned FPToI: since both default hardware behaviors and libgcc are
ignoring "returns 0 for negative input" spec. This pass follows this old way
to ignore unsigned FPToI. See this example:
https://gcc.godbolt.org/z/bnv3jqW1M

The end-to-end tests are uploaded at https://reviews.llvm.org/D138261

Reviewed By: LuoYuanke, mgehre-amd

Differential Revision: https://reviews.llvm.org/D137241
2022-12-01 13:47:43 +08:00
Marco Elver
b95646fe70 Revert "Use-after-return sanitizer binary metadata"
This reverts commit d3c851d3fc8b69dda70bf5f999c5b39dc314dd73.

Some bots broke:

- https://luci-milo.appspot.com/ui/p/fuchsia/builders/toolchain.ci/clang-linux-x64/b8796062278266465473/overview
- https://lab.llvm.org/buildbot/#/builders/124/builds/5759/steps/7/logs/stdio
2022-11-30 23:35:50 +01:00
Dmitry Vyukov
d3c851d3fc Use-after-return sanitizer binary metadata
Currently per-function metadata consists of:
(start-pc, size, features)

This adds a new UAR feature and if it's set an additional element:
(start-pc, size, features, stack-args-size)

Reviewed By: melver

Differential Revision: https://reviews.llvm.org/D136078
2022-11-30 14:50:22 +01:00
David Sherwood
f0f474dfd0 [AArch64][SME] Add codegen pass to handle ZA state in arm_new_za functions.
The new pass implements the following:

* Inserts code at the start of an arm_new_za function to
    commit a lazy-save when the lazy-save mechanism is active.
* Adds a smstart intrinsic at the start of the function.
* Adds a smstop intrinsic at the end of the function.

Patch co-authored by kmclaughlin.

Differential Revision: https://reviews.llvm.org/D133896
2022-10-05 09:43:57 +00:00
Matthias Gehre
2090e85fee [llvm/CodeGen] Enable the ExpandLargeDivRem pass for X86, Arm and AArch64
This adds the ExpandLargeDivRem to the default pass pipeline.
The limit at which it expands div/rem instructions is configured
via a new TargetTransformInfo hook (default: no expansion)
X86, Arm and AArch64 backends implement this hook to expand div/rem
instructions with more than 128 bits.

Differential Revision: https://reviews.llvm.org/D130076
2022-09-06 15:32:04 +01:00
Sami Tolvanen
cff5bef948 KCFI sanitizer
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
2022-08-24 22:41:38 +00:00
Sami Tolvanen
a79060e275 Revert "KCFI sanitizer"
This reverts commit 67504c95494ff05be2a613129110c9bcf17f6c13 as using
PointerEmbeddedInt to store 32 bits breaks 32-bit arm builds.
2022-08-24 19:30:13 +00:00
Sami Tolvanen
67504c9549 KCFI sanitizer
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
2022-08-24 18:52:42 +00:00
Momchil Velikov
b4ad28da19 [CodeGen] Async unwind - add a pass to fix CFI information
This pass inserts the necessary CFI instructions to compensate for the
inconsistency of the call-frame information caused by linear (non-CGA
aware) nature of the unwind tables.

Unlike the `CFIInstrInserer` pass, this one almost always emits only
`.cfi_remember_state`/`.cfi_restore_state`, which results in smaller
unwind tables and also transparently handles custom unwind info
extensions like CFA offset adjustement and save locations of SVE
registers.

This pass takes advantage of the constraints taht LLVM imposes on the
placement of save/restore points (cf. `ShrinkWrap.cpp`):

  * there is a single basic block, containing the function prologue

  * possibly multiple epilogue blocks, where each epilogue block is
    complete and self-contained, i.e. CSR restore instructions (and the
    corresponding CFI instructions are not split across two or more
    blocks.

  * prologue and epilogue blocks are outside of any loops

Thus, during execution, at the beginning and at the end of each basic
block the function can be in one of two states:

  - "has a call frame", if the function has executed the prologue, or
     has not executed any epilogue

  - "does not have a call frame", if the function has not executed the
    prologue, or has executed an epilogue

These properties can be computed for each basic block by a single RPO
traversal.

From the point of view of the unwind tables, the "has/does not have
call frame" state at beginning of each block is determined by the
state at the end of the previous block, in layout order.

Where these states differ, we insert compensating CFI instructions,
which come in two flavours:

- CFI instructions, which reset the unwind table state to the
    initial one.  This is done by a target specific hook and is
    expected to be trivial to implement, for example it could be:
```
     .cfi_def_cfa <sp>, 0
     .cfi_same_value <rN>
     .cfi_same_value <rN-1>
     ...
```
where `<rN>` are the callee-saved registers.

- CFI instructions, which reset the unwind table state to the one
    created by the function prologue. These are the sequence:
```
       .cfi_restore_state
       .cfi_remember_state
```
In this case we also insert a `.cfi_remember_state` after the
last CFI instruction in the function prologue.

Reviewed By: MaskRay, danielkiss, chill

Differential Revision: https://reviews.llvm.org/D114545
2022-04-11 13:27:26 +01:00
Muhammad Omair Javaid
0320115c16 Revert "[CodeGen] Async unwind - add a pass to fix CFI information"
This reverts commit 980c3e6dd223a8e628367144b8180117950bb364.

This commit had failing tests with clang crashing across various
AArch64/Linux buildots.

https://lab.llvm.org/buildbot/#/builders/179/builds/3346

Differential Revision: https://reviews.llvm.org/D114545
2022-04-05 13:12:30 +05:00
Momchil Velikov
980c3e6dd2 [CodeGen] Async unwind - add a pass to fix CFI information
This pass inserts the necessary CFI instructions to compensate for the
inconsistency of the call-frame information caused by linear (non-CFG
aware) nature of the unwind tables.

Unlike the `CFIInstrInserer` pass, this one almost always emits only
`.cfi_remember_state`/`.cfi_restore_state`, which results in smaller
unwind tables and also transparently handles custom unwind info
extensions like CFA offset adjustement and save locations of SVE
registers.

This pass takes advantage of the constraints that LLVM imposes on the
placement of save/restore points (cf. `ShrinkWrap.cpp`):

  * there is a single basic block, containing the function prologue

  * possibly multiple epilogue blocks, where each epilogue block is
    complete and self-contained, i.e. CSR restore instructions (and the
    corresponding CFI instructions are not split across two or more
    blocks.

  * prologue and epilogue blocks are outside of any loops

Thus, during execution, at the beginning and at the end of each basic
block the function can be in one of two states:

  - "has a call frame", if the function has executed the prologue, or
     has not executed any epilogue

  - "does not have a call frame", if the function has not executed the
    prologue, or has executed an epilogue

These properties can be computed for each basic block by a single RPO
traversal.

In order to accommodate backends which do not generate unwind info in
epilogues we compute an additional property "strong no call frame on
entry" which is set for the entry point of the function and for every
block reachable from the entry along a path that does not execute the
prologue. If this property holds, it takes precedence over the "has a
call frame" property.

From the point of view of the unwind tables, the "has/does not have
call frame" state at beginning of each block is determined by the
state at the end of the previous block, in layout order.

Where these states differ, we insert compensating CFI instructions,
which come in two flavours:

- CFI instructions, which reset the unwind table state to the
    initial one.  This is done by a target specific hook and is
    expected to be trivial to implement, for example it could be:
```
     .cfi_def_cfa <sp>, 0
     .cfi_same_value <rN>
     .cfi_same_value <rN-1>
     ...
```
where `<rN>` are the callee-saved registers.

- CFI instructions, which reset the unwind table state to the one
    created by the function prologue. These are the sequence:
```
       .cfi_restore_state
       .cfi_remember_state
```
In this case we also insert a `.cfi_remember_state` after the
last CFI instruction in the function prologue.

Reviewed By: MaskRay, danielkiss, chill

Differential Revision: https://reviews.llvm.org/D114545
2022-04-04 14:38:22 +01:00
Matt Arsenault
5a16306c09 GlobalISel: Always enable GISelKnownBits for InstructionSelect
This wasn't running at -O0, and causing crashes for AMDGPU. AMDGPU
needs this to match the addressing modes of stack access instructions,
which is even more important at -O0 than with optimizations.

It currently costs nothing to run ahead of time, so just always enable
it.
2022-01-12 18:57:24 -05:00
Archibald Elliott
52faad83c9 [AArch64] Use Feature for A53 Erratum 835769 Fix
When this pass was originally implemented, the fix pass was enabled
using a llvm command-line flag. This works fine, except in the case of
LTO, where the flag is not passed into the linker plugin in order to
enable the function pass in the LTO backend.

Now LTO exists, the expectation now is to use target features rather
than command-line arguments to control code generation, as this ensures
that different command-line arguments in different files are correctly
represented, and target-features always get to the LTO plugin as they
are encoded into LLVM IR.

The fall-out of this change is that the fix pass has to always be added
to the backend pass pipeline, so now it makes no changes if the function
does not have the right target feature to enable it. This should make a
minimal difference to compile time.

One advantage is it's now much easier to enable when compiling for a
Cortex-A53, as CPUs imply their own individual sets of target-features,
in a more fine-grained way. I haven't done this yet, but it is an
option, if the fix should be enabled in more places.

Existing tests of the user interface are unaffected, the changes are to
reflect that the argument is now turned into a target feature.

Reviewed By: tmatheson

Differential Revision: https://reviews.llvm.org/D114703
2021-12-10 15:09:59 +00:00
Dávid Bolvanský
49de6070a2 Revert "[Remarks] Emit optimization remarks for atomics generating CAS loop"
This reverts commit 435785214f73ff0c92e97f2ade6356e3ba3bf661. Still same compile time issues for -O0 -g, eg. +1.3% for sqlite3.
2021-08-15 11:44:13 +02:00
Anshil Gandhi
435785214f [Remarks] Emit optimization remarks for atomics generating CAS loop
Implements ORE in AtomicExpand pass to report atomics generating
a compare and swap loop.

Differential Revision: https://reviews.llvm.org/D106891
2021-08-14 23:37:23 -06:00
Djordje Todorovic
df686842bc [RemoveRedundantDebugValues] Add a Pass that removes redundant DBG_VALUEs
This new MIR pass removes redundant DBG_VALUEs.

After the register allocator is done, more precisely, after
the Virtual Register Rewriter, we end up having duplicated
DBG_VALUEs, since some virtual registers are being rewritten
into the same physical register as some of existing DBG_VALUEs.
Each DBG_VALUE should indicate (at least before the LiveDebugValues)
variables assignment, but it is being clobbered for function
parameters during the SelectionDAG since it generates new DBG_VALUEs
after COPY instructions, even though the parameter has no assignment.
For example, if we had a DBG_VALUE $regX as an entry debug value
representing the parameter, and a COPY and after the COPY,
DBG_VALUE $virt_reg, and after the virtregrewrite the $virt_reg gets
rewritten into $regX, we'd end up having redundant DBG_VALUE.

This breaks the definition of the DBG_VALUE since some analysis passes
might be built on top of that premise..., and this patch tries to fix
the MIR with the respect to that.

This first patch performs bacward scan, by trying to detect a sequence of
consecutive DBG_VALUEs, and to remove all DBG_VALUEs describing one
variable but the last one:

For example:

(1) DBG_VALUE $edi, !"var1", ...
(2) DBG_VALUE $esi, !"var2", ...
(3) DBG_VALUE $edi, !"var1", ...
 ...

in this case, we can remove (1).

By combining the forward scan that will be introduced in the next patch
(from this stack), by inspecting the statistics, the RemoveRedundantDebugValues
removes 15032 instructions by using gdb-7.11 as a testbed.

Differential Revision: https://reviews.llvm.org/D105279
2021-07-14 04:29:42 -07:00
Arthur Eubanks
8815ce03e8 Remove "Rewrite Symbols" from codegen pipeline
It breaks up the function pass manager in the codegen pipeline.

With empty parameters, it looks at the -mllvm flag -rewrite-map-file.
This is likely not in use.

Add a check that we only have one function pass manager in the codegen
pipeline.

Some tests relied on the fact that we had a module pass somewhere in the
codegen pipeline.

addr-label.ll crashes on ARM due to this change. This is because a
ARMConstantPoolConstant containing a BasicBlock to represent a
blockaddress may hold an invalid pointer to a BasicBlock if the
blockaddress is invalidated by its BasicBlock getting removed. In that
case all referencing blockaddresses are RAUW a constant int. Making
ARMConstantPoolConstant::CVal a WeakVH fixes the crash, but I'm not sure
that's the right fix. As a workaround, create a barrier right before
ISel so that IR optimizations can't happen while a
ARMConstantPoolConstant has been created.

Reviewed By: rnk, MaskRay, compnerd

Differential Revision: https://reviews.llvm.org/D99707
2021-05-31 08:32:36 -07:00
Amara Emerson
5b158093e2 [AArch64][GlobalISel] Create a new minimal combiner pass just for -O0.
We never bothered to have a separate set of combines for -O0 in the prelegalizer
before. This results in some minor performance hits for a mode where performance
isn't a concern (although not regressing code size significantly is still preferable).

This also removes the CSE option since we don't need it for -O0.

Through experiments, I've arrived at a set of combines that gets the most code
size improvement at -O0, while reducing the amount of time spent in the combiner
by around 35% give or take.

Differential Revision: https://reviews.llvm.org/D102038
2021-05-07 17:01:27 -07:00
Simon Moll
1db4dbba24 Recommit "[VP,Integer,#2] ExpandVectorPredication pass"
This reverts the revert 02c5ba8679873e878ae7a76fb26808a47940275b

Fix:

Pass was registered as DUMMY_FUNCTION_PASS causing the newpm-pass
functions to be doubly defined. Triggered in -DLLVM_ENABLE_MODULE=1
builds.

Original commit:

This patch implements expansion of llvm.vp.* intrinsics
(https://llvm.org/docs/LangRef.html#vector-predication-intrinsics).

VP expansion is required for targets that do not implement VP code
generation. Since expansion is controllable with TTI, targets can switch
on the VP intrinsics they do support in their backend offering a smooth
transition strategy for VP code generation (VE, RISC-V V, ARM SVE,
AVX512, ..).

Reviewed By: rogfer01

Differential Revision: https://reviews.llvm.org/D78203
2021-05-04 11:47:52 +02:00
Adrian Prantl
02c5ba8679 Revert "[VP,Integer,#2] ExpandVectorPredication pass"
This reverts commit 43bc584dc05e24c6d44ece8e07d4bff585adaf6d.

The commit broke the -DLLVM_ENABLE_MODULES=1 builds.

http://green.lab.llvm.org/green/view/LLDB/job/lldb-cmake/31603/consoleFull#2136199809a1ca8a51-895e-46c6-af87-ce24fa4cd561
2021-04-30 17:02:28 -07:00
Simon Moll
43bc584dc0 [VP,Integer,#2] ExpandVectorPredication pass
This patch implements expansion of llvm.vp.* intrinsics
(https://llvm.org/docs/LangRef.html#vector-predication-intrinsics).

VP expansion is required for targets that do not implement VP code
generation. Since expansion is controllable with TTI, targets can switch
on the VP intrinsics they do support in their backend offering a smooth
transition strategy for VP code generation (VE, RISC-V V, ARM SVE,
AVX512, ..).

Reviewed By: rogfer01

Differential Revision: https://reviews.llvm.org/D78203
2021-04-30 15:47:28 +02:00
Arthur Eubanks
c88b87f9ce Revert "Remove "Rewrite Symbols" from codegen pipeline"
This reverts commit 6210261ecb21c84c9a440a76c0ccbc8ad211bed3.

addr-label.ll crashes on armv7.
2021-04-10 23:28:16 -07:00
Arthur Eubanks
6210261ecb Remove "Rewrite Symbols" from codegen pipeline
It breaks up the function pass manager in the codegen pipeline.

With empty parameters, it looks at the -mllvm flag -rewrite-map-file.
This is likely not in use.

Add a check that we only have one function pass manager in the codegen
pipeline.

This required reverting commit 9583a3f2625818b78c0cf6d473cdedb9f23ad82c:
"[AsmPrinter] Delete dead takeDeletedSymbsForFunction()".
This was not NFC as initially thought. By coalescing two function
psas managers, this exposed the reverted code as necessary.
addr-label.ll was crashing due to an emitted blockaddress's block being
removed but the label not emitted.

Some tests relied on the fact that we had a module pass somewhere in the
codegen pipeline.

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D99707
2021-04-10 22:38:44 -07:00
Amara Emerson
8a316045ed [AArch64][GlobalISel] Enable use of the optsize predicate in the selector.
To do this while supporting the existing functionality in SelectionDAG of using
PGO info, we add the ProfileSummaryInfo and LazyBlockFrequencyInfo analysis
dependencies to the instruction selector pass.

Then, use the predicate to generate constant pool loads for f32 materialization,
if we're targeting optsize/minsize.

Differential Revision: https://reviews.llvm.org/D97732
2021-03-02 12:55:51 -08:00
Arthur Eubanks
040c1b49d7 Move EntryExitInstrumentation pass location
This seems to be more of a Clang thing rather than a generic LLVM thing,
so this moves it out of LLVM pipelines and as Clang extension hooks into
LLVM pipelines.

Move the post-inline EEInstrumentation out of the backend pipeline and
into a late pass, similar to other sanitizer passes. It doesn't fit
into the codegen pipeline.

Also fix up EntryExitInstrumentation not running at -O0 under the new
PM. PR49143

Reviewed By: hans

Differential Revision: https://reviews.llvm.org/D97608
2021-03-01 10:08:10 -08:00