1348 Commits

Author SHA1 Message Date
Fangrui Song
dd6e19a41c [IR] Rename comdat noduplicates to comdat nodeduplicate
In the textual format, `noduplicates` means no COMDAT/section group
deduplication is performed. Therefore, if both sets of sections are retained, and
they happen to define strong external symbols with the same names,
there will be a duplicate definition linker error.

In PE/COFF, the selection kind lowers to `IMAGE_COMDAT_SELECT_NODUPLICATES`.
The name describes the corollary instead of the immediate semantics.  The name
can cause confusion to other binary formats (ELF, wasm) which have implemented/
want to implement the "no deduplication" selection kind. Rename it to be clearer.

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D106319
2021-07-20 12:47:10 -07:00
Nikita Popov
db5e50afb3 [BitcodeReader] Handle type attributes more explicitly (NFCI)
For attributes in legacy bitcode that are now typed, explicitly
create a type attribute with nullptr type, the same as we do
for the attribute group representation. This is so we can assert
use of the correct constructor in the future.
2021-07-20 21:08:06 +02:00
Nikita Popov
dd3e030cca [BPF] Use elementtype attribute for preserve.array/struct.index intrinsics
Use the elementtype attribute introduced in D105407 for the
llvm.preserve.array/struct.index intrinsics. It carries the
element type of the GEP these intrinsics effectively encode.

This patch:

 * Adds a verifier check that the attribute is required.
 * Adds it in the IRBuilder methods for these intrinsics.
 * Autoupgrades old bitcode without the attribute.
 * Updates the lowering code to use the attribute rather than
   the pointer element type.
 * Updates lots of tests to specify the attribute.
 * Adds -force-opaque-pointers to the intrinsic-array.ll test
   to demonstrate they work now.

https://reviews.llvm.org/D106184
2021-07-17 11:09:18 +02:00
Nikita Popov
d58a8fbeab [IR] Add elementtype attribute
This implements the elementtype attribute specified in D105407. It
just adds the attribute and the specified verifier rules, but
doesn't yet make use of it anywhere.

Differential Revision: https://reviews.llvm.org/D106008
2021-07-15 18:04:26 +02:00
Nikita Popov
4966784718 [Attributes] Assert correct attribute constructor is used (NFCI)
Assert that enum/int/type attributes go through the constructor
they are supposed to use.

To make sure this can't happen via invalid bitcode, explicitly
verify that the attribute kind if correct there.
2021-07-12 21:11:59 +02:00
Nikita Popov
28e27a194e [Attributes] Make type attribute handling more generic (NFCI)
Followup to D105658 to make AttrBuilder automatically work with
new type attributes. TableGen is tweaked to emit First/LastTypeAttr
markers, based on which we can handle type attributes
programmatically.

Differential Revision: https://reviews.llvm.org/D105763
2021-07-12 20:49:38 +02:00
Jonas Devlieghere
3020664b33 Revert "[DebugInfo] Enforce implicit constraints on distinct MDNodes"
This reverts commit 8cd35ad854ab4458fd509447359066ea3578b494.

It breaks `TestMembersAndLocalsWithSameName.py` on GreenDragon and
Mikael Holmén points out in D104827 that bitcode files created with the
patch cannot be parsed with binaries built before it.
2021-07-02 15:57:07 -07:00
Arthur Eubanks
22a7347912 [OpaquePtr][BitcodeWriter] Handle attributes with types
For example, byval.

Skip the type attribute auto-upgrade if we already have the type.

I've actually seen this error of the ValueEnumerator missing a type
attribute's type in a non-opaque pointer context.

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D105138
2021-06-29 14:47:29 -07:00
Scott Linder
47e3a5ca06 [DebugInfo] Enforce implicit constraints on distinct MDNodes
Add UNIQUED and DISTINCT properties in Metadata.def and use them to
implement restrictions on the `distinct` property of MDNodes:

* DIExpression can currently be parsed from IR or read from bitcode
  as `distinct`, but this property is silently dropped when printing
  to IR. This causes accepted IR to fail to round-trip. As DIExpression
  appears inline at each use in the canonical form of IR, it cannot
  actually be `distinct` anyway, as there is no syntax to describe it.
* Similarly, DIArgList is conceptually always uniqued. It is currently
  restricted to only appearing in contexts where there is no syntax for
  `distinct`, but for consistency it is treated equivalently to
  DIExpression in this patch.
* DICompileUnit is already restricted to always being `distinct`, but
  along with adding general support for the inverse restriction I went
  ahead and described this in Metadata.def and updated the parser to be
  general. Future nodes which have this restriction can share this
  support.

The new UNIQUED property applies to DIExpression and DIArgList, and
forbids them to be `distinct`. It also implies they are canonically
printed inline at each use, rather than via MDNode ID.

The new DISTINCT property applies to DICompileUnit, and requires it to
be `distinct`.

A potential alternative change is to forbid the non-inline syntax for
DIExpression entirely, as is done with DIArgList implicitly by requiring
it appear in the context of a function. For example, we would forbid:

    !named = !{!0}
    !0 = !DIExpression()

Instead we would only accept the equivalent inlined version:

    !named = !{!DIExpression()}

This essentially removes the ability to create a `distinct` DIExpression
by construction, as there is no syntax for `distinct` inline. If this
patch is accepted as-is, the result would be that the non-canonical
version is accepted, but the following would be an error and produce a diagnostic:

    !named = !{!0}
    ; error: 'distinct' not allowed for !DIExpression()
    !0 = distinct !DIExpression()

Also update some documentation to consistently use the inline syntax for
DIExpression, and to describe the restrictions on `distinct` for nodes
where applicable.

Reviewed By: StephenTozer, t-tye

Differential Revision: https://reviews.llvm.org/D104827
2021-06-28 21:20:04 +00:00
Nathan Chancellor
a772deb8d1 [BitCode] Add noprofile to getAttrFromCode()
After D104475 / D104658, building the Linux kernel with ThinLTO is
broken:

ld.lld: error: Unknown attribute kind (73) (Producer: 'LLVM13.0.0git'
Reader: 'LLVM 13.0.0git')

getAttrFromCode() has never handled this attribute so it is written
during the ThinLTO phase but it cannot be handled during the linking
phase.

Add noprofile to getAttrFromCode() so that disassembly works properly.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D104995
2021-06-27 11:59:57 -07:00
Nikita Popov
415cc448d1 [OpaquePtr] Support invoke instruction
With call support in place, this is only a matter of relaxing a
bitcode reader assertion.
2021-06-23 20:24:33 +02:00
Nikita Popov
70eea896a4 [OpaquePtr] Support call instruction
Add support for call of opaque pointer, currently only possible for
indirect calls.

This requires a bit of special casing in LLParser, as calls do not
specify the callee operand type explicitly.

Differential Revision: https://reviews.llvm.org/D104740
2021-06-23 20:17:26 +02:00
Florian Hahn
0966169859 [BitcodeReader] Validate Strtab before accessing.
This fixes a crash with invalid bitcode files that have records
referencing names in Strtab, but Strtab is not present or the index is
out-of-bounds.

This fixes the following clusterfuzz issue:
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=29895

Reviewed By: arsenm

Differential Revision: https://reviews.llvm.org/D95554
2021-06-22 14:52:16 +01:00
Nikita Popov
609a4f9be4 [OpaquePtr] Support opaque constant expression GEP
Adjust assertions to use isOpaqueOrPointeeTypeMatches() and make
it return an opaque pointer result for an opaque base pointer. We
also need to enumerate the element type, as it is no longer
implicitly enumerated through the pointer type.

Differential Revision: https://reviews.llvm.org/D104655
2021-06-21 20:06:25 +02:00
Arthur Eubanks
675b987cd3 Move some code under NDEBUG from D103135 2021-06-14 11:39:12 -07:00
Arthur Eubanks
db00e9aaf8 Remove accidentally added debugging code from D103135 2021-06-14 11:11:40 -07:00
Arthur Eubanks
a32daab226 [OpaquePtr] Remove existing support for forward compatibility
It assumes that PointerType will keep having an optional pointee type,
but we'd like to remove the pointee type in PointerType at some point.

I feel like the current implementation could be simplified anyway,
although perhaps I'm underestimating the amount of work needed
throughout BitcodeReader.

We will still need a side table to keep track of pointee types. This
will be reimplemented at some point.

This is essentially a revert of a4771e9d (which doesn't look like it was
reviewed anyway).

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D103135
2021-06-14 10:52:56 -07:00
Arthur Eubanks
9085f7d6c9 [OpaquePtr] Make atomicrmw work with opaque pointers
FullTy is only necessary when we need to figure out what type an
instruction works with given a pointer's pointee type. However, we just
end up using the value operand's type, so FullTy isn't necessary.

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D102788
2021-05-25 20:16:21 -07:00
Arthur Eubanks
a1a83c59b0 [OpaquePtr] Create new bitcode encoding for atomicrmw
Since the opaque pointer type won't contain the pointee type, we need to
separately encode the value type for an atomicrmw.

Emit this new code for atomicrmw.

Handle this new code and the old one in the bitcode reader.

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D103123
2021-05-25 16:30:34 -07:00
Arthur Eubanks
35108af19f Revert "[OpaquePtr] Make atomicrmw work with opaque pointers"
This reverts commit 0bebda17bea38785c90a6fec3ca01cf74eb78b7c.

Causing "Invalid record" errors.
2021-05-25 10:14:58 -07:00
Marco Elver
b835b9cf36 [SanitizeCoverage] Add support for NoSanitizeCoverage function attribute
We really ought to support no_sanitize("coverage") in line with other
sanitizers. This came up again in discussions on the Linux-kernel
mailing lists, because we currently do workarounds using objtool to
remove coverage instrumentation. Since that support is only on x86, to
continue support coverage instrumentation on other architectures, we
must support selectively disabling coverage instrumentation via function
attributes.

Unfortunately, for SanitizeCoverage, it has not been implemented as a
sanitizer via fsanitize= and associated options in Sanitizers.def, but
rolls its own option fsanitize-coverage. This meant that we never got
"automatic" no_sanitize attribute support.

Implement no_sanitize attribute support by special-casing the string
"coverage" in the NoSanitizeAttr implementation. To keep the feature as
unintrusive to existing IR generation as possible, define a new negative
function attribute NoSanitizeCoverage to propagate the information
through to the instrumentation pass.

Fixes: https://bugs.llvm.org/show_bug.cgi?id=49035

Reviewed By: vitalybuka, morehouse

Differential Revision: https://reviews.llvm.org/D102772
2021-05-25 12:57:14 +02:00
Arthur Eubanks
586b51e638 [Verifier] Move some atomicrmw/cmpxchg checks to instruction creation
These checks already exist as asserts when creating the corresponding
instruction. Anybody creating these instructions already need to take
care to not break these checks.

Move the checks for success/failure ordering in cmpxchg from the
verifier to the LLParser and BitcodeReader plus an assert.

Add some tests for cmpxchg ordering. The .bc files are created from the
.ll files with an llvm-as with these checks disabled.

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D102803
2021-05-21 13:41:17 -07:00
Steven Wu
0da7fd24df [IR][AutoUpgrade] Drop alignment from non-pointer parameters and returns
This is a follow-up of D102201. After some discussion, it is a better idea
to upgrade all invalid uses of alignment attributes on function return
values and parameters, not just limited to void function return types.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D102726
2021-05-20 09:54:38 -07:00
Arthur Eubanks
63f5e603f7 [OpaquePtr] Make atomicrmw work with opaque pointers
FullTy is only necessary when we need to figure out what type an
instruction works with given a pointer's pointee type. However, we just
end up using the value operand's type, so FullTy isn't necessary.

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D102788
2021-05-19 12:49:28 -07:00
Arthur Eubanks
764e5745a3 [OpaquePtr] Make GEPs work with opaque pointers
No verifier changes needed, the verifier currently doesn't check that
the pointer operand's pointee type matches the GEP type. There is a
similar check in GetElementPtrInst::Create() though.

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D102744
2021-05-19 12:39:37 -07:00
Arthur Eubanks
c9fe8a87e5 [OpaquePtr] Make loads and stores work with opaque pointers
Don't check that types match when the pointer operand is an opaque
pointer.

I would separate the Assembler and Verifier changes, but
verify-uselistorder in the Assembler test ends up running the verifier.

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D102450
2021-05-18 13:43:50 -07:00
Tim Northover
5661b7eb80 IR+AArch64: add a "swiftasync" argument attribute.
This extends any frame record created in the function to include that
parameter, passed in X22.

The new record looks like [X22, FP, LR] in memory, and FP is stored with 0b0001
in bits 63:60 (CodeGen assumes they are 0b0000 in normal operation). The effect
of this is that tools walking the stack should expect to see one of three
values there:

  * 0b0000 => a normal, non-extended record with just [FP, LR]
  * 0b0001 => the extended record [X22, FP, LR]
  * 0b1111 => kernel space, and a non-extended record.

All other values are currently reserved.

If compiling for arm64e this context pointer is address-discriminated with the
discriminator 0xc31a and the DB (process-specific) key.

There is also an "i8** @llvm.swift.async.context.addr()" intrinsic providing
front-ends access to this slot (and forcing its creation initialized to nullptr
if necessary).
2021-05-14 11:43:58 +01:00
Arthur Eubanks
1b32fba3b3 [IR] Introduce the opaque pointer type
The opaque pointer type is essentially just a normal pointer type with a
null pointee type.

This also adds support for the opaque pointer type to the bitcode
reader/writer, as well as to textual IR.

To avoid confusion with existing pointer types, we disallow creating a
pointer to an opaque pointer.

Opaque pointer types should not be widely used at this point since many
parts of LLVM still do not support them. The next steps are to add some
very simple use cases of opaque pointers to make sure they work, then
start pretending that all pointers are opaque pointers and see what
breaks.

https://lists.llvm.org/pipermail/llvm-dev/2021-May/150359.html

Reviewed By: dblaikie, dexonsmith, pcc

Differential Revision: https://reviews.llvm.org/D101704
2021-05-13 15:22:27 -07:00
cynecx
729fe8041c Support unwinding from inline assembly
I've taken the following steps to add unwinding support from inline assembly:

1) Add a new `unwind` "attribute" (like `sideeffect`) to the asm syntax:

```
invoke void asm sideeffect unwind "call thrower", "~{dirflag},~{fpsr},~{flags}"()
    to label %exit unwind label %uexit
```

2.) Add Bitcode writing/reading support + LLVM-IR parsing.

3.) Emit EHLabels around inline assembly lowering (SelectionDAGBuilder + GlobalISel) when `InlineAsm::canThrow` is enabled.

4.) Tweak InstCombineCalls/InlineFunction pass to not mark inline assembly "calls" as nounwind.

5.) Add clang support by introducing a new clobber: "unwind", which lower to the `canThrow` being enabled.

6.) Don't allow unwinding callbr.

Reviewed By: Amanieu

Differential Revision: https://reviews.llvm.org/D95745
2021-05-13 19:13:03 +01:00
Steven Wu
5c8193b398 [IR][AutoUpgrade] Drop align attribute from void return types
Since D87304, `align` become an invalid attribute on none pointer types and
verifier will reject bitcode that has invalid `align` attribute.

The problem is before the change, DeadArgumentElimination can easily
turn a pointer return type into a void return type without removing
`align` attribute. Teach Autograde to remove invalid `align` attribute
from return types to maintain bitcode compatibility.

rdar://77022993

Reviewed By: dexonsmith

Differential Revision: https://reviews.llvm.org/D102201
2021-05-11 08:23:55 -07:00
Stephen Tozer
80d2f76226 [Bitcode] Ensure DIArgList in bitcode has no null or forward metadata refs
This patch fixes an issue in which ConstantAsMetadata arguments to a
DIArglist, as well as the Constant values referenced by that metadata,
would not be always be emitted correctly into bitcode. This patch fixes
this issue firstly by searching for ConstantAsMetadata in DIArgLists
(previously we would only search for them when directly wrapped in
MetadataAsValue), and secondly by enumerating all of a DIArgList's
arguments directly prior to enumerating the DIArgList itself.

This patch also adds a number of asserts, and no longer treats the
arguments to a DIArgList as optional fields when reading/writing to
bitcode.

Differential Revision: https://reviews.llvm.org/D100572
2021-04-22 12:03:33 +01:00
Matt Arsenault
efe6c99b52 Reapply "OpaquePtr: Turn inalloca into a type attribute"
This reverts commit 07e46367baeca96d84b03fa215b41775f69d5989.
2021-03-29 08:55:30 -04:00
Oliver Stannard
0914bea32c Revert "Reapply "OpaquePtr: Turn inalloca into a type attribute""
Reverting because test 'Bindings/Go/go.test' is failing on most
buildbots.

This reverts commit fc9df309917e57de704f3ce4372138a8d4a23d7a.
2021-03-29 11:32:22 +01:00
Matt Arsenault
403cadc380 Reapply "OpaquePtr: Turn inalloca into a type attribute"
This reverts commit 20d5c42e0ef5d252b434bcb610b04f1cb79fe771.
2021-03-28 13:35:21 -04:00
Nico Weber
755e1b95c9 Revert "OpaquePtr: Turn inalloca into a type attribute"
This reverts commit 4fefed65637ec46c8c2edad6b07b5569ac61e9e5.
Broke check-clang everywhere.
2021-03-28 13:02:52 -04:00
Matt Arsenault
9b63996812 OpaquePtr: Turn inalloca into a type attribute
I think byval/sret and the others are close to being able to rip out
the code to support the missing type case. A lot of this code is
shared with inalloca, so catch this up to the others so that can
happen.
2021-03-28 11:12:23 -04:00
Bradley Smith
839304c777 [IR] Add vscale_range IR function attribute
This attribute represents the minimum and maximum values vscale can
take. For now this attribute is not hooked up to anything during
codegen, this will be added in the future when such codegen is
considered stable.

Additionally hook up the -msve-vector-bits=<x> clang option to emit this
attribute.

Differential Revision: https://reviews.llvm.org/D98030
2021-03-22 12:05:06 +00:00
gbtozers
bfb6dad2ae [DebugInfo] Support DIArgList in DbgVariableIntrinsic
This patch updates DbgVariableIntrinsics to support use of a DIArgList for the
location operand, resulting in a significant change to its interface. This patch
does not update all IR passes to support multiple location operands in a
dbg.value; the only change is to update the DbgVariableIntrinsic interface and
its uses. All code outside of the intrinsic classes assumes that an intrinsic
will always have exactly one location operand; they will still support
DIArgLists, but only if they contain exactly one Value.

Among other changes, the setOperand and setArgOperand functions in
DbgVariableIntrinsic have been made private. This is to prevent code from
setting the operands of these intrinsics directly, which could easily result in
incorrect/invalid operands being set. This does not prevent these functions from
being called on a debug intrinsic at all, as they can still be called on any
CallInst pointer; it is assumed that any code directly setting the operands on a
generic call instruction is doing so safely. The intention for making these
functions private is to prevent DIArgLists from being overwritten by code that's
naively trying to replace one of the Values it points to, and also to fail fast
if a DbgVariableIntrinsic is updated to use a DIArgList without a valid
corresponding DIExpression.
2021-03-08 14:36:13 +00:00
gbtozers
c52cf11f42 [DebugInfo] Add DIArgList MD to store multple values in DbgVariableIntrinsics
This patch adds a new metadata node, DIArgList, which contains a list of SSA
values. This node is in many ways similar in function to the existing
ValueAsMetadata node, with the difference being that it tracks a list instead of
a single value. Internally, it uses ValueAsMetadata to track the individual
values, but there is also a reasonable amount of DIArgList-specific
value-tracking logic on top of that. Similar to ValueAsMetadata, it is a special
case in parsing and printing due to the fact that it requires a function state
(as it may reference function-local values).

This patch should not result in any immediate functional change; it allows for
DIArgLists to be parsed and printed, but debug variable intrinsics do not yet
recognize them as a valid argument (outside of parsing).

Differential Revision: https://reviews.llvm.org/D88175
2021-03-05 17:02:24 +00:00
Leonard Chan
1cfc220073 [llvm][Bitcode] Add bitcode reader/writer for DSOLocalEquivalent
This is necessary for compilation with [thin]lto.

Differential Revision: https://reviews.llvm.org/D96170
2021-02-22 10:37:57 -08:00
Wei Wang
58f68f472f [LTO] Perform DSOLocal propagation in combined index
Perform DSOLocal propagation within summary list of every GV. This
avoids the repeated query of this information during function
importing.

Differential Revision: https://reviews.llvm.org/D96398
2021-02-12 22:58:26 -08:00
James Y Knight
3a1ce2f6df Fix bitcode decoder error in "Encode alignment attribute for atomicrmw"
The wrong record field number was being used in bitcode decoding,
which broke a self-hosted LTO build. (Yet, somehow, this _doesn't_
seem to have broken simple bitcode encode/decode roundtrip tests, and
I'm not sure why...)

Fixes commit d06ab79816785fa362e7d96d7a398bea8064cba7
2021-02-11 22:29:03 -05:00
Guillaume Chatelet
d83a14c77d Encode alignment attribute for cmpxchg
This is a follow up patch to D83136 adding the align attribute to `cmpxchg`.
See also D83465 for `atomicrmw`.

Differential Revision: https://reviews.llvm.org/D87443
2021-02-11 15:17:50 -05:00
Guillaume Chatelet
1d36d2af13 Encode alignment attribute for atomicrmw
This is a follow up patch to D83136 adding the align attribute to `atomicwmw`.

Differential Revision: https://reviews.llvm.org/D83465
2021-02-11 15:17:37 -05:00
Fangrui Song
b3b970744d [ThinLTO] Add Visibility bits to GlobalValueSummary::GVFlags
Imported functions and variable get the visibility from the module supplying the
definition.  However, non-imported definitions do not get the visibility from
(ELF) the most constraining visibility among all modules (Mach-O) the visibility
of the prevailing definition.

This patch

* adds visibility bits to GlobalValueSummary::GVFlags
* computes the result visibility and propagates it to all definitions

Protected/hidden can imply dso_local which can enable some optimizations (this
is stronger than GVFlags::DSOLocal because the implied dso_local can be
leveraged for ELF -shared while default visibility dso_local has to be cleared
for ELF -shared).

Note: we don't have summaries for declarations, so for ELF if a declaration has
the most constraining visibility, the result visibility may not be that one.

Differential Revision: https://reviews.llvm.org/D92900
2021-01-27 10:43:51 -08:00
Kazu Hirata
0ec2908ce9 [llvm] Use pop_back_val (NFC) 2021-01-24 12:18:57 -08:00
Kazu Hirata
3109d596ee [llvm] Use llvm::append_range (NFC) 2021-01-06 18:27:33 -08:00
Luo, Yuanke
4ef6280b52 [X86] Add x86_amx type for intel AMX.
The x86_amx is used for AMX intrisics. <256 x i32> is bitcast to x86_amx when
it is used by AMX intrinsics, and x86_amx is bitcast to <256 x i32> when it
is used by load/store instruction. So amx intrinsics only operate on type x86_amx.
It can help to separate amx intrinsics from llvm IR instructions (+-*/).
Thank Craig for the idea. This patch depend on https://reviews.llvm.org/D87981.

Differential Revision: https://reviews.llvm.org/D91927
2020-12-30 13:52:13 +08:00
Chih-Ping Chen
c44b393235 [DebugInfo] Support Fortran 'use <external module>' statement.
The main change is to add a 'IsDecl' field to DIModule so
that when IsDecl is set to true, the debug info entry generated
for the module would be marked as a declaration. That way, the debugger
would look up the definition of the module in the gloabl scope.

Please see the comments in llvm/test/DebugInfo/X86/dimodule.ll
for what the debug info entries would look like.

Differential Revision: https://reviews.llvm.org/D93462
2020-12-18 13:10:57 -05:00
Rong Xu
92b9137fcb [IR][PGO] Add hot func attribute and use hot/cold attribute in func section
Clang FE currently has hot/cold function attribute. But we only have
cold function attribute in LLVM IR.

This patch adds support of hot function attribute to LLVM IR.  This
attribute will be used in setting function section prefix/suffix.
Currently .hot and .unlikely suffix only are added in PGO (Sample PGO)
compilation (through isFunctionHotInCallGraph and
isFunctionColdInCallGraph).

This patch changes the behavior. The new behavior is:
(1) If the user annotates a function as hot or isFunctionHotInCallGraph
    is true, this function will be marked as hot. Otherwise,
(2) If the user annotates a function as cold or
    isFunctionColdInCallGraph is true, this function will be marked as
    cold.

The changes are:
(1) user annotated function attribute will used in setting function
    section prefix/suffix.
(2) hot attribute overwrites profile count based hotness.
(3) profile count based hotness overwrite user annotated cold attribute.

The intention for these changes is to provide the user a way to mark
certain function as hot in cases where training input is hard to cover
all the hot functions.

Differential Revision: https://reviews.llvm.org/D92493
2020-12-17 18:41:12 -08:00