Commit Graph

8507 Commits

Author SHA1 Message Date
Tony Tye 72f1f08467 [NFC][AMDGPU] Clarify memory model support for volatile
Reorder the AMDGPUUage description of the memory model code sequences
for volatile so clear that it applies independent of the nontemporal
setting.

Differential Revision: https://reviews.llvm.org/D94358
2021-01-11 19:59:55 +00:00
Florian Hahn d98fc62ae6 [SimplifyCFG] Keep !dgb metadata of moved instruction, if they match.
Currently SimplifyCFG drops the debug locations of 'bonus' instructions.
Such instructions are moved before the first branch. The reason for the
current behavior is that this could lead to surprising debug stepping,
if the block that's folded is dead.

In case the first branch and the instructions to be folded have the same
debug location, this shouldn't be an issue and we can keep the debug
location.

Reviewed By: vsk

Differential Revision: https://reviews.llvm.org/D93662
2021-01-09 19:15:16 +00:00
Tony 2f499b9aff [AMDGPU] Add volatile support to SIMemoryLegalizer
Treat a non-atomic volatile load and store as a relaxed atomic at
system scope for the address spaces accessed. This will ensure all
relevant caches will be bypassed.

A volatile atomic is not changed and still only bypasses caches upto
the level specified by the SyncScope operand.

Differential Revision: https://reviews.llvm.org/D94214
2021-01-09 00:52:33 +00:00
Paul C. Anagnostopoulos 6e2b6351d2 [TableGen] Add the assert statement, step 1
Differential Revision: https://reviews.llvm.org/D93911

This first step adds the assert statement and supports it at top level
and in record definitions. Later steps will support it in class
definitions and multiclasses.
2021-01-08 09:47:51 -05:00
Fangrui Song 7afdc89c20 [sanitizer] Define SANITIZER_GLIBC to refine SANITIZER_LINUX feature detection and support musl
Several `#if SANITIZER_LINUX && !SANITIZER_ANDROID` guards are replaced
with the more appropriate `#if SANITIZER_GLIBC` (the headers are glibc
extensions, not specific to Linux (i.e. if we ever support GNU/kFreeBSD
or Hurd, the guards may automatically work)).

Several `#if SANITIZER_LINUX && !SANITIZER_ANDROID` guards are refined
with `#if SANITIZER_GLIBC` (the definitions are available on Linux glibc,
but may not be available on other libc (e.g. musl) implementations).

This patch makes `ninja asan cfi lsan msan stats tsan ubsan xray` build on a musl based Linux distribution (apk install musl-libintl)
Notes about disabled interceptors for musl:

* `SANITIZER_INTERCEPT_GLOB`: musl does not implement `GLOB_ALTDIRFUNC` (GNU extension)
* Some ioctl structs and functions operating on them.
* `SANITIZER_INTERCEPT___PRINTF_CHK`: `_FORTIFY_SOURCE` functions are GNU extension
* `SANITIZER_INTERCEPT___STRNDUP`: `dlsym(RTLD_NEXT, "__strndup")` errors so a diagnostic is formed. The diagnostic uses `write` which hasn't been intercepted => SIGSEGV
* `SANITIZER_INTERCEPT_*64`: the `_LARGEFILE64_SOURCE` functions are glibc specific. musl does something like `#define pread64 pread`
* Disabled `msg_iovlen msg_controllen cmsg_len` checks: musl is conforming while many implementations (Linux/FreeBSD/NetBSD/Solaris) are non-conforming. Since we pick the glibc definition, exclude the checks for musl (incompatible sizes but compatible offsets)

Pass through LIBCXX_HAS_MUSL_LIBC to make check-msan/check-tsan able to build libc++ (https://bugs.llvm.org/show_bug.cgi?id=48618).

Many sanitizer features are available now.

```
% ninja check-asan
(known issues:
* ASAN_OPTIONS=fast_unwind_on_malloc=0 odr-violations hangs
)
...
Testing Time: 53.69s
  Unsupported      : 185
  Passed           : 512
  Expectedly Failed:   1
  Failed           :  12

% ninja check-ubsan check-ubsan-minimal check-memprof # all passed

% ninja check-cfi
( all cross-dso/)
...
Testing Time: 8.68s
  Unsupported      : 264
  Passed           :  80
  Expectedly Failed:   8
  Failed           :  32

% ninja check-lsan
(With GetTls (D93972), 10 failures)
Testing Time: 4.09s
  Unsupported:  7
  Passed     : 65
  Failed     : 22

% ninja check-msan
(Many are due to functions not marked unsupported.)
Testing Time: 23.09s
  Unsupported      :   6
  Passed           : 764
  Expectedly Failed:   2
  Failed           :  58

% ninja check-tsan
Testing Time: 23.21s
  Unsupported      :  86
  Passed           : 295
  Expectedly Failed:   1
  Failed           :  25
```

Used `ASAN_OPTIONS=verbosity=2` to verify there is no unneeded interceptor.

Partly based on Jari Ronkainen's https://reviews.llvm.org/D63785#1921014

Note: we need to place `_FILE_OFFSET_BITS` above `#include "sanitizer_platform.h"` to avoid `#define __USE_FILE_OFFSET64 1` in 32-bit ARM `features.h`

Reviewed By: vitalybuka

Differential Revision: https://reviews.llvm.org/D93848
2021-01-06 10:55:40 -08:00
Alan Phipps 9f2967bcfe [Coverage] Add support for Branch Coverage in LLVM Source-Based Code Coverage
This is an enhancement to LLVM Source-Based Code Coverage in clang to track how
many times individual branch-generating conditions are taken (evaluate to TRUE)
and not taken (evaluate to FALSE).  Individual conditions may comprise larger
boolean expressions using boolean logical operators.  This functionality is
very similar to what is supported by GCOV except that it is very closely
anchored to the ASTs.

Differential Revision: https://reviews.llvm.org/D84467
2021-01-05 09:51:51 -06:00
Chih-Ping Chen 975b64b293 [docs] Release notes for IsDecl in DIModule.
Please see https://reviews.llvm.org/D93462 for the actual code change.

Differential Revision: https://reviews.llvm.org/D93558
2021-01-04 07:03:34 -05:00
Nuno Lopes f760d57052 LangRef: fix significand bits of fp128 2020-12-31 11:13:25 +00:00
Praveen Velliengiri 61177943c9 [AMDGPU] Use MUBUF instructions for global address space access
Currently, the compiler crashes in instruction selection of global
load/stores in gfx600 due to the lack of FLAT instructions. This patch
fix the crash by selecting MUBUF instructions for global load/stores
in gfx600.

Authored-by: Praveen Velliengiri <Praveen.Velliengiri@amd.com>

Reviewed by: t-tye

Differential revision: https://reviews.llvm.org/D92483
2020-12-24 10:13:04 +00:00
Paul C. Anagnostopoulos e122a71a0a [TableGen] Add the !substr() bang operator
Update the documentation and add a test.

Build failed: Change SIZE_MAX to std::numeric_limits<int64_t>::max().

Differential Revision: https://reviews.llvm.org/D93419
2020-12-23 10:59:33 -05:00
Arnold Schwaighofer 333108e8be Add a llvm.coro.end.async intrinsic
The llvm.coro.end.async intrinsic allows to specify a function that is
to be called as the last action before returning. This function will be
inlined after coroutine splitting.

This function can contain a 'musttail' call to allow for guaranteed tail
calling as the last action.

Differential Revision: https://reviews.llvm.org/D93568
2020-12-22 10:52:28 -08:00
Tom Stellard 7f40bb3b04 HowToReleaseLLVM: Update document to match the current release process
Change Summary:

* Clarify that release manager can commit without code owner approval
  (but are still highly encouraged to get approval).

* Clarify that there is no official release criteria.

* Document what types of changes are allowed in each release phase.

This is update is based on the RFC submitted here:
http://lists.llvm.org/pipermail/llvm-dev/2020-May/141730.html

Reviewed By: hans

Differential Revision: https://reviews.llvm.org/D93493
2020-12-21 15:16:11 -08:00
Hafiz Abid Qadeer 43def795aa Update references to 'master' branch.
This commit replace 'master' with 'main' in llvm/docs.

Reviewed By: sammccall, kristof.beyls

Differential Revision: https://reviews.llvm.org/D92831
2020-12-21 19:10:34 +00:00
Paul C. Anagnostopoulos 554eb1f6dc Revert "[TableGen] Add the !substr() bang operator"
This reverts commit 3a675c777d.
2020-12-21 10:46:25 -05:00
Paul C. Anagnostopoulos 3a675c777d [TableGen] Add the !substr() bang operator
Update the documentation and add a test.

Differential Revision: https://reviews.llvm.org/D93419
2020-12-21 09:41:59 -05:00
Jacques Pienaar 44f399ccc1 [FileCheck] Add a literal check directive modifier
Introduce CHECK modifiers that change the behavior of the CHECK
directive. Also add a LITERAL modifier for cases where matching could
end requiring escaping strings interpreted as regex where only
literal/fixed string matching is desired (making the CHECK's more
difficult to write/fragile and difficult to interpret).
2020-12-18 17:26:15 -08:00
Bjorn Pettersson a89d751fb4 Add intrinsics for saturating float to int casts
This patch adds support for the fptoui.sat and fptosi.sat intrinsics,
which provide basically the same functionality as the existing fptoui
and fptosi instructions, but will saturate (or return 0 for NaN) on
values unrepresentable in the target type, instead of returning
poison. Related mailing list discussion can be found at:
https://groups.google.com/d/msg/llvm-dev/cgDFaBmCnDQ/CZAIMj4IBAAJ

The intrinsics have overloaded source and result type and support
vector operands:

    i32 @llvm.fptoui.sat.i32.f32(float %f)
    i100 @llvm.fptoui.sat.i100.f64(double %f)
    <4 x i32> @llvm.fptoui.sat.v4i32.v4f16(half %f)
    // etc

On the SelectionDAG layer two new ISD opcodes are added,
FP_TO_UINT_SAT and FP_TO_SINT_SAT. These opcodes have two operands
and one result. The second operand is an integer constant specifying
the scalar saturation width. The idea here is that initially the
second operand and the scalar width of the result type are the same,
but they may change during type legalization. For example:

    i19 @llvm.fptsi.sat.i19.f32(float %f)
    // builds
    i19 fp_to_sint_sat f, 19
    // type legalizes (through integer result promotion)
    i32 fp_to_sint_sat f, 19

I went for this approach, because saturated conversion does not
compose well. There is no good way of "adjusting" a saturating
conversion to i32 into one to i19 short of saturating twice.
Specifying the saturation width separately allows directly saturating
to the correct width.

There are two baseline expansions for the fp_to_xint_sat opcodes. If
the integer bounds can be exactly represented in the float type and
fminnum/fmaxnum are legal, we can expand to something like:

    f = fmaxnum f, FP(MIN)
    f = fminnum f, FP(MAX)
    i = fptoxi f
    i = select f uo f, 0, i # unnecessary if unsigned as 0 = MIN

If the bounds cannot be exactly represented, we expand to something
like this instead:

    i = fptoxi f
    i = select f ult FP(MIN), MIN, i
    i = select f ogt FP(MAX), MAX, i
    i = select f uo f, 0, i # unnecessary if unsigned as 0 = MIN

It should be noted that this expansion assumes a non-trapping fptoxi.

Initial tests are for AArch64, x86_64 and ARM. This exercises all of
the scalar and vector legalization. ARM is included to test float
softening.

Original patch by @nikic and @ebevhan (based on D54696).

Differential Revision: https://reviews.llvm.org/D54749
2020-12-18 11:09:41 +01:00
Rong Xu 3733463dbb [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
Tony 8c6d516286 [NFC][AMDGPU] Reorganize description of scratch handling
Differential Revision: https://reviews.llvm.org/D93440
2020-12-17 19:33:14 +00:00
Fangrui Song 780741107e [LangRef] Update new ssp/sspstrong/sspreq semantics after D91816
Reviewed By: nickdesaulniers

Differential Revision: https://reviews.llvm.org/D93422
2020-12-17 09:16:37 -08:00
Jon Chesterfield daf39e3f2d [amdgpu] Default to code object v3
[amdgpu] Default to code object v3
v4 is not yet readily available, and doesn't appear
to be implemented in the back end

Reviewed By: t-tye, yaxunl

Differential Revision: https://reviews.llvm.org/D93258
2020-12-17 16:09:33 +00:00
serge-sans-paille 5e31e226b5 Remove Python2 fallback and only advertise Python3 in the doc
Differential Revision: https://www.youtube.com/watch?v=RsL0cipURA0
2020-12-17 15:40:16 +01:00
Xiang1 Zhang 39584ae5b5 [Debugify] Support checking Machine IR debug info
Add mir-check-debug pass to check MIR-level debug info.

For IR-level, currently, LLVM have debugify + check-debugify to generate
and check debug IR. Much like the IR-level pass debugify, mir-debugify
inserts sequentially increasing line locations to each MachineInstr in a
Module, But there is no equivalent MIR-level check-debugify pass, So now
we support it at "mir-check-debug".

Reviewed By: djtodoro

Differential Revision: https://reviews.llvm.org/D91595
2020-12-16 22:17:25 -08:00
Xiang1 Zhang 1e42ad9d62 Revert "[Debugify] Support checking Machine IR debug info"
This reverts commit 50aaa8c274.
2020-12-16 20:12:33 -08:00
Xiang1 Zhang 50aaa8c274 [Debugify] Support checking Machine IR debug info
Add mir-check-debug pass to check MIR-level debug info.

For IR-level, currently, LLVM have debugify + check-debugify to generate
and check debug IR. Much like the IR-level pass debugify, mir-debugify
inserts sequentially increasing line locations to each MachineInstr in a
Module, But there is no equivalent MIR-level check-debugify pass, So now
we support it at "mir-check-debug".

Reviewed By: djtodoro

Differential Revision: https://reviews.llvm.org/D91595
2020-12-16 18:04:05 -08:00
Kai Nacke e2e86f4e77 [Doc][SystemZ] Add Linux/SystemZ to Getting Started guide.
The Linux/SystemZ platform is missing in the Getting Started guide
as platform on which LLVM is known to work.

Reviewed by: uweigand

Differential Revision: https://reviews.llvm.org/D93388
2020-12-16 10:46:05 -05:00
Matt Arsenault f3e0431b76 LangRef: Update byval/sret description for required types 2020-12-16 10:25:36 -05:00
Fangrui Song 8c4e55762d [docs][unittest][Go][StackProtector] Migrate deprecated DebugInfo::get to DILocation::get 2020-12-15 14:17:04 -08:00
Tony d5ea8f7010 [AMDGPU] Clarify scratch initialization
- Clarify documentation on initializing scratch.
- Rename compute_pgm_rsrc2 field for enabling scratch from
  ENABLE_SGPR_PRIVATE_SEGMENT_WAVEFRONT_OFFSET to
  ENABLE_PRIVATE_SEGMENT to match hardware definition.

Differential Revision: https://reviews.llvm.org/D93271
2020-12-15 20:14:20 +00:00
Nico Weber da2551f3d1 Revert "[Debugify] Support checking Machine IR debug info"
This reverts commit c4d2d4337d.
Necessary to revert 2a5675f11d.
2020-12-14 22:14:48 -05:00
Nico Weber c9ede6f336 Revert "[amdgpu] Default to code object v3"
This reverts commit 4b2e7d0215.
Breaks check-clang, see https://reviews.llvm.org/D93258#2453600
2020-12-14 22:01:26 -05:00
Xiang1 Zhang c4d2d4337d [Debugify] Support checking Machine IR debug info
Add mir-check-debug pass to check MIR-level debug info.

For IR-level, currently, LLVM have debugify + check-debugify to generate
and check debug IR. Much like the IR-level pass debugify, mir-debugify
inserts sequentially increasing line locations to each MachineInstr in a
Module, But there is no equivalent MIR-level check-debugify pass, So now
we support it at "mir-check-debug".

Reviewed By: djtodoro

Differential Revision: https://reviews.llvm.org/D91595
2020-12-14 17:53:46 -08:00
Xiang1 Zhang fc0f4010bb Revert "[Debugify] Support checking Machine IR debug info"
This reverts commit 57a3d9ec4a.
2020-12-14 17:48:49 -08:00
Xiang1 Zhang 57a3d9ec4a [Debugify] Support checking Machine IR debug info
Add mir-check-debug pass to check MIR-level debug info.

For IR-level, currently, LLVM have debugify + check-debugify to generate
and check debug IR. Much like the IR-level pass debugify, mir-debugify
inserts sequentially increasing line locations to each MachineInstr in a
Module, But there is no equivalent MIR-level check-debugify pass, So now
we support it at "mir-check-debug".

Reviewed By: djtodoro

Differential Revision: https://reviews.llvm.org/D95195
2020-12-14 17:38:01 -08:00
Jon Chesterfield 4b2e7d0215 [amdgpu] Default to code object v3
[amdgpu] Default to code object v3
v4 is not yet readily available, and doesn't appear
to be implemented in the back end

Reviewed By: t-tye

Differential Revision: https://reviews.llvm.org/D93258
2020-12-15 01:11:09 +00:00
Tony 828602c772 [NFC]{AMDGPU] Update AMDGPUUsage with AMD RDNA 2 reference
Differential Revision: https://reviews.llvm.org/D93172
2020-12-13 17:21:02 +00:00
Tony 87a4e14e40 [NFC][AMDGPU] AMDGPUUsage updates
- Document which processors are supported by which runtimes.
- Add missing mappings for code object V2 note records

Differential Revision: https://reviews.llvm.org/D93016
2020-12-12 18:19:02 +00:00
Alexey Bader 3631e080c4 [Doc] Update branch name in Phabricator documentation
master -> main

Differential Revision: https://reviews.llvm.org/D93020
2020-12-10 22:25:04 +03:00
Alina Sbirlea 1289835a96 [MemorySSA/docs] Extend MemorySSA documentation. 2020-12-09 18:00:16 -08:00
Joe Ellis 80c33de2d3 [SelectionDAG] Add llvm.vector.{extract,insert} intrinsics
This commit adds two new intrinsics.

- llvm.experimental.vector.insert: used to insert a vector into another
  vector starting at a given index.

- llvm.experimental.vector.extract: used to extract a subvector from a
  larger vector starting from a given index.

The codegen work for these intrinsics has already been completed; this
commit is simply exposing the existing ISD nodes to LLVM IR.

Reviewed By: cameron.mcinally

Differential Revision: https://reviews.llvm.org/D91362
2020-12-09 11:08:41 +00:00
Nigel Perks 776bb71d88 [XCore][docs] Fix XCore compiler writer documentation links.
Fix links to XMOS website. Add link for XS2 architecture.

Reviewed By: jryans

Differential Revision: https://reviews.llvm.org/D92019
2020-12-08 12:21:09 +00:00
Sjoerd Meijer 1e260f955d [LICM][docs] Document that LICM is also a canonicalization transform. NFC.
This documents that LICM is a canonicalization transform, which we discussed
recently in:

http://lists.llvm.org/pipermail/llvm-dev/2020-December/147184.html

but which was also discused earlier, e.g. in:

http://lists.llvm.org/pipermail/llvm-dev/2019-September/135058.html
2020-12-08 11:56:35 +00:00
Jeremy Morse cda32aba4f [DebugInfo][Docs] Document MIR language debug-info constructs
This patch documents the MIR syntax for a number of things relevant to
debugging information:
 * Trailing 'debug-location' metadata that becomes a DebugLoc,
 * Variable location metadata for stack slots,
 * Syntax for DBG_VALUE metainstructions,
 * Syntax for DBG_INSTR_REF, including trailing instruction numbers
   attached to MIR instructions.

Differential Revision: https://reviews.llvm.org/D89337
2020-12-08 11:01:55 +00:00
Tim Northover c5978f42ec UBSAN: emit distinctive traps
Sometimes people get minimal crash reports after a UBSAN incident. This change
tags each trap with an integer representing the kind of failure encountered,
which can aid in tracking down the root cause of the problem.
2020-12-08 10:28:26 +00:00
wlei 1f05b1a9f5 [CSSPGO][llvm-profgen] Context-sensitive profile data generation
This stack of changes introduces `llvm-profgen` utility which generates a profile data file from given perf script data files for sample-based PGO. It’s part of(not only) the CSSPGO work. Specifically to support context-sensitive with/without pseudo probe profile, it implements a series of functionalities including perf trace parsing, instruction symbolization, LBR stack/call frame stack unwinding, pseudo probe decoding, etc. Also high throughput is achieved by multiple levels of sample aggregation and compatible format with one stop is generated at the end. Please refer to: https://groups.google.com/g/llvm-dev/c/1p1rdYbL93s for the CSSPGO RFC.

This change supports context-sensitive profile data generation into llvm-profgen. With simultaneous sampling for LBR and call stack, we can identify leaf of LBR sample with calling context from stack sample . During the process of deriving fall through path from LBR entries, we unwind LBR by replaying all the calls and returns (including implicit calls/returns due to inlining) backwards on top of the sampled call stack. Then the state of call stack as we unwind through LBR always represents the calling context of current fall through path.

we have two types of virtual unwinding 1) LBR unwinding and 2) linear range unwinding.
Specifically, for each LBR entry which can be classified into call, return, regular branch, LBR unwinding will replay the operation by pushing, popping or switching leaf frame towards the call stack and since the initial call stack is most recently sampled, the replay should be in anti-execution order, i.e. for the regular case, pop the call stack when LBR is call, push frame on call stack when LBR is return. After each LBR processed, it also needs to align with the next LBR by going through instructions from previous LBR's target to current LBR's source, which we named linear unwinding. As instruction from linear range can come from different function by inlining, linear unwinding will do the range splitting and record counters through the range with same inline context.

With each fall through path from LBR unwinding, we aggregate each sample into counters by the calling context and eventually generate full context sensitive profile (without relying on inlining) to driver compiler's PGO/FDO.

A breakdown of noteworthy changes:
- Added `HybridSample` class as the abstraction perf sample including LBR stack and call stack
* Extended `PerfReader` to implement auto-detect whether input perf script output contains CS profile, then do the parsing. Multiple `HybridSample` are extracted
* Speed up by aggregating  `HybridSample` into `AggregatedSamples`
* Added VirtualUnwinder that consumes aggregated  `HybridSample` and implements unwinding of calls, returns, and linear path that contains implicit call/return from inlining. Ranges and branches counters are aggregated by the calling context.
 Here calling context is string type, each context is a pair of function name and callsite location info, the whole context is like `main:1 @ foo:2 @ bar`.
* Added PorfileGenerater that accumulates counters by ranges unfolding or branch target mapping, then generates context-sensitive function profile including function body, inferring callee's head sample, callsite target samples, eventually records into ProfileMap.

* Leveraged LLVM build-in(`SampleProfWriter`) writer to support different serialization format with no stop
- `getCanonicalFnName` for callee name and name from ELF section
- Added regression test for both unwinding and profile generation

Test Plan:
ninja & ninja check-llvm

Reviewed By: hoy, wenlei, wmi

Differential Revision: https://reviews.llvm.org/D89723
2020-12-07 13:48:58 -08:00
Nico Weber b570f82f43 docs: Add pointer to cmake caches for PGO
Also add a link to end-user PGO documentation.

Differential Revision: https://reviews.llvm.org/D92768
2020-12-07 15:55:26 -05:00
Hans Wennborg 3d8b7465c3 Test commit 2020-12-07 17:27:03 +01:00
Tony 3242eaef27 [NFC][AMDGPU] AMDGPUUsage updates
- Document code object V2 gfx800.
- Document amdpal is supported by Linux Pro.

Differential Revision: https://reviews.llvm.org/D92708
2020-12-05 02:13:17 +00:00
Sean Silva ae9fd5578e [SmallVector] Allow SmallVector<T>
This patch adds a capability to SmallVector to decide a number of
inlined elements automatically. The policy is:

- A minimum of 1 inlined elements, with more as long as
sizeof(SmallVector<T>) <= 64.
- If sizeof(T) is "too big", then trigger a static_assert: this dodges
the more pathological cases

This is expected to systematically improve SmallVector use in the
LLVM codebase, which has historically been plagued by semi-arbitrary /
cargo culted N parameters, often leading to bad outcomes due to
excessive sizeof(SmallVector<T, N>). This default also makes
programming more convenient by avoiding edit/rebuild cycles due to
forgetting to type the N parameter.

Differential Revision: https://reviews.llvm.org/D92522
2020-12-03 17:21:44 -08:00
Paul C. Anagnostopoulos 415fab6f67 [TableGen] Eliminate the 'code' type
Update the documentation.

Rework various backends that relied on the code type.

Differential Revision: https://reviews.llvm.org/D92269
2020-12-03 10:19:11 -05:00