Bjorn Pettersson [Mon, 26 Aug 2019 09:29:53 +0000 (09:29 +0000)]
[LoopUnroll] Handle certain PHIs in full unrolling properly
Summary:
When reconstructing the CFG of the loop after unrolling,
LoopUnroll could in some cases remove the phi operands of
loop-carried values instead of preserving them, resulting
in undef phi values after loop unrolling.
When doing this reconstruction, avoid removing incoming
phi values for phis in the successor blocks if the successor
is the block we are jumping to anyway.
Craig Topper [Sun, 25 Aug 2019 17:59:49 +0000 (17:59 +0000)]
[X86][DAGCombiner] Teach narrowShuffle to use concat_vectors instead of inserting into undef
Summary:
Concat_vectors is more canonical during early DAG combine. For example, its what's used by SelectionDAGBuilder when converting IR shuffles into SelectionDAG shuffles when element counts between inputs and mask don't match. We also have combines in DAGCombiner than can pull concat_vectors through a shuffle. See partitionShuffleOfConcats. So it seems like concat_vectors is a better operation to use here. I had to teach DAGCombiner's SimplifyVBinOp to also handle concat_vectors with undef. I haven't checked yet if we can remove the INSERT_SUBVECTOR version in there or not.
I didn't want to mess with the other caller of getShuffleHalfVectors that's used during shuffle lowering where insert_subvector probably is what we want to produce so I've enabled this via a boolean passed to the function.
Xing Xue [Sun, 25 Aug 2019 15:17:25 +0000 (15:17 +0000)]
[PowerPC][AIX] Adds support for writing the .data section in assembly files
Summary:
Adds support for generating the .data section in assembly files for global variables with a non-zero initialization. The support for writing the .data section in XCOFF object files will be added in a follow-on patch. Any relocations are not included in this patch.
Bjorn Pettersson [Sun, 25 Aug 2019 10:54:44 +0000 (10:54 +0000)]
Fixup in test/DebugInfo/X86/live-debug-vars-discard-invalid.mir
The test case used invalid source operands as input
to BTS64rr instructions (feeding register operands with
immediates). This patch changes those instruction into
using BTS64ri8 instead, which seems to better match the
operand types.
Fixes problems seen in https://reviews.llvm.org/D63973.
Nikita Popov [Sun, 25 Aug 2019 08:04:22 +0000 (08:04 +0000)]
[SDAG] Fold umul_lohi with 0 or 1 multiplicand
These can turn up during multiplication legalization. In principle
these should also apply to smul_lohi, but I wasn't able to figure
out how to produce those with the necessary operands.
Matt Arsenault [Sat, 24 Aug 2019 22:14:37 +0000 (22:14 +0000)]
AMDGPU: Generate check lines
Checking all the instructions will help catch LICM changes when passes
are reordered. Also switch to using gfx9 since global stores make the
relevant instructions more obvious.
Benjamin Kramer [Sat, 24 Aug 2019 16:19:32 +0000 (16:19 +0000)]
Hack around a GCC ICE that was fixed in GCC 6.2
lib/Target/X86/AsmParser/X86AsmParser.cpp: In member function ‘void {anonymous}::X86AsmParser::SwitchMode(unsigned int)’:
lib/Target/X86/AsmParser/X86AsmParser.cpp:927:76: in constexpr expansion of ‘AllModes.llvm::FeatureBitset::FeatureBitset(std::initializer_list<unsigned int>{((const unsigned int*)(& ._157)), 3u})’
include/llvm/MC/SubtargetFeature.h:56:12: in constexpr expansion of ‘llvm::FeatureBitset::set(I)’
lib/Target/X86/AsmParser/X86AsmParser.cpp:927:76: internal compiler error: in fold_binary_loc, at fold-const.c:9921
FeatureBitset AllModes({X86::Mode64Bit, X86::Mode32Bit, X86::Mode16Bit});
^
Benjamin Kramer [Sat, 24 Aug 2019 15:46:49 +0000 (15:46 +0000)]
Try to make MSVC 2017 happy.
AArch64BaseInfo.h(316): error C3615: constexpr function 'llvm::SysAlias::SysAlias' cannot result in a constant expression
AArch64BaseInfo.h(316): note: failure was caused by call of undefined function or one not declared 'constexpr'
AArch64BaseInfo.h(316): note: see usage of 'llvm::FeatureBitset::FeatureBitset'
Benjamin Kramer [Sat, 24 Aug 2019 15:02:44 +0000 (15:02 +0000)]
Use a bit of relaxed constexpr to make FeatureBitset costant intializable
This requires std::intializer_list to be a literal type, which it is
starting with C++14. The downside is that std::bitset is still not
constexpr-friendly so this change contains a re-implementation of most
of it.
Roman Lebedev [Sat, 24 Aug 2019 06:49:51 +0000 (06:49 +0000)]
[Constant] Add 'isElementWiseEqual()' method
Promoting it from InstCombine's tryToReuseConstantFromSelectInComparison().
Return true if this constant and a constant 'Y' are element-wise equal.
This is identical to just comparing the pointers, with the exception that
for vectors, if only one of the constants has an `undef` element in some
lane, the constants still match.
Summary:
`matchThreeWayIntCompare()` looks for
```
select i1 (a == b),
i32 Equal,
i32 (select i1 (a < b), i32 Less, i32 Greater)
```
but both of these selects/compares can be in it's commuted form,
so out of 8 variants, only the two most basic ones is handled.
This fixes regression being introduced in D66232.
Roman Lebedev [Sat, 24 Aug 2019 06:49:25 +0000 (06:49 +0000)]
[InstCombine] Try to reuse constant from select in leading comparison
Summary:
If we have e.g.:
```
%t = icmp ult i32 %x, 65536
%r = select i1 %t, i32 %y, i32 65535
```
the constants `65535` and `65536` are suspiciously close.
We could perform a transformation to deduplicate them:
```
Name: ult
%t = icmp ult i32 %x, 65536
%r = select i1 %t, i32 %y, i32 65535
=>
%t.inv = icmp ugt i32 %x, 65535
%r = select i1 %t.inv, i32 65535, i32 %y
```
https://rise4fun.com/Alive/avb
While this may seem esoteric, this should certainly be good for vectors
(less constant pool usage) and for opt-for-size - need to have only one constant.
But the real fun part here is that it allows further transformation,
in particular it finishes cleaning up the `clamp` folding,
see e.g. `canonicalize-clamp-with-select-of-constant-threshold-pattern.ll`.
We start with e.g.
```
%dont_need_to_clamp_positive = icmp sle i32 %X, 32767
%dont_need_to_clamp_negative = icmp sge i32 %X, -32768
%clamp_limit = select i1 %dont_need_to_clamp_positive, i32 -32768, i32 32767
%dont_need_to_clamp = and i1 %dont_need_to_clamp_positive, %dont_need_to_clamp_negative
%R = select i1 %dont_need_to_clamp, i32 %X, i32 %clamp_limit
```
without this patch we currently produce
```
%1 = icmp slt i32 %X, 32768
%2 = icmp sgt i32 %X, -32768
%3 = select i1 %2, i32 %X, i32 -32768
%R = select i1 %1, i32 %3, i32 32767
```
which isn't really a `clamp` - both comparisons are performed on the original value,
this patch changes it into
```
%1.inv = icmp sgt i32 %X, 32767
%2 = icmp sgt i32 %X, -32768
%3 = select i1 %2, i32 %X, i32 -32768
%R = select i1 %1.inv, i32 32767, i32 %3
```
and then the magic happens! Some further transform finishes polishing it and we finally get:
```
%t1 = icmp sgt i32 %X, -32768
%t2 = select i1 %t1, i32 %X, i32 -32768
%t3 = icmp slt i32 %t2, 32767
%R = select i1 %t3, i32 %t2, i32 32767
```
which is beautiful and just what we want.
Proofs for `getFlippedStrictnessPredicateAndConstant()` for de-canonicalization:
https://rise4fun.com/Alive/THl
Proofs for the fold itself: https://rise4fun.com/Alive/THl
Lang Hames [Fri, 23 Aug 2019 20:37:32 +0000 (20:37 +0000)]
[ORC] Remove query dependencies when symbols are resolved.
If the dependencies are not removed then a late failure (one symbol covered by
the query failing after others have already been resolved) can result in an
attempt to detach the query from already finalized symbol, resulting in an
assert/crash. This patch fixes the issue by removing query dependencies in
JITDylib::resolve for symbols that meet the required state.
Lang Hames [Fri, 23 Aug 2019 20:37:31 +0000 (20:37 +0000)]
[ORC] Fix a FIXME: Propagate errors to dependencies.
When symbols are failed (via MaterializationResponsibility::failMaterialization)
any symbols depending on them will now be moved to an error state. Attempting
to resolve or emit a symbol in the error state (via the notifyResolved or
notifyEmitted methods on MaterializationResponsibility) will result in an error.
If notifyResolved or notifyEmitted return an error due to failure of a
dependence then the caller should log or discard the error and call
failMaterialization to propagate the failure to any queries waiting on the
symbols being resolved/emitted (plus their dependencies).
Jessica Paquette [Fri, 23 Aug 2019 20:31:34 +0000 (20:31 +0000)]
[AArch64][GlobalISel] Import XRO load/store patterns instead of custom selection
Instead of using custom C++ in `earlySelect` for loads and stores, just import
the patterns.
Remove `earlySelectLoad`, since we can just import the work it's doing.
Some minor changes to how `ComplexRendererFns` are returned for the XRO
addressing modes. If you add immediates in two steps, sometimes they are not
imported properly and you only end up with one immediate. I'm not sure if this
is intentional.
- Update load-addressing-modes.mir to include the instructions we can now
import.
- Add a similar test, store-addressing-modes.mir to show which store opcodes we
currently import, and show that we can pull in shifts etc.
- Update arm64-fastisel-gep-promote-before-add.ll to use FastISel instead of
GISel. This test failed with GISel because GISel folds the gep into the load.
The test checks that FastISel doesn't fold non-pointer-width adds into loads.
GISel on the other hand, produces a G_CONSTANT of -128 for the add, and then
a G_GEP, which must be pointer-width.
Note that we don't get STRBRoX right now. It seems like the importer can't
handle `FPR8Op:{ *:[Untyped] }:$Rt` source operands. So, those are not currently
supported.
Volkan Keles [Fri, 23 Aug 2019 20:30:35 +0000 (20:30 +0000)]
[GlobalISel] Legalizer: Retry combining illegal artifacts as long as there new artifacts
Summary:
Currently, Legalizer aborts if it’s unable to legalize artifacts. However, it’s
possible to combine them after processing the rest of the instruction because
the legalization is likely to generate more artifacts that allow ArtifactCombiner
to combine away them.
Instead, move illegal artifacts to another list called RetryList and wait until all of the
instruction in InstList are legalized. After that, check if there is any new artifacts and
try to combine them again if that’s the case. If not, abort. The idea is similar to D59339,
but the approach is a bit different.
This patch fixes the issue described above, but the legalizer still may be unable to handle
some cases depending on when to legalize artifacts. So, in the long run, we probably need
a different legalization strategy that handles this dependency in a better way.
Craig Topper [Fri, 23 Aug 2019 19:52:24 +0000 (19:52 +0000)]
[X86] Move a transform out of combineConcatVectorOps so we don't prematurely turn CONCAT_VECTORS into INSERT_SUBVECTORS.
CONCAT_VECTORS and INSERT_SUBVECTORS can both call combineConcatVectorOps,
but we shouldn't produce INSERT_SUBVECTORS from there. We should
keep CONCAT_VECTORS until vector legalization.
Noticed while looking at the madd_quad_reduction test from madd.ll
Wei Mi [Fri, 23 Aug 2019 19:05:30 +0000 (19:05 +0000)]
[SampleFDO] Add ExtBinary format to support extension of binary profile.
This is a patch split from https://reviews.llvm.org/D66374. It tries to add
a new format of profile called ExtBinary. The format adds a section header
table to the profile and organize the profile in sections, so the future
extension like adding a new section or extending an existing section will be
easier while keeping backward compatiblity feasible.
Philip Reames [Fri, 23 Aug 2019 18:27:57 +0000 (18:27 +0000)]
Fix a bug in just submitted rL369789
Started implementing the vector case and realized the scalar case hadn't handled the GEP producing a different type than the base correctly. It's entertaining seeing what slips through review when we're focused on the 'hard' parts. :(
Also adding an extra vector test as it happened to be in workspace and wasn't worth separating.
This generalizes the isGEPKnownNonNull rule from ValueTracking to apply when we do not know if the base is non-null, and thus need to replace one condition with another.
The core notion is that since an inbounds GEP can only form null if the base pointer is null and the offset is zero. However, if the offset is non-zero, the the "inbounds" marker makes the result poison. Thus, we're free to ignore the case where the offset is non-zero. Similarly, there's no case under which a non-null base can result in a null result without generating poison.
[BasicAA] Use dereferenceability to reason about aliasing
Summary:
We already use the fact that an object with known size X does not alias
another objection of size Y > X before. With this commit, we use
dereferenceability information to determine a lower bound for Y and not
only rely on the user provided query size.
The result for @global_and_deref_arg_2() and @local_and_deref_ret_2()
in test/Analysis/BasicAA/dereferenceable.ll improved with this patch.
[Attributor] Deal with shrinking dereferenceability in a loop
Summary:
If we have a loop in which the dereferenceability of a pointer decreases
we did slowly decrease it iteration by iteration, leading to a timeout.
With this patch we detect such circular reasoning and indicate a
fixpoint early.
Allow Compiler.h to be included in C files and fix fallthrough warnings
Summary:
Since clang does not support comment style fallthrough annotations
these should be switched to macros defined in Compiler.h. This
requires some fixing to Compiler.h.
Jeremy Morse [Fri, 23 Aug 2019 16:33:42 +0000 (16:33 +0000)]
[DebugInfo] Remove invalidated locations during LiveDebugValues
LiveDebugValues gives variable locations to blocks, but it should also take
away. There are various circumstances where a variable location is known
until a loop backedge with a different location is detected. In those
circumstances, where there's no agreement on the variable location, it
should be undef / removed, otherwise we end up picking a location that's
valid on some loop iterations but not others.
However, LiveDebugValues doesn't currently do this, see the new testcase
attached. Without this patch, the location of !3 is assumed to be %bar
through the loop. Once it's added to the In-Locations list, it's never
removed, even though the later dbg.value(0... of !3 makes the location
un-knowable.
This patch checks during block-location-joining to see whether any
previously-present locations have been removed in a predecessor. If they
have, the live-ins have changed, and the block needs reprocessing.
Similarly, in transferTerminator, assign rather than |= the Out-Locations
after processing a block, as we may have deleted some previously valid
locations. This will mean that LiveDebugValues performs more propagation
-- but that's necessary for it being correct.
[Attributor][Fix] Deal with "growing" dereferenceability
Summary:
If we have a negative inbounds offset dereferenceabily "grows". However,
until we do not handle the overflow that can occur in the
dereferenceable bytes and the problem with loops, we simply do not grow
the state.
[Attributor][NFCI] Avoid lookups when resolving returned values
If the number of potentially returned values not change since the last
traversal we do not need to visit the returned values again. This works
as we only add values to the returned values set now.
[Attributor] FIX: Treat new attributes as changed ones
Summary:
When we have new attributes and we end the fixpoint iteration because
the iteration limit is reached, we need to treat the new ones as if they
changed in the last iteration, as they might have.
This adds a test for which we should not derive anything regardless of
the iteration limit, e.g., if we abort there should not be any
attributes manifested in the IR.
Teresa Johnson [Fri, 23 Aug 2019 15:18:58 +0000 (15:18 +0000)]
[ThinLTO] Fix handling of weak interposable symbols
Summary:
Keep aliasees alive if their alias is live, otherwise we end up with an
alias to a declaration, which is invalid. This can happen when the
aliasee is weak and non-prevailing.
This fix exposed the fact that we were then attempting to internalize
the weak symbol, which was not exported as it was not prevailing. We
should not internalize interposable symbols in general, unless this is
the prevailing copy, since it can lead to incorrect inlining and other
optimizations. Most of the changes in this patch are due to the
restructuring required to pass down the prevailing callback.
Finally, while implementing the test cases, I found that in the case of
a weak aliasee that is still marked not live because its alias isn't
live, after dropping the definition we incorrectly marked the
declaration with weak linkage when resolving prevailing symbols in the
module. This was due to some special case handling for symbols marked
WeakLinkage in the summary located before instead of after a subsequent
check for the symbol being a declaration. It turns out that we don't
actually need this special case handling any more (looking back at the
history, when that was added the code was structured quite differently)
- we will correctly mark with weak linkage further below when the
definition hasn't been dropped.
[MustExec] Add a generic "must-be-executed-context" explorer
Given an instruction I, the MustBeExecutedContextExplorer allows to
easily traverse instructions that are guaranteed to be executed whenever
I is. For now, these instruction have to be statically "after" I, in
the same or different basic blocks.
This patch also adds a pass which prints the must-be-executed-context
for each instruction in a module. It is used to test the
MustBeExecutedContextExplorer, for now on the examples given in the
class comment of the MustBeExecutedIterator.
Jordan Rupprecht [Fri, 23 Aug 2019 14:28:58 +0000 (14:28 +0000)]
[llvm-objcopy] Strip debug sections when running with --strip-unneeded.
Summary:
GNU --strip-unneeded strips debugging sections as well. Do that for llvm-objcopy as well.
Additionally, add a test that verifies we keep the .gnu_debuglink section. This apparently was not always the case, and I'm not sure which commit fixed it, but there doesn't appear to be any test coverage to make sure we continue to do so.
Simon Atanasyan [Fri, 23 Aug 2019 13:36:24 +0000 (13:36 +0000)]
[mips] Reduce number of instructions used for loading a global symbol's value
Now `lw/sw $reg, sym+offset` pseudo instructions for global symbol `sym`
are lowering into the following three instructions.
```
lw $reg, %got(symbol)($gp)
addiu $reg, $reg, offset
lw/sw $reg, 0($reg)
```
It's possible to reduce the number of instructions by taking the offset
in account in the final `lw/sw` command. This patch implements that
optimization.
```
lw $reg, %got(symbol)($gp)
lw/sw $reg, offset($reg)
```
Simon Atanasyan [Fri, 23 Aug 2019 13:36:14 +0000 (13:36 +0000)]
[mips] Do not include offset into `%got` expression for global symbols
Now pseudo instruction `la $6, symbol+8($6)` is expanding into the following
chain of commands:
```
lw $1, %got(symbol+8)($gp)
addiu $1, $1, 8
addu $6, $1, $6
```
This is incorrect. When a linker handles the `R_MIPS_GOT16` relocation,
it does not expect to get any addend and breaks on assertion. Otherwise
it has to create new GOT entry for each unique "sym + offset" pair.
Offset for a global symbol should be added to result of loading GOT
entry by a separate `add` command.
The patch fixes the problem by stripping off an offset from the expression
passed to the `%got`. That's interesting that even current code inserts
a separate `add` command.
Andrea Di Biagio [Fri, 23 Aug 2019 12:19:45 +0000 (12:19 +0000)]
[X86][BtVer2] Add a read-advance to every implicit register use of CMPXCHG8B/16B.
This is a follow up of r369642.
This patch assigns a ReadAfterLd to every implicit register use of instruction
CMPXCHG8B and instruction CMPXCHG16B. Perf micro-benchmarks show that implicit
registers are read after 3cy from the start of execution.
Andrea Di Biagio [Fri, 23 Aug 2019 11:34:10 +0000 (11:34 +0000)]
[X86][BtVer2] Fix latency of ALU RMW instructions.
Excluding ADC/SBB and the bit-test instructions (BTR/BTS/BTC), the observed
latency of all other RMW integer arithmetic/logic instructions is 6cy and not
5cy.
The same latency profile applies to SUB/AND/OR/XOR/INC/DEC.
The observed latency of ADC/SBB is 7-8cy. So we need a different write to model
those. Latency of BTS/BTR/BTC is not fixed by this patch (they are much slower
than what the model for btver2 currently reports).
Martin Storsjo [Fri, 23 Aug 2019 11:18:11 +0000 (11:18 +0000)]
[llvm-dlltool] Make sure to strip decorations from ExtName for renamed exports
ExtName should not be decorated, just like Name.
This avoids double decoration on symbols in import libraries
that use = for renaming functions. (Weak aliases, which use ==,
worked fine with respect to decoration.)
George Rimar [Fri, 23 Aug 2019 09:31:07 +0000 (09:31 +0000)]
[yaml2obj] - Allow setting the symbol st_other field to any integer.
st_other field of a symbol usually contains its visibility.
Other bits are usually 0, though some targets, like
MIPS can set them using the named bit field values.
Problem is that there is no way to set an arbitrary value now,
though that might be useful for our test cases.
In this patch I introduced a way to set st_other to any numeric
value using the new StOther field.
I added a test and simplified the existent one to show the effect/benefit
Craig Topper [Fri, 23 Aug 2019 07:38:25 +0000 (07:38 +0000)]
[X86] Add a further unrolled madd reduction test case that shows several deficiencies.
The AVX2 check lines show two issues. An ADD that became an OR
because we knew the input was disjoint, but really it was zero
so we should have just removed the ADD/OR all together.
Relatedly we use 128-bit VPMADDWD instructions followed by
256-bit VPADDD operations. We should be able to narrow these
VPADDDs.
Craig Topper [Fri, 23 Aug 2019 05:33:27 +0000 (05:33 +0000)]
[X86] Improve lowering of v2i32 SAD handling in combineLoopSADPattern.
For v2i32 we only feed 2 i8 elements into the psadbw instructions
with 0s in the other 14 bytes. The resulting psadbw instruction
will produce zeros in bits [127:16] of the output. We need to take
the result and feed it to a v2i32 add where the first element
includes bits [15:0] of the sad result. The other element should
be zero.
Prior to this patch we were using a truncate to take 0 from
bits 95:64 of the psadbw. This results in a pshufd to move those
bits to 63:32. But since we also have zeroes in bits 63:32 of
the psadbw output, we should just take those bits.
The previous code probably worked better with promoting legalization,
but now we use widening legalization. I've preserved the old
behavior if -x86-experimental-vector-widening-legalization=false
until we get that option removed.
Philip Reames [Fri, 23 Aug 2019 04:03:23 +0000 (04:03 +0000)]
[IndVars] Fix a bug noticed by inspection
We were computing the loop exit value, but not ensuring the addrec belonged to the loop whose exit value we were computing. I couldn't actually trip this; the test case shows the basic setup which *might* trip this, but none of the variations I've tried actually do.
Fangrui Song [Fri, 23 Aug 2019 02:17:04 +0000 (02:17 +0000)]
[AlignmentFromAssumptions] getNewAlignmentDiff(): use getURemExpr()
The alignment is calculated incorrectly, thus sometimes it doesn't generate aligned mov instructions, as shown by the example below:
```
// b.cc
typedef long long index;
extern "C" index g_tid;
extern "C" index g_num;
void add3(float* __restrict__ a, float* __restrict__ b, float* __restrict__ c) {
index n = 64*1024;
index m = 16*1024;
index k = 4*1024;
index tid = g_tid;
index num = g_num;
__builtin_assume_aligned(a, 32);
__builtin_assume_aligned(b, 32);
__builtin_assume_aligned(c, 32);
for (index i0=tid*k; i0<m; i0+=num*k)
for (index i1=0; i1<n*m; i1+=m)
for (index i2=0; i2<k; i2++)
c[i1+i0+i2] = b[i0+i2] + a[i1+i0+i2];
}
```
Compile with `clang b.cc -Ofast -march=skylake -mavx2 -S`
```
vmovaps -224(%rdi,%rbx,4), %ymm0
vmovups -192(%rdi,%rbx,4), %ymm1 # should be movaps
vmovups -160(%rdi,%rbx,4), %ymm2 # should be movaps
vmovups -128(%rdi,%rbx,4), %ymm3 # should be movaps
vaddps -224(%rsi,%rbx,4), %ymm0, %ymm0
vaddps -192(%rsi,%rbx,4), %ymm1, %ymm1
vaddps -160(%rsi,%rbx,4), %ymm2, %ymm2
vaddps -128(%rsi,%rbx,4), %ymm3, %ymm3
vmovaps %ymm0, -224(%rdx,%rbx,4)
vmovups %ymm1, -192(%rdx,%rbx,4) # should be movaps
vmovups %ymm2, -160(%rdx,%rbx,4) # should be movaps
vmovups %ymm3, -128(%rdx,%rbx,4) # should be movaps
```
Differential Revision: https://reviews.llvm.org/D66575
Patch by Dun Liang
hwasan: Untag unwound stack frames by wrapping personality functions.
One problem with untagging memory in landing pads is that it only works
correctly if the function that catches the exception is instrumented.
If the function is uninstrumented, we have no opportunity to untag the
memory.
To address this, replace landing pad instrumentation with personality function
wrapping. Each function with an instrumented stack has its personality function
replaced with a wrapper provided by the runtime. Functions that did not have
a personality function to begin with also get wrappers if they may be unwound
past. As the unwinder calls personality functions during stack unwinding,
the original personality function is called and the function's stack frame is
untagged by the wrapper if the personality function instructs the unwinder
to keep unwinding. If unwinding stops at a landing pad, the function is
still responsible for untagging its stack frame if it resumes unwinding.
The old landing pad mechanism is preserved for compatibility with old runtimes.
Sam Clegg [Fri, 23 Aug 2019 01:00:55 +0000 (01:00 +0000)]
[MC] Minor cleanup to MCFixup::Kind handling. NFC.
Prefer `MCFixupKind` where possible and add getTargetKind() to
convert to `unsigned` when needed rather than scattering cast
operators around the place.
projects / llvm / log