eraseInstFromFunction() adds the operands of the erased instructions,
as those might now be dead as well. However, this is limited to
instructions with less than 8 operands.
This check doesn't make a lot of sense to me. As the instruction
gets removed afterwards, I don't see a potential for anything
overly pathological happening here (as we can only add those
operands to the worklist once). The impact on CTMark is in
the noise. We also have the same code in instruction sinking
and don't limit the operand count there.
Differential Revision: https://reviews.llvm.org/D77325
Summary:
When we insert a call to the personality function wrapper
(`_Unwind_CallPersonality`) for a catch pad, we store some necessary
info in `__wasm_lpad_context` struct and pass it. One of the info is the
LSDA address for the function. For this, we insert a call to
`wasm.lsda()`, which will be lowered down to the address of LSDA, and
store it in a field in `__wasm_lpad_context`.
There are exceptions to this personality call insertion: catchpads for
`catch (...)` and cleanuppads (for destructors) don't need personality
function calls, because we don't need to figure out whether the current
exception should be caught or not. (They always should.)
There was a little optimization to `wasm.lsda()` call insertion. Because
the LSDA address is the same throughout a function, we don't need to
insert a store of `wasm.lsda()` return value in every catchpad. For
example:
```
try {
foo();
} catch (int) {
// wasm.lsda() call and a store are inserted here, like, in
// pseudocode,
// %lsda = wasm.lsda();
// store %lsda to a field in __wasm_lpad_context
try {
foo();
} catch (int) {
// We don't need to insert the wasm.lsda() and store again, because
// to arrive here, we have already stored the LSDA address to
// __wasm_lpad_context in the outer catch.
}
}
```
So the previous algorithm checked if the current catch has a parent EH
pad, we didn't insert a call to `wasm.lsda()` and its store.
But this was incorrect, because what if the outer catch is `catch (...)`
or a cleanuppad?
```
try {
foo();
} catch (...) {
// wasm.lsda() call and a store are NOT inserted here
try {
foo();
} catch (int) {
// We need wasm.lsda() here!
}
}
```
In this case we need to insert `wasm.lsda()` in the inner catchpad,
because the outer catchpad does not have one.
To minimize the number of inserted `wasm.lsda()` calls and stores, we
need a way to figure out whether we have encountered `wasm.lsda()` call
in any of EH pads that dominates the current EH pad. To figure that
out, we now visit EH pads in BFS order in the dominator tree so that we
visit parent BBs first before visiting its child BBs in the domtree.
We keep a set named `ExecutedLSDA`, which basically means "Do we have
`wasm.lsda()` either in the current EH pad or any of its parent EH
pads in the dominator tree?". This is to prevent scanning the domtree up
to the root in the worst case every time we examine an EH pad: each EH
pad only needs to examine its immediate parent EH pad.
- If any of its parent EH pads in the domtree has `wasm.lsda()`, this
means we don't need `wasm.lsda()` in the current EH pad. We also insert
the current EH pad in `ExecutedLSDA` set.
- If none of its parent EH pad has `wasm.lsda()`
- If the current EH pad is a `catch (...)` or a cleanuppad, done.
- If the current EH pad is neither a `catch (...)` nor a cleanuppad,
add `wasm.lsda()` and the store in the current EH pad, and add the
current EH pad to `ExecutedLSDA` set.
Reviewers: dschuff
Subscribers: sbc100, jgravelle-google, hiraditya, sunfish, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D77423
Similar to the lowerV16I8Shuffle implementation, for binary compaction v8i16 shuffles we can avoid the PUNPCKLDQ(PSHUFB,PSHUFB) pattern on SSE41+ targets by using PACKUSDW and PBLENDW. Before SSE41 we would need to use PACKSSDW but that requires sign extension that seems to destroy any gains, even on targets without PSHUFB.
This is a bigger gain on AMD than Intel targets but should never be a regression, and avoiding the shuffle mask load(s) is always useful.
Noticed in codegen while dealing with PR31443.
Since D73835 we no longer need to define the whole IRBuilder
implementation in the header. This patch moves some of the larger
methods out of line, into the C++ file.
Differential Revision: https://reviews.llvm.org/D77332
Summary:
Note: This revision is very similar to D62296.
In D75756, we need `getDynamicSymbolIterators()` to skip first NULL symbol in `.dynsym`. And I believe it might be worth pointing this out in a separate patch to gather you experts' opinions.
I have checked that current code base will not be affected by this change.
```
dynamic_symbol_begin()
|- dynamic_symbol_end(): Ok
`- getDynamicSymbolIterators()
|- addDynamicElfSymbols(): llvm/tools/llvm-objdump/llvm-objdump.cpp, Line 934
| Ok, NULL symbol will be omitted by Line 945-947
| StringRef Name = unwrapOrError(Symbol.getName(), Obj->getName());
| if (Name.empty()) continue;
|- dumpSymbolNameFromObject(): llvm/tools/llvm-nm/llvm-nm.cpp, Line 1192
| There's no test for dumping dynamic debugging symbol. This patch helps improve llvm-nm behavior. (we should add test for this later)
`- computeSymbolSizes(): llvm/lib/Object/SymbolSize.cpp, Line 52
|- OProfileJITEventListener::notifyObjectLoaded(): llvm/lib/ExecutionEngine/OProfileJIT/OProfileJITEventListener.cpp, Line 92
| Ok, NULL symbol will be omitted by Line 94-95
| if (!Sym.getType() || *Sym.getType() != SF_Function) continue;
|- IntelJITEventListener::notifyObjectLoaded(): llvm/lib/ExecutionEngine/IntelJITEvents/IntelJITEventListener.cpp, Line 98
| Ok, NULL symbol will be omitted by Line 124-126 (same as previous one)
|- PerfJITEventListener::notifyObjectLoaded(): llvm/lib/ExecutionEngine/PerfJITEvents/PerfJITEventListener.cpp, Line 244
| Ok, NULL symbol will be omitted by Line 254-256, (same as previous one)
|- SymbolizableObjectFile::create(): llvm/lib/DebugInfo/Symbolize/SymbolizableObjectFile.cpp, Line 73
| Ok, NULL symbol will be omitted by Line 75
| res->addSymbol()
| In addSymbol(), Line 167-168
| if (!Sec || (Obj && Obj->section_end() == *Sec)) return std::error_code();
|- dumpCXXData(): llvm/tools/llvm-cxxdump/llvm-cxxdump.cpp, Line 189
| Ok, NULL symbol will be omitted by Line 199-202
| object::section_iterator SecI = *SecIOrErr;
| // Skip external symbols.
| if (SecI == Obj->section_end())
| continue;
`- printLineInfoForInput(): llvm/tools/llvm-rtdyld/llvm-rtdyld.cpp, Line 418
Ok, NULL symbol will be omitted by Line 430-477
if (Type == object::SymbolRef::ST_Function) {
...
}
```
Reviewers: grimar, jhenderson, MaskRay
Reviewed By: jhenderson, MaskRay
Subscribers: rupprecht, arphaman, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D76081
Forward declare DemandedBits in IVDescriptors, and move include
into the cpp file. Also drop the include from LoopUtils, which
does not need it at all.
When clang is built against a prebuilt LLVM, LLVM_SOURCE_DIR is
empty, which due to a cmake quirk caused list lengths to get out
of sync. Add a workaround.
After finding all such gadgets in a given function, the pass minimally inserts
LFENCE instructions in such a manner that the following property is satisfied:
for all SOURCE+SINK pairs, all paths in the CFG from SOURCE to SINK contain at
least one LFENCE instruction. The algorithm that implements this minimal
insertion is influenced by an academic paper that minimally inserts memory
fences for high-performance concurrent programs:
http://www.cs.ucr.edu/~lesani/companion/oopsla15/OOPSLA15.pdf
The algorithm implemented in this pass is as follows:
1. Build a condensed CFG (i.e., a GadgetGraph) consisting only of the following components:
-SOURCE instructions (also includes function arguments)
-SINK instructions
-Basic block entry points
-Basic block terminators
-LFENCE instructions
2. Analyze the GadgetGraph to determine which SOURCE+SINK pairs (i.e., gadgets) are already mitigated by existing LFENCEs. If all gadgets have been mitigated, go to step 6.
3. Use a heuristic or plugin to approximate minimal LFENCE insertion.
4. Insert one LFENCE along each CFG edge that was cut in step 3.
5. Go to step 2.
6. If any LFENCEs were inserted, return true from runOnFunction() to tell LLVM that the function was modified.
By default, the heuristic used in Step 3 is a greedy heuristic that avoids
inserting LFENCEs into loops unless absolutely necessary. There is also a
CLI option to load a plugin that can provide even better optimization,
inserting fewer fences, while still mitigating all of the LVI gadgets.
The plugin can be found here: https://github.com/intel/lvi-llvm-optimization-plugin,
and a description of the pass's behavior with the plugin can be found here:
https://software.intel.com/security-software-guidance/insights/optimized-mitigation-approach-load-value-injection.
Differential Revision: https://reviews.llvm.org/D75937
Graceful lit shutdown on user keyboard interrupt [Ctrl+C] was a
longstanding goal of mine. After a few refactorings this revision
finally enables it. We use the following strategy to deal with
KeyboardInterrupt:
https://noswap.com/blog/python-multiprocessing-keyboardinterrupt
Printing of a helpful summary for interrupted runs (just as the one for
completed runs) will be tackled in future revisions.
Reviewed By: serge-sans-paille, rnk
Differential Revision: https://reviews.llvm.org/D77365
Adds a new data structure, ImmutableGraph, and uses RDF to find LVI gadgets and add them to a MachineGadgetGraph.
More specifically, a new X86 machine pass finds Load Value Injection (LVI) gadgets consisting of a load from memory (i.e., SOURCE), and any operation that may transmit the value loaded from memory over a covert channel, or use the value loaded from memory to determine a branch/call target (i.e., SINK).
Also adds a new target feature to X86: +lvi-load-hardening
The feature can be added via the clang CLI using -mlvi-hardening.
Differential Revision: https://reviews.llvm.org/D75936
Summary:
This patch includes two extensions:
1. It extends the GraphDiff to also keep the original list of updates
after legalization, not just the deletes/insert vectors.
It also provides an API to pop the first update (the updates are store
in reverse, such that the first update is at the end of the list)
2. It adds a bool to mark whether the given updates should be applied as
given, or applied in reverse. This moves the task of reversing the
updates (when the caller needs this) to a functionality inside
GraphDiff, versus having the caller do this.
The two changes could be split into two patches, but they seemed
reasonably small to be reviewed together.
Reviewers: kuhar, dblaikie
Subscribers: hiraditya, george.burgess.iv, mgrang, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D77167
Adding a pass that replaces every ret instruction with the sequence:
pop <scratch-reg>
lfence
jmp *<scratch-reg>
where <scratch-reg> is some available scratch register, according to the
calling convention of the function being mitigated.
Differential Revision: https://reviews.llvm.org/D75935
Summary:
Remove usages of asserting vector getters in Type in preparation for the
VectorType refactor. The existence of these functions complicates the
refactor while adding little value.
Reviewers: kparzysz, sdesmalen, efriedma
Reviewed By: kparzysz
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D77267
Previously, the tablegen() cmake command, which defines custom
commands for running tablegen, included several hardcoded paths. This
becomes unwieldy as there are more users for which these paths are
insufficient. For most targets, cmake uses include_directories() and
the INCLUDE_DIRECTORIES directory property to specify include paths.
This change picks up the INCLUDE_DIRECTORIES property and adds it
to the include path used when running tablegen. As a side effect, this
allows us to remove several hard coded paths to tablegen that are redundant
with specified include_directories().
I haven't removed the hardcoded path to CMAKE_CURRENT_SOURCE_DIR, which
seems generically useful. There are several users in clang which apparently
don't have the current directory as an include_directories(). This could
be considered separately.
The new version of this path uses list APPEND rather than list TRANSFORM,
in order to be compatible with cmake 3.4.3. If we update to cmake 3.12 then
we can use list TRANSFORM instead.
Differential Revision: https://reviews.llvm.org/D77156
We can fix register class of PHI based on its all AGPR uses.
That leaves behind all PHIs which were already processed
earlier. Propagate RC back to PHI operands of a PHI.
Differential Revision: https://reviews.llvm.org/D77344
As detailed on PR45043, static analysis was warning that the StringRef::iterator Position argument was being ignored and the function was hardwired to use the Current iterator.
This patch ensures we use the provided iterator and removes the (barely necessary) setError wrapper that always used Current.
Differential Revision: https://reviews.llvm.org/D76512
Extracting to the same index that we are going to insert back into
allows forming select ("blend") shuffles and enables further transforms.
Admittedly, this is a quick-fix for a more general problem that I'm
hoping to solve by adding transforms for patterns that start with an
insertelement.
But this might resolve some regressions known to be caused by the
extract-extract transform (although I have not gotten more details on
those yet).
In the motivating case from PR34724:
https://bugs.llvm.org/show_bug.cgi?id=34724
The combination of subsequent instcombine and codegen transforms gets us this improvement:
vmovshdup %xmm0, %xmm2 ## xmm2 = xmm0[1,1,3,3]
vhaddps %xmm1, %xmm1, %xmm4
vmovshdup %xmm1, %xmm3 ## xmm3 = xmm1[1,1,3,3]
vaddps %xmm0, %xmm2, %xmm0
vaddps %xmm1, %xmm3, %xmm1
vshufps $200, %xmm4, %xmm0, %xmm0 ## xmm0 = xmm0[0,2],xmm4[0,3]
vinsertps $177, %xmm1, %xmm0, %xmm0 ## xmm0 = zero,xmm0[1,2],xmm1[2]
-->
vmovshdup %xmm0, %xmm2 ## xmm2 = xmm0[1,1,3,3]
vhaddps %xmm1, %xmm1, %xmm1
vaddps %xmm0, %xmm2, %xmm0
vshufps $200, %xmm1, %xmm0, %xmm0 ## xmm0 = xmm0[0,2],xmm1[0,3]
Differential Revision: https://reviews.llvm.org/D76623
Added unit tests for 2 scenarios that were failing.
Made replace_path_prefix back to 3 parameters instead of 5, simplifying the implementation. The other 2 were always used with the default value.
This commit is intended to be the first of 3:
1) simplify/fix replace_path_prefix.
2) use it in the context of -fdebug-prefix-map and -fmacro-prefix-map (see D76869).
3) Make Windows version of replace_path_prefix insensitive to both case and separators (slash vs backslash).
Differential Revision: https://reviews.llvm.org/D77223
Previously, the tablegen() cmake command, which defines custom
commands for running tablegen, included several hardcoded paths. This
becomes unwieldy as there are more users for which these paths are
insufficient. For most targets, cmake uses include_directories() and
the INCLUDE_DIRECTORIES directory property to specify include paths.
This change picks up the INCLUDE_DIRECTORIES property and adds it
to the include path used when running tablegen. As a side effect, this
allows us to remove several hard coded paths to tablegen that are redundant
with specified include_directories().
I haven't removed the hardcoded path to CMAKE_CURRENT_SOURCE_DIR, which
seems generically useful. There are several users in clang which apparently
don't have the current directory as an include_directories(). This could
be considered separately.
Differential Revision: https://reviews.llvm.org/D77156
Extend lowerShuffleWithPACK/matchShuffleWithPACK/createPackShuffleMask to handle compaction style shuffle masks that can be lowered to chains of PACKSS/PACKUS if their inputs are suitably sign/zero extended.
This helps avoid PSHUFB (and its mask load) for short shuffle chains, shuffle combining will still replace with a PSHUFB if we have enough shuffles as getFauxShuffleMask should recognise the PACKSS/PACKUS chains.
As discussed in post-commit review in https://reviews.llvm.org/D73501
if the goal of this is to help vectorizer, then we should actually
be teaching vectorizer to do this, because right now this rewrite
is still budget-limited, which isn't what we'd want.
Additionally, while the rest of the patch series was universally profitable,
this particular patch is reportedly (https://reviews.llvm.org/D73501#1905171)
exposing cost-modeling issues on ARM.
So let's just back this particular patch out. Once there's an undo transform,
this could be considered for reintegration.
This reverts commit 44edc6fd2c.
Nikita Popov