The profitability check is: we don't want to create more than a single PHI
per instruction sunk. We need to create the PHI unless we'll sink
all of it's would-be incoming values.
But there is a caveat there.
This profitability check doesn't converge on the first iteration!
If we first decide that we want to sink 10 instructions,
but then determine that 5'th one is unprofitable to sink,
that may result in us not sinking some instructions that
resulted in determining that some other instruction
we've determined to be profitable to sink becoming unprofitable.
So we need to iterate until we converge, as in determine
that all leftover instructions are profitable to sink.
But, the direct approach of just re-iterating seems dumb,
because in the worst case we'd find that the last instruction
is unprofitable, which would result in revisiting instructions
many many times.
Instead, i think we can get away with just two passes - forward and backward.
However then it isn't obvious what is the most performant way to update
InstructionsToSink.
Pointers in non-zero address spaces need to be address space
casted before appending to the used list.
Reviewed by: vitalybuka
Differential Revision: https://reviews.llvm.org/D101363
While we have a known profitability issue for sinking in presence of
non-unconditional predecessors, there isn't any known issues
for having multiple such non-unconditional predecessors,
so said restriction appears to be artificial. Lift it.
We can just eagerly pre-check all the instructions that we *could*
sink that we'd actually want to sink them, clamping the number of
instructions that we'll sink to stop just before the first unprofitable one.
This patch causes the loop vectorizer to not interleave loops that have
nounroll loop hints (llvm.loop.unroll.disable and llvm.loop.unroll_count(1)).
Note that if a particular interleave count is being requested
(through llvm.loop.interleave_count), it will still be honoured, regardless
of the presence of nounroll hints.
Reviewed By: Meinersbur
Differential Revision: https://reviews.llvm.org/D101374
Before this change LLVM cannot simplify printf in following cases:
printf("%s", "") --> noop
printf("%s", str"\n") --> puts(str)
From the other hand GCC can perform such transformations for many years:
https://godbolt.org/z/7nnqbedfe
Differential Revision: https://reviews.llvm.org/D100724
When replacing a conditional branch by an unconditional one because the targets are identical, transfer the metadata to the new branch instruction.
Reviewed By: lebedev.ri
Differential Revision: https://reviews.llvm.org/D101226
When replacing a conditional branch by an unconditional one because the condition is a constant, transfer the metadata to the new branch instruction.
Part of fix for llvm.org/PR50060
Reviewed By: lebedev.ri
Differential Revision: https://reviews.llvm.org/D101141
While doing speculative execution opt, it conservatively drops all insn's debug info in the merged `ThenBB`(see the loop at line 2384) including the dangling probe. The missing debug info of the dangling probe will cause the wrong inference computation.
So we should avoid dropping the debug info from pseudo probe, this change try to fix this by moving the to-be dangling probe to the merging target BB before the debug info is dropped.
Reviewed By: hoy, wenlei
Differential Revision: https://reviews.llvm.org/D101195
Previous build failures were caused by an error in bitcode reading and
writing for DIArgList metadata, which has been fixed in e5d844b587.
There were also some unnecessary asserts that were being triggered on
certain builds, which have been removed.
This reverts commit dad5caa59e.
On ELF targets, if a function has uwtable or personality, or does not have
nounwind (`needsUnwindTableEntry`), it marks that `.eh_frame` is needed in the module.
Then, a function gets `.eh_frame` if `needsUnwindTableEntry` or `-g[123]` is specified.
(i.e. If -g[123], every function gets `.eh_frame`.
This behavior is strange but that is the status quo on GCC and Clang.)
Let's take asan as an example. Other sanitizers are similar.
`asan.module_[cd]tor` has no attribute. `needsUnwindTableEntry` returns true,
so every function gets `.eh_frame` if `-g[123]` is specified.
This is the root cause that
`-fno-exceptions -fno-asynchronous-unwind-tables -g` produces .debug_frame
while
`-fno-exceptions -fno-asynchronous-unwind-tables -g -fsanitize=address` produces .eh_frame.
This patch
* sets the nounwind attribute on sanitizer module ctor/dtor.
* let Clang emit a module flag metadata "uwtable" for -fasynchronous-unwind-tables. If "uwtable" is set, sanitizer module ctor/dtor additionally get the uwtable attribute.
The "uwtable" mechanism is generic: synthesized functions not cloned/specialized
from existing ones should consider `Function::createWithDefaultAttr` instead of
`Function::create` if they want to get some default attributes which
have more of module semantics.
Other candidates: "frame-pointer" (https://github.com/ClangBuiltLinux/linux/issues/955https://github.com/ClangBuiltLinux/linux/issues/1238), dso_local, etc.
Differential Revision: https://reviews.llvm.org/D100251
Trying to evaluate a GEP would assert with
"Ty == cast<PointerType>(C->getType()->getScalarType())->getElementType()"
because the type of the pointer we would evaluate the GEP argument to
would be a different type than the GEP was expecting. We should treat
pointer stripping as a bitcast.
The test adds a redundant GEP that would crash due to type mismatch.
Reviewed By: rnk
Differential Revision: https://reviews.llvm.org/D100970
Fix for PR49984
This was discovered during Attributor testing.
Memset was always created with alignment of 1
and in case when strncpy alignment was changed
it triggered an assertion in the AttrBuilder.
Memset will now be created with appropriate alignment.
Differential Revision: https://reviews.llvm.org/D100875
CommandLine.h is indirectly included in ~50% of TUs when building
clang, and VirtualFileSystem.h is large.
(Already remarked by jhenderson on D70769.)
No behavior change.
Differential Revision: https://reviews.llvm.org/D100957
Previously we would use the type of the pointee to determine what to
cast the result of constant folding a load. To aid with opaque pointer
types, we should explicitly pass the type of the load rather than
looking at pointee types.
ConstantFoldLoadThroughBitcast() converts the const prop'd value to the
proper load type (e.g. [1 x i32] -> i32). Instead of calling this in
every intermediate step like bitcasts, we only call this when we
actually see the global initializer value.
In some existing uses of this API, we don't know the exact type we're
loading from immediately (e.g. first we visit a bitcast, then we visit
the load using the bitcast). In those cases we have to manually call
ConstantFoldLoadThroughBitcast() when simplifying the load to make sure
that we cast to the proper type.
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D100718
I guess this case hasn't come up thus far, and i'm not sure if it can
really happen for the existing usages, thus no test in *this* commit.
But, the following commit adds test coverage,
there we'd expirience a crash without this fix.
Currently, InsertNoopCastOfTo() would implicitly insert that cast,
but now that we have SCEVPtrToIntExpr, i'm hoping we could stop
InsertNoopCastOfTo() from doing that. But first all users must be fixed.
Move the findDbg* functions into lib/IR/DebugInfo.cpp from
lib/Transforms/Utils/Local.cpp.
D99169 adds a call to a function (findDbgUsers) that lives in
lib/Transforms/Utils/Local.cpp (LLVMTransformUtils) from lib/IR/Value.cpp
(LLVMCore). The Core lib doesn't include TransformUtils. The builtbots caught
this here: https://lab.llvm.org/buildbot/#/builders/109/builds/12664. This patch
moves the function, and the 3 similar ones for consistency, into DebugInfo.cpp
which is part of LLVMCore.
Reviewed By: dblaikie, rnk
Differential Revision: https://reviews.llvm.org/D100632
Debug intrinsics are free to hoist and should be skipped when looking
for terminator-only blocks. As a consequence, we have to delegate to the
main hoisting loop to hoist any dbg intrinsics instead of jumping to the
terminator case directly.
This fixes PR49982.
Reviewed By: lebedev.ri
Differential Revision: https://reviews.llvm.org/D100640
It will not do anything useful for them, as we already know that
they don't modref with any accessible memory.
In particular, this prevents noalias metadata from being placed
on noalias.scope.decl intrinsics. This reduces the amount of
metadata needed, and makes it more likely that unnecessary decls
can be eliminated.
Such attributes can either be unset, or set to "true" or "false" (as string).
throughout the codebase, this led to inelegant checks ranging from
if (Fn->getFnAttribute("no-jump-tables").getValueAsString() == "true")
to
if (Fn->hasAttribute("no-jump-tables") && Fn->getFnAttribute("no-jump-tables").getValueAsString() == "true")
Introduce a getValueAsBool that normalize the check, with the following
behavior:
no attributes or attribute set to "false" => return false
attribute set to "true" => return true
Differential Revision: https://reviews.llvm.org/D99299
str(n)cat appends a copy of the second argument to the end of the first
argument. To find the end of the first argument, str(n)cat has to read
from it until it finds the terminating 0. So it should not be marked as
writeonly. I think this means the argument should not be marked as
writeonly.
(This is causing a mis-compile with legacy DSE, before it got removed)
Reviewed By: efriedma
Differential Revision: https://reviews.llvm.org/D100601
Avoid visiting repeated instructions for processHeaderPhiOperands as it can cause a scenario of endless loop. Test case is attached and can be ran with `opt -basic-aa -tbaa -loop-unroll-and-jam -allow-unroll-and-jam -unroll-and-jam-count=4`.
Reviewed By: dmgreen
Differential Revision: https://reviews.llvm.org/D97407
This reverts commit ab98f2c712 and 98eea392cd.
It includes a fix for the clang test which triggered the revert. I failed to notice this one because there was another AMDGPU llvm test with a similiar name and the exact same text in the error message. Odd. Since only one build bot reported the clang test, I didn't notice that one.
Breaks check-clang, see comments on D100400
Also revert follow-up "[NFC] Move a recently added utility into a location to enable reuse"
This reverts commit 3ce61fb6d6.
This reverts commit 61a85da882.
This refactors SCCP and creates a SCCPSolver interface and class so that it can
be used by other passes and transformations. We will use this in D93838, which
adds a function specialisation pass.
This is based on an early version by Vinay Madhusudan.
Differential Revision: https://reviews.llvm.org/D93762
As a side-effect of the change to default HoistCommonInsts to false
early in the pipeline, we fail to convert conditional branch & phis to
selects early on, which prevents vectorization for loops that contain
conditional branches that effectively are selects (or if the loop gets
vectorized, it will get vectorized very inefficiently).
This patch updates SimplifyCFG to perform hoisting if the only
instruction in both BBs is an equal branch. In this case, the only
additional instructions are selects for phis, which should be cheap.
Even though we perform hoisting, the benefits of this kind of hoisting
should by far outweigh the negatives.
For example, the loop in the code below will not get vectorized on
AArch64 with the current default, but will with the patch. This is a
fundamental pattern we should definitely vectorize. Besides that, I
think the select variants should be easier to use for reasoning across
other passes as well.
https://clang.godbolt.org/z/sbjd8Wshx
```
double clamp(double v) {
if (v < 0.0)
return 0.0;
if (v > 6.0)
return 6.0;
return v;
}
void loop(double* X, double *Y) {
for (unsigned i = 0; i < 20000; i++) {
X[i] = clamp(Y[i]);
}
}
```
Reviewed By: lebedev.ri
Differential Revision: https://reviews.llvm.org/D100329
Lookup tables generate non PIC-friendly code, which requires dynamic relocation as described in:
https://bugs.llvm.org/show_bug.cgi?id=45244
This patch adds a new pass that converts lookup tables to relative lookup tables to make them PIC-friendly.
Differential Revision: https://reviews.llvm.org/D94355
Turning on -fstrict-vtable-pointers in Chrome caused an extra global
initializer. Turns out that a llvm.strip.invariant.group intrinsic was
causing GlobalOpt to fail to step through some simple code.
We can treat *.invariant.group uses as simply their operand.
Value::stripPointerCastsForAliasAnalysis() does exactly this. This
should be safe because the Evaluator does not skip memory accesses due
to invariants or alias analysis.
However, we don't want to leak that we've stripped arbitrary pointer
casts to users of Evaluator, so we bail out if we evaluate a function to
any constant, since we may have looked through *.invariant.group calls
and aliasing pointers cannot be arbitrarily substituted.
Reviewed By: rnk
Differential Revision: https://reviews.llvm.org/D98843
D24453 enabled libcalls simplication for ARM PCS. This may cause
caller/callee calling conventions mismatch in some situations such as
LTO. This patch makes instcombine aware that the compatible calling
conventions differences are benign (not emitting undef idom).
Differential Revision: https://reviews.llvm.org/D99773
Nathan Chancellor