Summary:
This is RFC for fixes in poison-related functions of ValueTracking.
These functions assume that a value can be poison bitwisely, but the semantics
of bitwise poison is not clear at the moment.
Allowing a value to have bitwise poison adds complexity to reasoning about
correctness of optimizations.
This patch makes the analysis functions simply assume that a value is
either fully poison or not, which has been used to understand the correctness
of a few previous optimizations.
The bitwise poison semantics seems to be only used by these functions as well.
In terms of implementation, using value-wise poison concept makes existing
functions do more precise analysis, which is what this patch contains.
Reviewers: spatel, lebedev.ri, jdoerfert, reames, nikic, nlopes, regehr
Reviewed By: nikic
Subscribers: fhahn, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D78503
Several external build users contain some heuristics for finding llvm-lit.
There are several cases we need to worry about:
- External builds against a build tree (with LLVM_BUILD_UTILS)
- External builds against an install tree (with LLMV_BUILD_UTIL
and LLVM_INSTALL_UTILS)
- External builds against some location which doesn't have an
llvm-lit, but llvm-lit is available through some other means, such
as an available source tree, or a packager provided llvm-lit.
For the third case, LLVM_EXTERNAL_LIT suffices, but in other cases
there's no standard way to find llvm-lit. It seems like each user
cooks their own heuristics:
- clang tries to look in the LLVM source tree, and failing that falls
back to looking for a packaged llvm-lit.
- libcxx tries to look in the LLVM source tree, which might come from
llvm-config or be explicitly specified.
This patch is a first stop to solving this by providing a default location
for llvm-lit using LLVM_DEFAULT_EXTERNAL_LIT. The expectation is that
future patches can clean up users like clang and libcxx to rely
on this mechanism for out-of-tree builds.
Differential Revision: https://reviews.llvm.org/D77110
Time profiler emits relative timestamps for events (the number of
microseconds passed since the start of the current process).
This patch allows combining events from different processes while
preserving their relative timing by emitting a new attribute
"beginningOfTime". This attribute contains the system time that
corresponds to the zero timestamp of the time profiler.
This has at least two use cases:
- Build systems can use this to merge time traces from multiple compiler
invocations and generate statistics for the whole build. Tools like
ClangBuildAnalyzer could also leverage this feature.
- Compilers that use LLVM as their backend by invoking llc/opt in
a child process. If such a compiler supports generating time traces
of its own events, it could merge those events with LLVM-specific
events received from llc/opt, and produce a more complete time trace.
A proof-of-concept script that merges multiple logs that
contain a synchronization point into one log:
https://github.com/broadwaylamb/merge_trace_events
Differential Revision: https://reviews.llvm.org/D78030
Make --remove-section clean up dead symbols, return an Error if it can't be safely done.
Test plan: make check-all
Differential revision: https://reviews.llvm.org/D78474
Preserving liveness can be useful even late in the pipeline, if we're
doing substantial optimization work afterwards. (See, for example,
D76065.) Teach MachineOutliner how to correctly set live-ins on the
basic block in outlined functions.
Differential Revision: https://reviews.llvm.org/D78605
This patch changes Block::removeEdge to return a valid iterator to the new next
element, and uses this to update the edge removal algorithm in
LinkGraph::splitBlock.
visitExtractValueInst uses mergeInValue, so it already can handle
constant ranges. Initially the early exit was using isOverdefined to
keep things as NFC during the initial move to ValueLatticeElement.
As the function already supports constant ranges, it can just use
ValueState[&I].isOverdefined.
Reviewers: efriedma, mssimpso, davide
Reviewed By: efriedma
Differential Revision: https://reviews.llvm.org/D78393
Hash Jump Table Indices uniquely within a basic block for MIR
Canonicalizer / MIR VReg Renamer passes.
Differential Revision: https://reviews.llvm.org/D77966
Add support for relocations for MachO to ObjectYAML / yaml2obj / obj2yaml.
Test plan: make check-all
Differential revision: https://reviews.llvm.org/D77844
Currently an indirect call produces the following sequence on PCRelative mode:
extern void function( );
extern void (*ptrfunc) ( );
void g() {
ptrfunc=function;
}
void f() {
(*ptrfunc) ( );
}
Producing
paddi 3, 0, .LC0@PCREL, 1
ld 3, 0(3)
std 2, 24(1)
ld 12, 0(3)
mtctr 12
bctrl
ld 2, 24(1)
Though the caller does not use or preserve r2, it is still saved and restored
across a function call. This patch is added to remove these redundant save and
restores for indirect calls.
Differential Revision: https://reviews.llvm.org/D77749
llvm/lib/Target/Hexagon/HexagonTargetObjectFile.cpp:296:11: warning: enumeration value 'ScalableVectorTyID' not handled in switch [-Wswitch]
switch (Ty->getTypeID()) {
^
This was reported as PR45635, committed first as
72a9e7c926f4e32f209e528ec407fe526da5587e, reverted by
188f5cde9635a29a3f20ee2a73abd02890a752c7, and now recommitted with the
test change.
Summary:
This commit recommits the reversion of https://reviews.llvm.org/D75039.
Concensus appears to be in favour of assembly-time resolution of
these ADR and LDR relocations, in line with GNU. The previous
backout broke many lld tests, now fixed by Peter Smith in
61bccda9d9d920c72f49025f11e8601daeb096ec.
Reviewers: psmith
Subscribers: kristof.beyls, hiraditya, danielkiss, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D78301
Add initial support for PC Relative addressing to get jump table base
address instead of using TOC.
Differential Revision: https://reviews.llvm.org/D75931
Summary:
This change mentions CDE assembly in the LLVM release notes and CDE
intrinsics in both Clang and LLVM release notes.
Reviewers: kristof.beyls, simon_tatham
Reviewed By: kristof.beyls
Subscribers: danielkiss, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D78481
Add support to optionally emit different instrumentation for accesses to
volatile variables. While the default TSAN runtime likely will never
require this feature, other runtimes for different environments that
have subtly different memory models or assumptions may require
distinguishing volatiles.
One such environment are OS kernels, where volatile is still used in
various places for various reasons, and often declare volatile to be
"safe enough" even in multi-threaded contexts. One such example is the
Linux kernel, which implements various synchronization primitives using
volatile (READ_ONCE(), WRITE_ONCE()). Here the Kernel Concurrency
Sanitizer (KCSAN) [1], is a runtime that uses TSAN instrumentation but
otherwise implements a very different approach to race detection from
TSAN.
While in the Linux kernel it is generally discouraged to use volatiles
explicitly, the topic will likely come up again, and we will eventually
need to distinguish volatile accesses [2]. The other use-case is
ignoring data races on specially marked variables in the kernel, for
example bit-flags (here we may hide 'volatile' behind a different name
such as 'no_data_race').
[1] https://github.com/google/ktsan/wiki/KCSAN
[2] https://lkml.kernel.org/r/CANpmjNOfXNE-Zh3MNP=-gmnhvKbsfUfTtWkyg_=VqTxS4nnptQ@mail.gmail.com
Author: melver (Marco Elver)
Reviewed-in: https://reviews.llvm.org/D78554
As discussed in http://lists.llvm.org/pipermail/llvm-dev/2020-March/140349.html,
the minimum version of CMake required to build LLVM will be upgraded to
3.13.4 right after we create the release branch for LLVM 11.0.0.
As part of this effort, this commit adds a warning to give a heads up
to folks regarding the upcoming upgrade. This should allow users to
upgrade their CMake in advance so that the upgrade can sail right
through when the time comes.
Differential Revision: https://reviews.llvm.org/D77740
If a 16-bit thumb STM with writeback stores the base register but it isn't the
first register in the list, then an unknown value is stored. The load/store
optimizer knows this and generates a 32-bit STM without writeback instead, but
thumb2 size reduction converts it into a 16-bit STM. Fix this by having thumb2
size reduction notice such STMs and leave them as they are.
Differential Revision: https://reviews.llvm.org/D78493
This adds some extra processing into the Pre-RA ARM load/store optimizer
to detect and merge MVE loads/stores and adds of the same base. This we
don't always turn into a post-inc during ISel, and due to the nature of
it being a graph we don't always know an order to use for the nodes, not
knowing which nodes to make post-inc and which to use the new post-inc
of. After ISel, we have an order that we can use to post-inc the
following instructions.
So this looks for a loads/store with a starting offset of 0, and an
add/sub from the same base, plus a number of other loads/stores. We then
do some checks and convert the zero offset load/store into a postinc
variant. Any loads/stores after it have the offset subtracted from their
immediates. For example:
LDR #4 LDR #4
LDR #0 LDR_POSTINC #16
LDR #8 LDR #-8
LDR #12 LDR #-4
ADD #16
It only handles MVE loads/stores at the moment. Normal loads/store will
be added in a followup patch, they just have some extra details to
ensure that we keep generating LDRD/LDM successfully.
Differential Revision: https://reviews.llvm.org/D77813
