The CountPrev variable was only used to forward a value from
the if statement to the conditional operator under the same
condition.
While there move some variable declarations to their first
assignment.
The file was added in 2007 but the functions have never been implemented.
Having the file can only cause confusion to existing C API (llvm-c/lto.h) users.
Notes about a few declarations:
* LiveVariables::RegisterDefIsDead: deleted by r47927
* createForwardControlFlowIntegrityPass, createJumpInstrTablesPass: deleted by r230780
* RegScavenger::setLiveInsUsed: deleted by r292543
* ScheduleDAGInstrs::{toggleKillFlag,startBlockForKills}: deleted by r304055
* Localizer::shouldLocalize: remnant of D75207
* DwarfDebug::addSectionLabel: deleted by r373273
For some inputs, the constraint system can grow quite large during
solving, because it replaces complex constraints with one or more
simpler constraints. This adds a cut-off to avoid compile-time explosion
on problematic inputs.
This change adds the context-senstive sample PGO infracture described in CSSPGO RFC (https://groups.google.com/g/llvm-dev/c/1p1rdYbL93s). It introduced an abstraction between input profile and profile loader that queries input profile for functions. Specifically, there's now the notion of base profile and context profile, and they are managed by the new SampleContextTracker for adjusting and merging profiles based on inline decisions. It works with top-down profiled guided inliner in profile loader (https://reviews.llvm.org/D70655) for better inlining with specialization and better post-inline profile fidelity. In the future, we can also expose this infrastructure to CGSCC inliner in order for it to take advantage of context-sensitive profile. This change is the consumption part of context-sensitive profile (The generation part is in this stack: https://reviews.llvm.org/D89707). We've seen good results internally in conjunction with Pseudo-probe (https://reviews.llvm.org/D86193). Pacthes for integration with Pseudo-probe coming up soon.
Currently the new infrastructure kick in when input profile contains the new context-sensitive profile; otherwise it's no-op and does not affect existing AutoFDO.
**Interface**
There're two sets of interfaces for query and tracking respectively exposed from SampleContextTracker. For query, now instead of simply getting a profile from input for a function, we can explicitly query base profile or context profile for given call path of a function. For tracking, there're separate APIs for marking context profile as inlined, or promoting and merging not inlined context profile.
- Query base profile (`getBaseSamplesFor`)
Base profile is the merged synthetic profile for function's CFG profile from any outstanding (not inlined) context. We can query base profile by function.
- Query context profile (`getContextSamplesFor`)
Context profile is a function's CFG profile for a given calling context. We can query context profile by context string.
- Track inlined context profile (`markContextSamplesInlined`)
When a function is inlined for given calling context, we need to mark the context profile for that context as inlined. This is to make sure we don't include inlined context profile when synthesizing base profile for that inlined function.
- Track not-inlined context profile (`promoteMergeContextSamplesTree`)
When a function is not inlined for given calling context, we need to promote the context profile tree so the not inlined context becomes top-level context. This preserve the sub-context under that function so later inline decision for that not inlined function will still have context profile for its call tree. Note that profile will be merged if needed when promoting a context profile tree if any of the node already exists at its promoted destination.
**Implementation**
Implementation-wise, `SampleContext` is created as abstraction for context. Currently it's a string for call path, and we can later optimize it to something more efficient, e.g. context id. Each `SampleContext` also has a `ContextState` indicating whether it's raw context profile from input, whether it's inlined or merged, whether it's synthetic profile created by compiler. Each `FunctionSamples` now has a `SampleContext` that tells whether it's base profile or context profile, and for context profile what is the context and state.
On top of the above context representation, a custom trie tree is implemented to track and manager context profiles. Specifically, `SampleContextTracker` is implemented that encapsulates a trie tree with `ContextTireNode` as node. Each node of the trie tree represents a frame in calling context, thus the path from root to a node represents a valid calling context. We also track `FunctionSamples` for each node, so this trie tree can serve efficient query for context profile. Accordingly, context profile tree promotion now becomes moving a subtree to be under the root of entire tree, and merge nodes for subtree if this move encounters existing nodes.
**Integration**
`SampleContextTracker` is now also integrated with AutoFDO, `SampleProfileReader` and `SampleProfileLoader`. When we detected input profile contains context-sensitive profile, `SampleContextTracker` will be used to track profiles, and all profile query will go to `SampleContextTracker` instead of `SampleProfileReader` automatically. Tracking APIs are called automatically for each inline decision from `SampleProfileLoader`.
Differential Revision: https://reviews.llvm.org/D90125
Move fold of (sext (not i1 x)) -> (add (zext i1 x), -1) from X86 to DAGCombiner to improve codegen on other targets.
Differential Revision: https://reviews.llvm.org/D91589
Noticed while looking at D92701 - we only really handle TCK_RecipThroughput gather/scatter costs - for now drop back to the default implementation for non-legal gathers/scatters.
BasicAA has some special bit of logic for "same base pointer" GEPs
that performs a structural comparison: It only looks at two GEPs
with the same base (as opposed to two GEP chains with a MustAlias
base) and compares their indexes in a limited way. I generalized
part of this code in D91027, and this patch merges the remainder
into the normal decomposed GEP logic.
What this code ultimately wants to do is to determine that
gep %base, %idx1 and gep %base, %idx2 don't alias if %idx1 != %idx2,
and the access size fits within the stride.
We can express this in terms of a decomposed GEP expression with
two indexes scale*%idx1 + -scale*%idx2 where %idx1 != %idx2, and
some appropriate checks for sizes and offsets.
This makes the reasoning slightly more powerful, and more
importantly brings all the GEP logic under a common umbrella.
Differential Revision: https://reviews.llvm.org/D92723
687b83ceabafe81970cd4639e7f0c89036402081 has fixed the X86FastISel bug.
We can revert the workaround now. Actually, the commit introduced a
bug that ppc64 should be excluded.
This fixes the bug referenced by 5582a7987662a92eda5d883b88fc4586e755acf5
which was exposed by 961f31d8ad14c66829991522d73e14b5a96ff6d4.
With this change, `movq src@GOTPCREL, %rcx` => `movq src@GOTPCREL(%rip), %rcx`
The x86-64 backend currently has a bug which uses a wrong register when for the GOTPCREL reference.
The program will crash without the dso_local specifier.
On the surface this would be slightly less optimal for the isel
table, but due to a tablegen issue with HW mode this ends up
generating a smaller isel table.
AddressSanitizer instrumentation does not set dso_local on non-thread-local
global variables in -fno-pic and it seems to rely on implied dso_local to work.
Add a hack until we have fixed AddressSanitizer to call setDSOLocal() as
appropriate.
Thanks to Vitaly Buka for reporting the issue and suggesting the way to detect asan.
The basic idea is that by looking through operand instructions which don't change the equality result that we can push the existing known bits comparison down past instructions which would obscure them.
We have analogous handling in InstSimplify for most - though weirdly not all - of these cases starting from an icmp root. It's a bit unfortunate to duplicate logic, but since my actual goal is to extend BasicAA, the icmp logic doesn't help. (And just makes it hard to test here.) The BasicAA change will be posted separately for review.
Differential Revision: https://reviews.llvm.org/D92698
This does not deserve special handling. The code should be added to Clang
instead if deemed useful. With this simplification, we can additionally delete
the PIC extern_weak special case.
With my previous commit, X86Subtarget::classifyGlobalReference has learned to
use MO_NO_FLAG for 32-bit ELF -fno-pic code, the x86-32 special case in
TargetMachine::shouldAssumeDSOLocal can be removed. Since we no longer imply
dso_local for function declarations, we can drop the ppc64 special case as well.
This is NFC in terms of Clang emitted assembly.
clang/lib/CodeGen/CodeGenModule sets dso_local on applicable function declarations,
we don't need to duplicate the work in TargetMachine:shouldAssumeDSOLocal.
(Actually the long-term goal (started by r324535) is to drop TargetMachine::shouldAssumeDSOLocal.)
By not implying dso_local, we will respect dso_local/dso_preemptable specifiers
set by the frontend. This allows the proposed -fno-direct-access-external-data
option to work with -fno-pic and prevent a canonical PLT entry (SHN_UNDEF with non-zero st_value)
when taking the address of a function symbol.
This patch should be NFC in terms of the Clang emitted assembly because the case
we don't set dso_local is a case Clang sets dso_local. However, some tests don't
set dso_local on some function declarations and expose some differences. Most
tests have been fixed to be more robust in the previous commit.
They are currently implicit because TargetMachine::shouldAssumeDSOLocal implies
dso_local.
For such function declarations, clang -fno-pic emits the dso_local specifier.
Adding explicit dso_local makes these tests align with the clang behavior and
helps implementing an option to use GOT indirection when taking the address of a
function symbol in -fno-pic (to avoid a canonical PLT entry (SHN_UNDEF with
non-zero st_value)).
Due to the recursion through phis basicaa does, the code needs to be extremely careful not to reason about equality between values which might represent distinct iterations. I'm generally skeptical of the correctness of the whole scheme, but this particular patch fixes one particular instance which is demonstrateable incorrect.
Interestingly, this appears to be the second attempted fix for the same issue. The former fix is incomplete and doesn't address the actual issue.
Differential Revision: https://reviews.llvm.org/D92694
This essentially reverts the x86-64 side effect of r327198.
For x86-32, @PLT (R_386_PLT32) is not suitable in -fno-pic mode so the
code forces MO_NO_FLAG (like a forced dso_local) (https://bugs.llvm.org//show_bug.cgi?id=36674#c6).
For x86-64, both `call/jmp foo` and `call/jmp foo@PLT` emit R_X86_64_PLT32
(https://sourceware.org/bugzilla/show_bug.cgi?id=22791) so there is no
difference using @PLT. Using @PLT is actually favorable because this drops
a difference with -fpie/-fpic code and makes it possible to avoid a canonical
PLT entry when taking the address of an undefined function symbol.
LLVMBuild has been removed from the build system. However, three LLVMBuild.txt
files remain in the tree. This patch simply removes them.
llvm/lib/ExecutionEngine/Orc/TargetProcess/LLVMBuild.txt
llvm/tools/llvm-jitlink/llvm-jitlink-executor/LLVMBuild.txt
llvm/tools/llvm-profgen/LLVMBuild.txt
Differential Revision: https://reviews.llvm.org/D92693
The function accrues many `GV` nullness checks. Process `!GV`
(ExternalSymbolSDNode) early to simplify code.
Also improve a comment added in r327198 (intrinsics is a subset of
ExternalSymbolSDNode).
Intended to be NFC.
PPCMCInstLower does not actually call shouldAssumeDSOLocal for ppc32 so this is dead.
Actually Clang ppc32 does produce a pair of absolute relocations which match GCC.
This also fixes a comment (R_PPC_COPY and R_PPC64_COPY do exist).
