r303763 caused build failures in some out-of-tree tests due to an assertion in
TTI. The original patch updated cost estimates for induction variable update
instructions marked for scalarization. However, it didn't consider that the
incoming value of an induction variable phi node could be a cast instruction.
This caused queries for cast instruction costs with a mix of vector and scalar
types. This patch includes a fix for cast instructions and the test case from
PR33193.
The fix was suggested by Jonas Paulsson <paulsson@linux.vnet.ibm.com>.
Reference: https://bugs.llvm.org/show_bug.cgi?id=33193
Original Differential Revision: https://reviews.llvm.org/D33457
llvm-svn: 304235
Summary:
In rL302576, DISubprograms gained the constraint that a !dbg attachments to functions must
have a 1:1 mapping to DISubprograms. As part of that change, the function cloning support
was adjusted to attempt to enforce this invariant during cloning. However, there
were several problems with the implementation. Part of these were fixed in rL304079.
However, there was a more fundamental problem with these changes, namely that it
bypasses the matadata value map, causing the cloned metadata to be a mix of metadata
pointing to the new suprogram (where manual code was added to fix those up) and the
old suprogram (where this was not the case). This mismatch could cause a number of
different assertion failures in the DWARF emitter. Some of these are given at
https://github.com/JuliaLang/julia/issues/22069, but some others have been observed
as well. Attempt to rectify this by partially reverting the manual DI metadata fixup,
and instead using the standard value map approach. To retain the desired semantics
of not duplicating the compilation unit and inlined subprograms, explicitly freeze
these in the value map.
Reviewers: dblaikie, aprantl, GorNishanov, echristo
Reviewed By: aprantl
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D33655
llvm-svn: 304226
Summary:
I believe https://reviews.llvm.org/rL302576 introduced two bugs:
1) it produces duplicate distinct variables for every: dbg.value describing the same variable.
To fix the problme I switched form getDistinct() to get() in DebugLoc.cpp: auto reparentVar = [&](DILocalVariable *Var) {
return DILocalVariable::getDistinct(
2) It passes NewFunction plain name as a linkagename parameter to Subprogram constructor. Breaks assert in:
|| DeclLinkageName.empty()) || LinkageName == DeclLinkageName) && "decl has a linkage name and it is different"' failed.
#9 0x00007f5010261b75 llvm::DwarfUnit::applySubprogramDefinitionAttributes(llvm::DISubprogram const*, llvm::DIE&) /home/gor/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp:1173:3
#
(Edit: reproducer added)
Here how https://reviews.llvm.org/rL302576 broke coroutine debug info.
Coroutine body of the original function is split into several parts by cloning and removing unneeded code.
All parts describe the original function and variables present in the original function.
For a simple case, prior to Split, original function has these two blocks:
```
PostSpill: ; preds = %AllocaSpillBB
call void @llvm.dbg.value(metadata i32 %x, i64 0, metadata !14, metadata !15), !dbg !13
store i32 %x, i32* %x.addr, align 4
...
and
sw.epilog: ; preds = %sw.bb
%x.addr.reload.addr = getelementptr inbounds %f.Frame, %f.Frame* %FramePtr, i32 0, i32 4, !dbg !20
%4 = load i32, i32* %x.addr.reload.addr, align 4, !dbg !20
call void @llvm.dbg.value(metadata i32 %4, i64 0, metadata !14, metadata !15), !dbg !13!14 = !DILocalVariable(name: "x", arg: 1, scope: !6, file: !7, line: 55, type: !11)
```
Note that in two blocks different expression represent the same original user variable X.
Before rL302576, for every cloned function there was exactly one cloned DILocalVariable(name: "x" as in:
```
define i8* @f(i32 %x) #0 !dbg !6 {
...
!6 = distinct !DISubprogram(name: "f", scope: !7, file: !7, line: 55, type: !8, isLocal: false, isDefinition: true, scopeLine: 55, flags: DIFlagPrototyped,
...
!14 = !DILocalVariable(name: "x", arg: 1, scope: !6, file: !7, line: 55, type: !11)
define internal fastcc void @f.resume(%f.Frame* %FramePtr) #0 !dbg !25 {
...
!25 = distinct !DISubprogram(name: "f", scope: !7, file: !7, line: 55, type: !8, isLocal: false, isDefinition: true, scopeLine: 55, flags: DIFlagPrototyped, isOptimized: false, unit: !0, variables: !2)
!28 = !DILocalVariable(name: "x", arg: 1, scope: !25, file: !7, line: 55, type: !11)
```
After rL302576, for every cloned function there were as many DILocalVariable(name: "x" as there were "call void @llvm.dbg.value" for that variable.
This was causing asserts in VerifyDebugInfo and AssemblyPrinter.
Example:
```
!27 = distinct !DISubprogram(name: "f", linkageName: "f.resume", scope: !7, file: !7, line: 55, type: !8, isLocal: false, isDefinition: true, scopeLine: 55,
!29 = distinct !DILocalVariable(name: "x", arg: 1, scope: !27, file: !7, line: 55, type: !11)
!39 = distinct !DILocalVariable(name: "x", arg: 1, scope: !27, file: !7, line: 55, type: !11)
!41 = distinct !DILocalVariable(name: "x", arg: 1, scope: !27, file: !7, line: 55, type: !11)
```
Second problem:
Prior to rL302576, all clones were described by DISubprogram referring to original function.
```
define i8* @f(i32 %x) #0 !dbg !6 {
...
!6 = distinct !DISubprogram(name: "f", scope: !7, file: !7, line: 55, type: !8, isLocal: false, isDefinition: true, scopeLine: 55, flags: DIFlagPrototyped,
define internal fastcc void @f.resume(%f.Frame* %FramePtr) #0 !dbg !25 {
...
!25 = distinct !DISubprogram(name: "f", scope: !7, file: !7, line: 55, type: !8, isLocal: false, isDefinition: true, scopeLine: 55, flags: DIFlagPrototyped,
```
After rL302576, DISubprogram for clones is of two minds, plain name refers to the original name, linkageName refers to plain name of the clone.
```
!27 = distinct !DISubprogram(name: "f", linkageName: "f.resume", scope: !7, file: !7, line: 55, type: !8, isLocal: false, isDefinition: true, scopeLine: 55,
```
I think the assumption in AsmPrinter is that both name and linkageName should refer to the same entity. It asserts here when they are not:
```
|| DeclLinkageName.empty()) || LinkageName == DeclLinkageName) && "decl has a linkage name and it is different"' failed.
#9 0x00007f5010261b75 llvm::DwarfUnit::applySubprogramDefinitionAttributes(llvm::DISubprogram const*, llvm::DIE&) /home/gor/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp:1173:3
```
After this fix, behavior (with respect to coroutines) reverts to exactly as it was before and therefore making them debuggable again, or even more importantly, compilable, with "-g"
Reviewers: dblaikie, echristo, aprantl
Reviewed By: dblaikie
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D33614
llvm-svn: 304079
The recommit is to fix a bug about ExtractValue and InsertValue ops. For those
ops, some varargs inside GVN::Expression are not value numbers but raw index
numbers. It is wrong to do phi-translate for raw index numbers, and the fix is
to stop doing that.
Right now scalarpre doesn't have phi-translate support, so it will miss some
simple pre opportunities. Like the following testcase, current scalarpre cannot
recognize the last "a * b" is fully redundent because a and b used by the last
"a * b" expr are both defined by phis.
long a[100], b[100], g1, g2, g3;
__attribute__((pure)) long goo();
void foo(long a, long b, long c, long d) {
g1 = a * b;
if (__builtin_expect(g2 > 3, 0)) {
a = c;
b = d;
g2 = a * b;
}
g3 = a * b; // fully redundant.
}
The patch adds phi-translate support in scalarpre. This is only a temporary
solution before the newpre based on newgvn is available.
Differential Revision: https://reviews.llvm.org/D32252
llvm-svn: 304050
The whole-program-devirt pass needs to run at -O0 because only it
knows about the llvm.type.checked.load intrinsic: it needs to both
lower the intrinsic itself and handle it in the summary.
Differential Revision: https://reviews.llvm.org/D33571
llvm-svn: 304019
Every other place in InstCombine that uses these methods in ValueTracking already pass this information. This makes the remaining sites consistent.
Differential Revision: https://reviews.llvm.org/D33567
llvm-svn: 304018
We have wrappers for several other ValueTracking methods that take care of passing all of the analysis and assumption cache parameters. This extends it to isKnownToBeAPowerOfTwo.
llvm-svn: 303924
Right now scalarpre doesn't have phi-translate support, so it will miss some
simple pre opportunities. Like the following testcase, current scalarpre cannot
recognize the last "a * b" is fully redundent because a and b used by the last
"a * b" expr are both defined by phis.
long a[100], b[100], g1, g2, g3;
__attribute__((pure)) long goo();
void foo(long a, long b, long c, long d) {
g1 = a * b;
if (__builtin_expect(g2 > 3, 0)) {
a = c;
b = d;
g2 = a * b;
}
g3 = a * b; // fully redundant.
}
The patch adds phi-translate support in scalarpre. This is only a temporary
solution before the newpre based on newgvn is available.
Differential Revision: https://reviews.llvm.org/D32252
llvm-svn: 303923
There's probably a lot more like this (see also comments in D33338 about responsibility),
but I suspect we don't usually get a visible manifestation.
Given the recent interest in improving InstCombine efficiency, another potential micro-opt
that could be repeated several times in this function: morph the existing icmp pred/operands
instead of creating a new instruction.
llvm-svn: 303860
This patch provides an initial prototype for a pass that sinks instructions based on GVN information, similar to GVNHoist. It is not yet ready for commiting but I've uploaded it to gather some initial thoughts.
This pass attempts to sink instructions into successors, reducing static
instruction count and enabling if-conversion.
We use a variant of global value numbering to decide what can be sunk.
Consider:
[ %a1 = add i32 %b, 1 ] [ %c1 = add i32 %d, 1 ]
[ %a2 = xor i32 %a1, 1 ] [ %c2 = xor i32 %c1, 1 ]
\ /
[ %e = phi i32 %a2, %c2 ]
[ add i32 %e, 4 ]
GVN would number %a1 and %c1 differently because they compute different
results - the VN of an instruction is a function of its opcode and the
transitive closure of its operands. This is the key property for hoisting
and CSE.
What we want when sinking however is for a numbering that is a function of
the *uses* of an instruction, which allows us to answer the question "if I
replace %a1 with %c1, will it contribute in an equivalent way to all
successive instructions?". The (new) PostValueTable class in GVN provides this
mapping.
This pass has some shown really impressive improvements especially for codesize already on internal benchmarks, so I have high hopes it can replace all the sinking logic in SimplifyCFG.
Differential revision: https://reviews.llvm.org/D24805
llvm-svn: 303850
pass.
The original logic only considered direct successors of the hoisted
domtree nodes, but that isn't really enough. If there are other basic
blocks that are completely within the subtree, their successors could
just as easily be impacted by the hoisting.
The more I think about it, the more I think the correct update here is
to hoist every block on the dominance frontier which has an idom in the
chain we hoist across. However, this is subtle enough that I'd
definitely appreciate some more eyes on it.
Sadly, if this is the correct algorithm, it requires computing a (highly
localized) dominance frontier. I've done this in the simplest (IE, least
code) way I could come up with, but that may be too naive. Suggestions
welcome here, dominance update algorithms are not an area I've studied
much, so I don't have strong opinions.
In good news, with this patch, turning on simple unswitch passes the
LLVM test suite for me with asserts enabled.
Differential Revision: https://reviews.llvm.org/D32740
llvm-svn: 303843
having it internally allocate the loop.
This is a much more flexible API and necessary in the new loop unswitch
to reasonably support both new and old PMs in common code. It also just
seems like a cleaner separation of concerns.
NFC, this should just be a pure refactoring.
Differential Revision: https://reviews.llvm.org/D33528
llvm-svn: 303834
Coverage instrumentation which does not instrument full post-dominators
and full-dominators may skip valid paths, as the reasoning for skipping
blocks may become circular.
This patch fixes that, by only skipping
full post-dominators with multiple predecessors, as such predecessors by
definition can not be full-dominators.
llvm-svn: 303827
Summary:
Frontend generates store instructions after allocas, for example:
```
define i8* @f(i64 %this) "coroutine.presplit"="1" personality i32 0 {
entry:
%this.addr = alloca i64
store i64 %this, i64* %this.addr
..
%hdl = call i8* @llvm.coro.begin(token %id, i8* %alloc)
```
Such instructions may require spilling into coro.frame, but, coro-frame address is only available after coro.begin and thus needs to be moved after coro.begin.
The only instructions that should not be moved are the arguments of coro.begin and all of their operands.
Reviewers: GorNishanov, majnemer
Reviewed By: GorNishanov
Subscribers: llvm-commits, EricWF
Differential Revision: https://reviews.llvm.org/D33527
llvm-svn: 303825
The swapped operands in the first test is a manifestation of an
inefficiency for vectors that doesn't exist for scalars because
the IRBuilder checks for an all-ones mask for scalars, but not
vectors.
llvm-svn: 303818
While there avoid resizing the DemandedMask twice. Make a copy into a separate variable instead. This potentially removes an allocation on large bit widths.
With the use of the zextOrTrunc methods on APInt and KnownBits these can be made almost source identical. The only difference is the zero of the upper bits for ZExt. This is similar to how its done in computeKnownBits in ValueTracking.
llvm-svn: 303791
The current code created a NewBits mask and used it as a mask several times. One of them just before a call to trunc making it unnecessary. A call to getActiveBits can get us the same information for the case. We also ORed with this mask later when we should have just sign extended the known bits.
We also called trunc on the guaranteed to be zero KnownZeros/Ones masks entering this code. Creating appropriately sized temporary APInts is probably better.
Differential Revision: https://reviews.llvm.org/D32098
llvm-svn: 303779
This continues the changes started when computeSignBit was replaced with this new version of computeKnowBits.
Differential Revision: https://reviews.llvm.org/D33431
llvm-svn: 303773
For non-uniform instructions marked for scalarization, we should update
`VectorTy` when computing instruction costs to reflect the scalar type. In
addition to determining instruction costs, this type is also used to signal
that all instructions in the loop will be scalarized. This currently affects
memory instructions and non-pointer induction variables and their updates. (We
also mark GEPs scalar after vectorization, but their cost is computed together
with memory instructions.) For scalarized induction updates, this patch also
scales the scalar cost by the vectorization factor, corresponding to each
induction step.
llvm-svn: 303763
The loop vectorizer usually vectorizes any instruction it can and then
extracts the elements for a scalarized use. On SystemZ, all elements
containing addresses must be extracted into address registers (GRs). Since
this extraction is not free, it is better to have the address in a suitable
register to begin with. By forcing address arithmetic instructions and loads
of addresses to be scalar after vectorization, two benefits result:
* No need to extract the register
* LSR optimizations trigger (LSR isn't handling vector addresses currently)
Benchmarking show improvements on SystemZ with this new behaviour.
Any other target could try this by returning false in the new hook
prefersVectorizedAddressing().
Review: Renato Golin, Elena Demikhovsky, Ulrich Weigand
https://reviews.llvm.org/D32422
llvm-svn: 303744
Otherwise we don't revisit an instruction that could be simplified,
and when we verify, we discover there's something that changed, i.e.
what we had wasn't a maximal fixpoint.
Fixes PR32836.
llvm-svn: 303715
Instead of using the SCCP homegrown one. We should eventually
make the private SCCP version disappear, but that wont' be today.
PR33143 tracks this issue.
Add braces for consistency while here. No functional change intended.
llvm-svn: 303706
Coverage instrumentation has an optimization not to instrument extra
blocks, if the pass is already "accounted for" by a
successor/predecessor basic block.
However (https://github.com/google/sanitizers/issues/783) this
reasoning may become circular, which stops valid paths from having
coverage.
In the worst case this can cause fuzzing to stop working entirely.
This change simplifies logic to something which trivially can not have
such circular reasoning, as losing valid paths does not seem like a
good trade-off for a ~15% decrease in the # of instrumented basic blocks.
llvm-svn: 303698
Summary:
Before this change, AttributeLists stored a pair of index and
AttributeSet. This is memory efficient if most arguments do not have
attributes. However, it requires doing a search over the pairs to test
an argument or function attribute. Profiling shows that this loop was
0.76% of the time in 'opt -O2' of sqlite3.c, because LLVM constantly
tests values for nullability.
This was worth about 2.5% of mid-level optimization cycles on the
sqlite3 amalgamation. Here are the full perf results:
https://reviews.llvm.org/P7995
Here are just the before and after cycle counts:
```
$ perf stat -r 5 ./opt_before -O2 sqlite3.bc -o /dev/null
13,274,181,184 cycles # 3.047 GHz ( +- 0.28% )
$ perf stat -r 5 ./opt_after -O2 sqlite3.bc -o /dev/null
12,906,927,263 cycles # 3.043 GHz ( +- 0.51% )
```
This patch *does not* change the indices used to query attributes, as
requested by reviewers. Tracking whether an index is usable for array
indexing is a huge pain that affects many of the internal APIs, so it
would be good to come back later and do a cleanup to remove this
internal adjustment.
Reviewers: pete, chandlerc
Subscribers: javed.absar, llvm-commits
Differential Revision: https://reviews.llvm.org/D32819
llvm-svn: 303654
This patch builds over https://reviews.llvm.org/rL303349 and replaces
the use of the condition only if it is safe to do so.
We should not blindly RAUW the condition if experimental.guard or assume
is a use of that
condition. This is because LVI may have used the guard/assume to
identify the
value of the condition, and RUAWing will fold the guard/assume and uses
before the guards/assumes.
Reviewers: sanjoy, reames, trentxintong, mkazantsev
Reviewed by: sanjoy, reames
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D33257
llvm-svn: 303633
The default behavior of -Rpass-analysis=loop-vectorizer is to report only the
first reason encountered for not vectorizing, if one is found, at which time the
vectorizer aborts its handling of the loop. This patch allows multiple reasons
for not vectorizing to be identified and reported, at the potential expense of
additional compile-time, under allowExtraAnalysis which can currently be turned
on by Clang's -fsave-optimization-record and opt's -pass-remarks-missed.
Removed from LoopVectorizationLegality::canVectorize() the redundant checking
and reporting if we CantComputeNumberOfIterations, as LAI::canAnalyzeLoop() also
does that. This redundancy is caught by a lit test once multiple reasons are
reported.
Patch initially developed by Dror Barak.
Differential Revision: https://reviews.llvm.org/D33396
llvm-svn: 303613
