From:
int M, total;
void foo() {
int i;
for (i = 0; i < M; i++) {
total = total + i / 2;
}
}
This is the kernel loop:
.LBB0_2: # %for.body
=>This Inner Loop Header: Depth=1
movl %edx, %esi
movl %ecx, %edx
shrl $31, %edx
addl %ecx, %edx
sarl %edx
addl %esi, %edx
incl %ecx
cmpl %eax, %ecx
jl .LBB0_2
--------------------------
The first mov insn "movl %edx, %esi" could be removed if we change "addl %esi, %edx" to "addl %edx, %esi".
The IR before TwoAddressInstructionPass is:
BB#2: derived from LLVM BB %for.body
Predecessors according to CFG: BB#1 BB#2
%vreg3<def> = COPY %vreg12<kill>; GR32:%vreg3,%vreg12
%vreg2<def> = COPY %vreg11<kill>; GR32:%vreg2,%vreg11
%vreg7<def,tied1> = SHR32ri %vreg3<tied0>, 31, %EFLAGS<imp-def,dead>; GR32:%vreg7,%vreg3
%vreg8<def,tied1> = ADD32rr %vreg3<tied0>, %vreg7<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg8,%vreg3,%vreg7
%vreg9<def,tied1> = SAR32r1 %vreg8<kill,tied0>, %EFLAGS<imp-def,dead>; GR32:%vreg9,%vreg8
%vreg4<def,tied1> = ADD32rr %vreg9<kill,tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg4,%vreg9,%vreg2
%vreg5<def,tied1> = INC64_32r %vreg3<kill,tied0>, %EFLAGS<imp-def,dead>; GR32:%vreg5,%vreg3
CMP32rr %vreg5, %vreg0, %EFLAGS<imp-def>; GR32:%vreg5,%vreg0
%vreg11<def> = COPY %vreg4; GR32:%vreg11,%vreg4
%vreg12<def> = COPY %vreg5<kill>; GR32:%vreg12,%vreg5
JL_4 <BB#2>, %EFLAGS<imp-use,kill>
Now TwoAddressInstructionPass will choose vreg9 to be tied with vreg4. However, it doesn't see that there is copy from vreg4 to vreg11 and another copy from vreg11 to vreg2 inside the loop body. To remove those copies, it is necessary to choose vreg2 to be tied with vreg4 instead of vreg9. This code pattern commonly appears when there is reduction operation in a loop.
So check for a reversed copy chain and if we encounter one then we can commute the add instruction so we can avoid a copy.
Patch by Wei Mi.
http://reviews.llvm.org/D7806
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231148 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This does not conceptually belongs here. Instead provide a shortcut
getModule() that provides access to the DataLayout.
Reviewers: chandlerc, echristo
Reviewed By: echristo
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D8027
From: Mehdi Amini <mehdi.amini@apple.com>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231147 91177308-0d34-0410-b5e6-96231b3b80d8
I removed the copy ctor, thinking that'd be the end of it - these
iterators should be perfectly assignable even from disjoint ranges (as
any iterator would be) - exkcept that the member was const.
Unconstify it.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231146 91177308-0d34-0410-b5e6-96231b3b80d8
The assertion was just checking a class invariant that's pretty easy to
verify by inspection (no mutating operations, and the two non-copy ctors
already ensure the state is maintained) so remove the explicit copy ctor
in favor of the default, thus allowing the use of the default copy
assignment operator without hitting the C++11 deprecation here.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231143 91177308-0d34-0410-b5e6-96231b3b80d8
There's no reason to disallow assigning an iterator from one range to an
iterator that previously iterated over a disjoint range. This then
follows the Rule of Zero, allowing implicit copy construction to be used
without hitting the case that's deprecated in C++11.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231142 91177308-0d34-0410-b5e6-96231b3b80d8
There doesn't seem to be any need to assert that iterator assignment is
between iterators over the same node - if you want to reuse an iterator
variable to iterate another node, that's perfectly acceptable. Just
don't mix comparisons between iterators into disjoint sequences, as
usual.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231138 91177308-0d34-0410-b5e6-96231b3b80d8
Accidentally committed a few more of these cleanup changes than
intended. Still breaking these out & tidying them up.
This reverts commit r231135.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231136 91177308-0d34-0410-b5e6-96231b3b80d8
There doesn't seem to be any need to assert that iterator assignment is
between iterators over the same node - if you want to reuse an iterator
variable to iterate another node, that's perfectly acceptable. Just
don't mix comparisons between iterators into disjoint sequences, as
usual.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231135 91177308-0d34-0410-b5e6-96231b3b80d8
There doesn't seem to be any need to assert that iterator assignment is
between iterators over the same node - if you want to reuse an iterator
variable to iterate another node, that's perfectly acceptable. Just
don't mix comparisons between iterators into disjoint sequences, as
usual.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231134 91177308-0d34-0410-b5e6-96231b3b80d8
This type could be made copyable (= default a protected copy ctor in the
base class, and preferably make the derived class final to avoid risks
of providing a slicing copy operation to further derived classes) but it
seemed easier to avoid that complexity for a dump function that I assume
(by symmetry with ResourcePriorityQueue's dump, which was actively
buggy) not often used.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231133 91177308-0d34-0410-b5e6-96231b3b80d8
This patch was landed in r231035 and reverted because it was buggy.
This is fixed version of the same change.
Summary:
This patch is an attempt at making `DenseMapIterator`s "fail-fast".
Fail-fast iterators that have been invalidated due to insertion into
the host `DenseMap` deterministically trip an assert (in debug mode)
on access, instead of non-deterministically hitting memory corruption
issues.
Reviewers: dexonsmith, dberlin, ruiu, chandlerc
Reviewed By: chandlerc
Subscribers: yaron.keren, chandlerc, llvm-commits
Differential Revision: http://reviews.llvm.org/D7931
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231125 91177308-0d34-0410-b5e6-96231b3b80d8
frame register before checking if there is a DWARF register number for it.
Thanks to H.J. Lu for diagnosing this and providing the testcase!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231121 91177308-0d34-0410-b5e6-96231b3b80d8
Without this, use of this copy ctor is deprecated in C++11 due to the
presence of a user-declared dtor.
Marking the class final is just a little extra security that there are
no further derived classes that may then end up using the intermediate
base class's copy assignment operator and cause slicing to occur.
I didn't bother marking the other (non-test) base class final, since it
has reference members so it won't have any implicit assignment operators
anyway. Open to ideas on that, though.
We probably want a warning about use of a slicing assignment operator,
then I wouldn't worry so much about marking the class as final.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231114 91177308-0d34-0410-b5e6-96231b3b80d8
Making this type a little harder to abuse (see workaround relating to
use of the implicit copy ctor in the prior commit)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231104 91177308-0d34-0410-b5e6-96231b3b80d8
The cause of the issue is the interaction of two factors:
1) When generating a DW_TAG_imported_declaration DIE which imports another
imported declaration, the code in AsmPrinter/DwarfCompileUnit.cpp
asserts that the second imported declaration must already have a DIE.
2) There is a non-determinism in the order in which imported declarations
within the same scope are processed.
Because of the non-determinism (2), it is possible that an imported
declaration is processed before another one it depends on, breaking the
assumption in (1).
The source of the non-determinism is that the imported declaration
DIDescriptors are sorted by scope in DwarfDebug::beginModule(); however that
sort is not a stable_sort, therefore the order of the declarations within
the same scope is not preserved. The attached patch changes the std::sort to
a std::stable_sort and it fixes the problem.
Test omitted due to it being non-deterministic and depending on the
implementation of std::sort.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231100 91177308-0d34-0410-b5e6-96231b3b80d8
I tried making these private & friended to the BitVector, but that
didn't work - there's one use of BitVector::reference in Clang that
actually copies it into a local variable & uses it from there, rather
than just using the result of op[] in a temporary expression.
Whether or not this is desired is debatable (we could just fix that one
use in Clang) & it's not clear which way the C++ standard falls on this
for std::bitset's reference type (it has the same bug at least in
libstdc++, but Clang's -Wdeprecated doesn't flag it, because it's in a
standard header)
While it was only BitVector::reference's copy ctor that was referenced
by user code, I made SmallBitVector::reference's copy ctor public too,
for consistency.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231099 91177308-0d34-0410-b5e6-96231b3b80d8
Ultimately, __CxxFrameHandler3 needs us to put a stack offset in a
table, and it will take responsibility for copying the exception object
into that slot. Modelling the exception object as an SSA value returned
by begincatch isn't going to work in general, so make it use an output
parameter.
Reviewers: andrew.w.kaylor
Differential Revision: http://reviews.llvm.org/D7920
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231086 91177308-0d34-0410-b5e6-96231b3b80d8
Move the specialized metadata nodes for the new debug info hierarchy
into place, finishing off PR22464. I've done bootstraps (and all that)
and I'm confident this commit is NFC as far as DWARF output is
concerned. Let me know if I'm wrong :).
The code changes are fairly mechanical:
- Bumped the "Debug Info Version".
- `DIBuilder` now creates the appropriate subclass of `MDNode`.
- Subclasses of DIDescriptor now expect to hold their "MD"
counterparts (e.g., `DIBasicType` expects `MDBasicType`).
- Deleted a ton of dead code in `AsmWriter.cpp` and `DebugInfo.cpp`
for printing comments.
- Big update to LangRef to describe the nodes in the new hierarchy.
Feel free to make it better.
Testcase changes are enormous. There's an accompanying clang commit on
its way.
If you have out-of-tree debug info testcases, I just broke your build.
- `upgrade-specialized-nodes.sh` is attached to PR22564. I used it to
update all the IR testcases.
- Unfortunately I failed to find way to script the updates to CHECK
lines, so I updated all of these by hand. This was fairly painful,
since the old CHECKs are difficult to reason about. That's one of
the benefits of the new hierarchy.
This work isn't quite finished, BTW. The `DIDescriptor` subclasses are
almost empty wrappers, but not quite: they still have loose casting
checks (see the `RETURN_FROM_RAW()` macro). Once they're completely
gutted, I'll rename the "MD" classes to "DI" and kill the wrappers. I
also expect to make a few schema changes now that it's easier to reason
about everything.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231082 91177308-0d34-0410-b5e6-96231b3b80d8
Add the final bits of API that `DIBuilder` needs before the new nodes
can be moved into place.
- Add `MDType::clone()` and `MDType::setFlags()` to support
`DIBuilder::createTypeWithFlags()`.
- Add `MDBasicType::get()` overload that just requires a tag and a
name, as a convenience for `DIBuilder::createUnspecifiedType()`.
- Add `MDLocalVariable::withInline()` and
`MDLocalVariable::withoutInline()` to support
`llvm::createInlinedVariable()` and
`llvm::cleanseInlinedVariable()`.
(Somehow these got lost inside the "move into place" patch I'm about to
commit -- better to commit separately!)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231079 91177308-0d34-0410-b5e6-96231b3b80d8
This prevents the behavior observed in llvm.org/PR22369. I am not sure
whether I am reading the code correctly, but the early exit based on
isLiveOutPastPHIs() seems to make the wrong assumption that
RegisterCoalescer won't be able to coalesce those copies later.
This change hides the new behavior behind -no-phi-elim-live-out-early-exit
as it currently breaks four tests:
* Assertion in:
CodeGen/Hexagon/hwloop-cleanup.ll
* Worse code in:
CodeGen/X86/coalescer-commute4.ll
CodeGen/X86/phys_subreg_coalesce-2.ll
CodeGen/X86/zlib-longest-match.ll
The root cause here seems to be that the heuristic that determines
the visitation order in RegisterCoalescer gets less lucky.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231064 91177308-0d34-0410-b5e6-96231b3b80d8
