The way that stack coloring updated MMOs when merging stack slots, while
correct, is suboptimal, and is incompatible with the use of AA during
instruction scheduling. The solution, which involves the use of const_cast (and
more importantly, updating the IR from within an MI-level pass), obviously
requires some explanation:
When the stack coloring pass was originally committed, the code in
ScheduleDAGInstrs::buildSchedGraph tracked possible alias sets by using
GetUnderlyingObject, and all load/store and store/store memory control
dependencies where added between SUs at the object level (where only one
object, that returned by GetUnderlyingObject, was used to identify the object
associated with each MMO). When stack coloring merged stack slots, it would
replace MMOs derived from the remapped alloca with the alloca with which the
remapped alloca was being replaced. Because ScheduleDAGInstrs only used single
objects, and tracked alias sets at the object level, this was a fine solution.
In r169744, (Andy and) I updated the code in ScheduleDAGInstrs to use
GetUnderlyingObjects, and track alias sets using, potentially, multiple
underlying objects for each MMO. This was done, primarily, to provide the
ability to look through PHIs, and provide better scheduling for
induction-variable-dependent loads and stores inside loops. At this point, the
MMO-updating code in stack coloring became suboptimal, because it would clear
the MMOs for (i.e. completely pessimize) all instructions for which r169744
might help in scheduling. Updating the IR directly is the simplest fix for this
(and the one with, by far, the least compile-time impact), but others are
possible (we could give each MMO a small vector of potential values, or make
use of a remapping table, constructed from MFI, inside ScheduleDAGInstrs).
Unfortunately, replacing all MMO values derived from the remapped alloca with
the base replacement alloca fundamentally breaks our ability to use AA during
instruction scheduling (which is critical to performance on some targets). The
reason is that the original MMO might have had an offset (either constant or
dynamic) from the base remapped alloca, and that offset is not present in the
updated MMO. One possible way around this would be to use
GetPointerBaseWithConstantOffset, and update not only the MMO's value, but also
its offset based on the original offset. Unfortunately, this solution would
only handle constant offsets, and for safety (because AA is not completely
restricted to deducing relationships with constant offsets), we would need to
clear all MMOs without constant offsets over the entire function. This would be
an even worse pessimization than the current single-object restriction. Any
other solution would involve passing around a vector of remapped allocas, and
teaching AA to use it, introducing additional complexity and overhead into AA.
Instead, when remapping an alloca, we replace all IR uses of that alloca as
well (optionally inserting a bitcast as necessary). This is even more efficient
that the old MMO-updating code in the stack coloring pass (because it removes
the need to call GetUnderlyingObject on all MMO values), removes the
single-object pessimization in the default configuration, and enables the
correct use of AA during instruction scheduling (all without any additional
overhead).
LLVM now no longer miscompiles itself on x86_64 when using -enable-misched
-enable-aa-sched-mi -misched-bottomup=0 -misched-topdown=0 -misched=shuffle!
Fixed PR18497.
Because the alloca replacement is now done at the IR level, unless the MMO
directly refers to the remapped alloca, the change cannot be seen at the MI
level. As a result, there is no good way to fix test/CodeGen/X86/pr14090.ll.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199658 91177308-0d34-0410-b5e6-96231b3b80d8
The addition of IC_OPSIZE_ADSIZE in r198759 wasn't quite complete. It
also turns out to have been unnecessary. The disassembler handles the
AdSize prefix for itself, and doesn't care about the difference between
(e.g.) MOV8ao8 and MOB8ao8_16 definitions. So just let them coexist and
don't worry about it.
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The disassembler has a special case for 'L' vs. 'W' in its heuristic for
checking for 32-bit and 16-bit equivalents. We could expand the heuristic,
but better just to be consistent in using the 'L' suffix.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199652 91177308-0d34-0410-b5e6-96231b3b80d8
Not quite sure why this was marked isAsmParserOnly, but it means that the
disassembler can't see it either.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199651 91177308-0d34-0410-b5e6-96231b3b80d8
When disassembling in 16-bit mode the meaning of the OpSize bit is
inverted. Instructions found in the IC_OPSIZE context will actually
*not* have the 0x66 prefix, and instructions in the IC context will
have the 0x66 prefix. Make use of the existing special-case handling
for the 0x66 prefix being in the wrong place, to cope with this.
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various opt verifier commandline options.
Mostly mechanical wiring of the verifier to the new pass manager.
Exercises one of the more unusual aspects of it -- a pass can be either
a module or function pass interchangably. If this is ever problematic,
we can make things more constrained, but for things like the verifier
where there is an "obvious" applicability at both levels, it seems
convenient.
This is the next-to-last piece of basic functionality left to make the
opt commandline driving of the new pass manager minimally functional for
testing and further development. There is still a lot to be done there
(notably the factoring into .def files to kill the current boilerplate
code) but it is relatively uninteresting. The only interesting bit left
for minimal functionality is supporting the registration of analyses.
I'm planning on doing that on top of the .def file switch mostly because
the boilerplate for the analyses would be significantly worse.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199646 91177308-0d34-0410-b5e6-96231b3b80d8
Add support for the symbol(tlsldo) relocation. This is required in order to
solve PR18554.
Reviewed by R. Golin, A. Korobeynikov.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199644 91177308-0d34-0410-b5e6-96231b3b80d8
This logic hadn't been updated to handle FastMathFlags, and it took me a while to detect it because it doesn't show up in a simple search for CreateFAdd.
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For FCMEQ, FCMGE, FCMGT, FCMLE and FCMLT, floating point zero will be
printed as #0.0 instead of #0. To support the history codes using #0,
we consider to let asm parser accept both #0.0 and #0.
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intrinsics.
Reported on the list by Evan with a couple of attempts to fix, but it
took a while to dig down to the root cause. There are two overlapping
bugs here, both centering around the circumstance of discovering
a memcpy operand which is known to be completely outside the bounds of
the alloca.
First, we need to kill the *other* side of the memcpy if it was added to
this alloca. Otherwise we'll factor it into our slicing and try to
rewrite it even though we know for a fact that it is dead. This is made
more tricky because we can visit the sides in either order. So we have
to both kill the other side and skip instructions marked as dead. The
latter really should be goodness in every case, but here is a matter of
correctness.
Second, we need to actually remove the *uses* of the alloca by the
memcpy when queuing it for later deletion. Otherwise it may still be
using the alloca when we go to promote it (if the rewrite re-uses the
existing alloca instruction). Do this by factoring out the
use-clobbering used when for nixing a Phi argument and re-using it
across the operands of a to-be-deleted instruction.
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Ensure that the tag types are reflected on a replacement. This is particularly
important for the compatibility tag which has multiple representations where the
last definition wins.
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a reduction.
Really. Under certain circumstances (the use list of an instruction has to be
set up right - hence the extra pass in the test case) we would not recognize
when a value in a potential reduction cycle was used multiple times by the
reduction cycle.
Fixes PR18526.
radar://15851149
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This makes the 'verifyFunction' and 'verifyModule' functions totally
independent operations on the LLVM IR. It also cleans up their API a bit
by lifting the abort behavior into their clients and just using an
optional raw_ostream parameter to control printing.
The implementation of the verifier is now just an InstVisitor with no
multiple inheritance. It also is significantly more const-correct, and
hides the const violations internally. The two layers that force us to
break const correctness are building a DomTree and dispatching through
the InstVisitor.
A new VerifierPass is used to implement the legacy pass manager
interface in terms of the other pieces.
The error messages produced may be slightly different now, and we may
have slightly different short circuiting behavior with different usage
models of the verifier, but generally everything works equivalently and
this unblocks wiring the verifier up to the new pass manager.
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llvm-tblgen is not built when external LLVM_TABLEGEN is specified.
Even then, llvm-tblgen should be built for testing tblgen itself.
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getOrCreateSubprogramDIE to avoid attributes being added twice when DIEs
are merged.
rdar://problem/15842330.
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Summary:
The only current use of this flag is to mark the alloca as dynamic, even
if its in the entry block. The stack adjustment for the alloca can
never be folded into the prologue because the call may clear it and it
has to be allocated at the top of the stack.
Reviewers: majnemer
CC: llvm-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D2571
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This patch adds two new target-independent calling conventions for runtime
calls - PreserveMost and PreserveAll.
The target-specific implementation for X86-64 is defined as following:
- Arguments are passed as for the default C calling convention
- The same applies for the return value(s)
- PreserveMost preserves all GPRs - except R11
- PreserveAll preserves all GPRs and all XMMs/YMMs - except R11
Reviewed by Lang and Philip
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Fix MLA defs to use register class GPRnopc.
Add encoding tests for multiply instructions.
(Alias for MUL/SMLAL/UMLAL added by r199026.)
Patch by Zhaoshi.
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This makes things a lot easier, because we can now talk about the
"argument allocation", which allocates all the memory for the call in
one shot.
The only functional change is to the verifier for a feature that hasn't
shipped yet.
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