Explicitly inserting undef is overly defensive. Any values computed
nside the loop that are referenced by dbg.values should naturally
become undef when the loop is deleted, and all other values that
are loop invariant must be preserved.
Reviewed By: scott.linder
Differential Revision: https://reviews.llvm.org/D153539
Do not convert dbg.declares to dbg.assigns for variables backed by scalable
vector allocas as this isn't yet supported.
Reviewed By: jmorse
Differential Revision: https://reviews.llvm.org/D149959
`shortenAssignment` inserts dbg.assigns with fragments describing the dead part
of a shortened store after each dbg.assign linked to the store.
Without this patch it doesn't take into account that the dead part of a
shortened store may be outside the bounds of a variable of a linked
dbg.assign. It also doesn't correctly account for a non-zero offset in the
address modifying `DIExpression` of the dbg.assign (which is possible for
fragments now even though whole variables currently cannot have a non-zero
offset in their alloca).
Fix this by moving the dead slice into variable-space and performing an
intersect of that adjusted slice with the existing fragment.
This fixes a verifier error reported when building fuchsia with assignment
tracking enabled:
https://ci.chromium.org/ui/p/fuchsia/builders/ci/
clang_toolchain.ci.core.x64-release/b8784000953022145169/overview
Reviewed By: jmorse
Differential Revision: https://reviews.llvm.org/D148536
Debug intrinsics sometimes end up with empty metadata location operands. The
debug intrinsic interfaces return nullptr when retrieving location operand in
this case.
Skip empty-metadata dbg.declares to avoid dereferencing the nullptr. This
doesn't affect the final debug info in any way.
Reviewed By: jryans
Differential Revision: https://reviews.llvm.org/D148204
VLA backed variables currently trip an assertion in SROA with D146987 (enabling
assignment tracking). Disable assignment tracking for VLA variables until that
can be investigated.
Reviewed By: jmorse
Differential Revision: https://reviews.llvm.org/D148140
The assertion exists to ensure all variables passed into `trackAssignments` end
up with dbg.assigns associated with their backing allocas. The assertion
compared the passed-in and tracked variables using `DebugVariable`, which
includes the fragment as part of the variable identity.
It is possible for the backing alloca to be smaller than a variable (see test
case). In this case the input variable `(Var X, no fragment, no InlinedAt)`
isn't equal to the dbg.assign variable `(Var X, some fragment, no
InlinedAt)`. To cover this case the assertion now ignores fragments through the
use of `DebugVariableAggregate`.
Reviewed By: jmorse
Differential Revision: https://reviews.llvm.org/D148100
In D147777 emitDbgAssign was fixed to discard assignments which touched any
bits outside the bounds of a variable. This patch changes emitDbgAssign to
discard assignments which touch bits only outside the variable bounds, and
creates a truncated fragment expression for stores partially overlapping the
variable. This is necessary because the alloca is interpreted as a store (of
undef), meaning without this patch emitDbgAssign would discard the inital
dbg.assign for a variable that is smaller than the alloca.
Reviewed By: jmorse
Differential Revision: https://reviews.llvm.org/D148018
Some dbg.assigns using poison become un-poisoned in SROA. The reason this
happens at all is because dbg.assigns linked to memory intrinsics use poison to
indicate they can't describe the stored value, but the value becomes available
after some optimisations. This needs reworking eventually, but for now we need
to ensure that when it does occur we don't create invalid expressions.
D147312 prevented this occuring when the dbg.assign uses DIArgLists, but that
wasn't a complete fix. We also need to ensure we avoid un-poisoning when the
existing expression uses more than one location operand (DW_OP_arg, n).
Reviewed By: jmorse
Differential Revision: https://reviews.llvm.org/D148020
Prior to this patch the trackAssignments function would attribute all stores to
an alloca to all variables linked to the alloca. This is wrong in the case
where the alloca contains variables which are smaller than the alloca, and
caused erroneous fragment information to be generated.
Now stores outside the variable bounds are discarded, and we check whether a
fragment is needed based on whether the store covers the entire variable as
opposed to whether it covers the entire alloca (except for variables of unknown
size).
Note that trackAssignments doesn't yet understand whole variables sitting at
anything other than offset 0 in an alloca - those variables are still tracked
using dbg.declares.
Fixes https://lab.llvm.org/buildbot/#/builders/70/builds/36007
Reviewed By: jmorse
Differential Revision: https://reviews.llvm.org/D147777
Correctly handle the case of splitting an alloca which backs contiguous
distinct variables, where a slice's size equals the size of a backed variable.
We need to ensure that we don't generate fragments expressions with fragments
of the same size as the variable as this is a verifier error.
Prior to this patch a fragment expression would be created in this
situation. e.g. splitting an alloca i64 with two adjacent 32-bit variables into
two 32-bit allocas, the new dbg.assign expressions would contain
(DW_OP_LLVM_fragment, 0, 32) and (DW_OP_LLVM_fragment, 32, 32) even though
those fragments cover each variable entirely.
Reviewed By: jmorse
Differential Revision: https://reviews.llvm.org/D147696
createFragmentExpression will fail if it determines that the expression cannot
be split over fragments. Handle this case in SROA. Similarly to D147312 this
should be a rare occurrence as the `dbg.assign` will usually reference the
`Value` being stored without modifying it with a `DIExpression`.
Reviewed By: jmorse
Differential Revision: https://reviews.llvm.org/D147431
If the to-be-split dbg.assign has a `DIArgList` and a new `Value` has been
requested then use a kill-location for the new dbg.assign. We can't simply
replace the value component (a `DIArgList`) with the new `Value` as that would
leave the `DIExpression` in an invalid state (`DW_OP_LLVM_arg` operands with no
arglist).
Reviewed By: jmorse
Differential Revision: https://reviews.llvm.org/D147312
Assignment tracking doesn't add value when optimisations are disabled - don't
apply it to functions marked optnone.
Reviewed By: jryans
Differential Revision: https://reviews.llvm.org/D147129
updateForDeletedStore updates the assignment tracking debug info for a store
that is about to be deleted by mem2reg. For each variable backed by the target
alloca, if a dbg.assign exists it is kept (well - it's downgraded to a
dbg.value). A dbg.value is inserted if there's not a linked dbg.assign for a
variable which is backed by the target alloca. This patch fixes a bug whereby a
store with a linked dbg.assign that describes a fragment different to the one
linked to the alloca was not counted for the variable, leading to both keeping
the dbg.assign (downgrading it) and inserting a new dbg.value.
Reviewed By: StephenTozer
Differential Revision: https://reviews.llvm.org/D146299
For fully promoted variables dbg.assigns and dbg.values convey the same
information and can be used interchangeably. This patch converts dbg.assigns to
dbg.values for variables promoted by mem2reg. This reduces resource usage by
reducing the amount of unnecessary function local metadata. The compile time
tracker reports that CTMark projects build with LTO-O3-g with 0.4% fewer
instructions retired and peak memory usage is reduced by 2.2%.
Reviewed By: jryans
Differential Revision: https://reviews.llvm.org/D145511
Allow the value-component of a dbg.assign to be salvaged using a variadic
DIExpression.
Reviewed By: StephenTozer
Differential Revision: https://reviews.llvm.org/D145915
The module flag "debug-info-assignment-tracking" is set by the
declare-to-assign pass to indicate that assignment tracking is enabled. This
patch changes declare-to-assign to only set the flag if it makes a
modification. This lets the compiler avoid doing extra work for no benefit,
such as is currently the case if assignment tracking is requested for a build
with line tables only (-gmlt) or a build without debug info.
Reviewed By: scott.linder
Differential Revision: https://reviews.llvm.org/D144481
Enabling assignment tracking without this patch, a significant amount of
additional compiler run time comes from the RemoveRedundantDbgInstrs call in
InstCombine. This patch reduces compiler run time by choosing better places to
call RemoveRedundantDbgInstrs.
In non-assignment-tracking builds, RemoveRedundantDbgInstrs is called by
InstCombine if LowerDbgDeclare makes a change (i.e. it is _sometimes_
called). In assignment tracking builds LowerDbgDeclare doesn't do anything. We
still need to clean up redundant intrinsics to avoid a large performance hit
due to the number of instructions, so the current approach is to have
InstCombine _always_ call RemoveRedundantDbgInstrs.
Instrumenting the compiler to run RemoveRedundantDbgInstrs after every pass and
dump the numbers and building CTMark/tramp3d-v4 indicates that SROA and
LoopVectorize give us a bigger bang (number removed) for buck (times pass is
run).
The compile time tracker reports that this patch reduces the number of
instructions retired building CTMark projects by an average of 1.1%.
Reviewed By: scott.linder
Differential Revision: https://reviews.llvm.org/D144483
Without this patch, migrateDebugInfo doesn't understand how to handle existing
fragments that are smaller than the to-be-split store. This can occur
if. e.g. a vector store (1 dbg.assign) is split (many dbg.assigns - 1 fragment
for each scalar) and later those stores are re-vectorized (many dbg.assigns),
and then SROA runs on that.
The approach taken in this patch is to drop intrinsics with fragments outside
of the slice.
For example, starting with:
store <2 x float> %v, ptr %dest !DIAssignID !1
call void @llvm.dbg.assign(..., DIExpression(DW_OP_LLVM_fragment, 0, 32), !1, ...)
call void @llvm.dbg.assign(..., DIExpression(DW_OP_LLVM_fragment, 32, 32), !1, ...)
When visiting the slice of bits 0 to 31 we get:
store float %v.extract.0, ptr %dest !DIAssignID !2
call void @llvm.dbg.assign(..., DIExpression(DW_OP_LLVM_fragment, 0, 32), !2, ...)
The other dbg.assign associated with the currently-split store is dropped for
this split part. And visiting bits 32 to 63 we get the following:
store float %v.extract.1, ptr %adjusted.dest !DIAssignID !3
call void @llvm.dbg.assign(..., DIExpression(DW_OP_LLVM_fragment, 32, 32), !3, ...)
I've added two tests that cover this case.
Implementing this meant re-writing the fragment-calculation part of
migrateDebugInfo to work with the absolute offset of the new slice in terms of
the base alloca (instead of the offset of the slice into the new alloca), the
fragment (if any) of the variable associated with the base alloca, and the
fragment associated with the split store. Because we need the offset into the
base alloca for the variables being split, some careful wiring is required for
memory intrinsics due to the fact that memory intrinsics can be split when
either the source or dest allocas are split. In the case where the source
alloca drives the splitting, we need to be careful to pass migrateDebugInfo the
information in relation to the dest alloca.
Reviewed By: StephenTozer
Differential Revision: https://reviews.llvm.org/D143146
AggLoadStoreRewriter splits aggregate loads and stores into scalars (before the
alloca is split up). The new stores and debug intrinsics are already wired up
correctly - we just need to also delete the dbg.assign that is linked to the
split to-be-deleted store too.
Reviewed By: jmorse
Differential Revision: https://reviews.llvm.org/D142882
The intrinsics don't add anything to the tests and the tests are easier to
debug without the additional noise.
Some SSA value names have changed as a result of no longer visiting the
intrinsics.
Reviewed By: jryans
Differential Revision: https://reviews.llvm.org/D143141
Remove LLVM flag -experimental-assignment-tracking. Assignment tracking is
still enabled from Clang with the command line -Xclang
-fexperimental-assignment-tracking which tells Clang to ask LLVM to run the
pass declare-to-assign. That pass converts conventional debug intrinsics to
assignment tracking metadata. With this patch it now also sets a module flag
debug-info-assignment-tracking with the value `i1 true` (using the flag conflict
rule `Max` since enabling assignment tracking on IR that contains only
conventional debug intrinsics should cause no issues).
Update the docs and tests too.
Reviewed By: CarlosAlbertoEnciso
Differential Revision: https://reviews.llvm.org/D142027
IR is now always parsed in opaque pointer mode, unless
-opaque-pointers=0 is explicitly given. There is no automatic
detection of typed pointers anymore.
The -opaque-pointers=0 option is added to any remaining IR tests
that haven't been migrated yet.
Differential Revision: https://reviews.llvm.org/D141912
This copies existing behaviour from other debug intrinsics to `dbg.assign`s.
Reviewed By: scott.linder
Differential Revision: https://reviews.llvm.org/D141140
* This is a recommit of 3c4d2a0396,
* which was reverted in 25f01d593c,
because it exposed a miscompile in PPC backend, which was resolved
in https://reviews.llvm.org/D140089 / cb3f415cd2.
* which was a recommit of cf624b23bc,
* which was reverted in 5cfc22cafe,
because the cut-off on the number of vector elements was not low enough,
and it triggered both SDAG SDNode operand number assertions,
5and caused compile time explosions in some cases.
Let's try with something really *REALLY* conservative first,
just to get somewhere, and try to bump it later.
FIXME: should this respect TTI reg width * num vec regs?
Original commit message:
Now, there's a big caveat here - these bytes
are abstract bytes, not the i8 we have in LLVM,
so strictly speaking this is not exactly legal,
see e.g. https://github.com/AliveToolkit/alive2/issues/860
^ the "bytes" "could" have been a pointer,
and loading it as an integer inserts an implicit ptrtoint.
But at the same time,
InstCombine's `InstCombinerImpl::SimplifyAnyMemTransfer()`
would expand a memtransfer of 1/2/4/8 bytes
into integer-typed load+store,
so this isn't exactly a new problem.
Note that in memory, poison is byte-wise,
so we really can't widen elements,
but SROA seems to be inconsistent here.
Fixes#59116.
As per post-commit feedback, DebugInfo owners are not receptive of the
idea of having a single source of truth instead of relying on everyone
to know how to update these tests manually.
This reverts commit 4ff8d1e315.
This reverts commit a33b40d61c.
The Assignment Tracking debug-info feature is outlined in this RFC:
https://discourse.llvm.org/t/
rfc-assignment-tracking-a-better-way-of-specifying-variable-locations-in-ir
Split dbg.assign intrinsics into fragments similarly to what SROA already does
for dbg.declares, except that there's many more intrinsics to split. The
function migrateDebugInfo generates new dbg.assigns intrinsic for each part of
a split store.
Reviewed By: jmorse
Differential Revision: https://reviews.llvm.org/D133296
The Assignment Tracking debug-info feature is outlined in this RFC:
https://discourse.llvm.org/t/
rfc-assignment-tracking-a-better-way-of-specifying-variable-locations-in-ir
Split dbg.assign intrinsics into fragments similarly to what SROA already does
for dbg.declares, except that there's many more intrinsics to split. The
function migrateDebugInfo generates new dbg.assigns intrinsic for each part of
a split store.
Reviewed By: jmorse
Differential Revision: https://reviews.llvm.org/D133296
Over the past day or so, i've took a large swing at our tests,
and reduced the number of tests that were still using the old syntax
from ~1800 to just 200.
Left to handle: (as it is seen in this patch)
* Transforms/LSR
* Transforms/CGP
* Transforms/TypePromotion
* Transforms/HardwareLoops
* Analysis/*
* some misc.
I think this is the right point to start actively refusing
to honor the old syntax, except for the old tests,
to prevent the old syntax from creeping back in.
Thus, let's add temporary default-off flag,
and if it is not passed refuse to accept old syntax.
The tests that still need porting are annotated with this flag.
Reviewed By: aeubanks
Differential Revision: https://reviews.llvm.org/D139647
The Assignment Tracking debug-info feature is outlined in this RFC:
https://discourse.llvm.org/t/
rfc-assignment-tracking-a-better-way-of-specifying-variable-locations-in-ir
Split dbg.assign intrinsics into fragments similarly to what SROA already does
for dbg.declares, except that there's many more intrinsics to split. The
function migrateDebugInfo generates new dbg.assigns intrinsic for each part of
a split store.
Reviewed By: jmorse
Differential Revision: https://reviews.llvm.org/D133296
The Assignment Tracking debug-info feature is outlined in this RFC:
https://discourse.llvm.org/t/
rfc-assignment-tracking-a-better-way-of-specifying-variable-locations-in-ir
Reviewed By: StephenTozer
Differential Revision: https://reviews.llvm.org/D136255
The Assignment Tracking debug-info feature is outlined in this RFC:
https://discourse.llvm.org/t/
rfc-assignment-tracking-a-better-way-of-specifying-variable-locations-in-ir
This reduces peak memory overhead by 15% when building CTMark's tramp3d-v4 with
-O2 -g with assignment tracking enabled.
Reviewed By: jmorse
Differential Revision: https://reviews.llvm.org/D133321
The Assignment Tracking debug-info feature is outlined in this RFC:
https://discourse.llvm.org/t/
rfc-assignment-tracking-a-better-way-of-specifying-variable-locations-in-ir
The inliner requires two additions:
fixupAssignments - Update inlined instructions' DIAssignID metadata so that
inlined DIAssignID attachments are unique to the inlined instance.
trackInlinedStores - Treat inlined stores to caller-local variables
(i.e. callee stores to argument pointers that point to the caller's allocas) as
assignments. Track them using trackAssignments, which is the same method as is
used by the AssignmentTrackingPass. This means that we're able to detect stale
memory locations due to DSE after inlining. Because the stores are only tracked
_after_ inlining, any DSE or movement of stores _before_ inlining will not be
accounted for. This is an accepted limitation mentioned in the RFC.
One change is also required:
Update CloneBlock to preserve debug use-before-defs. Otherwise the assignments
will be dropped due to having the intrinsic operands replaced with empty
metadata (see use-before-def.ll in this patch and this related discourse post.
Reviewed By: jmorse
Differential Revision: https://reviews.llvm.org/D133318
The Assignment Tracking debug-info feature is outlined in this RFC:
https://discourse.llvm.org/t/
rfc-assignment-tracking-a-better-way-of-specifying-variable-locations-in-ir
Update simplifycfg:
sinkLastInstruction - preserve debug use-before-defs.
SpeculativelyExecuteBB - replace the value component of dbg.assign intrinsics
when stores are hoisted and merged using a select, and don't delete them.
Reviewed By: jmorse
Differential Revision: https://reviews.llvm.org/D133310
The Assignment Tracking debug-info feature is outlined in this RFC:
https://discourse.llvm.org/t/
rfc-assignment-tracking-a-better-way-of-specifying-variable-locations-in-ir
Most of the updates here are just to ensure DIAssignID attachments are
maintained and propagated correctly.
Reviewed By: jmorse
Differential Revision: https://reviews.llvm.org/D133307
The Assignment Tracking debug-info feature is outlined in this RFC:
https://discourse.llvm.org/t/
rfc-assignment-tracking-a-better-way-of-specifying-variable-locations-in-ir
Update the RemoveRedundantDbgInstrs utility to avoid sometimes losing
information when deleting dbg.assign intrinsics.
removeRedundantDbgInstrsUsingBackwardScan - treat dbg.assign intrinsics that
are not linked to any instruction just like dbg.values. That is, in a block of
contiguous debug intrinsics, delete all other than the last definition for a
fragment. Leave linked dbg.assign intrinsics in place.
removeRedundantDbgInstrsUsingForwardScan - Don't delete linked dbg.assign
intrinsics and don't delete the next intrinsic found even if it would otherwise
be eligible for deletion.
remomveUndefDbgAssignsFromEntryBlock - Delete undef and unlinked dbg.assign
intrinsics encountered in the entry block that come before non-undef
non-unlinked intrinsics for the same variable.
Reviewed By: jmorse
Differential Revision: https://reviews.llvm.org/D133294
