[llvm/DebugInfo] Emit DW_OP_implicit_value when tuning for LLDB

This patch enables emitting DWARF `DW_OP_implicit_value` opcode when
tuning debug information for LLDB (`-debugger-tune=lldb`).

This

[llvm/DebugInfo] Emit DW_OP_implicit_value when tuning for LLDB

This patch enables emitting DWARF `DW_OP_implicit_value` opcode when
tuning debug information for LLDB (`-debugger-tune=lldb`).

This will also propagate to Darwin platforms, since they use LLDB tuning
as a default.

rdar://67406059

Differential Revision: https://reviews.llvm.org/D90001

Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>

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DWARFDebugLoc(v4): Add an incremental parsing function

Summary:
This adds a visitLocationList function to the DWARF v4 location lists,
similar to what already exists for DWARF v5. It follows the app

DWARFDebugLoc(v4): Add an incremental parsing function

Summary:
This adds a visitLocationList function to the DWARF v4 location lists,
similar to what already exists for DWARF v5. It follows the approach
outlined in previous patches (D69672), where the parsed form is always
stored in the DWARF v5 format, which makes it easier for generic code to
be built on top of that. v4 location lists are "upgraded" during
parsing, and then this upgrade is undone while dumping.

Both "inline" and section-based dumping is rewritten to reuse the
existing "generic" location list dumper. This means that the output
format is consistent for all location lists (the only thing one needs to
implement is the function which prints the "raw" form of a location
list), and that debug_loc dumping correctly processes base address
selection entries, etc.

The previous existing debug_loc functionality (e.g.,
parseOneLocationList) is rewritten on top of the new API, but it is not
removed as there is still code which uses them. This will be done in
follow-up patches, after I build the API to access the "interpreted"
location lists in a generic way (as that is what those users really
want).

Reviewers: dblaikie, probinson, JDevlieghere, aprantl, SouraVX

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D69847

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DWARFDebugLoclists: Move to a incremental parsing model

Summary:
This patch stems from the discussion D68270 (including some offline
talks). The idea is to provide an "incremental" api for parsing l

DWARFDebugLoclists: Move to a incremental parsing model

Summary:
This patch stems from the discussion D68270 (including some offline
talks). The idea is to provide an "incremental" api for parsing location
lists, which will avoid caching or materializing parsed data. An
additional goal is to provide a high level location list api, which
abstracts the differences between different encoding schemes, and can be
used by users which don't care about those (such as LLDB).

This patch implements the first part. It implements a call-back based
"visitLocationList" api. This function parses a single location list,
calling a user-specified callback for each entry. This is going to be
the base api, which other location list functions (right now, just the
dumping code) are going to be based on.

Future patches will do something similar for the v4 location lists, and
add a mechanism to translate raw entries into concrete address ranges.

Reviewers: dblaikie, probinson, JDevlieghere, aprantl, SouraVX

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D69672

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[DebugInfo] Terminate all location-lists at end of block

This commit reapplies r359426 (which was reverted in r360301 due to
performance problems) and rolls in D61940 to address the performance prob

[DebugInfo] Terminate all location-lists at end of block

This commit reapplies r359426 (which was reverted in r360301 due to
performance problems) and rolls in D61940 to address the performance problem.
I've combined the two to avoid creating a span of slow-performance, and to
ease reverting if more problems crop up.

The summary of D61940: This patch removes the "ChangingRegs" facility in
DbgEntityHistoryCalculator, as its overapproximate nature can produce incorrect
variable locations. An unchanging register doesn't mean a variable doesn't
change its location.

The patch kills off everything that calculates the ChangingRegs vector.
Previously ChangingRegs spotted epilogues and marked registers as unchanging if
they weren't modified outside the epilogue, increasing the chance that we can
emit a single-location variable record. Without this feature,
debug-loc-offset.mir and pr19307.mir become temporarily XFAIL. They'll be
re-enabled by D62314, using the FrameDestroy flag to identify epilogues, I've
split this into two steps as FrameDestroy isn't necessarily supported by all
backends.

The logic for terminating variable locations at the end of a basic block now
becomes much more enjoyably simple: we just terminate them all.

Other test changes: inlined-argument.ll becomes XFAIL, but for a longer term.
The current algorithm for detecting that a variable has a single-location
doesn't work in this scenario (inlined function in multiple blocks), only other
bugs were making this test work. fission-ranges.ll gets slightly refreshed too,
as the location of "p" is now correctly determined to be a single location.

Differential Revision: https://reviews.llvm.org/D61940

llvm-svn: 362951

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[DebugInfo] Normalize common kinds of DWARF sub-expressions.

Normalize common kinds of DWARF sub-expressions to make debug info
encoding a bit more compact:

DW_OP_constu [X < 32] -> DW_OP_litX

[DebugInfo] Normalize common kinds of DWARF sub-expressions.

Normalize common kinds of DWARF sub-expressions to make debug info
encoding a bit more compact:

DW_OP_constu [X < 32] -> DW_OP_litX
DW_OP_constu [all ones] -> DW_OP_lit0, DW_OP_not (64-bit only)

Differential revision: https://reviews.llvm.org/D51640

llvm-svn: 341457

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[DebugInfo] Unify dumping of address ranges

Summary:
This patch unifies the printing of address ranges as [0x0, 0x1).

rdar://34822059

Reviewers: aprantl, dblaikie

Subscribers: mehdi_amini, llvm-c

[DebugInfo] Unify dumping of address ranges

Summary:
This patch unifies the printing of address ranges as [0x0, 0x1).

rdar://34822059

Reviewers: aprantl, dblaikie

Subscribers: mehdi_amini, llvm-commits

Differential Revision: https://reviews.llvm.org/D42056

llvm-svn: 322543

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llvm-dwarfdump: Make -brief the default and add a -verbose option instead.

Differential Revision: https://reviews.llvm.org/D37717

llvm-svn: 312972

[dwarfdump] Pretty print location expressions and location lists

Summary:
Based on Fred's patch here: https://reviews.llvm.org/D6771

I can't seem to commandeer the old review, so I'm creating a new

[dwarfdump] Pretty print location expressions and location lists

Summary:
Based on Fred's patch here: https://reviews.llvm.org/D6771

I can't seem to commandeer the old review, so I'm creating a new one.

With that change the locations exrpessions are pretty printed inline in the
DIE tree. The output looks like this for debug_loc entries:

DW_AT_location [DW_FORM_data4] (0x00000000
0x0000000000000001 - 0x000000000000000b: DW_OP_consts +3
0x000000000000000b - 0x0000000000000012: DW_OP_consts +7
0x0000000000000012 - 0x000000000000001b: DW_OP_reg0 RAX, DW_OP_piece 0x4
0x000000000000001b - 0x0000000000000024: DW_OP_breg5 RDI+0)

And like this for debug_loc.dwo entries:
DW_AT_location [DW_FORM_sec_offset] (0x00000000
Addr idx 2 (w/ length 190): DW_OP_consts +0, DW_OP_stack_value
Addr idx 3 (w/ length 23): DW_OP_reg0 RAX, DW_OP_piece 0x4)

Simple locations without ranges are printed inline:

DW_AT_location [DW_FORM_block1] (DW_OP_reg4 RSI, DW_OP_piece 0x4, DW_OP_bit_piece 0x20 0x0)

The debug_loc(.dwo) dumping in changed accordingly to factor the code.

Reviewers: dblaikie, aprantl, friss

Subscribers: mgorny, javed.absar, hiraditya, llvm-commits, JDevlieghere

Differential Revision: https://reviews.llvm.org/D37123

llvm-svn: 312042

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Remove the obsolete offset parameter from @llvm.dbg.value

There is no situation where this rarely-used argument cannot be
substituted with a DIExpression and removing it allows us to simplify
the DW

Remove the obsolete offset parameter from @llvm.dbg.value

There is no situation where this rarely-used argument cannot be
substituted with a DIExpression and removing it allows us to simplify
the DWARF backend. Note that this patch does not yet remove any of
the newly dead code.

rdar://problem/33580047
Differential Revision: https://reviews.llvm.org/D35951

llvm-svn: 309426

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[DIExpression] Introduce a dedicated DW_OP_LLVM_fragment operation
so we can stop using DW_OP_bit_piece with the wrong semantics.

The entire back story can be found here:
http://lists.llvm.org/piper

[DIExpression] Introduce a dedicated DW_OP_LLVM_fragment operation
so we can stop using DW_OP_bit_piece with the wrong semantics.

The entire back story can be found here:
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20161114/405934.html

The gist is that in LLVM we've been misinterpreting DW_OP_bit_piece's
offset field to mean the offset into the source variable rather than
the offset into the location at the top the DWARF expression stack. In
order to be able to fix this in a subsequent patch, this patch
introduces a dedicated DW_OP_LLVM_fragment operation with the
semantics that we used to apply to DW_OP_bit_piece, which is what we
actually need while inside of LLVM. This patch is complete with a
bitcode upgrade for expressions using the old format. It does not yet
fix the DWARF backend to use DW_OP_bit_piece correctly.

Implementation note: We discussed several options for implementing
this, including reserving a dedicated field in DIExpression for the
fragment size and offset, but using an custom operator at the end of
the expression works just fine and is more efficient because we then
only pay for it when we need it.

Differential Revision: https://reviews.llvm.org/D27361
rdar://problem/29335809

llvm-svn: 288683

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Emit DW_OP_piece also if the previous value was a constant.
This fixes a bug in the DWARF backend.

llvm-svn: 285826