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
The replaceAllDbgUsesWith utility helps passes preserve debug info when
replacing one value with another.
This improves upon the existing insertReplacementDbgValues API by:
- Updating debug intrinsics in-place, while preventing use-before-def of
the replacement value.
- Falling back to salvageDebugInfo when a replacement can't be made.
- Moving the responsibiliy for rewriting llvm.dbg.* DIExpressions into
common utility code.
Along with the API change, this teaches replaceAllDbgUsesWith how to
create DIExpressions for three basic integer and pointer conversions:
- The no-op conversion. Applies when the values have the same width, or
have bit-for-bit compatible pointer representations.
- Truncation. Applies when the new value is wider than the old one.
- Zero/sign extension. Applies when the new value is narrower than the
old one.
Testing:
- check-llvm, check-clang, a stage2 `-g -O3` build of clang,
regression/unit testing.
- This resolves a number of mis-sized dbg.value diagnostics from
Debugify.
Differential Revision: https://reviews.llvm.org/D48676
llvm-svn: 336451
For local variables the first DW_OP_deref is consumed by turning the
location kind into a memeory location, but that only makes sense for
values that are in a register to begin with, which cannot happen for
global variables that are attached to a symbol.
rdar://problem/39741860
This reapplies r330970 after fixing an uncovered bug in r331086 and
working around the situation caused by it.
llvm-svn: 331090
Preserve debug info from a dead 'and' instruction with a constant.
Patch by Djordje Todorovic.
Differential Revision: https://reviews.llvm.org/D43163
llvm-svn: 325119
Also make a drive-by-fix of a bug in the subregister scan code that
only triggers with an incomplete or otherwise very irregular machine
description.
rdar://problem/37404493
This re-applies r324972 with an early exit in the case of a complete
failure to make this commit NFC again as intended.
llvm-svn: 325041
Here are the number of additional debug values salvaged in a stage2
build of clang:
63 SALVAGE: MUL
1250 SALVAGE: SDIV
(No values were salvaged from `srem` instructions in this experiment,
but it's a simple case to handle so we might as well.)
llvm-svn: 324976
Here are the number of additional debug values salvaged in a stage2
build of clang:
1912 SALVAGE: ASHR
405 SALVAGE: LSHR
249 SALVAGE: SHL
llvm-svn: 324975
Also make a drive-by-fix of a bug in the subregister scan code that
only triggers with an incomplete or otherwise very irregular machine
description.
rdar://problem/37404493
llvm-svn: 324972
Extend salvageDebugInfo to preserve the debug info from a dead 'or'
with a constant.
Patch by Ismail Badawi!
Differential Revision: https://reviews.llvm.org/D43129
llvm-svn: 324764
All these headers already depend on CodeGen headers so moving them into
CodeGen fixes the layering (since CodeGen depends on Target, not the
other way around).
llvm-svn: 318490
This patch contains fix for reverted commit
rL312318 which was causing failure due to use
of unchecked dyn_cast to CIInit.
Patch by: Nikola Prica.
llvm-svn: 313870
r312318 - Debug info for variables whose type is shrinked to bool
r312325, r312424, r312489 - Test case for r312318
Revision 312318 introduced a null dereference bug.
Details in https://bugs.llvm.org/show_bug.cgi?id=34490
llvm-svn: 312758
This patch provides such debug information for integer
variables whose type is shrinked to bool by providing
dwarf expression which returns either constant initial
value or other value.
Patch by Nikola Prica.
Differential Revision: https://reviews.llvm.org/D35994
llvm-svn: 312318
Summary:
This patch is part of 3 patches that together form a single patch, but must be introduced in stages in order not to break things.
The way that LLVM interprets DW_OP_plus in DIExpression nodes is basically that of the DW_OP_plus_uconst operator since LLVM expects an unsigned constant operand. This unnecessarily restricts the DW_OP_plus operator, preventing it from being used to describe the evaluation of runtime values on the expression stack. These patches try to align the semantics of DW_OP_plus and DW_OP_minus with that of the DWARF definition, which pops two elements off the expression stack, performs the operation and pushes the result back on the stack.
This is done in three stages:
• The first patch (LLVM) adds support for DW_OP_plus_uconst.
• The second patch (Clang) contains changes all its uses from DW_OP_plus to DW_OP_plus_uconst.
• The third patch (LLVM) changes the semantics of DW_OP_plus and DW_OP_minus to be in line with its DWARF meaning. This patch includes the bitcode upgrade from legacy DIExpressions.
Patch by Sander de Smalen.
Reviewers: echristo, pcc, aprantl
Reviewed By: aprantl
Subscribers: fhahn, javed.absar, aprantl, llvm-commits
Differential Revision: https://reviews.llvm.org/D33894
llvm-svn: 305386
Summary:
This patch is part of 3 patches that together form a single patch, but must be introduced in stages in order not to break things.
The way that LLVM interprets DW_OP_plus in DIExpression nodes is basically that of the DW_OP_plus_uconst operator since LLVM expects an unsigned constant operand. This unnecessarily restricts the DW_OP_plus operator, preventing it from being used to describe the evaluation of runtime values on the expression stack. These patches try to align the semantics of DW_OP_plus and DW_OP_minus with that of the DWARF definition, which pops two elements off the expression stack, performs the operation and pushes the result back on the stack.
This is done in three stages:
• The first patch (LLVM) adds support for DW_OP_plus_uconst.
• The second patch (Clang) contains changes all its uses from DW_OP_plus to DW_OP_plus_uconst.
• The third patch (LLVM) changes the semantics of DW_OP_plus and DW_OP_minus to be in line with its DWARF meaning. This patch includes the bitcode upgrade from legacy DIExpressions.
Patch by Sander de Smalen.
Reviewers: pcc, echristo, aprantl
Reviewed By: aprantl
Subscribers: fhahn, aprantl, javed.absar, llvm-commits
Differential Revision: https://reviews.llvm.org/D33892
llvm-svn: 305304
This creates a new library called BinaryFormat that has all of
the headers from llvm/Support containing structure and layout
definitions for various types of binary formats like dwarf, coff,
elf, etc as well as the code for identifying a file from its
magic.
Differential Revision: https://reviews.llvm.org/D33843
llvm-svn: 304864
1. RegisterClass::getSize() is split into two functions:
- TargetRegisterInfo::getRegSizeInBits(const TargetRegisterClass &RC) const;
- TargetRegisterInfo::getSpillSize(const TargetRegisterClass &RC) const;
2. RegisterClass::getAlignment() is replaced by:
- TargetRegisterInfo::getSpillAlignment(const TargetRegisterClass &RC) const;
This will allow making those values depend on subtarget features in the
future.
Differential Revision: https://reviews.llvm.org/D31783
llvm-svn: 301221
- introduced in r300522 and found via the Swift LLDB testsuite.
The fix is to set the location kind to memory whenever an FrameIndex
location is emitted.
rdar://problem/31707602
llvm-svn: 300793
- introduced in r300522 and found via the Swift LLDB testsuite.
The fix is to set the location kind to memory whenever an FrameIndex
location is emitted.
rdar://problem/31707602
llvm-svn: 300790
The DWARF specification knows 3 kinds of non-empty simple location
descriptions:
1. Register location descriptions
- describe a variable in a register
- consist of only a DW_OP_reg
2. Memory location descriptions
- describe the address of a variable
3. Implicit location descriptions
- describe the value of a variable
- end with DW_OP_stack_value & friends
The existing DwarfExpression code is pretty much ignorant of these
restrictions. This used to not matter because we only emitted very
short expressions that we happened to get right by accident. This
patch makes DwarfExpression aware of the rules defined by the DWARF
standard and now chooses the right kind of location description for
each expression being emitted.
This would have been an NFC commit (for the existing testsuite) if not
for the way that clang describes captured block variables. Based on
how the previous code in LLVM emitted locations, DW_OP_deref
operations that should have come at the end of the expression are put
at its beginning. Fixing this means changing the semantics of
DIExpression, so this patch bumps the version number of DIExpression
and implements a bitcode upgrade.
There are two major changes in this patch:
I had to fix the semantics of dbg.declare for describing function
arguments. After this patch a dbg.declare always takes the *address*
of a variable as the first argument, even if the argument is not an
alloca.
When lowering a DBG_VALUE, the decision of whether to emit a register
location description or a memory location description depends on the
MachineLocation — register machine locations may get promoted to
memory locations based on their DIExpression. (Future) optimization
passes that want to salvage implicit debug location for variables may
do so by appending a DW_OP_stack_value. For example:
DBG_VALUE, [RBP-8] --> DW_OP_fbreg -8
DBG_VALUE, RAX --> DW_OP_reg0 +0
DBG_VALUE, RAX, DIExpression(DW_OP_deref) --> DW_OP_reg0 +0
All testcases that were modified were regenerated from clang. I also
added source-based testcases for each of these to the debuginfo-tests
repository over the last week to make sure that no synchronized bugs
slip in. The debuginfo-tests compile from source and run the debugger.
https://bugs.llvm.org/show_bug.cgi?id=32382
<rdar://problem/31205000>
Differential Revision: https://reviews.llvm.org/D31439
llvm-svn: 300522
If a register location can only be described by a complex expression
(i.e., multiple subregisters) it doesn't safely compose with another
complex expression. For example, it is not possible to apply a
DW_OP_deref operation to multiple DW_OP_pieces.
llvm-svn: 298472
until the rest of the expression is known.
This is still an NFC refactoring in preparation of a subsequent bugfix.
This reapplies r298388 with a bugfix for non-physical frame registers.
llvm-svn: 298471
If a register location can only be described by a complex expression
(i.e., multiple subregisters) it doesn't safely compose with another
complex expression. For example, it is not possible to apply a
DW_OP_deref operation to multiple DW_OP_pieces.
llvm-svn: 298389
Citing http://bugs.llvm.org/show_bug.cgi?id=32288
The DWARF generated by LLVM includes this location:
0x55 0x93 0x04 DW_OP_reg5 DW_OP_piece(4) When GCC's DWARF is simply
0x55 (DW_OP_reg5) without the DW_OP_piece. I believe it's reasonable
to assume the DWARF consumer knows which part of a register
logically holds the value (low bytes, high bytes, how many bytes,
etc) for a primitive value like an integer.
This patch gets rid of the redundant DW_OP_piece when a subregister is
at offset 0. It also adds previously missing subregister masking when
a subregister is followed by another operation.
(This reapplies r297960 with two additional testcase updates).
rdar://problem/31069390
https://reviews.llvm.org/D31010
llvm-svn: 297965
Citing http://bugs.llvm.org/show_bug.cgi?id=32288
The DWARF generated by LLVM includes this location:
0x55 0x93 0x04 DW_OP_reg5 DW_OP_piece(4) When GCC's DWARF is simply
0x55 (DW_OP_reg5) without the DW_OP_piece. I believe it's reasonable
to assume the DWARF consumer knows which part of a register
logically holds the value (low bytes, high bytes, how many bytes,
etc) for a primitive value like an integer.
This patch gets rid of the redundant DW_OP_piece when a subregister is
at offset 0. It also adds previously missing subregister masking when
a subregister is followed by another operation.
rdar://problem/31069390
https://reviews.llvm.org/D31010
llvm-svn: 297960
When DwarfExpression is emitting a fragment that is located in a
register and that fragment is smaller than the register, and the
register must be composed from sub-registers (are you still with me?)
the last DW_OP_piece operation must not be larger than the size of the
fragment itself, since the last piece of the fragment could be smaller
than the last subregister that is being emitted.
rdar://problem/29779065
llvm-svn: 290324
LLVM's use of DW_OP_bit_piece is incorrect and a based on a
misunderstanding of the wording in the DWARF specification. The offset
argument of DW_OP_bit_piece refers to the offset into the location
that is on the top of the DWARF expression stack, and not an offset
into the source variable. This has since also been clarified in the
DWARF specification.
This patch fixes all uses of DW_OP_bit_piece to emit the correct
offset and simplifies the DwarfExpression class to semi-automaticaly
emit empty DW_OP_pieces to adjust the offset of the source variable,
thus simplifying the code using DwarfExpression.
While this is an incompatible bugfix, in practice I don't expect this
to be much of a problem since LLVM's old interpretation and the
correct interpretation of DW_OP_bit_piece differ only when there are
gaps in the fragmented locations of the described variables or if
individual fragments are smaller than a byte. LLDB at least won't
interpret locations with gaps in them because is has no way to present
undefined bits in a variable, and there is a high probability that an
old-form expression will be malformed when interpreted correctly,
because the DW_OP_bit_piece offset will be outside of the location at
the top of the stack.
As a nice side-effect, this patch enables us to use a more efficient
encoding for subregisters: In order to express a sub-register at a
non-zero offset we now use a DW_OP_bit_piece instead of shifting the
value into place manually.
This patch also adds missing test coverage for code paths that weren't
exercised before.
<rdar://problem/29335809>
Differential Revision: https://reviews.llvm.org/D27550
llvm-svn: 289266
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
This patch reverses the edge from DIGlobalVariable to GlobalVariable.
This will allow us to more easily preserve debug info metadata when
manipulating global variables.
Fixes PR30362. A program for upgrading test cases is attached to that
bug.
Differential Revision: http://reviews.llvm.org/D20147
llvm-svn: 281284
This fixes an embarrassing bug when emitting .debug_loc entries for 64-bit+ constants,
which were previously silently truncated to 32 bits.
<rdar://problem/26843232>
llvm-svn: 273736
Jonas Devlieghere