This patch was reverted in 7c182663a8 due to some failures
observed on PCC based machines. Failures were due to Endianness issue and
long double representation issues.
Patch is revised to address Endianness issue. Furthermore, support
for emission of `DW_OP_implicit_value` for `long double` has been removed
(since it was unclean at the moment). Planning to handle this in
a clean way soon!
For more context, please refer to following review link.
Reviewed By: aprantl
Differential Revision: https://reviews.llvm.org/D83560
llvm is missing support for DW_OP_implicit_value operation.
DW_OP_implicit_value op is indispensable for cases such as
optimized out long double variables.
For intro refer: DWARFv5 Spec Pg: 40 2.6.1.1.4 Implicit Location Descriptions
Consider the following example:
```
int main() {
long double ld = 3.14;
printf("dummy\n");
ld *= ld;
return 0;
}
```
when compiled with tunk `clang` as
`clang test.c -g -O1` produces following location description
of variable `ld`:
```
DW_AT_location (0x00000000:
[0x0000000000201691, 0x000000000020169b): DW_OP_constu 0xc8f5c28f5c28f800, DW_OP_stack_value, DW_OP_piece 0x8, DW_OP_constu 0x4000, DW_OP_stack_value, DW_OP_bit_piece 0x10 0x40, DW_OP_stack_value)
DW_AT_name ("ld")
```
Here one may notice that this representation is incorrect(DWARF4
stack could only hold integers(and only up to the size of address)).
Here the variable size itself is `128` bit.
GDB and LLDB confirms this:
```
(gdb) p ld
$1 = <invalid float value>
(lldb) frame variable ld
(long double) ld = <extracting data from value failed>
```
GCC represents/uses DW_OP_implicit_value in these sort of situations.
Based on the discussion with Jakub Jelinek regarding GCC's motivation
for using this, I concluded that DW_OP_implicit_value is most appropriate
in this case.
Link: https://gcc.gnu.org/pipermail/gcc/2020-July/233057.html
GDB seems happy after this patch:(LLDB doesn't have support
for DW_OP_implicit_value)
```
(gdb) p ld
p ld
$1 = 3.14000000000000012434
```
Reviewed By: aprantl
Differential Revision: https://reviews.llvm.org/D83560
This patch was reverted in 9d2da6759b due to assertion failure seen
in `test/DebugInfo/Sparc/subreg.ll`. Assertion failure was happening
due to malformed/unhandeled DwarfExpression.
Differential Revision: https://reviews.llvm.org/D83560
Summary:
llvm is missing support for DW_OP_implicit_value operation.
DW_OP_implicit_value op is indispensable for cases such as
optimized out long double variables.
For intro refer: DWARFv5 Spec Pg: 40 2.6.1.1.4 Implicit Location Descriptions
Consider the following example:
```
int main() {
long double ld = 3.14;
printf("dummy\n");
ld *= ld;
return 0;
}
```
when compiled with tunk `clang` as
`clang test.c -g -O1` produces following location description
of variable `ld`:
```
DW_AT_location (0x00000000:
[0x0000000000201691, 0x000000000020169b): DW_OP_constu 0xc8f5c28f5c28f800, DW_OP_stack_value, DW_OP_piece 0x8, DW_OP_constu 0x4000, DW_OP_stack_value, DW_OP_bit_piece 0x10 0x40, DW_OP_stack_value)
DW_AT_name ("ld")
```
Here one may notice that this representation is incorrect(DWARF4
stack could only hold integers(and only up to the size of address)).
Here the variable size itself is `128` bit.
GDB and LLDB confirms this:
```
(gdb) p ld
$1 = <invalid float value>
(lldb) frame variable ld
(long double) ld = <extracting data from value failed>
```
GCC represents/uses DW_OP_implicit_value in these sort of situations.
Based on the discussion with Jakub Jelinek regarding GCC's motivation
for using this, I concluded that DW_OP_implicit_value is most appropriate
in this case.
Link: https://gcc.gnu.org/pipermail/gcc/2020-July/233057.html
GDB seems happy after this patch:(LLDB doesn't have support
for DW_OP_implicit_value)
```
(gdb) p ld
p ld
$1 = 3.14000000000000012434
```
Reviewed By: aprantl
Differential Revision: https://reviews.llvm.org/D83560
In order to set breakpoints on labels and list source code around
labels, we need collect debug information for labels, i.e., label
name, the function label belong, line number in the file, and the
address label located. In order to keep these information in LLVM
IR and to allow backend to generate debug information correctly.
We create a new kind of metadata for labels, DILabel. The format
of DILabel is
!DILabel(scope: !1, name: "foo", file: !2, line: 3)
We hope to keep debug information as much as possible even the
code is optimized. So, we create a new kind of intrinsic for label
metadata to avoid the metadata is eliminated with basic block.
The intrinsic will keep existing if we keep it from optimized out.
The format of the intrinsic is
llvm.dbg.label(metadata !1)
It has only one argument, that is the DILabel metadata. The
intrinsic will follow the label immediately. Backend could get the
label metadata through the intrinsic's parameter.
We also create DIBuilder API for labels to be used by Frontend.
Frontend could use createLabel() to allocate DILabel objects, and use
insertLabel() to insert llvm.dbg.label intrinsic in LLVM IR.
Differential Revision: https://reviews.llvm.org/D45024
Patch by Hsiangkai Wang.
llvm-svn: 331841
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
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
Currently the MIR framework prints all its outputs (errors and actual
representation) on stderr.
This patch fixes that by printing the regular output in the output
specified with -o.
Differential Revision: http://reviews.llvm.org/D22251
llvm-svn: 275314
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
Currently each Function points to a DISubprogram and DISubprogram has a
scope field. For member functions the scope is a DICompositeType. DIScopes
point to the DICompileUnit to facilitate type uniquing.
Distinct DISubprograms (with isDefinition: true) are not part of the type
hierarchy and cannot be uniqued. This change removes the subprograms
list from DICompileUnit and instead adds a pointer to the owning compile
unit to distinct DISubprograms. This would make it easy for ThinLTO to
strip unneeded DISubprograms and their transitively referenced debug info.
Motivation
----------
Materializing DISubprograms is currently the most expensive operation when
doing a ThinLTO build of clang.
We want the DISubprogram to be stored in a separate Bitcode block (or the
same block as the function body) so we can avoid having to expensively
deserialize all DISubprograms together with the global metadata. If a
function has been inlined into another subprogram we need to store a
reference the block containing the inlined subprogram.
Attached to https://llvm.org/bugs/show_bug.cgi?id=27284 is a python script
that updates LLVM IR testcases to the new format.
http://reviews.llvm.org/D19034
<rdar://problem/25256815>
llvm-svn: 266446
This patch closes a gap in the DWARF backend that caused LLVM to drop
debug info for floating point variables that were constant for part of
their scope. Floating point constants are emitted as one or more
DW_OP_constu joined via DW_OP_piece.
This fixes a regression caught by the LLDB testsuite that I introduced
in r262247 when we stopped blindly expanding the range of singular
DBG_VALUEs to span the entire scope and started to emit location lists
with accurate ranges instead.
Also deletes a now-impossible testcase (debug-loc-empty-entries).
<rdar://problem/25448338>
llvm-svn: 265760
Sourabh Singh Tomar