Try to revert D113741 once again.
This also reverts 0ac75e82ff (D114705)
as it causes LLDB's lldb-api.lang/cpp/nsimport.TestCppNsImport.py test
failure w/o D113741.
This reverts commit f9607d45f3.
Differential Revision: https://reviews.llvm.org/D116225
This patch proposes to move emission of global variables, types,
imported entities, etc from DwarfDebug::beginModule() to DwarfDebug::endModule().
Effectively, this changes nothing but the order of debug entities which
will be as follows:
* subprograms (including related context, local variables/labels,
local imported entities; related types can be created as a part of
the emission of local entities of an abstract subprogram);
* global variables (including related context and types);
* retained types and enums;
* non-local-scoped imported entities;
* basic types;
* other types left (as a part of local variables attributes emission).
Note that the order of emitted compile units may also be changed as now we emit
units that contain subprograms first and then all other non-empty units.
The motivation behind this change is the following:
(1) DwarfDebug::beginModule() is run at the very beginning of backend's pipeline,
from this time IR can be significantly changed by target-specific passes.
If it happens for debug metadata of global entities, those changes will not
be reflected in the emitted DWARF.
(2) imported subprogram names should refer to an abstract subprogram if it exists,
but it isn't known in DwarfDebug::beginModule() (it's possible to make some
guesses based on location info, but it's not quite reliable);
(3) aforementioned entities if they are scoped within a bracketed block
(subject of D113741) couldn't be emitted in DwarfDebug::beginModule()
(they need parent emitted first). Another problem is if to try to gather
some information about local entities and defer their emission
(till subprogram's processing or DwarfDebug::endModule()) all the gathered
details might be irrelevant / invalid by the time the entities are being
emitted (because of (1)).
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D114705
This patch proposes to move emission of global variables, types,
imported entities, etc from DwarfDebug::beginModule() to DwarfDebug::endModule().
Effectively, this changes nothing but the order of debug entities which
will be as follows:
* subprograms (including related context, local variables/labels,
local imported entities; related types can be created as a part of
the emission of local entities of an abstract subprogram);
* global variables (including related context and types);
* retained types and enums;
* non-local-scoped imported entities;
* basic types;
* other types left (as a part of local variables attributes emission).
Note that the order of emitted compile units may also be changed as now we emit
units that contain subprograms first and then all other non-empty units.
The motivation behind this change is the following:
(1) DwarfDebug::beginModule() is run at the very beginning of backend's pipeline,
from this time IR can be significantly changed by target-specific passes.
If it happens for debug metadata of global entities, those changes will not
be reflected in the emitted DWARF.
(2) imported subprogram names should refer to an abstract subprogram if it exists,
but it isn't known in DwarfDebug::beginModule() (it's possible to make some
guesses based on location info, but it's not quite reliable);
(3) aforementioned entities if they are scoped within a bracketed block
(subject of D113741) couldn't be emitted in DwarfDebug::beginModule()
(they need parent emitted first). Another problem is if to try to gather
some information about local entities and defer their emission
(till subprogram's processing or DwarfDebug::endModule()) all the gathered
details might be irrelevant / invalid by the time the entities are being
emitted (because of (1)).
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D114705
Commit d77ae1552f ("[DebugInfo] Support to emit debugInfo
for extern variables") added support to emit debuginfo
for extern variables. Currently, only BPF target enables to
emit debuginfo for extern variables.
But if the extern variable has "void" type, the compilation will
fail.
-bash-4.4$ cat t.c
extern void bla;
void *test() {
void *x = &bla;
return x;
}
-bash-4.4$ clang -target bpf -g -O2 -S t.c
missing global variable type
!1 = distinct !DIGlobalVariable(name: "bla", scope: !2, file: !3, line: 1,
isLocal: false, isDefinition: false)
...
fatal error: error in backend: Broken module found, compilation aborted!
PLEASE submit a bug report to https://bugs.llvm.org/ and include the crash backtrace,
preprocessed source, and associated run script.
Stack dump:
...
The IR requires a DIGlobalVariable must have a valid type and the
"void" type does not generate any type, hence the above fatal error.
Note that if the extern variable is defined as "const void", the
compilation will succeed.
-bash-4.4$ cat t.c
extern const void bla;
const void *test() {
const void *x = &bla;
return x;
}
-bash-4.4$ clang -target bpf -g -O2 -S t.c
-bash-4.4$ cat t.ll
...
!1 = distinct !DIGlobalVariable(name: "bla", scope: !2, file: !3, line: 1,
type: !6, isLocal: false, isDefinition: false)
!6 = !DIDerivedType(tag: DW_TAG_const_type, baseType: null)
...
Since currently, "const void extern_var" is supported by the
debug info, it is natural that "void extern_var" should also
be supported. This patch disabled assertion of "void extern_var"
in IR verifier and add proper guarding when emiting potential
null debug info type to dwarf types.
Differential Revision: https://reviews.llvm.org/D81131
Kristina Bessonova