Those instructions should not be "visible" for debugging and for diagnostic messages.
Fixes a wrong "unreachable code" warning.
https://bugs.swift.org/browse/SR-14873
rdar://80237870
- If any of the `-g<kind>` flag is given -- except `-gnone`, debug
info will be printed into every generated SIL files.
- The `-gsil` is deprecated in favor of `-sil-based-debuginfo`. The
SILDebugInfoGenerator Pass now generates intermediate SIL file with
name "<output file>.sil_dbg_<n>.sil". Other functionalities of that
Pass remain the same.
Store the 1-byte kindAndFlags of SILLocation in the instruction's SILNode bitfield and only store SILLocation::storage in SILInstruction directly.
This reduces the space for the location from 2 to 1 word in SILInstruction.
My goal was to reduce the size of SILLocation. It now contains only of a storage union, which is basically a pointer and a bitfield containing the Kind, StorageKind and flags. By far, most locations are only single pointers to an AST node. For the few cases where more data needs to be stored, this data is allocated separately: with the SILModule's bump pointer allocator.
While working on this, I couldn't resist to do a major refactoring to simplify the code:
* removed unused stuff
* The term "DebugLoc" was used for 3 completely different things:
- for `struct SILLocation::DebugLoc` -> renamed it to `FilePosition`
- for `hasDebugLoc()`/`getDebugSourceLoc()` -> renamed it to `hasASTNodeForDebugging()`/`getSourceLocForDebugging()`
- for `class SILDebugLocation` -> kept it as it is (though, `SILScopedLocation` would be a better name, IMO)
* made SILLocation more "functional", i.e. replaced some setters with corresponding constructors
* replaced the hand-written bitfield `KindData` with C bitfields
* updated and improved comments
This ensures that we do not emit diagnostics onto these functions. I noticed we
were doing this with my work on opt-remarks when I was hitting diagnostics in
these functions in a set of subsequent commits.
The way that I found these is that I went through this file and looked for any
cases where we were never calling emitStmt on a user provided function body.
I also eliminated two places where we were setting a new DebugScope even though
preEmitFunction already does that for us.
The reason to do this is that one can now do:
```
if (auto debugLoc = i.getDebugLocation()) {
// do something with debug loc.
}
```
I also cleaned up the style a little bit by renaming the internal ivars to be
camelCase.
* [SILGenFunction] Don't create redundant nested debug scopes
Instead of emitting:
```
sil_scope 4 { loc "main.swift":6:19 parent 3 }
sil_scope 5 { loc "main.swift":7:3 parent 4 }
sil_scope 6 { loc "main.swift":7:3 parent 5 }
sil_scope 7 { loc "main.swift":7:3 parent 5 }
sil_scope 8 { loc "main.swift":9:5 parent 4 }
```
Emit:
```
sil_scope 4 { loc "main.swift":6:19 parent 3 }
sil_scope 5 { loc "main.swift":7:3 parent 4 }
sil_scope 6 { loc "main.swift":9:5 parent 5 }
```
* [IRGenSIL] Diagnose conflicting shadow copies
If we attempt to store a value with the wrong type into a slot reserved
for a shadow copy, diagnose what went wrong.
* [SILGenPattern] Defer debug description of case variables
Create unique nested debug scopes for a switch, each of its case labels,
and each of its case bodies. This looks like:
```
switch ... { // Enter scope 1.
case ... : // Enter scope 2, nested within scope 1.
<body-1> // Enter scope 3, nested within scope 2.
case ... : // Enter scope 4, nested within scope 1.
<body-2> // Enter scope 5, nested within scope 4.
}
```
Use the new scope structure to defer emitting debug descriptions of case
bindings. Specifically, defer the work until we can nest the scope for a
case body under the scope for a pattern match.
This fixes SR-7973, a problem where it was impossible to inspect a case
binding in lldb when stopped at a case with multiple items.
Previously, we would emit the debug descriptions too early (in the
pattern match), leading to duplicate/conflicting descriptions. The only
reason that the ambiguous description was allowed to compile was because
the debug scopes were nested incorrectly.
rdar://41048339
* Update tests
Commit 2948ec5ca98f8593584f2117bc92fe8d75f6f098 removed the
PointerUnion3 and PointerUnion4 aliases and migrated everything
to the variadic template. Let's do the same here to get the
build running.
While tightening the requirements of the debug info generator in
IRGenSIL I noticed that SILCloner didn't correctly transfer variable
debug info on alloc_box and alloc_stack instructions. In order to make
these mistakes easier to find I added an assertion to SILBuilder and
fixed all issues uncovered by that assertion, too.
The result is a moderate increase in debug info coverage in optimized code.
On stdlib/public/core/OSX/x86_64/Swift.o "variables with location"
increases from 60134 to 60299.
There was one case which was not handled and that's inlining of a compiler intrinsic.
In this case there is a different location type on the function call.
rdar://problem/49651421
Since SIL instructions get used a /lot/, this may result in a
compile-time speedup and/or lowered peak memory usage.
(It's not a lot in practice, though.)
Summary:
CodeView does not recognize zero as an artificial line location
and so a line location of zero causes unexpected behavior when
stepping through user code. If we find a line location of zero
and our scope has not changed, we use the most recent debug
location. That is expected to be the user code that most likely
relates to the current instruction and is similar to the behavior
in LLDB.
Test Plan:
test/DebugInfo/linetable-codeview.swift
Summary:
CodeView does not recognize zero as an artificial line location
and so a line location of zero causes unexpected behavior when
stepping through user code. If we find a line location of zero
and our scope has not changed, we use the most recent debug
location. That is expected to be the user code that most likely
relates to the current instruction and is similar to the behavior
in LLDB.
Test Plan:
test/DebugInfo/linetable-codeview.swift
Summary:
There are a few problems with how Swift currently emits location
information for CodeView.
1. WinDbg does not work well with column information so all column
locations must be set to zero.
2. Some instructions, e.g., ``a + b``, will emit ``@llvm.trap()``
and ``unreachable``. Those instructions should have artificial
locations, i.e., they should have a line location of zero.
3. Some instructions, e.g., ``a / b``, will emit ``unreachable``
sandwiched between other code for that instruction. This makes
WinDbg confused and it cannot decide which set of instructions
to break on. Those instructions should have the same line location
as the others.
4. There are several prologue instructions with artificial line
locations that create breaks in the linetables. Those instructions
should have valid line locations, usually at the start of the
function.
5. Case bodies have cleanup instructions with artificial line
locations unless it has a ``do`` block. Those locations should
be the last line in the case block.
Test Plan:
test/DebugInfo/basic.swift
test/DebugInfo/columns.swift
test/DebugInfo/linetable-codeview.swift
test/DebugInfo/line-directive-codeview.swift
For the majority of artificial helper functions the filename is
actively misleading since it usually represents the file of the caller
that triggered the helper to be generated. Instead, this patch creates
a virtual filname `<compiler-generated>` to make it very obvious that
the function has not correspondence to any source code.
<rdar://problem/33809560>
This commit changes how inline information is stored in SILDebugScope
from a tree to a linear chain of inlined call sites (similar to what
LLVM is using). This makes creating inlined SILDebugScopes slightly
more expensive, but makes lowering SILDebugScopes into LLVM metadata
much faster because entire inlined-at chains can now be cached. This
means that SIL is no longer preserve the inlining history (i.e., ((a
was inlined into b) was inlined into c) is represented the same as (a
was inlined into (b was inlined into c)), but this information was not
used by anyone.
On my late 2012 i7 iMac, this saves about 4 seconds when compiling the
RelWithDebInfo x86_64 swift standard library — or 40% of IRGen time.
rdar://problem/28311051
A lot of files transitively include Expr.h, because it was
included from SILInstruction.h, SILLocation.h and SILDeclRef.h.
However in reality most of these files don't do anything
with Exprs, especially not anything in IRGen or the SILOptimizer.
Now we're down to 171 files in the frontend which depend on
Expr.h, which is still a lot but much better than before.
In all cases the DeclCtx field was supposed to be initialized from the
SILLocation of the function, so we can save one pointer per
SILFunction.
There is one test case change where a different (more precise)
diagnostic is being generated after this change.
llvm r283043 and possibly other recent changes switch to use StringRef
instead of char* pointers. Update Swift to match. In some cases, this is
a clear improvement. It would be good to assess the impact on memory use,
particularly for the Filename component of source locations.
Note that the change to SILLocation::isNull fixes an apparent bug where
the location was treated as null when the filename was *not* null.
This ireapplies commit 255c52de9f.
Original commit message:
Serialize debug scope and location info in the SIL assembler language.
At the moment it is only possible to test the effects that SIL
optimization passes have on debug information by observing the
effects of a full .swift -> LLVM IR compilation. This change enable us
to write targeted testcases for single SIL optimization passes.
The new syntax is as follows:
sil-scope-ref ::= 'scope' [0-9]+
sil-scope ::= 'sil_scope' [0-9]+ '{'
sil-loc
'parent' scope-parent
('inlined_at' sil-scope-ref )?
'}'
scope-parent ::= sil-function-name ':' sil-type
scope-parent ::= sil-scope-ref
sil-loc ::= 'loc' string-literal ':' [0-9]+ ':' [0-9]+
Each instruction may have a debug location and a SIL scope reference
at the end. Debug locations consist of a filename, a line number, and
a column number. If the debug location is omitted, it defaults to the
location in the SIL source file. SIL scopes describe the position
inside the lexical scope structure that the Swift expression a SIL
instruction was generated from had originally. SIL scopes also hold
inlining information.
<rdar://problem/22706994>
At the moment it is only possible to test the effects that SIL
optimization passes have on debug information by observing the
effects of a full .swift -> LLVM IR compilation. This change enable us
to write targeted testcases for single SIL optimization passes.
The new syntax is as follows:
sil-scope-ref ::= 'scope' [0-9]+
sil-scope ::= 'sil_scope' [0-9]+ '{'
sil-loc
'parent' scope-parent
('inlined_at' sil-scope-ref )?
'}'
scope-parent ::= sil-function-name ':' sil-type
scope-parent ::= sil-scope-ref
sil-loc ::= 'loc' string-literal ':' [0-9]+ ':' [0-9]+
Each instruction may have a debug location and a SIL scope reference
at the end. Debug locations consist of a filename, a line number, and
a column number. If the debug location is omitted, it defaults to the
location in the SIL source file. SIL scopes describe the position
inside the lexical scope structure that the Swift expression a SIL
instruction was generated from had originally. SIL scopes also hold
inlining information.
<rdar://problem/22706994>
The overhead of uniquing the locations in a Densemap isn't worth any of
the potential memory savings: While this adds an extra pointer and
unsigned to each SILInstruction, any extra memory is completely lost in
the noise (measured on a release -emit-ir build of the x86_64 stdlib).
This is not too surpising as the ratio between SILInstructions and unique
SILLocations is not very high and the DenseMap also needs space.
<rdar://problem/22706994>
remove the mixed concept that was SILFileLocation.
Also add support for a third type of underlying storage that will be used
for deserialized debug lcoations from textual SIL.
NFC
<rdar://problem/22706994>
