mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-10-06 08:54:47 +01:00
Start plumbing through debug info type information with function parameters/return value (#6410)
This adds just enough debug info for i32/int parameters and return
values, with a path forward for adding DWARF type metadata for other
types.
As it happens, return type information is carried separately from
parameter information:
* Return type information is carried in the `type` of the `DISubprogram`
(as a `DISubroutineType` - which does carry parameter type information
as well, but that's unused when the DWARF is emitted by LLVM)
* Parameter information is carried by `DILocalVariable`s with a non-zero
`arg` value (representing the order of function parameters)
In the absence of locations for the parameters (future work), nothing
would usually keep the `DILocalVariable` live/reachable when emitting
DWARF - so for cases where this can happen (for clang, this happens in
optimized builds where all references to the parameter variable might be
optimized away) the variables can be "retained" in a list on the
`DISubprogram` - achieved by passing `AlwaysPreserve` parameter to
`createParameterVariable` (adds them to a list, then that list gets
attached to the `DISubprogram` when it's finalized later)
For now, any unsupported types are emitted as `void*` (except void
return, which is implemented as void) as a placeholder.
Given this example:
```
import Core library "io";
class MyClass {
}
fn Unsupported(v: MyClass) {
}
fn Ret() -> i32 {
return 42;
}
fn Arg(x: i32) {
Core.Print(x);
}
fn Run() {
}
```
this is the resulting DWARF:
```
DW_TAG_compile_unit
DW_AT_name ("test.carbon")
DW_TAG_subprogram
DW_AT_name ("Unsupported")
DW_TAG_formal_parameter
DW_AT_type (0x00000066 "void *")
DW_TAG_subprogram
DW_AT_name ("Ret")
DW_AT_type (0x00000062 "int")
DW_TAG_subprogram
DW_AT_name ("Arg")
DW_TAG_formal_parameter
DW_AT_type (0x00000062 "int")
DW_TAG_subprogram
DW_AT_name ("Run")
DW_TAG_base_type
DW_AT_name ("int")
DW_TAG_pointer_type
```
And the debugger:
```
(gdb) p Ret()
$1 = 42
(gdb) p Arg(4)
4
$2 = void
```
I'm not sure if there's a way this logic should be merged with the logic
for making the `llvm::Function` type (which the `DISubroutineType`
building code was inspired by/copied from) - since they're done at
different times/places, I don't think there's an easy way to do it in
one pass, but maybe the code can be shared (even if it's run twice) in
some generic `SemIR::Function` type walker.
---------
Co-authored-by: Dana Jansens <danakj@orodu.net>
This commit is contained in:
David Blaikie
co-authored by
Dana Jansens
Dana Jansens
parent
0baa74d96f
commit
a179bd461b
+8
-7
@@ -240,7 +240,7 @@ fn GetRefs() {
|
||||
// CHECK:STDOUT: !6 = !DIFile(filename: "pass_references.carbon", directory: "")
|
||||
// CHECK:STDOUT: !7 = distinct !DISubprogram(name: "PassRefs", linkageName: "_CPassRefs.Main", scope: null, file: !6, line: 16, type: !8, spFlags: DISPFlagDefinition, unit: !5)
|
||||
// CHECK:STDOUT: !8 = !DISubroutineType(types: !9)
|
||||
// CHECK:STDOUT: !9 = !{}
|
||||
// CHECK:STDOUT: !9 = !{null}
|
||||
// CHECK:STDOUT: !10 = !DILocation(line: 17, column: 3, scope: !7)
|
||||
// CHECK:STDOUT: !11 = !DILocation(line: 19, column: 17, scope: !7)
|
||||
// CHECK:STDOUT: !12 = !DILocation(line: 22, column: 3, scope: !7)
|
||||
@@ -300,7 +300,7 @@ fn GetRefs() {
|
||||
// CHECK:STDOUT: %.addr = alloca ptr, align 8
|
||||
// CHECK:STDOUT: %agg.tmp = alloca %class.ForceThunk, align 1
|
||||
// CHECK:STDOUT: store ptr %0, ptr %.addr, align 8
|
||||
// CHECK:STDOUT: %1 = load ptr, ptr %.addr, align 8, !nonnull !9
|
||||
// CHECK:STDOUT: %1 = load ptr, ptr %.addr, align 8, !nonnull !22
|
||||
// CHECK:STDOUT: call void @_Z8TakeCRefR1C10ForceThunk(ptr nonnull align 1 dereferenceable(1) %1)
|
||||
// CHECK:STDOUT: ret void
|
||||
// CHECK:STDOUT: }
|
||||
@@ -339,7 +339,7 @@ fn GetRefs() {
|
||||
// CHECK:STDOUT: %.addr = alloca ptr, align 8
|
||||
// CHECK:STDOUT: %agg.tmp = alloca %class.ForceThunk, align 1
|
||||
// CHECK:STDOUT: store ptr %0, ptr %.addr, align 8
|
||||
// CHECK:STDOUT: %1 = load ptr, ptr %.addr, align 8, !nonnull !9, !align !22
|
||||
// CHECK:STDOUT: %1 = load ptr, ptr %.addr, align 8, !nonnull !22, !align !23
|
||||
// CHECK:STDOUT: call void @_Z10TakeIntRefRi10ForceThunk(ptr nonnull align 4 dereferenceable(4) %1)
|
||||
// CHECK:STDOUT: ret void
|
||||
// CHECK:STDOUT: }
|
||||
@@ -393,7 +393,7 @@ fn GetRefs() {
|
||||
// CHECK:STDOUT: !6 = !DIFile(filename: "pass_references_via_thunk.carbon", directory: "")
|
||||
// CHECK:STDOUT: !7 = distinct !DISubprogram(name: "PassRefs", linkageName: "_CPassRefs.Main", scope: null, file: !6, line: 17, type: !8, spFlags: DISPFlagDefinition, unit: !5)
|
||||
// CHECK:STDOUT: !8 = !DISubroutineType(types: !9)
|
||||
// CHECK:STDOUT: !9 = !{}
|
||||
// CHECK:STDOUT: !9 = !{null}
|
||||
// CHECK:STDOUT: !10 = !DILocation(line: 18, column: 3, scope: !7)
|
||||
// CHECK:STDOUT: !11 = !DILocation(line: 20, column: 17, scope: !7)
|
||||
// CHECK:STDOUT: !12 = !DILocation(line: 23, column: 3, scope: !7)
|
||||
@@ -406,7 +406,8 @@ fn GetRefs() {
|
||||
// CHECK:STDOUT: !19 = !DILocation(line: 25, column: 3, scope: !7)
|
||||
// CHECK:STDOUT: !20 = !DILocation(line: 26, column: 3, scope: !7)
|
||||
// CHECK:STDOUT: !21 = !DILocation(line: 17, column: 1, scope: !7)
|
||||
// CHECK:STDOUT: !22 = !{i64 4}
|
||||
// CHECK:STDOUT: !22 = !{}
|
||||
// CHECK:STDOUT: !23 = !{i64 4}
|
||||
// CHECK:STDOUT: ; ModuleID = 'return_references.carbon'
|
||||
// CHECK:STDOUT: source_filename = "return_references.carbon"
|
||||
// CHECK:STDOUT: target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
|
||||
@@ -475,7 +476,7 @@ fn GetRefs() {
|
||||
// CHECK:STDOUT: !6 = !DIFile(filename: "return_references.carbon", directory: "")
|
||||
// CHECK:STDOUT: !7 = distinct !DISubprogram(name: "GetRefs", linkageName: "_CGetRefs.Main", scope: null, file: !6, line: 16, type: !8, spFlags: DISPFlagDefinition, unit: !5)
|
||||
// CHECK:STDOUT: !8 = !DISubroutineType(types: !9)
|
||||
// CHECK:STDOUT: !9 = !{}
|
||||
// CHECK:STDOUT: !9 = !{null}
|
||||
// CHECK:STDOUT: !10 = !DILocation(line: 17, column: 3, scope: !7)
|
||||
// CHECK:STDOUT: !11 = !DILocation(line: 18, column: 3, scope: !7)
|
||||
// CHECK:STDOUT: !12 = !DILocation(line: 19, column: 3, scope: !7)
|
||||
@@ -609,7 +610,7 @@ fn GetRefs() {
|
||||
// CHECK:STDOUT: !6 = !DIFile(filename: "return_references_via_thunk.carbon", directory: "")
|
||||
// CHECK:STDOUT: !7 = distinct !DISubprogram(name: "GetRefs", linkageName: "_CGetRefs.Main", scope: null, file: !6, line: 17, type: !8, spFlags: DISPFlagDefinition, unit: !5)
|
||||
// CHECK:STDOUT: !8 = !DISubroutineType(types: !9)
|
||||
// CHECK:STDOUT: !9 = !{}
|
||||
// CHECK:STDOUT: !9 = !{null}
|
||||
// CHECK:STDOUT: !10 = !DILocation(line: 18, column: 3, scope: !7)
|
||||
// CHECK:STDOUT: !11 = !DILocation(line: 19, column: 3, scope: !7)
|
||||
// CHECK:STDOUT: !12 = !DILocation(line: 20, column: 3, scope: !7)
|
||||
|
||||
Reference in New Issue
Block a user