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Native: don't use aliases for kclass:* globals, fix KT-61417

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Currently, when generating a TypeInfo with a vtable attached, the K/N
compiler generates two globals to the resulting LLVM module:
- "ktypeglobal:$fqName#internal" -- an internal global of the aggregate
type (TypeInfo+vtable)
- "kclass:$fqName" -- an internal or hidden alias pointing to the
TypeInfo part of that global

The reason for emitting two globals is to have everything strict-typed,
since other LLVM modules might import the kclass as a TypeInfo.
Importing an aggregate TypeInfo+vtable global as a TypeInfo global works
too, of course. It is just a little bit less clean.

The new Xcode 15 linker now emits symbols for the ktypeglobal to the
symbol table, including an STSYM. This happens for classes compiled to
cache, when the kclass is hidden, not internal.

The problem is: for some reason, such an STSYM for
"ktypeglobal:kotlin.String#internal" makes lldb find a wrong address
(0xffffffffffffffff) for "kclass:kotlin.String", despite those being
two different symbol names. This seems to be related to them having
the same address though.
The K/N lldb script, konan_lldb.py, uses "kclass:kotlin.String" to
determine if an object is a string, in order to display it properly.

Therefore, using the new Xcode 15 linker when compiling with caches
makes the debugger unable to display string variables properly. As a
side effect, this also breaks displaying array-typed variables (because
the script first checks if an object is a string).

This commit fixes this by removing ktypeglobals completely, making the
compiler emit only a kclass as an aggregate global directly.

Now, there are other ways to fix the problem. For example, making the
ktypeglobal private instead of internal, or making konan_lldb.py use a
runtime function instead of querying "kclass:kotlin.String" directly.
But it seems that LLVM aliases are not common on darwin platforms. For
example, Clang doesn't support `__attribute__((alias(...)))` on these
platforms.
So it is safer to just stop using aliases here.

^KT-61417
This commit is contained in:
Svyatoslav Scherbina
2023-08-23 11:18:02 +02:00
committed by Space Team
parent 070f0197fc
commit 4774912fdc
2 changed files with 26 additions and 22 deletions
Download Patch File Download Diff File Expand all files Collapse all files
kotlin-native/backend.native/tests/filecheck/constants_merge.kt
+6 -6
View File
@@ -5,14 +5,14 @@
import kotlin.reflect.*
// CHECK: [[REG_FOR_1024:@[0-9]+]] = internal unnamed_addr constant { %struct.ObjHeader, i32 } { %struct.ObjHeader { %struct.TypeInfo* bitcast (i8* getelementptr (i8, i8* bitcast (%struct.TypeInfo* @"kclass:kotlin.Int" to i8*), i32 1) to %struct.TypeInfo*) }, i32 1024 }
// CHECK-NOT: internal unnamed_addr constant { %struct.ObjHeader, i32 } { %struct.ObjHeader { %struct.TypeInfo* bitcast (i8* getelementptr (i8, i8* bitcast (%struct.TypeInfo* @"kclass:kotlin.Int" to i8*), i32 1) to %struct.TypeInfo*) }, i32 1024 }
// CHECK: [[REG_FOR_1024:@[0-9]+]] = internal unnamed_addr constant { %struct.ObjHeader, i32 } { %struct.ObjHeader { %struct.TypeInfo* {{.*}} }, i32 1024 }
// CHECK-NOT: internal unnamed_addr constant { %struct.ObjHeader, i32 } { %struct.ObjHeader { %struct.TypeInfo* {{.*}} }, i32 1024 }
// CHECK: internal unnamed_addr constant { %struct.ArrayHeader, [3 x %struct.ObjHeader*] } { %struct.ArrayHeader { %struct.TypeInfo* bitcast (i8* getelementptr (i8, i8* bitcast (%struct.TypeInfo* @"kclass:kotlin.Array" to i8*), i32 1) to %struct.TypeInfo*), i32 3 }, [3 x %struct.ObjHeader*] [%struct.ObjHeader* getelementptr inbounds ({ %struct.ObjHeader, i32 }, { %struct.ObjHeader, i32 }* [[REG_FOR_1024]], i32 0, i32 0), %struct.ObjHeader* getelementptr inbounds ({ %struct.ObjHeader, i32 }, { %struct.ObjHeader, i32 }* [[REG_FOR_2048:@[0-9]+]], i32 0, i32 0), %struct.ObjHeader* getelementptr inbounds ({ %struct.ObjHeader, i32 }, { %struct.ObjHeader, i32 }* [[REG_FOR_4096:@[0-9]+]], i32 0, i32 0)] }
// CHECK-NOT: internal unnamed_addr constant { %struct.ArrayHeader, [3 x %struct.ObjHeader*] } { %struct.ArrayHeader { %struct.TypeInfo* bitcast (i8* getelementptr (i8, i8* bitcast (%struct.TypeInfo* @"kclass:kotlin.Array" to i8*), i32 1) to %struct.TypeInfo*), i32 3 }, [3 x %struct.ObjHeader*] [%struct.ObjHeader* getelementptr inbounds ({ %struct.ObjHeader, i32 }, { %struct.ObjHeader, i32 }* [[REG_FOR_1024]], i32 0, i32 0), %struct.ObjHeader* getelementptr inbounds ({ %struct.ObjHeader, i32 }, { %struct.ObjHeader, i32 }* [[REG_FOR_2048]], i32 0, i32 0), %struct.ObjHeader* getelementptr inbounds ({ %struct.ObjHeader, i32 }, { %struct.ObjHeader, i32 }* [[REG_FOR_4096]], i32 0, i32 0)] }
// CHECK: internal unnamed_addr constant { %struct.ArrayHeader, [3 x %struct.ObjHeader*] } { %struct.ArrayHeader { %struct.TypeInfo* {{.*}}, i32 3 }, [3 x %struct.ObjHeader*] [%struct.ObjHeader* getelementptr inbounds ({ %struct.ObjHeader, i32 }, { %struct.ObjHeader, i32 }* [[REG_FOR_1024]], i32 0, i32 0), %struct.ObjHeader* getelementptr inbounds ({ %struct.ObjHeader, i32 }, { %struct.ObjHeader, i32 }* [[REG_FOR_2048:@[0-9]+]], i32 0, i32 0), %struct.ObjHeader* getelementptr inbounds ({ %struct.ObjHeader, i32 }, { %struct.ObjHeader, i32 }* [[REG_FOR_4096:@[0-9]+]], i32 0, i32 0)] }
// CHECK-NOT: internal unnamed_addr constant { %struct.ArrayHeader, [3 x %struct.ObjHeader*] } { %struct.ArrayHeader { %struct.TypeInfo* {{.*}}, i32 3 }, [3 x %struct.ObjHeader*] [%struct.ObjHeader* getelementptr inbounds ({ %struct.ObjHeader, i32 }, { %struct.ObjHeader, i32 }* [[REG_FOR_1024]], i32 0, i32 0), %struct.ObjHeader* getelementptr inbounds ({ %struct.ObjHeader, i32 }, { %struct.ObjHeader, i32 }* [[REG_FOR_2048:@[0-9]+]], i32 0, i32 0), %struct.ObjHeader* getelementptr inbounds ({ %struct.ObjHeader, i32 }, { %struct.ObjHeader, i32 }* [[REG_FOR_4096:@[0-9]+]], i32 0, i32 0)] }
// CHECK: internal unnamed_addr constant { %struct.ObjHeader, %struct.ObjHeader*, %struct.ObjHeader*, i1 } { %struct.ObjHeader { %struct.TypeInfo* bitcast (i8* getelementptr (i8, i8* bitcast (%struct.TypeInfo* @"kclass:kotlin.native.internal.KTypeImpl" to i8*), i32 1) to %struct.TypeInfo*) }, %struct.ObjHeader* getelementptr inbounds ({ %struct.ObjHeader, i8* }, { %struct.ObjHeader, i8* }* [[REG_FOR_CLASSIFIER_FIELD:@[0-9]+]], i32 0, i32 0), %struct.ObjHeader* getelementptr inbounds ({ %struct.ObjHeader, %struct.ObjHeader*, %struct.ObjHeader* }, { %struct.ObjHeader, %struct.ObjHeader*, %struct.ObjHeader* }* [[REG_FOR_ARGUMENTS_FIELD:@[0-9]+]], i32 0, i32 0), i1 false }
// CHECK-NOT: internal unnamed_addr constant { %struct.ObjHeader, %struct.ObjHeader*, %struct.ObjHeader*, i1 } { %struct.ObjHeader { %struct.TypeInfo* bitcast (i8* getelementptr (i8, i8* bitcast (%struct.TypeInfo* @"kclass:kotlin.native.internal.KTypeImpl" to i8*), i32 1) to %struct.TypeInfo*) }, %struct.ObjHeader* getelementptr inbounds ({ %struct.ObjHeader, i8* }, { %struct.ObjHeader, i8* }* [[REG_FOR_CLASSIFIER_FIELD]], i32 0, i32 0), %struct.ObjHeader* getelementptr inbounds ({ %struct.ObjHeader, %struct.ObjHeader*, %struct.ObjHeader* }, { %struct.ObjHeader, %struct.ObjHeader*, %struct.ObjHeader* }* [[REG_FOR_ARGUMENTS_FIELD]], i32 0, i32 0), i1 false }
// CHECK: internal unnamed_addr constant { %struct.ObjHeader, %struct.ObjHeader*, %struct.ObjHeader*, i1 } { %struct.ObjHeader { %struct.TypeInfo* {{.*}} }, %struct.ObjHeader* getelementptr inbounds ({ %struct.ObjHeader, i8* }, { %struct.ObjHeader, i8* }* [[REG_FOR_CLASSIFIER_FIELD:@[0-9]+]], i32 0, i32 0), %struct.ObjHeader* getelementptr inbounds ({ %struct.ObjHeader, %struct.ObjHeader*, %struct.ObjHeader* }, { %struct.ObjHeader, %struct.ObjHeader*, %struct.ObjHeader* }* [[REG_FOR_ARGUMENTS_FIELD:@[0-9]+]], i32 0, i32 0), i1 false }
// CHECK-NOT: internal unnamed_addr constant { %struct.ObjHeader, %struct.ObjHeader*, %struct.ObjHeader*, i1 } { %struct.ObjHeader { %struct.TypeInfo* {{.*}} }, %struct.ObjHeader* getelementptr inbounds ({ %struct.ObjHeader, i8* }, { %struct.ObjHeader, i8* }* [[REG_FOR_CLASSIFIER_FIELD:@[0-9]+]], i32 0, i32 0), %struct.ObjHeader* getelementptr inbounds ({ %struct.ObjHeader, %struct.ObjHeader*, %struct.ObjHeader* }, { %struct.ObjHeader, %struct.ObjHeader*, %struct.ObjHeader* }* [[REG_FOR_ARGUMENTS_FIELD:@[0-9]+]], i32 0, i32 0), i1 false }
fun main() {
println(1024)