[lld-macho] Stop crash when emitting personalities with -dead_strip

[abrachet]

Summary

The <internal> symbol was tripping an assertion in getVA() because it was not marked as used. Per the comment above that symbols creation, dead stripping has already occurred so marking this symbol as used is accurate.

Fixes https://github.com/llvm/llvm-project/issues/55565

[paulkirth]

This is intended to address https://github.com/llvm/llvm-project/issues/55565

@abrachet can you add that issue to the summary?

[MaskRay]

lld/test/MachO/personality-dead-strip.s

1 ↗

(On Diff #430977)

We can place rm and mkdir on one line.

5 ↗

(On Diff #430977)

It's more useful to check some basic properties of the test, instead of just checking whether a command succeeds.

[abrachet]

Make a test that tests some functionality.

[abrachet]

lld/test/MachO/personality-dead-strip.s

5 ↗

(On Diff #430977)

I've just used an existing test, which is easier.

[MaskRay]

lld/test/MachO/weak-definition-gc.s

76

off-by-1 I think

lld/MachO/UnwindInfoSection.cpp

if (auto *referentIsec = r.referent.dyn_cast<InputSection *>()) {
         // This runs after dead stripping, so the noDeadStrip argument does not
         // matter.
         s = make<Defined>("<internal>", /*file=*/nullptr, referentIsec,
                           r.addend, /*size=*/0, /*isWeakDef=*/false,
                           /*isExternal=*/false, /*isPrivateExtern=*/false,
                           /*includeInSymtab=*/true,
                           /*isThumb=*/false, /*isReferencedDynamically=*/false,
                           /*noDeadStrip=*/false);
+        s->used = true;
         in.got->addEntry(s);
       }
       r.referent = s;
       r.addend = 0;
     }
   }
 }
 

lld/test/MachO/weak-definition-gc.s

 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin19.0.0 %t/weak-sub-alt.s -o %t/weak-sub-alt.o
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin19.0.0 %t/weak-sub-alt2.s -o %t/weak-sub-alt2.o
 # RUN: %lld -dylib -o %t/out.dylib %t/weak-sub-alt.o %t/weak-sub-alt2.o
 # RUN: %lld -dylib -o %t/out.dylib %t/weak-sub-alt2.o %t/weak-sub-alt.o
 
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin19.0.0 %t/weak-aligned-1.s -o %t/weak-aligned-1.o
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin19.0.0 %t/weak-aligned-2.s -o %t/weak-aligned-2.o
 # RUN: %lld -o %t/out -lSystem %t/weak-aligned-1.o %t/weak-aligned-2.o
-# RUN: llvm-objdump --syms --section=__const --full-contents %t/out | FileCheck --check-prefix=ALIGN %s
+# RUN: llvm-objdump --syms --section=__const --full-contents %t/out | FileCheck --check-prefixes=ALIGN,ALIGN2 %s
+# RUN: %lld -o %t/out -lSystem %t/weak-aligned-1.o %t/weak-aligned-2.o -dead_strip
+# RUN: llvm-objdump --syms --section=__const --full-contents %t/out | FileCheck --check-prefixes=ALIGN,ALIGN3 %s
 # ALIGN:      SYMBOL TABLE:
 # ALIGN-DAG:  [[#%x, ADDR:]]       l     O __DATA_CONST,__const _weak1
-# ALIGN-DAG:  {{0*}}[[#ADDR+ 0x4]] l     O __DATA_CONST,__const _weak3
-# ALIGN-DAG:  {{0*}}[[#ADDR+ 0x8]] l     O __DATA_CONST,__const _weak2
+# ALIGN2-DAG: {{0*}}[[#ADDR+ 0x4]] l     O __DATA_CONST,__const _weak3
+# ALIGN3-DAG: {{0*}}[[#ADDR+ 0x4]] l     O __DATA_CONST,__const _weak2
+# ALIGN2-DAG:  {{0*}}[[#ADDR+ 0x8]] l     O __DATA_CONST,__const _weak2
 # ALIGN-DAG:  {{0*}}[[#ADDR+0x10]] g     O __DATA_CONST,__const _aligned
 # ALIGN:      Contents of section __DATA_CONST,__const:
-# ALIGN-NEXT: {{0*}}[[#ADDR]]      11111111 33333333 22222222 00000000
+# ALIGN2-NEXT: {{0*}}[[#ADDR]]      11111111 33333333 22222222 00000000
+# ALIGN3-NEXT: {{0*}}[[#ADDR]]      11111111 22222222 00000000 00000000
 # ALIGN-NEXT: {{0*}}[[#ADDR+0x10]] 81818181 81818181 82828282 82828282
 
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin19.0.0 %t/weak-def.s -o %t/weak-def.o
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin19.0.0 %t/strong-def.s -o %t/strong-def.o
 # RUN: %lld -dylib -lc++ -o %t/weak-strong-mixed.dylib %t/weak-def.o %t/strong-def.o
 # RUN: %lld -dylib -lc++ -o %t/strong-weak-mixed.dylib %t/strong-def.o %t/weak-def.o
 ## Check that omitted weak symbols are not adding their section and unwind stuff.