[lld/mac] Set ordinal on dynamic undefined symbols in symbol table

This lets `nm -m` print "(from libfoo)" in its output, which is more accessible than dumping the bind table. See https://reviews.llvm.org/D57190#2455761 for the somewhat surprising `AltEntry` that appears in symtab.s. Differential Revision: https://reviews.llvm.org/D93318
syntacore · Dec 15, 2020 · 601f0fb · 601f0fb
1 parent a048e2f
commit 601f0fb
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Showing 3 changed files with 13 additions and 2 deletions.
diff --git a/lld/MachO/SyntheticSections.cpp b/lld/MachO/SyntheticSections.cpp
@@ -753,6 +753,10 @@ void SymtabSection::writeTo(uint8_t *buf) const {
         nList->n_value = defined->getVA();
       }
       nList->n_desc |= defined->isWeakDef() ? MachO::N_WEAK_DEF : 0;
+    } else if (auto *dysym = dyn_cast<DylibSymbol>(entry.sym)) {
+      uint16_t n_desc = nList->n_desc;
+      MachO::SET_LIBRARY_ORDINAL(n_desc, dysym->file->ordinal);
+      nList->n_desc = n_desc;
     }
     ++nList;
   }

diff --git a/lld/test/MachO/dylink.s b/lld/test/MachO/dylink.s
@@ -38,6 +38,12 @@
 # CHECK-DAG: __DATA       __data 0x{{0*}}[[#%x, DATA_ADDR + 8]]                       pointer 8   libhello   _hello_its_me
 # CHECK-DAG: __DATA       __data 0x{{0*}}[[#%x, DATA_ADDR + 16]]                      pointer -15 libgoodbye _goodbye_world
 
+# RUN: llvm-nm -m %t/dylink | FileCheck --check-prefix=NM %s
+
+# NM-DAG: _goodbye_world (from libgoodbye)
+# NM-DAG: _hello_its_me (from libhello)
+# NM-DAG: _hello_world (from libhello)
+
 # RUN: llvm-objdump --macho --all-headers %t/dylink | FileCheck %s \
 # RUN:   --check-prefix=LOAD --implicit-check-not LC_LOAD_DYLIB
 ## Check that we don't create duplicate LC_LOAD_DYLIBs.

diff --git a/lld/test/MachO/symtab.s b/lld/test/MachO/symtab.s
@@ -62,7 +62,7 @@
 # CHECK-NEXT:     Type: Undef (0x0)
 # CHECK-NEXT:     Section:  (0x0)
 # CHECK-NEXT:     RefType: UndefinedNonLazy (0x0)
-# CHECK-NEXT:     Flags [ (0x0)
+# CHECK-NEXT:     Flags [ (0x100)
 # CHECK-NEXT:     ]
 # CHECK-NEXT:     Value: 0x0
 # CHECK-NEXT:   }
@@ -71,7 +71,8 @@
 # CHECK-NEXT:     Type: Undef (0x0)
 # CHECK-NEXT:     Section:  (0x0)
 # CHECK-NEXT:     RefType: UndefinedNonLazy (0x0)
-# CHECK-NEXT:     Flags [ (0x0)
+# CHECK-NEXT:     Flags [ (0x200)
+# CHECK-NEXT:       AltEntry (0x200)
 # CHECK-NEXT:     ]
 # CHECK-NEXT:     Value: 0x0
 # CHECK-NEXT:   }