Bring r329960 back.

The fix is to copy Used when replacing the symbol.

Original message:

Do not keep shared symbols created from garbage-collected eliminated DSOs.

If all references to a DSO happen to be weak, and if the DSO is
specified with --as-needed, the DSO is not added to DT_NEEDED.
If that happens, we also need to eliminate shared symbols created
from the DSO. Otherwise, they become dangling references that point
to non-exsitent DSO.

Fixes https://bugs.llvm.org/show_bug.cgi?id=36991

Differential Revision: https://reviews.llvm.org/D45536

llvm-svn: 330788

2 files changed, 32 insertions, 62 deletions

diff --git a/lld/test/ELF/as-needed-weak.s b/lld/test/ELF/as-needed-weak.s
new file mode 100644
index 00000000000..f009c72d6f4
--- /dev/null
+++ b/lld/test/ELF/as-needed-weak.s
@@ -0,0 +1,22 @@
+# REQUIRES: x86
+
+# RUN: echo '.globl foo; .type foo, @function; foo:' | \
+# RUN:   llvm-mc -filetype=obj -triple=x86_64-unknown-linux - -o %t1.o
+# RUN: ld.lld -shared -o %t1.so -soname libfoo %t1.o
+
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t2.o
+# RUN: ld.lld -o %t.exe %t2.o --as-needed %t1.so
+# RUN: llvm-readelf -dynamic-table -dyn-symbols %t.exe | FileCheck %s
+
+# CHECK-NOT: libfoo
+
+# CHECK:      Symbol table of .hash for image:
+# CHECK-NEXT: Num Buc:    Value          Size   Type   Bind Vis      Ndx Name
+# CHECK-NEXT:   1   1: 0000000000000000     0 FUNC    WEAK   DEFAULT UND foo@
+
+.globl _start
+.weak foo
+
+_start:
+  mov $foo, %eax
+  callq foo
diff --git a/lld/test/ELF/gc-sections-shared.s b/lld/test/ELF/gc-sections-shared.s
index 55b3ef556ce..c0ebf403a33 100644
--- a/lld/test/ELF/gc-sections-shared.s
+++ b/lld/test/ELF/gc-sections-shared.s
@@ -25,6 +25,15 @@
 # CHECK-NEXT:     Section: Undefined (0x0)
 # CHECK-NEXT:   }
 # CHECK-NEXT:   Symbol {
+# CHECK-NEXT:     Name: qux
+# CHECK-NEXT:     Value:
+# CHECK-NEXT:     Size:
+# CHECK-NEXT:     Binding: Weak
+# CHECK-NEXT:     Type:
+# CHECK-NEXT:     Other:
+# CHECK-NEXT:     Section: Undefined
+# CHECK-NEXT:   }
+# CHECK-NEXT:   Symbol {
 # CHECK-NEXT:     Name: bar
 # CHECK-NEXT:     Value:
 # CHECK-NEXT:     Size:
@@ -51,15 +60,6 @@
 # CHECK-NEXT:     Other:
 # CHECK-NEXT:     Section: .text
 # CHECK-NEXT:   }
-# CHECK-NEXT:   Symbol {
-# CHECK-NEXT:     Name: qux
-# CHECK-NEXT:     Value:
-# CHECK-NEXT:     Size:
-# CHECK-NEXT:     Binding: Weak
-# CHECK-NEXT:     Type:
-# CHECK-NEXT:     Other:
-# CHECK-NEXT:     Section: Undefined
-# CHECK-NEXT:   }
 # CHECK-NEXT: ]
 
 # CHECK-NOT: NEEDED
@@ -68,59 +68,7 @@
 
 # Test with %t.o at the end too.
 # RUN: ld.lld --gc-sections --export-dynamic-symbol foo -o %t --as-needed %t2.so %t3.so %t4.so %t.o
-# RUN: llvm-readobj --dynamic-table --dyn-symbols %t | FileCheck --check-prefix=CHECK2 %s
-
-# CHECK2:      DynamicSymbols [
-# CHECK2-NEXT:   Symbol {
-# CHECK2-NEXT:     Name:
-# CHECK2-NEXT:     Value:
-# CHECK2-NEXT:     Size:
-# CHECK2-NEXT:     Binding: Local
-# CHECK2-NEXT:     Type:
-# CHECK2-NEXT:     Other:
-# CHECK2-NEXT:     Section: Undefined (0x0)
-# CHECK2-NEXT:   }
-# CHECK2-NEXT:   Symbol {
-# CHECK2-NEXT:     Name: bar
-# CHECK2-NEXT:     Value:
-# CHECK2-NEXT:     Size:
-# CHECK2-NEXT:     Binding: Global
-# CHECK2-NEXT:     Type:
-# CHECK2-NEXT:     Other:
-# CHECK2-NEXT:     Section: .text
-# CHECK2-NEXT:   }
-# CHECK2-NEXT:   Symbol {
-# CHECK2-NEXT:     Name: baz
-# CHECK2-NEXT:     Value:
-# CHECK2-NEXT:     Size:
-# CHECK2-NEXT:     Binding: Global
-# CHECK2-NEXT:     Type:
-# CHECK2-NEXT:     Other:
-# CHECK2-NEXT:     Section: Undefined
-# CHECK2-NEXT:   }
-# CHECK2-NEXT:   Symbol {
-# CHECK2-NEXT:     Name: qux
-# CHECK2-NEXT:     Value:
-# CHECK2-NEXT:     Size:
-# CHECK2-NEXT:     Binding: Weak
-# CHECK2-NEXT:     Type:
-# CHECK2-NEXT:     Other:
-# CHECK2-NEXT:     Section: Undefined
-# CHECK2-NEXT:   }
-# CHECK2-NEXT:   Symbol {
-# CHECK2-NEXT:     Name: foo
-# CHECK2-NEXT:     Value:
-# CHECK2-NEXT:     Size:
-# CHECK2-NEXT:     Binding: Global
-# CHECK2-NEXT:     Type:
-# CHECK2-NEXT:     Other:
-# CHECK2-NEXT:     Section: .text
-# CHECK2-NEXT:   }
-# CHECK2-NEXT: ]
-
-# CHECK2-NOT: NEEDED
-# CHECK2:     NEEDED Shared library: [{{.*}}3.so]
-# CHECK2-NOT: NEEDED
+# RUN: llvm-readobj --dynamic-table --dyn-symbols %t | FileCheck --check-prefix=CHECK %s
 
 .section .text.foo, "ax"
 .globl foo