Change llvm-nm for Mach-O files to use dyld info in some cases when printing symbols.

In order to reduce swift binary sizes, Apple is now stripping swift symbols
from the nlist symbol table.  llvm-nm currently only looks at the nlist symbol
table and misses symbols that are present in dyld info.   This makes it hard to
know the set of symbols for a binary using just llvm-nm.  Unless you know to
run llvm-objdump -exports-trie that can output the exported symbols in the dyld
info from the export trie, which does so but in a different format.

Also moving forward the time may come a when a fully linked Mach-O file that
uses dyld will no longer have an nlist symbol table to avoid duplicating the
symbol information.

This change adds three flags to llvm-nm, -add-dyldinfo, -no-dyldinfo, and
-dyldinfo-only.

The first, -add-dyldinfo, has the same effect as when the new bit in the Mach-O
header, MH_NLIST_OUTOFSYNC_WITH_DYLDINFO, appears in a binary.  In that it
looks through the dyld info from the export trie and adds symbols to be printed
that are not already in its internal SymbolList variable.  The -no-dyldinfo
option turns this behavior off.

The -dyldinfo-only option only looks at the dyld information and recreates the
symbol table from the dyld info from the export trie and binding information.
As if it the Mach-O file had no nlist symbol table.

Also fixed a few bugs with Mach-O N_INDR symbols not correctly printing the
indirect name, or in the same format as the old nm-classic program.

rdar://32021551

llvm-svn: 305733

2 files changed, 18 insertions, 0 deletions

diff --git a/llvm/test/tools/llvm-nm/X86/Inputs/Strip-ST.dylib.macho-x86_64 b/llvm/test/tools/llvm-nm/X86/Inputs/Strip-ST.dylib.macho-x86_64
new file mode 100755
index 00000000000..65eb0ece374
--- /dev/null
+++ b/llvm/test/tools/llvm-nm/X86/Inputs/Strip-ST.dylib.macho-x86_64
diff --git a/llvm/test/tools/llvm-nm/X86/dyldinfo.test b/llvm/test/tools/llvm-nm/X86/dyldinfo.test
new file mode 100644
index 00000000000..3a632c57737
--- /dev/null
+++ b/llvm/test/tools/llvm-nm/X86/dyldinfo.test
@@ -0,0 +1,18 @@
+# RUN: llvm-nm %p/Inputs/Strip-ST.dylib.macho-x86_64 | FileCheck --check-prefix=DEFAULT %s
+# RUN: llvm-nm -no-dyldinfo %p/Inputs/Strip-ST.dylib.macho-x86_64 | FileCheck --check-prefix=NO-DYLDINFO %s
+# RUN: llvm-nm -dyldinfo-only %p/Inputs/Strip-ST.dylib.macho-x86_64 | FileCheck --check-prefix=DYLDINFO-ONLY %s
+
+# DEFAULT: 0000000000000f90 T __Bob_is_slow
+# DEFAULT: 0000000000001008 D __T0ims_data
+# DEFAULT: 0000000000000f80 T __T0om_is_not_swift
+# DEFAULT: U dyld_stub_binder
+
+# NO-DYLDINFO: 0000000000000f90 T __Bob_is_slow
+# NO-DYLDINFO-NOT: __T0ims_data
+# NO-DYLDINFO-NOT: __T0om_is_not_swift
+# NO-DYLDINFO: U dyld_stub_binder
+
+# DYLDINFO-ONLY: 0000000000000f90 T __Bob_is_slow
+# DYLDINFO-ONLY: 0000000000001008 D __T0ims_data
+# DYLDINFO-ONLY: 0000000000000f80 T __T0om_is_not_swift
+# DYLDINFO-ONLY-NOT: U dyld_stub_binder