[llvm-objcopy] Implement -G/--keep-global-symbol(s).

Summary:
Port GNU Objcopy -G/--keep-global-symbol(s).

This is slightly different than the already-implemented --globalize-symbol, which marks a symbol as global when copying. When --keep-global-symbol (alias -G) is used, *only* those symbols marked will stay global, and all other globals are demoted to local. (Also note that it doesn't *promote* a symbol to global). Additionally, there is a pluralized version of the flag --keep-global-symbols, which effectively applies --keep-global-symbol for every non-comment in a file.

Reviewers: jakehehrlich, jhenderson, alexshap

Reviewed By: jhenderson

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D50589

llvm-svn: 340105

2 files changed, 146 insertions, 0 deletions

diff --git a/llvm/test/tools/llvm-objcopy/keep-global-symbols-mix-globalize.test b/llvm/test/tools/llvm-objcopy/keep-global-symbols-mix-globalize.test
new file mode 100644
index 00000000000..2de5807173c
--- /dev/null
+++ b/llvm/test/tools/llvm-objcopy/keep-global-symbols-mix-globalize.test
@@ -0,0 +1,51 @@
+# RUN: yaml2obj %s > %t.o
+
+# Tests --keep-global-symbol when used in combination with --globalize-symbol on
+# a different symbol.
+
+# RUN: llvm-objcopy \
+# RUN:   --globalize-symbol Local1 \
+# RUN:   --keep-global-symbol Local2 \
+# RUN:   --globalize-symbol Weak1 \
+# RUN:   --keep-global-symbol Weak2 \
+# RUN:   --globalize-symbol Global1 \
+# RUN:   --keep-global-symbol Global2 \
+# RUN:   %t.o %t.2.o
+# RUN: llvm-readobj -elf-output-style=GNU -symbols %t.2.o | FileCheck %s
+
+!ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_REL
+  Machine:         EM_X86_64
+Sections:
+  - Name:          .text
+    Type:          SHT_PROGBITS
+    Flags:         [ SHF_ALLOC, SHF_EXECINSTR ]
+Symbols:
+  Local:
+    - Name:        Local1
+      Section:     .text
+    - Name:        Local2
+      Section:     .text
+  Weak:
+    - Name:        Weak1
+      Section:     .text
+    - Name:        Weak2
+      Section:     .text
+  Global:
+    - Name:        Global1
+      Section:     .text
+    - Name:        Global2
+      Section:     .text
+
+# CHECK:      Symbol table '.symtab' contains 7 entries:
+# CHECK-NEXT:    Num: Value Size Type Bind Vis Ndx Name
+# CHECK-NEXT:      0: {{.*}}  LOCAL  {{.*}}
+# CHECK-NEXT:      1: {{.*}}  LOCAL  {{.*}} Local2
+# CHECK-NEXT:      2: {{.*}}  GLOBAL {{.*}} Local1
+# CHECK-NEXT:      3: {{.*}}  GLOBAL {{.*}} Global1
+# CHECK-NEXT:      4: {{.*}}  GLOBAL {{.*}} Global2
+# CHECK-NEXT:      5: {{.*}}  GLOBAL {{.*}} Weak1
+# CHECK-NEXT:      6: {{.*}}  WEAK   {{.*}} Weak2
diff --git a/llvm/test/tools/llvm-objcopy/keep-global-symbols.test b/llvm/test/tools/llvm-objcopy/keep-global-symbols.test
new file mode 100644
index 00000000000..4f580b4ae8a
--- /dev/null
+++ b/llvm/test/tools/llvm-objcopy/keep-global-symbols.test
@@ -0,0 +1,95 @@
+# RUN: yaml2obj %s > %t.o
+
+# Tests that only global symbols (via -G/--keep-global-symbols) are kept via
+# the several different variants of -G/--keep-global-symbol(s).
+#
+# Local1: Local because "-G Local1" doesn't make symbols global.
+# Local2: Global because of "--globalize-symbol Local2".
+# Weak1: Weak because "-G Weak1" doesn't make symbols global.
+# Weak2: Global because of "--globalize-symbol Weak2".
+# Weak3: Local because no -G flag covers it.
+# Global1: Global because of "-G Global1".
+# Global2: Global because of "--keep-global-symbol Global2".
+# Global3: Global because of "--keep-global-symbols %t-globals1.txt".
+# Global4: Global because of "--keep-global-symbols %t-globals2.txt".
+# Global5: Local, it appears in %t-globals2.txt but only in comments and as
+#     part of another symbol
+# Global6: Local, it appears in %t-globals2.txt but only part of another symbol
+# "Global5 Global6": Global, because it appears in %t-globals2.txt, but we only
+#     trim leading and trailing whitespace. We don't just take the first chunk
+#     that looks like a symbol.
+
+# RUN: echo Global2 > %t-globals1.txt
+# RUN: echo "  Global3  " > %t-globals2.txt
+# RUN: echo "Global4 # Global5" >> %t-globals2.txt
+# RUN: echo "  Global5 Global6  " >> %t-globals2.txt
+# RUN: echo "Unknown" >> %t-globals2.txt
+# RUN: echo "   " >> %t-globals2.txt
+# RUN: echo "# File with no symbols" > %t-globals3.txt
+
+# RUN: llvm-objcopy \
+# RUN:   -G Global1 \
+# RUN:   --keep-global-symbol Global2 \
+# RUN:   --keep-global-symbols %t-globals1.txt \
+# RUN:   --keep-global-symbols %t-globals2.txt \
+# RUN:   -G Local1 \
+# RUN:   --globalize-symbol Local2 \
+# RUN:   -G Weak1 \
+# RUN:   --globalize-symbol Weak2 \
+# RUN:   %t.o %t.2.o
+# RUN: llvm-readobj -elf-output-style=GNU -symbols %t.2.o | FileCheck %s
+
+!ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_REL
+  Machine:         EM_X86_64
+Sections:
+  - Name:          .text
+    Type:          SHT_PROGBITS
+    Flags:         [ SHF_ALLOC, SHF_EXECINSTR ]
+Symbols:
+  Local:
+    - Name:        Local1
+      Section:     .text
+    - Name:        Local2
+      Section:     .text
+  Weak:
+    - Name:        Weak1
+      Section:     .text
+    - Name:        Weak2
+      Section:     .text
+    - Name:        Weak3
+      Section:     .text
+  Global:
+    - Name:        Global1
+      Section:     .text
+    - Name:        Global2
+      Section:     .text
+    - Name:        Global3
+      Section:     .text
+    - Name:        Global4
+      Section:     .text
+    - Name:        Global5
+      Section:     .text
+    - Name:        Global6
+      Section:     .text
+    - Name:        "Global5 Global6"
+      Section:     .text
+
+# CHECK:      Symbol table '.symtab' contains 13 entries:
+# CHECK-NEXT:    Num: Value Size Type Bind Vis Ndx Name
+# CHECK-NEXT:      0: {{.*}}  LOCAL  {{.*}}
+# CHECK-NEXT:      1: {{.*}}  LOCAL  {{.*}} Local1
+# CHECK-NEXT:      2: {{.*}}  LOCAL  {{.*}} Global5
+# CHECK-NEXT:      3: {{.*}}  LOCAL  {{.*}} Global6
+# CHECK-NEXT:      4: {{.*}}  LOCAL  {{.*}} Weak3
+# CHECK-NEXT:      5: {{.*}}  GLOBAL {{.*}} Local2
+# CHECK-NEXT:      6: {{.*}}  GLOBAL {{.*}} Global1
+# CHECK-NEXT:      7: {{.*}}  GLOBAL {{.*}} Global2
+# CHECK-NEXT:      8: {{.*}}  GLOBAL {{.*}} Global3
+# CHECK-NEXT:      9: {{.*}}  GLOBAL {{.*}} Global4
+# CHECK-NEXT:     10: {{.*}}  GLOBAL {{.*}} Global5 Global6
+# CHECK-NEXT:     11: {{.*}}  WEAK   {{.*}} Weak1
+# CHECK-NEXT:     12: {{.*}}  GLOBAL {{.*}} Weak2