Add llvm-objcopy option --ignore-symbol

Author: kuilpd

llvm/include/llvm/ObjCopy/ELF/ELFConfig.h

@@ -9,6 +9,7 @@
 #ifndef LLVM_OBJCOPY_ELF_ELFCONFIG_H
 #define LLVM_OBJCOPY_ELF_ELFCONFIG_H
 
+#include "llvm/ObjCopy/CommonConfig.h"
 #include "llvm/Object/ELFTypes.h"
 
 namespace llvm {
@@ -18,6 +19,8 @@ namespace objcopy {
 struct ELFConfig {
   uint8_t NewSymbolVisibility = (uint8_t)ELF::STV_DEFAULT;
 
+  NameMatcher SymbolsToIgnore;
+
   // ELF entry point address expression. The input parameter is an entry point
   // address in the input ELF file. The entry address in the output file is
   // calculated with EntryExpr(input_address), when either --set-start or

llvm/lib/ObjCopy/ELF/ELFObjcopy.cpp

@@ -290,6 +290,8 @@ static Error updateAndRemoveSymbols(const CommonConfig &Config,
     return Error::success();
 
   Obj.SymbolTable->updateSymbols([&](Symbol &Sym) {
+    if (ELFConfig.SymbolsToIgnore.matches(Sym.Name))
+      return;
     // Common and undefined symbols don't make sense as local symbols, and can
     // even cause crashes if we localize those, so skip them.
     if (!Sym.isCommon() && Sym.getShndx() != SHN_UNDEF &&

llvm/test/tools/llvm-objcopy/ELF/ignore-symbols.test

@@ -0,0 +1,41 @@
+
+# RUN: yaml2obj %s -o %t.o
+# RUN: echo 'foo[2-3]' > %t.ignore.regex
+
+# RUN: cp  %t.o  %t1.o
+# RUN: llvm-objcopy  %t1.o --localize-hidden --ignore-symbols=%t.ignore.regex --regex
+# RUN: llvm-readelf -s  %t1.o | FileCheck %s --check-prefix=SYMS
+# SYMS-DAG: LOCAL  HIDDEN      1 foo1
+# SYMS-DAG: GLOBAL HIDDEN      1 foo2
+# SYMS-DAG: GLOBAL HIDDEN      1 foo3
+
+# RUN: cp  %t.o  %t1.o
+# RUN: llvm-objcopy  %t1.o --localize-hidden --ignore-symbol=foo3
+# RUN: llvm-readelf -s  %t1.o | FileCheck %s --check-prefix=SYM
+# SYM-DAG: LOCAL  HIDDEN      1 foo1
+# SYM-DAG: LOCAL  HIDDEN      1 foo2
+# SYM-DAG: GLOBAL HIDDEN      1 foo3
+
+!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:
+  - Name:    foo1
+    Section: .text
+    Binding:  STB_GLOBAL
+    Other:    [ STV_HIDDEN ]
+  - Name:    foo2
+    Section: .text
+    Binding:  STB_GLOBAL
+    Other:    [ STV_HIDDEN ]
+  - Name:    foo3
+    Section: .text
+    Binding:  STB_GLOBAL
+    Other:    [ STV_HIDDEN ]

llvm/tools/llvm-objcopy/ObjcopyOptions.cpp

@@ -955,6 +955,15 @@ objcopy::parseObjcopyOptions(ArrayRef<const char *> RawArgsArr,
             addSymbolsFromFile(Config.SymbolsToKeep, DC.Alloc, Arg->getValue(),
                                SymbolMatchStyle, ErrorCallback))
       return std::move(E);
+  for (auto *Arg : InputArgs.filtered(OBJCOPY_ignore_symbol))
+    if (Error E = ELFConfig.SymbolsToIgnore.addMatcher(NameOrPattern::create(
+            Arg->getValue(), SymbolMatchStyle, ErrorCallback)))
+      return std::move(E);
+  for (auto *Arg : InputArgs.filtered(OBJCOPY_ignore_symbols))
+    if (Error E = addSymbolsFromFile(ELFConfig.SymbolsToIgnore, DC.Alloc,
+                                     Arg->getValue(), SymbolMatchStyle,
+                                     ErrorCallback))
+      return std::move(E);
   for (auto *Arg : InputArgs.filtered(OBJCOPY_add_symbol)) {
     Expected<NewSymbolInfo> SymInfo = parseNewSymbolInfo(Arg->getValue());
     if (!SymInfo)

llvm/tools/llvm-objcopy/ObjcopyOpts.td

@@ -196,6 +196,20 @@ defm keep_symbols
          "be repeated to read symbols from many files">,
       MetaVarName<"filename">;
 
+defm ignore_symbol : Eq<"ignore-symbol", "Do not change parameters of symbol <symbol> "
+                        "when executing other options that can change the symbol's "
+                        "name, binding or visibility">,
+                     MetaVarName<"symbol">;
+
+defm ignore_symbols
+    : Eq<"ignore-symbols",
+         "Reads a list of symbols from <filename> and runs as if "
+         "--ignore-symbol=<symbol> is set for each one. <filename> "
+         "contains one symbol per line and may contain comments beginning with "
+         "'#'. Leading and trailing whitespace is stripped from each line. May "
+         "be repeated to read symbols from many files">,
+      MetaVarName<"filename">;
+
 defm dump_section
     : Eq<"dump-section",
          "Dump contents of section named <section> into file <file>">,