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Pull in r365760 from upstream lld trunk (by Fangrui Song):

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[ELF] Handle non-glob patterns before glob patterns in version
  scripts & fix a corner case of --dynamic-list

  This fixes PR38549, which is silently accepted by ld.bfd.
  This seems correct because it makes sense to let non-glob patterns
  take precedence over glob patterns.

  lld issues an error because
  `assignWildcardVersion(ver, VER_NDX_LOCAL);` is processed before
  `assignExactVersion(ver, v.id, v.name);`.

  Move all assignWildcardVersion() calls after assignExactVersion()
  calls to fix this.

  Also, move handleDynamicList() to the bottom. computeBinding() called
  by includeInDynsym() has this cryptic rule:

      if (versionId == VER_NDX_LOCAL && isDefined() && !isPreemptible)
	return STB_LOCAL;

  Before the change:

  * foo's version is set to VER_NDX_LOCAL due to `local: *`
  * handleDynamicList() is called
    - foo.computeBinding() is STB_LOCAL
    - foo.includeInDynsym() is false
    - foo.isPreemptible is not set (wrong)
  * foo's version is set to V1

  After the change:

  * foo's version is set to VER_NDX_LOCAL due to `local: *`
  * foo's version is set to V1
  * handleDynamicList() is called
    - foo.computeBinding() is STB_GLOBAL
    - foo.includeInDynsym() is true
    - foo.isPreemptible is set (correct)

  Reviewed By: ruiu

  Differential Revision: https://reviews.llvm.org/D64550

This makes it longer necessary to patch the version scripts for the
samba ports, to avoid "duplicate symbol 'pdb_search_init' in version
script" errors.

PR:		230602
MFC after:	3 days
This commit is contained in:
Dimitry Andric 2019-07-13 15:04:30 +00:00
parent 409a80e5a4
commit f7e8f5d439
2 changed files with 18 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

40
contrib/llvm/tools/lld/ELF/SymbolTable.cpp
View File

@ -654,20 +654,6 @@ std::vector<Symbol *> SymbolTable::findAllByVersion(SymbolVersion Ver) {
return Res;
}
// If there's only one anonymous version definition in a version
// script file, the script does not actually define any symbol version,
// but just specifies symbols visibilities.
void SymbolTable::handleAnonymousVersion() {
for (SymbolVersion &Ver : Config->VersionScriptGlobals)
assignExactVersion(Ver, VER_NDX_GLOBAL, "global");
for (SymbolVersion &Ver : Config->VersionScriptGlobals)
assignWildcardVersion(Ver, VER_NDX_GLOBAL);
for (SymbolVersion &Ver : Config->VersionScriptLocals)
assignExactVersion(Ver, VER_NDX_LOCAL, "local");
for (SymbolVersion &Ver : Config->VersionScriptLocals)
assignWildcardVersion(Ver, VER_NDX_LOCAL);
}
// Handles -dynamic-list.
void SymbolTable::handleDynamicList() {
for (SymbolVersion &Ver : Config->DynamicList) {
@ -731,23 +717,27 @@ void SymbolTable::assignWildcardVersion(SymbolVersion Ver, uint16_t VersionId) {
// This function processes version scripts by updating VersionId
// member of symbols.
// If there's only one anonymous version definition in a version
// script file, the script does not actually define any symbol version,
// but just specifies symbols visibilities.
void SymbolTable::scanVersionScript() {
// Handle edge cases first.
handleAnonymousVersion();
handleDynamicList();
// Now we have version definitions, so we need to set version ids to symbols.
// Each version definition has a glob pattern, and all symbols that match
// with the pattern get that version.
// First, we assign versions to exact matching symbols,
// i.e. version definitions not containing any glob meta-characters.
for (SymbolVersion &Ver : Config->VersionScriptGlobals)
assignExactVersion(Ver, VER_NDX_GLOBAL, "global");
for (SymbolVersion &Ver : Config->VersionScriptLocals)
assignExactVersion(Ver, VER_NDX_LOCAL, "local");
for (VersionDefinition &V : Config->VersionDefinitions)
for (SymbolVersion &Ver : V.Globals)
assignExactVersion(Ver, V.Id, V.Name);
// Next, we assign versions to fuzzy matching symbols,
// i.e. version definitions containing glob meta-characters.
for (SymbolVersion &Ver : Config->VersionScriptGlobals)
assignWildcardVersion(Ver, VER_NDX_GLOBAL);
for (SymbolVersion &Ver : Config->VersionScriptLocals)
assignWildcardVersion(Ver, VER_NDX_LOCAL);
// Note that because the last match takes precedence over previous matches,
// we iterate over the definitions in the reverse order.
for (VersionDefinition &V : llvm::reverse(Config->VersionDefinitions))
@ -759,6 +749,12 @@ void SymbolTable::scanVersionScript() {
// Let them parse and update their names to exclude version suffix.
for (Symbol *Sym : SymVector)
Sym->parseSymbolVersion();
// isPreemptible is false at this point. To correctly compute the binding of a
// Defined (which is used by includeInDynsym()), we need to know if it is
// VER_NDX_LOCAL or not. If defaultSymbolVersion is VER_NDX_LOCAL, we should
// compute symbol versions before handling --dynamic-list.
handleDynamicList();
}
template void SymbolTable::addFile<ELF32LE>(InputFile *);

1
contrib/llvm/tools/lld/ELF/SymbolTable.h
View File

@ -90,7 +90,6 @@ class SymbolTable {
std::vector<Symbol *> findAllByVersion(SymbolVersion Ver);
llvm::StringMap<std::vector<Symbol *>> &getDemangledSyms();
void handleAnonymousVersion();
void assignExactVersion(SymbolVersion Ver, uint16_t VersionId,
StringRef VersionName);
void assignWildcardVersion(SymbolVersion Ver, uint16_t VersionId);