[LLD][COFF] Check both mangled and demangled symbols before adding a lazy archive symbol to the symbol table on ARM64EC #113284
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
|
@llvm/pr-subscribers-platform-windows @llvm/pr-subscribers-lld Author: Jacek Caban (cjacek) ChangesOn ARM64EC, a function symbol may appear in both mangled and demangled forms:
If more than one archive defines the same function, this could lead to different libraries being used for the same function depending on how they are referenced. Avoid this by checking if the paired symbol is already defined before adding a symbol to the table. Full diff: https://github.com/llvm/llvm-project/pull/113284.diff 6 Files Affected:
diff --git a/lld/COFF/InputFiles.cpp b/lld/COFF/InputFiles.cpp
index 292c3bfc1eaa9d..fdbc1de4beaf32 100644
--- a/lld/COFF/InputFiles.cpp
+++ b/lld/COFF/InputFiles.cpp
@@ -455,11 +455,34 @@ void ObjFile::initializeSymbols() {
COFFSymbolRef coffSym = check(coffObj->getSymbol(i));
bool prevailingComdat;
if (coffSym.isUndefined()) {
- symbols[i] = createUndefined(coffSym);
+ symbols[i] = createUndefined(coffSym, false);
} else if (coffSym.isWeakExternal()) {
- symbols[i] = createUndefined(coffSym);
- weakAliases.emplace_back(symbols[i],
- coffSym.getAux<coff_aux_weak_external>());
+ auto aux = coffSym.getAux<coff_aux_weak_external>();
+ bool overrideLazy = true;
+
+ // On ARM64EC, external functions don't emit undefined symbols. Instead,
+ // they emit a pair of weak-dependency aliases: func to #func and
+ // #func to the func guess exit thunk. Allow such aliases to be overridden
+ // by lazy archive symbols, just as we would for undefined symbols.
+ if (isArm64EC(getMachineType()) &&
+ aux->Characteristics == IMAGE_WEAK_EXTERN_ANTI_DEPENDENCY) {
+ COFFSymbolRef targetSym = check(coffObj->getSymbol(aux->TagIndex));
+ if (!targetSym.isAnyUndefined()) {
+ // If the target is defined, it may be either a guess exit thunk or
+ // the actual implementation. If it's the latter, consider the alias
+ // to be part of the implementation and override potential lazy archive
+ // symbols.
+ StringRef targetName = check(coffObj->getSymbolName(targetSym));
+ StringRef name = check(coffObj->getSymbolName(coffSym));
+ std::optional<std::string> mangledName =
+ getArm64ECMangledFunctionName(name);
+ overrideLazy = mangledName == targetName;
+ } else {
+ overrideLazy = false;
+ }
+ }
+ symbols[i] = createUndefined(coffSym, overrideLazy);
+ weakAliases.emplace_back(symbols[i], aux);
} else if (std::optional<Symbol *> optSym =
createDefined(coffSym, comdatDefs, prevailingComdat)) {
symbols[i] = *optSym;
@@ -508,9 +531,9 @@ void ObjFile::initializeSymbols() {
decltype(sparseChunks)().swap(sparseChunks);
}
-Symbol *ObjFile::createUndefined(COFFSymbolRef sym) {
+Symbol *ObjFile::createUndefined(COFFSymbolRef sym, bool overrideLazy) {
StringRef name = check(coffObj->getSymbolName(sym));
- return ctx.symtab.addUndefined(name, this, sym.isWeakExternal());
+ return ctx.symtab.addUndefined(name, this, overrideLazy);
}
static const coff_aux_section_definition *findSectionDef(COFFObjectFile *obj,
diff --git a/lld/COFF/InputFiles.h b/lld/COFF/InputFiles.h
index a20b097cbe04af..77f7e298166eec 100644
--- a/lld/COFF/InputFiles.h
+++ b/lld/COFF/InputFiles.h
@@ -272,7 +272,7 @@ class ObjFile : public InputFile {
&comdatDefs,
bool &prevailingComdat);
Symbol *createRegular(COFFSymbolRef sym);
- Symbol *createUndefined(COFFSymbolRef sym);
+ Symbol *createUndefined(COFFSymbolRef sym, bool overrideLazy);
std::unique_ptr<COFFObjectFile> coffObj;
diff --git a/lld/COFF/SymbolTable.cpp b/lld/COFF/SymbolTable.cpp
index 230ae74dfb21d0..c93f74c6924192 100644
--- a/lld/COFF/SymbolTable.cpp
+++ b/lld/COFF/SymbolTable.cpp
@@ -18,6 +18,7 @@
#include "lld/Common/Timer.h"
#include "llvm/DebugInfo/DIContext.h"
#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Mangler.h"
#include "llvm/LTO/LTO.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Parallel.h"
@@ -620,9 +621,9 @@ void SymbolTable::initializeECThunks() {
}
Symbol *SymbolTable::addUndefined(StringRef name, InputFile *f,
- bool isWeakAlias) {
+ bool overrideLazy) {
auto [s, wasInserted] = insert(name, f);
- if (wasInserted || (s->isLazy() && isWeakAlias)) {
+ if (wasInserted || (s->isLazy() && overrideLazy)) {
replaceSymbol<Undefined>(s, name);
return s;
}
@@ -631,15 +632,52 @@ Symbol *SymbolTable::addUndefined(StringRef name, InputFile *f,
return s;
}
+// On ARM64EC, a function symbol may appear in both mangled and demangled forms:
+// - ARM64EC archives contain only the mangled name, while the demangled symbol is
+// defined by the object file as an alias.
+// - x86_64 archives contain only the demangled name (the mangled name is usually
+// defined by an object referencing the symbol as an alias to a guess exit thunk).
+// - ARM64EC import files contain both the mangled and demangled names for thunks.
+// If more than one archive defines the same function, this could lead to
+// different libraries being used for the same function depending on how they
+// are referenced. Avoid this by checking if the paired symbol is already defined
+// before adding a symbol to the table.
+template <typename T>
+bool checkLazyECPair(SymbolTable *symtab, StringRef name, InputFile *f) {
+ if (name.starts_with("__imp_"))
+ return true;
+ std::string pairName;
+ if (std::optional<std::string> mangledName =
+ getArm64ECMangledFunctionName(name))
+ pairName = std::move(*mangledName);
+ else
+ pairName = *getArm64ECDemangledFunctionName(name);
+
+ Symbol *sym = symtab->find(pairName);
+ if (!sym)
+ return true;
+ if (sym->pendingArchiveLoad)
+ return false;
+ if (auto u = dyn_cast<Undefined>(sym))
+ return !u->weakAlias || u->isAntiDep;
+ // If the symbol is lazy, allow it only if it originates from the same archive.
+ auto lazy = dyn_cast<T>(sym);
+ return lazy && lazy->file == f;
+}
+
void SymbolTable::addLazyArchive(ArchiveFile *f, const Archive::Symbol &sym) {
StringRef name = sym.getName();
+ if (isArm64EC(ctx.config.machine) &&
+ !checkLazyECPair<LazyArchive>(this, name, f))
+ return;
auto [s, wasInserted] = insert(name);
if (wasInserted) {
replaceSymbol<LazyArchive>(s, f, sym);
return;
}
auto *u = dyn_cast<Undefined>(s);
- if (!u || u->weakAlias || s->pendingArchiveLoad)
+ if (!u || (u->weakAlias && !u->isECAlias(ctx.config.machine)) ||
+ s->pendingArchiveLoad)
return;
s->pendingArchiveLoad = true;
f->addMember(sym);
@@ -647,13 +685,16 @@ void SymbolTable::addLazyArchive(ArchiveFile *f, const Archive::Symbol &sym) {
void SymbolTable::addLazyObject(InputFile *f, StringRef n) {
assert(f->lazy);
+ if (isArm64EC(ctx.config.machine) && !checkLazyECPair<LazyObject>(this, n, f))
+ return;
auto [s, wasInserted] = insert(n, f);
if (wasInserted) {
replaceSymbol<LazyObject>(s, f, n);
return;
}
auto *u = dyn_cast<Undefined>(s);
- if (!u || u->weakAlias || s->pendingArchiveLoad)
+ if (!u || (u->weakAlias && !u->isECAlias(ctx.config.machine)) ||
+ s->pendingArchiveLoad)
return;
s->pendingArchiveLoad = true;
f->lazy = false;
diff --git a/lld/COFF/SymbolTable.h b/lld/COFF/SymbolTable.h
index dab03afde3f987..1d9e908b8b9918 100644
--- a/lld/COFF/SymbolTable.h
+++ b/lld/COFF/SymbolTable.h
@@ -91,7 +91,7 @@ class SymbolTable {
Symbol *addSynthetic(StringRef n, Chunk *c);
Symbol *addAbsolute(StringRef n, uint64_t va);
- Symbol *addUndefined(StringRef name, InputFile *f, bool isWeakAlias);
+ Symbol *addUndefined(StringRef name, InputFile *f, bool overrideLazy);
void addLazyArchive(ArchiveFile *f, const Archive::Symbol &sym);
void addLazyObject(InputFile *f, StringRef n);
void addLazyDLLSymbol(DLLFile *f, DLLFile::Symbol *sym, StringRef n);
diff --git a/lld/COFF/Symbols.h b/lld/COFF/Symbols.h
index ff84ff8ad7b28b..203a542466c68e 100644
--- a/lld/COFF/Symbols.h
+++ b/lld/COFF/Symbols.h
@@ -353,6 +353,10 @@ class Undefined : public Symbol {
isAntiDep = antiDep;
}
+ bool isECAlias(MachineTypes machine) const {
+ return weakAlias && isAntiDep && isArm64EC(machine);
+ }
+
// If this symbol is external weak, replace this object with aliased symbol.
bool resolveWeakAlias();
};
diff --git a/lld/test/COFF/arm64ec-lib.test b/lld/test/COFF/arm64ec-lib.test
index a26c098547fdbe..c63c59b46e5740 100644
--- a/lld/test/COFF/arm64ec-lib.test
+++ b/lld/test/COFF/arm64ec-lib.test
@@ -7,10 +7,17 @@ RUN: llvm-mc -filetype=obj -triple=aarch64-windows nsymref.s -o nsymref-aarch64.
RUN: llvm-mc -filetype=obj -triple=arm64ec-windows sym.s -o sym-arm64ec.obj
RUN: llvm-mc -filetype=obj -triple=x86_64-windows sym.s -o sym-x86_64.obj
RUN: llvm-mc -filetype=obj -triple=aarch64-windows nsym.s -o nsym-aarch64.obj
+RUN: llvm-mc -filetype=obj -triple=arm64ec-windows ref-alias.s -o ref-alias.obj
+RUN: llvm-mc -filetype=obj -triple=arm64ec-windows ref-thunk.s -o ref-thunk.obj
+RUN: llvm-mc -filetype=obj -triple=arm64ec-windows func.s -o func.obj
+RUN: llvm-mc -filetype=obj -triple=x86_64-windows func-x86_64.s -o func-x86_64.obj
RUN: llvm-mc -filetype=obj -triple=arm64ec-windows %S/Inputs/loadconfig-arm64ec.s -o loadconfig-arm64ec.obj
RUN: llvm-lib -machine:arm64ec -out:sym-arm64ec.lib sym-arm64ec.obj nsym-aarch64.obj
RUN: llvm-lib -machine:amd64 -out:sym-x86_64.lib sym-x86_64.obj
+RUN: llvm-lib -machine:arm64ec -out:func.lib func.obj
+RUN: llvm-lib -machine:arm64ec -out:func-x86_64.lib func-x86_64.obj
+RUN: llvm-lib -machine:arm64ec -out:func-imp.lib -def:func.def
Verify that a symbol can be referenced from ECSYMBOLS.
RUN: lld-link -machine:arm64ec -dll -noentry -out:test.dll symref-arm64ec.obj sym-arm64ec.lib loadconfig-arm64ec.obj
@@ -26,6 +33,63 @@ RUN: not lld-link -machine:arm64ec -dll -noentry -out:test-err.dll nsymref-arm64
RUN: FileCheck --check-prefix=ERR %s
ERR: error: undefined symbol: nsym
+Verify that a library symbol can be referenced, even if its name conflicts with an anti-dependency alias.
+RUN: lld-link -machine:arm64ec -dll -noentry -out:ref-alias-1.dll ref-alias.obj func.lib loadconfig-arm64ec.obj
+RUN: llvm-objdump -d ref-alias-1.dll | FileCheck -check-prefix=DISASM %s
+DISASM: 0000000180001000 <.text>:
+DISASM-NEXT: 180001000: d65f03c0 ret
+DISASM-EMPTY:
+
+RUN: llvm-readobj --hex-dump=.test ref-alias-1.dll | FileCheck -check-prefix=TESTSEC %s
+TESTSEC: 0x180004000 00100000
+
+The same test, but with a different input order.
+RUN: lld-link -machine:arm64ec -dll -noentry -out:ref-alias-2.dll func.lib ref-alias.obj loadconfig-arm64ec.obj
+RUN: llvm-objdump -d ref-alias-2.dll | FileCheck -check-prefix=DISASM %s
+RUN: llvm-readobj --hex-dump=.test ref-alias-2.dll | FileCheck -check-prefix=TESTSEC %s
+
+Verify that when an anti-dependency to a guess exit thunk is present, it is overridden by an archive symbol.
+RUN: lld-link -machine:arm64ec -dll -noentry -out:ref-thunk-1.dll ref-thunk.obj func.lib loadconfig-arm64ec.obj
+RUN: llvm-objdump -d ref-thunk-1.dll | FileCheck -check-prefix=DISASM %s
+RUN: llvm-readobj --hex-dump=.test ref-thunk-1.dll | FileCheck -check-prefix=TESTSEC %s
+
+The same test, but with a different input order.
+RUN: lld-link -machine:arm64ec -dll -noentry -out:ref-thunk-2.dll func.lib ref-thunk.obj loadconfig-arm64ec.obj
+RUN: llvm-objdump -d ref-thunk-2.dll | FileCheck -check-prefix=DISASM %s
+RUN: llvm-readobj --hex-dump=.test ref-thunk-2.dll | FileCheck -check-prefix=TESTSEC %s
+
+Pass multiple libraries containing `func` with different manglings and ensure they don't conflict with each other.
+RUN: lld-link -machine:arm64ec -dll -noentry -out:ref-thunk-3.dll func.lib loadconfig-arm64ec.obj func-x86_64.lib func-imp.lib ref-thunk.obj
+RUN: llvm-objdump -d ref-thunk-3.dll | FileCheck -check-prefix=DISASM %s
+RUN: llvm-readobj --hex-dump=.test ref-thunk-3.dll | FileCheck -check-prefix=TESTSEC %s
+
+RUN: lld-link -machine:arm64ec -dll -noentry -out:ref-thunk-4.dll ref-thunk.obj func.lib loadconfig-arm64ec.obj func-x86_64.lib func-imp.lib
+RUN: llvm-objdump -d ref-thunk-4.dll | FileCheck -check-prefix=DISASM %s
+RUN: llvm-readobj --hex-dump=.test ref-thunk-4.dll | FileCheck -check-prefix=TESTSEC %s
+
+Test linking against an x86_64 library (which uses a demangled function name).
+RUN: lld-link -machine:arm64ec -dll -noentry -out:ref-x86-1.dll ref-thunk.obj func-x86_64.lib loadconfig-arm64ec.obj
+RUN: llvm-objdump -d ref-x86-1.dll | FileCheck -check-prefix=DISASM-X86 %s
+RUN: llvm-readobj --hex-dump=.test ref-x86-1.dll | FileCheck -check-prefix=TESTSEC %s
+
+DISASM-X86: 0000000180001000 <.text>:
+DISASM-X86-NEXT: 180001000: c3 retq
+
+The same test, but with a different input order.
+RUN: lld-link -machine:arm64ec -dll -noentry -out:ref-x86-2.dll func-x86_64.lib ref-thunk.obj loadconfig-arm64ec.obj
+RUN: llvm-objdump -d ref-x86-2.dll | FileCheck -check-prefix=DISASM-X86 %s
+RUN: llvm-readobj --hex-dump=.test ref-x86-2.dll | FileCheck -check-prefix=TESTSEC %s
+
+A similar test using -start-lib for linking.
+RUN: lld-link -machine:arm64ec -dll -noentry -out:start-lib-1.dll ref-thunk.obj -start-lib func.obj -end-lib loadconfig-arm64ec.obj
+RUN: llvm-objdump -d start-lib-1.dll | FileCheck -check-prefix=DISASM %s
+RUN: llvm-readobj --hex-dump=.test start-lib-1.dll | FileCheck -check-prefix=TESTSEC %s
+
+RUN: lld-link -machine:arm64ec -dll -noentry -out:start-lib-2.dll ref-thunk.obj -start-lib func.obj -end-lib loadconfig-arm64ec.obj \
+RUN: -start-lib func-x86_64.obj -end-lib func-imp.lib
+RUN: llvm-objdump -d ref-thunk-3.dll | FileCheck -check-prefix=DISASM %s
+RUN: llvm-readobj --hex-dump=.test ref-thunk-3.dll | FileCheck -check-prefix=TESTSEC %s
+
#--- symref.s
.data
.rva sym
@@ -45,3 +109,44 @@ sym:
.globl nsym
nsym:
.word 0
+
+#--- ref-alias.s
+ .weak_anti_dep func
+.set func,"#func"
+
+ .section .test, "r"
+ .rva func
+
+#--- ref-thunk.s
+ .weak_anti_dep func
+.set func, "#func"
+ .weak_anti_dep "#func"
+.set "#func", thunksym
+
+ .section .test, "r"
+ .rva func
+
+ .section .thnk,"xr",discard,thunksym
+thunksym:
+ mov w0, #2
+ ret
+
+#--- func.s
+ .text
+ .globl "#func"
+"#func":
+ ret
+
+ .weak_anti_dep func
+.set func,"#func"
+
+#--- func-x86_64.s
+ .text
+ .globl func
+func:
+ ret
+
+#--- func.def
+LIBRARY func.dll
+EXPORTS
+ func
\ No newline at end of file
|
|
Depends on #113283. The primary example of this issue occurs when |
|
✅ With the latest revision this PR passed the C/C++ code formatter. |
mstorsjo
approved these changes
Oct 22, 2024
lld/test/COFF/arm64ec-lib.test
Outdated
| #--- func.def | ||
| LIBRARY func.dll | ||
| EXPORTS | ||
| func |
There was a problem hiding this comment.
The file seems to be missing a trailing newline here.
…lazy archive symbol to the symbol table on ARM64EC On ARM64EC, a function symbol may appear in both mangled and demangled forms: - ARM64EC archives contain only the mangled name, while the demangled symbol is defined by the object file as an alias. - x86_64 archives contain only the demangled name (the mangled name is usually defined by an object referencing the symbol as an alias to a guess exit thunk). - ARM64EC import files contain both the mangled and demangled names for thunks. If more than one archive defines the same function, this could lead to different libraries being used for the same function depending on how they are referenced. Avoid this by checking if the paired symbol is already defined before adding a symbol to the table.
|
LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/123/builds/8006 Here is the relevant piece of the build log for the reference |
Closed
NoumanAmir657
pushed a commit
to NoumanAmir657/llvm-project
that referenced
this pull request
Nov 4, 2024
…lazy archive symbol to the symbol table on ARM64EC (llvm#113284) On ARM64EC, a function symbol may appear in both mangled and demangled forms: - ARM64EC archives contain only the mangled name, while the demangled symbol is defined by the object file as an alias. - x86_64 archives contain only the demangled name (the mangled name is usually defined by an object referencing the symbol as an alias to a guess exit thunk). - ARM64EC import files contain both the mangled and demangled names for thunks. If more than one archive defines the same function, this could lead to different libraries being used for the same function depending on how they are referenced. Avoid this by checking if the paired symbol is already defined before adding a symbol to the table.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
On ARM64EC, a function symbol may appear in both mangled and demangled forms:
If more than one archive defines the same function, this could lead to different libraries being used for the same function depending on how they are referenced. Avoid this by checking if the paired symbol is already defined before adding a symbol to the table.