[LLD][COFF] Avoid resolving symbols with -alternatename if the target is undefined #149496
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@llvm/pr-subscribers-lld Author: Jacek Caban (cjacek) ChangesThis change fixes an issue with the use of The root cause isn't specific to ARM64EC, it can affect other targets as well, even when anti-dependency aliases aren't involved. The accompanying test case demonstrates a scenario where the symbol could be resolved from an archive. However, because the archive member is pulled in after the first pass of alternate name resolution, and archive members don't override weak aliases, eager resolution would incorrectly skip it. Full diff: https://github.com/llvm/llvm-project/pull/149496.diff 7 Files Affected:
diff --git a/lld/COFF/Driver.cpp b/lld/COFF/Driver.cpp
index 283aeed1a19cd..f31cf0a42abbb 100644
--- a/lld/COFF/Driver.cpp
+++ b/lld/COFF/Driver.cpp
@@ -2527,28 +2527,7 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
e.symbolName = symtab.mangleMaybe(e.sym);
}
- // Add weak aliases. Weak aliases is a mechanism to give remaining
- // undefined symbols final chance to be resolved successfully.
- for (auto pair : symtab.alternateNames) {
- StringRef from = pair.first;
- StringRef to = pair.second;
- Symbol *sym = symtab.find(from);
- if (!sym)
- continue;
- if (auto *u = dyn_cast<Undefined>(sym)) {
- if (u->weakAlias) {
- // On ARM64EC, anti-dependency aliases are treated as undefined
- // symbols unless a demangled symbol aliases a defined one, which
- // is part of the implementation.
- if (!symtab.isEC() || !u->isAntiDep)
- continue;
- if (!isa<Undefined>(u->weakAlias) &&
- !isArm64ECMangledFunctionName(u->getName()))
- continue;
- }
- u->setWeakAlias(symtab.addUndefined(to));
- }
- }
+ symtab.resolveAlternateNames();
});
ctx.forEachActiveSymtab([&](SymbolTable &symtab) {
diff --git a/lld/COFF/SymbolTable.cpp b/lld/COFF/SymbolTable.cpp
index 0062df5820e63..189e75dfc3ff5 100644
--- a/lld/COFF/SymbolTable.cpp
+++ b/lld/COFF/SymbolTable.cpp
@@ -1344,6 +1344,43 @@ void SymbolTable::parseAlternateName(StringRef s) {
alternateNames.insert(it, std::make_pair(from, to));
}
+void SymbolTable::resolveAlternateNames() {
+ // Add weak aliases. Weak aliases is a mechanism to give remaining
+ // undefined symbols final chance to be resolved successfully.
+ for (auto pair : alternateNames) {
+ StringRef from = pair.first;
+ StringRef to = pair.second;
+ Symbol *sym = find(from);
+ if (!sym)
+ continue;
+ if (auto *u = dyn_cast<Undefined>(sym)) {
+ if (u->weakAlias) {
+ // On ARM64EC, anti-dependency aliases are treated as undefined
+ // symbols unless a demangled symbol aliases a defined one, which
+ // is part of the implementation.
+ if (!isEC() || !u->isAntiDep)
+ continue;
+ if (!isa<Undefined>(u->weakAlias) &&
+ !isArm64ECMangledFunctionName(u->getName()))
+ continue;
+ }
+
+ // Check if the destination symbol is defined. If not, skip it.
+ // It may still be resolved later if more input files are added.
+ // Also skip anti-dependency targets, as they can't be chained anyway.
+ Symbol *toSym = find(to);
+ if (!toSym)
+ continue;
+ auto toUndef = dyn_cast<Undefined>(toSym);
+ if (toUndef && (!toUndef->weakAlias || toUndef->isAntiDep))
+ continue;
+ if (toSym->isLazy())
+ forceLazy(toSym);
+ u->setWeakAlias(toSym);
+ }
+ }
+}
+
// Parses /aligncomm option argument.
void SymbolTable::parseAligncomm(StringRef s) {
auto [name, align] = s.split(',');
diff --git a/lld/COFF/SymbolTable.h b/lld/COFF/SymbolTable.h
index 15e2644a6f519..7eb067640dc85 100644
--- a/lld/COFF/SymbolTable.h
+++ b/lld/COFF/SymbolTable.h
@@ -69,6 +69,9 @@ class SymbolTable {
// symbols and warn about imported local symbols.
void resolveRemainingUndefines();
+ // Try to resolve undefined symbols with alternate names.
+ void resolveAlternateNames();
+
// Load lazy objects that are needed for MinGW automatic import and for
// doing stdcall fixups.
void loadMinGWSymbols();
diff --git a/lld/test/COFF/alternatename-alias.s b/lld/test/COFF/alternatename-alias.s
new file mode 100644
index 0000000000000..bd0a861380e94
--- /dev/null
+++ b/lld/test/COFF/alternatename-alias.s
@@ -0,0 +1,15 @@
+// REQUIRES: x86
+
+// Check that a weak alias can be used as an alternate name target.
+// RUN: llvm-mc -filetype=obj -triple=x86_64-windows %s -o %t.obj
+// RUN: lld-link -dll -noentry %t.obj -alternatename:sym=altsym
+
+ .data
+ .rva sym
+
+ .weak altsym
+ .set altsym,a
+
+ .globl a
+a:
+ .word 1
diff --git a/lld/test/COFF/alternatename-antidep.s b/lld/test/COFF/alternatename-antidep.s
new file mode 100644
index 0000000000000..1188a9b75d481
--- /dev/null
+++ b/lld/test/COFF/alternatename-antidep.s
@@ -0,0 +1,16 @@
+// REQUIRES: x86
+
+// Check that an anti-dependency alias can't be used as an alternate name target.
+// RUN: llvm-mc -filetype=obj -triple=x86_64-windows %s -o %t.obj
+// RUN: not lld-link -dll -noentry %t.obj -alternatename:sym=altsym 2>&1 | FileCheck %s
+// CHECK: error: undefined symbol: sym
+
+ .data
+ .rva sym
+
+ .weak_anti_dep altsym
+ .set altsym,a
+
+ .globl a
+a:
+ .word 1
diff --git a/lld/test/COFF/alternatename-lib.s b/lld/test/COFF/alternatename-lib.s
new file mode 100644
index 0000000000000..206fe6bc23978
--- /dev/null
+++ b/lld/test/COFF/alternatename-lib.s
@@ -0,0 +1,43 @@
+// REQUIRES: x86
+// RUN: split-file %s %t.dir && cd %t.dir
+
+// RUN: llvm-mc -filetype=obj -triple=x86_64-windows refab.s -o refab.obj
+// RUN: llvm-mc -filetype=obj -triple=x86_64-windows aa.s -o aa.obj
+// RUN: llvm-mc -filetype=obj -triple=x86_64-windows b.s -o b.obj
+// RUN: llvm-mc -filetype=obj -triple=x86_64-windows antidep.s -o antidep.obj
+// RUN: llvm-lib -out:aa.lib aa.obj
+// RUN: llvm-lib -out:b.lib b.obj
+
+// Check that -alternatename with an undefined target does not prevent the symbol from being resolved to a library,
+// once another alternate name is resolved and pulls in the source symbol.
+// RUN: lld-link -out:out.dll -dll -noentry -machine:amd64 refab.obj aa.lib -alternatename:a=aa -alternatename:b=undef
+
+// Check that -alternatename with an anti-dependency target does not prevent the symbol from being resolved to a library,
+// after another alternate name is resolved and pulls in the source symbol.
+// RUN: lld-link -out:out2.dll -dll -noentry -machine:amd64 antidep.obj refab.obj aa.lib -alternatename:a=aa -alternatename:b=u
+
+#--- refab.s
+ .data
+ .rva a
+ .rva b
+
+#--- aa.s
+ .globl aa
+aa:
+ .word 1
+
+ .section .drectve, "yn"
+ .ascii "/defaultlib:b.lib"
+
+#--- b.s
+ .globl b
+b:
+ .word 2
+
+#--- antidep.s
+ .weak_anti_dep u
+ .set u,d
+
+ .globl d
+d:
+ .word 3
diff --git a/lld/test/COFF/arm64ec-altnames.s b/lld/test/COFF/arm64ec-altnames.s
index b2abb24efe4c3..cca778ab8dc64 100644
--- a/lld/test/COFF/arm64ec-altnames.s
+++ b/lld/test/COFF/arm64ec-altnames.s
@@ -2,6 +2,7 @@ REQUIRES: aarch64
RUN: split-file %s %t.dir && cd %t.dir
RUN: llvm-mc -filetype=obj -triple=arm64ec-windows ext.s -o ext.obj
+RUN: llvm-mc -filetype=obj -triple=arm64ec-windows ext-mangled.s -o ext-mangled.obj
RUN: llvm-mc -filetype=obj -triple=arm64ec-windows impl.s -o impl.obj
RUN: llvm-mc -filetype=obj -triple=arm64ec-windows impl-cpp.s -o impl-cpp.obj
RUN: llvm-mc -filetype=obj -triple=arm64ec-windows %S/Inputs/loadconfig-arm64ec.s -o loadconfig.obj
@@ -49,6 +50,20 @@ RUN: lld-link -machine:arm64ec -dll -noentry -out:out4.dll impl-cpp.obj loadconf
RUN: llvm-objdump -d out4.dll | FileCheck --check-prefix=DISASM %s
RUN: llvm-readobj --hex-dump=.test out4.dll | FileCheck --check-prefix=TESTSEC %s
+# Check that when both mangled and demangled alternate names are used,
+# only the one whose target is defined is used (the mangled one in this case).
+
+RUN: lld-link -machine:arm64ec -dll -noentry -out:out5.dll ext-mangled.obj loadconfig.obj "-alternatename:#func=#altsym" -alternatename:func=altsym
+RUN: llvm-objdump -d out5.dll | FileCheck --check-prefix=DISASM %s
+RUN: llvm-readobj --hex-dump=.test out5.dll | FileCheck --check-prefix=TESTSEC %s
+
+# Check that when both mangled and demangled alternate names are used,
+# only the one whose target is defined is used (the demangled one in this case).
+
+RUN: lld-link -machine:arm64ec -dll -noentry -out:out6.dll ext.obj loadconfig.obj "-alternatename:#func=#altsym" -alternatename:func=altsym
+RUN: llvm-objdump -d out6.dll | FileCheck --check-prefix=DISASM2 %s
+RUN: llvm-readobj --hex-dump=.test out6.dll | FileCheck --check-prefix=TESTSEC2 %s
+
#--- ext.s
.weak_anti_dep func
.set func, "#func"
@@ -70,6 +85,30 @@ altsym:
mov w0, #1
ret
+#--- ext-mangled.s
+ .weak_anti_dep func
+.set func, "#func"
+ .weak_anti_dep "#func"
+.set "#func", thunksym
+
+ .section .test, "r"
+ .rva func
+ .rva "#func"
+
+ .section .thnk,"xr",discard,thunksym
+thunksym:
+ mov w0, #2
+ ret
+
+ .section .text,"xr",discard,"#altsym"
+ .globl "#altsym"
+"#altsym":
+ mov w0, #1
+ ret
+
+ .weak_anti_dep altsym
+ .set altsym,"#altsym"
+
#--- impl.s
.weak_anti_dep func
.set func, "#func"
|
|
@llvm/pr-subscribers-lld-coff Author: Jacek Caban (cjacek) ChangesThis change fixes an issue with the use of The root cause isn't specific to ARM64EC, it can affect other targets as well, even when anti-dependency aliases aren't involved. The accompanying test case demonstrates a scenario where the symbol could be resolved from an archive. However, because the archive member is pulled in after the first pass of alternate name resolution, and archive members don't override weak aliases, eager resolution would incorrectly skip it. Full diff: https://github.com/llvm/llvm-project/pull/149496.diff 7 Files Affected:
diff --git a/lld/COFF/Driver.cpp b/lld/COFF/Driver.cpp
index 283aeed1a19cd..f31cf0a42abbb 100644
--- a/lld/COFF/Driver.cpp
+++ b/lld/COFF/Driver.cpp
@@ -2527,28 +2527,7 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
e.symbolName = symtab.mangleMaybe(e.sym);
}
- // Add weak aliases. Weak aliases is a mechanism to give remaining
- // undefined symbols final chance to be resolved successfully.
- for (auto pair : symtab.alternateNames) {
- StringRef from = pair.first;
- StringRef to = pair.second;
- Symbol *sym = symtab.find(from);
- if (!sym)
- continue;
- if (auto *u = dyn_cast<Undefined>(sym)) {
- if (u->weakAlias) {
- // On ARM64EC, anti-dependency aliases are treated as undefined
- // symbols unless a demangled symbol aliases a defined one, which
- // is part of the implementation.
- if (!symtab.isEC() || !u->isAntiDep)
- continue;
- if (!isa<Undefined>(u->weakAlias) &&
- !isArm64ECMangledFunctionName(u->getName()))
- continue;
- }
- u->setWeakAlias(symtab.addUndefined(to));
- }
- }
+ symtab.resolveAlternateNames();
});
ctx.forEachActiveSymtab([&](SymbolTable &symtab) {
diff --git a/lld/COFF/SymbolTable.cpp b/lld/COFF/SymbolTable.cpp
index 0062df5820e63..189e75dfc3ff5 100644
--- a/lld/COFF/SymbolTable.cpp
+++ b/lld/COFF/SymbolTable.cpp
@@ -1344,6 +1344,43 @@ void SymbolTable::parseAlternateName(StringRef s) {
alternateNames.insert(it, std::make_pair(from, to));
}
+void SymbolTable::resolveAlternateNames() {
+ // Add weak aliases. Weak aliases is a mechanism to give remaining
+ // undefined symbols final chance to be resolved successfully.
+ for (auto pair : alternateNames) {
+ StringRef from = pair.first;
+ StringRef to = pair.second;
+ Symbol *sym = find(from);
+ if (!sym)
+ continue;
+ if (auto *u = dyn_cast<Undefined>(sym)) {
+ if (u->weakAlias) {
+ // On ARM64EC, anti-dependency aliases are treated as undefined
+ // symbols unless a demangled symbol aliases a defined one, which
+ // is part of the implementation.
+ if (!isEC() || !u->isAntiDep)
+ continue;
+ if (!isa<Undefined>(u->weakAlias) &&
+ !isArm64ECMangledFunctionName(u->getName()))
+ continue;
+ }
+
+ // Check if the destination symbol is defined. If not, skip it.
+ // It may still be resolved later if more input files are added.
+ // Also skip anti-dependency targets, as they can't be chained anyway.
+ Symbol *toSym = find(to);
+ if (!toSym)
+ continue;
+ auto toUndef = dyn_cast<Undefined>(toSym);
+ if (toUndef && (!toUndef->weakAlias || toUndef->isAntiDep))
+ continue;
+ if (toSym->isLazy())
+ forceLazy(toSym);
+ u->setWeakAlias(toSym);
+ }
+ }
+}
+
// Parses /aligncomm option argument.
void SymbolTable::parseAligncomm(StringRef s) {
auto [name, align] = s.split(',');
diff --git a/lld/COFF/SymbolTable.h b/lld/COFF/SymbolTable.h
index 15e2644a6f519..7eb067640dc85 100644
--- a/lld/COFF/SymbolTable.h
+++ b/lld/COFF/SymbolTable.h
@@ -69,6 +69,9 @@ class SymbolTable {
// symbols and warn about imported local symbols.
void resolveRemainingUndefines();
+ // Try to resolve undefined symbols with alternate names.
+ void resolveAlternateNames();
+
// Load lazy objects that are needed for MinGW automatic import and for
// doing stdcall fixups.
void loadMinGWSymbols();
diff --git a/lld/test/COFF/alternatename-alias.s b/lld/test/COFF/alternatename-alias.s
new file mode 100644
index 0000000000000..bd0a861380e94
--- /dev/null
+++ b/lld/test/COFF/alternatename-alias.s
@@ -0,0 +1,15 @@
+// REQUIRES: x86
+
+// Check that a weak alias can be used as an alternate name target.
+// RUN: llvm-mc -filetype=obj -triple=x86_64-windows %s -o %t.obj
+// RUN: lld-link -dll -noentry %t.obj -alternatename:sym=altsym
+
+ .data
+ .rva sym
+
+ .weak altsym
+ .set altsym,a
+
+ .globl a
+a:
+ .word 1
diff --git a/lld/test/COFF/alternatename-antidep.s b/lld/test/COFF/alternatename-antidep.s
new file mode 100644
index 0000000000000..1188a9b75d481
--- /dev/null
+++ b/lld/test/COFF/alternatename-antidep.s
@@ -0,0 +1,16 @@
+// REQUIRES: x86
+
+// Check that an anti-dependency alias can't be used as an alternate name target.
+// RUN: llvm-mc -filetype=obj -triple=x86_64-windows %s -o %t.obj
+// RUN: not lld-link -dll -noentry %t.obj -alternatename:sym=altsym 2>&1 | FileCheck %s
+// CHECK: error: undefined symbol: sym
+
+ .data
+ .rva sym
+
+ .weak_anti_dep altsym
+ .set altsym,a
+
+ .globl a
+a:
+ .word 1
diff --git a/lld/test/COFF/alternatename-lib.s b/lld/test/COFF/alternatename-lib.s
new file mode 100644
index 0000000000000..206fe6bc23978
--- /dev/null
+++ b/lld/test/COFF/alternatename-lib.s
@@ -0,0 +1,43 @@
+// REQUIRES: x86
+// RUN: split-file %s %t.dir && cd %t.dir
+
+// RUN: llvm-mc -filetype=obj -triple=x86_64-windows refab.s -o refab.obj
+// RUN: llvm-mc -filetype=obj -triple=x86_64-windows aa.s -o aa.obj
+// RUN: llvm-mc -filetype=obj -triple=x86_64-windows b.s -o b.obj
+// RUN: llvm-mc -filetype=obj -triple=x86_64-windows antidep.s -o antidep.obj
+// RUN: llvm-lib -out:aa.lib aa.obj
+// RUN: llvm-lib -out:b.lib b.obj
+
+// Check that -alternatename with an undefined target does not prevent the symbol from being resolved to a library,
+// once another alternate name is resolved and pulls in the source symbol.
+// RUN: lld-link -out:out.dll -dll -noentry -machine:amd64 refab.obj aa.lib -alternatename:a=aa -alternatename:b=undef
+
+// Check that -alternatename with an anti-dependency target does not prevent the symbol from being resolved to a library,
+// after another alternate name is resolved and pulls in the source symbol.
+// RUN: lld-link -out:out2.dll -dll -noentry -machine:amd64 antidep.obj refab.obj aa.lib -alternatename:a=aa -alternatename:b=u
+
+#--- refab.s
+ .data
+ .rva a
+ .rva b
+
+#--- aa.s
+ .globl aa
+aa:
+ .word 1
+
+ .section .drectve, "yn"
+ .ascii "/defaultlib:b.lib"
+
+#--- b.s
+ .globl b
+b:
+ .word 2
+
+#--- antidep.s
+ .weak_anti_dep u
+ .set u,d
+
+ .globl d
+d:
+ .word 3
diff --git a/lld/test/COFF/arm64ec-altnames.s b/lld/test/COFF/arm64ec-altnames.s
index b2abb24efe4c3..cca778ab8dc64 100644
--- a/lld/test/COFF/arm64ec-altnames.s
+++ b/lld/test/COFF/arm64ec-altnames.s
@@ -2,6 +2,7 @@ REQUIRES: aarch64
RUN: split-file %s %t.dir && cd %t.dir
RUN: llvm-mc -filetype=obj -triple=arm64ec-windows ext.s -o ext.obj
+RUN: llvm-mc -filetype=obj -triple=arm64ec-windows ext-mangled.s -o ext-mangled.obj
RUN: llvm-mc -filetype=obj -triple=arm64ec-windows impl.s -o impl.obj
RUN: llvm-mc -filetype=obj -triple=arm64ec-windows impl-cpp.s -o impl-cpp.obj
RUN: llvm-mc -filetype=obj -triple=arm64ec-windows %S/Inputs/loadconfig-arm64ec.s -o loadconfig.obj
@@ -49,6 +50,20 @@ RUN: lld-link -machine:arm64ec -dll -noentry -out:out4.dll impl-cpp.obj loadconf
RUN: llvm-objdump -d out4.dll | FileCheck --check-prefix=DISASM %s
RUN: llvm-readobj --hex-dump=.test out4.dll | FileCheck --check-prefix=TESTSEC %s
+# Check that when both mangled and demangled alternate names are used,
+# only the one whose target is defined is used (the mangled one in this case).
+
+RUN: lld-link -machine:arm64ec -dll -noentry -out:out5.dll ext-mangled.obj loadconfig.obj "-alternatename:#func=#altsym" -alternatename:func=altsym
+RUN: llvm-objdump -d out5.dll | FileCheck --check-prefix=DISASM %s
+RUN: llvm-readobj --hex-dump=.test out5.dll | FileCheck --check-prefix=TESTSEC %s
+
+# Check that when both mangled and demangled alternate names are used,
+# only the one whose target is defined is used (the demangled one in this case).
+
+RUN: lld-link -machine:arm64ec -dll -noentry -out:out6.dll ext.obj loadconfig.obj "-alternatename:#func=#altsym" -alternatename:func=altsym
+RUN: llvm-objdump -d out6.dll | FileCheck --check-prefix=DISASM2 %s
+RUN: llvm-readobj --hex-dump=.test out6.dll | FileCheck --check-prefix=TESTSEC2 %s
+
#--- ext.s
.weak_anti_dep func
.set func, "#func"
@@ -70,6 +85,30 @@ altsym:
mov w0, #1
ret
+#--- ext-mangled.s
+ .weak_anti_dep func
+.set func, "#func"
+ .weak_anti_dep "#func"
+.set "#func", thunksym
+
+ .section .test, "r"
+ .rva func
+ .rva "#func"
+
+ .section .thnk,"xr",discard,thunksym
+thunksym:
+ mov w0, #2
+ ret
+
+ .section .text,"xr",discard,"#altsym"
+ .globl "#altsym"
+"#altsym":
+ mov w0, #1
+ ret
+
+ .weak_anti_dep altsym
+ .set altsym,"#altsym"
+
#--- impl.s
.weak_anti_dep func
.set func, "#func"
|
|
@llvm/pr-subscribers-platform-windows Author: Jacek Caban (cjacek) ChangesThis change fixes an issue with the use of The root cause isn't specific to ARM64EC, it can affect other targets as well, even when anti-dependency aliases aren't involved. The accompanying test case demonstrates a scenario where the symbol could be resolved from an archive. However, because the archive member is pulled in after the first pass of alternate name resolution, and archive members don't override weak aliases, eager resolution would incorrectly skip it. Full diff: https://github.com/llvm/llvm-project/pull/149496.diff 7 Files Affected:
diff --git a/lld/COFF/Driver.cpp b/lld/COFF/Driver.cpp
index 283aeed1a19cd..f31cf0a42abbb 100644
--- a/lld/COFF/Driver.cpp
+++ b/lld/COFF/Driver.cpp
@@ -2527,28 +2527,7 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
e.symbolName = symtab.mangleMaybe(e.sym);
}
- // Add weak aliases. Weak aliases is a mechanism to give remaining
- // undefined symbols final chance to be resolved successfully.
- for (auto pair : symtab.alternateNames) {
- StringRef from = pair.first;
- StringRef to = pair.second;
- Symbol *sym = symtab.find(from);
- if (!sym)
- continue;
- if (auto *u = dyn_cast<Undefined>(sym)) {
- if (u->weakAlias) {
- // On ARM64EC, anti-dependency aliases are treated as undefined
- // symbols unless a demangled symbol aliases a defined one, which
- // is part of the implementation.
- if (!symtab.isEC() || !u->isAntiDep)
- continue;
- if (!isa<Undefined>(u->weakAlias) &&
- !isArm64ECMangledFunctionName(u->getName()))
- continue;
- }
- u->setWeakAlias(symtab.addUndefined(to));
- }
- }
+ symtab.resolveAlternateNames();
});
ctx.forEachActiveSymtab([&](SymbolTable &symtab) {
diff --git a/lld/COFF/SymbolTable.cpp b/lld/COFF/SymbolTable.cpp
index 0062df5820e63..189e75dfc3ff5 100644
--- a/lld/COFF/SymbolTable.cpp
+++ b/lld/COFF/SymbolTable.cpp
@@ -1344,6 +1344,43 @@ void SymbolTable::parseAlternateName(StringRef s) {
alternateNames.insert(it, std::make_pair(from, to));
}
+void SymbolTable::resolveAlternateNames() {
+ // Add weak aliases. Weak aliases is a mechanism to give remaining
+ // undefined symbols final chance to be resolved successfully.
+ for (auto pair : alternateNames) {
+ StringRef from = pair.first;
+ StringRef to = pair.second;
+ Symbol *sym = find(from);
+ if (!sym)
+ continue;
+ if (auto *u = dyn_cast<Undefined>(sym)) {
+ if (u->weakAlias) {
+ // On ARM64EC, anti-dependency aliases are treated as undefined
+ // symbols unless a demangled symbol aliases a defined one, which
+ // is part of the implementation.
+ if (!isEC() || !u->isAntiDep)
+ continue;
+ if (!isa<Undefined>(u->weakAlias) &&
+ !isArm64ECMangledFunctionName(u->getName()))
+ continue;
+ }
+
+ // Check if the destination symbol is defined. If not, skip it.
+ // It may still be resolved later if more input files are added.
+ // Also skip anti-dependency targets, as they can't be chained anyway.
+ Symbol *toSym = find(to);
+ if (!toSym)
+ continue;
+ auto toUndef = dyn_cast<Undefined>(toSym);
+ if (toUndef && (!toUndef->weakAlias || toUndef->isAntiDep))
+ continue;
+ if (toSym->isLazy())
+ forceLazy(toSym);
+ u->setWeakAlias(toSym);
+ }
+ }
+}
+
// Parses /aligncomm option argument.
void SymbolTable::parseAligncomm(StringRef s) {
auto [name, align] = s.split(',');
diff --git a/lld/COFF/SymbolTable.h b/lld/COFF/SymbolTable.h
index 15e2644a6f519..7eb067640dc85 100644
--- a/lld/COFF/SymbolTable.h
+++ b/lld/COFF/SymbolTable.h
@@ -69,6 +69,9 @@ class SymbolTable {
// symbols and warn about imported local symbols.
void resolveRemainingUndefines();
+ // Try to resolve undefined symbols with alternate names.
+ void resolveAlternateNames();
+
// Load lazy objects that are needed for MinGW automatic import and for
// doing stdcall fixups.
void loadMinGWSymbols();
diff --git a/lld/test/COFF/alternatename-alias.s b/lld/test/COFF/alternatename-alias.s
new file mode 100644
index 0000000000000..bd0a861380e94
--- /dev/null
+++ b/lld/test/COFF/alternatename-alias.s
@@ -0,0 +1,15 @@
+// REQUIRES: x86
+
+// Check that a weak alias can be used as an alternate name target.
+// RUN: llvm-mc -filetype=obj -triple=x86_64-windows %s -o %t.obj
+// RUN: lld-link -dll -noentry %t.obj -alternatename:sym=altsym
+
+ .data
+ .rva sym
+
+ .weak altsym
+ .set altsym,a
+
+ .globl a
+a:
+ .word 1
diff --git a/lld/test/COFF/alternatename-antidep.s b/lld/test/COFF/alternatename-antidep.s
new file mode 100644
index 0000000000000..1188a9b75d481
--- /dev/null
+++ b/lld/test/COFF/alternatename-antidep.s
@@ -0,0 +1,16 @@
+// REQUIRES: x86
+
+// Check that an anti-dependency alias can't be used as an alternate name target.
+// RUN: llvm-mc -filetype=obj -triple=x86_64-windows %s -o %t.obj
+// RUN: not lld-link -dll -noentry %t.obj -alternatename:sym=altsym 2>&1 | FileCheck %s
+// CHECK: error: undefined symbol: sym
+
+ .data
+ .rva sym
+
+ .weak_anti_dep altsym
+ .set altsym,a
+
+ .globl a
+a:
+ .word 1
diff --git a/lld/test/COFF/alternatename-lib.s b/lld/test/COFF/alternatename-lib.s
new file mode 100644
index 0000000000000..206fe6bc23978
--- /dev/null
+++ b/lld/test/COFF/alternatename-lib.s
@@ -0,0 +1,43 @@
+// REQUIRES: x86
+// RUN: split-file %s %t.dir && cd %t.dir
+
+// RUN: llvm-mc -filetype=obj -triple=x86_64-windows refab.s -o refab.obj
+// RUN: llvm-mc -filetype=obj -triple=x86_64-windows aa.s -o aa.obj
+// RUN: llvm-mc -filetype=obj -triple=x86_64-windows b.s -o b.obj
+// RUN: llvm-mc -filetype=obj -triple=x86_64-windows antidep.s -o antidep.obj
+// RUN: llvm-lib -out:aa.lib aa.obj
+// RUN: llvm-lib -out:b.lib b.obj
+
+// Check that -alternatename with an undefined target does not prevent the symbol from being resolved to a library,
+// once another alternate name is resolved and pulls in the source symbol.
+// RUN: lld-link -out:out.dll -dll -noentry -machine:amd64 refab.obj aa.lib -alternatename:a=aa -alternatename:b=undef
+
+// Check that -alternatename with an anti-dependency target does not prevent the symbol from being resolved to a library,
+// after another alternate name is resolved and pulls in the source symbol.
+// RUN: lld-link -out:out2.dll -dll -noentry -machine:amd64 antidep.obj refab.obj aa.lib -alternatename:a=aa -alternatename:b=u
+
+#--- refab.s
+ .data
+ .rva a
+ .rva b
+
+#--- aa.s
+ .globl aa
+aa:
+ .word 1
+
+ .section .drectve, "yn"
+ .ascii "/defaultlib:b.lib"
+
+#--- b.s
+ .globl b
+b:
+ .word 2
+
+#--- antidep.s
+ .weak_anti_dep u
+ .set u,d
+
+ .globl d
+d:
+ .word 3
diff --git a/lld/test/COFF/arm64ec-altnames.s b/lld/test/COFF/arm64ec-altnames.s
index b2abb24efe4c3..cca778ab8dc64 100644
--- a/lld/test/COFF/arm64ec-altnames.s
+++ b/lld/test/COFF/arm64ec-altnames.s
@@ -2,6 +2,7 @@ REQUIRES: aarch64
RUN: split-file %s %t.dir && cd %t.dir
RUN: llvm-mc -filetype=obj -triple=arm64ec-windows ext.s -o ext.obj
+RUN: llvm-mc -filetype=obj -triple=arm64ec-windows ext-mangled.s -o ext-mangled.obj
RUN: llvm-mc -filetype=obj -triple=arm64ec-windows impl.s -o impl.obj
RUN: llvm-mc -filetype=obj -triple=arm64ec-windows impl-cpp.s -o impl-cpp.obj
RUN: llvm-mc -filetype=obj -triple=arm64ec-windows %S/Inputs/loadconfig-arm64ec.s -o loadconfig.obj
@@ -49,6 +50,20 @@ RUN: lld-link -machine:arm64ec -dll -noentry -out:out4.dll impl-cpp.obj loadconf
RUN: llvm-objdump -d out4.dll | FileCheck --check-prefix=DISASM %s
RUN: llvm-readobj --hex-dump=.test out4.dll | FileCheck --check-prefix=TESTSEC %s
+# Check that when both mangled and demangled alternate names are used,
+# only the one whose target is defined is used (the mangled one in this case).
+
+RUN: lld-link -machine:arm64ec -dll -noentry -out:out5.dll ext-mangled.obj loadconfig.obj "-alternatename:#func=#altsym" -alternatename:func=altsym
+RUN: llvm-objdump -d out5.dll | FileCheck --check-prefix=DISASM %s
+RUN: llvm-readobj --hex-dump=.test out5.dll | FileCheck --check-prefix=TESTSEC %s
+
+# Check that when both mangled and demangled alternate names are used,
+# only the one whose target is defined is used (the demangled one in this case).
+
+RUN: lld-link -machine:arm64ec -dll -noentry -out:out6.dll ext.obj loadconfig.obj "-alternatename:#func=#altsym" -alternatename:func=altsym
+RUN: llvm-objdump -d out6.dll | FileCheck --check-prefix=DISASM2 %s
+RUN: llvm-readobj --hex-dump=.test out6.dll | FileCheck --check-prefix=TESTSEC2 %s
+
#--- ext.s
.weak_anti_dep func
.set func, "#func"
@@ -70,6 +85,30 @@ altsym:
mov w0, #1
ret
+#--- ext-mangled.s
+ .weak_anti_dep func
+.set func, "#func"
+ .weak_anti_dep "#func"
+.set "#func", thunksym
+
+ .section .test, "r"
+ .rva func
+ .rva "#func"
+
+ .section .thnk,"xr",discard,thunksym
+thunksym:
+ mov w0, #2
+ ret
+
+ .section .text,"xr",discard,"#altsym"
+ .globl "#altsym"
+"#altsym":
+ mov w0, #1
+ ret
+
+ .weak_anti_dep altsym
+ .set altsym,"#altsym"
+
#--- impl.s
.weak_anti_dep func
.set func, "#func"
|
|
Depends on #149495, which enables the use of |
github-project-automation
bot
moved this from Needs Backport PR
to Needs Merge
in LLVM Release Status
… is undefined This change fixes an issue with the use of -alternatename in the MSVC CRT, where both mangled and demangled symbol names are specified. Without this patch, the demangled name could be resolved to an anti-dependency alias of the target. Since chaining anti-dependency aliases is not allowed, this results in an undefined symbol. The root cause isn't specific to ARM64EC, it can affect other targets as well, even when anti-dependency aliases aren't involved. The accompanying test case demonstrates a scenario where the symbol could be resolved from an archive. However, because the archive member is pulled in after the first pass of alternate name resolution, and archive members don't override weak aliases, eager resolution would incorrectly skip it.
github-project-automation
bot
moved this from Needs Merge
to Done
in LLVM Release Status
|
I guess we should backport this, too, as it's needed for linking MSVC's arm64ec libraries? (Edit: And this should be doable as one single backport request with "slash-cherrypick hash1 hash2".) |
|
/pull-request #151027 |
tru
pushed a commit
to llvmbot/llvm-project
that referenced
this pull request
Jul 29, 2025
… is undefined (llvm#149496) This change fixes an issue with the use of `-alternatename` in the MSVC CRT on ARM64EC, where both mangled and demangled symbol names are specified. Without this patch, the demangled name could be resolved to an anti-dependency alias of the target. Since chaining anti-dependency aliases is not allowed, this results in an undefined symbol. The root cause isn't specific to ARM64EC, it can affect other targets as well, even when anti-dependency aliases aren't involved. The accompanying test case demonstrates a scenario where the symbol could be resolved from an archive. However, because the archive member is pulled in after the first pass of alternate name resolution, and archive members don't override weak aliases, eager resolution would incorrectly skip it. (cherry picked from commit ac31d64)
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This change fixes an issue with the use of
-alternatenamein the MSVC CRT on ARM64EC, where both mangled and demangled symbol names are specified. Without this patch, the demangled name could be resolved to an anti-dependency alias of the target. Since chaining anti-dependency aliases is not allowed, this results in an undefined symbol.The root cause isn't specific to ARM64EC, it can affect other targets as well, even when anti-dependency aliases aren't involved. The accompanying test case demonstrates a scenario where the symbol could be resolved from an archive. However, because the archive member is pulled in after the first pass of alternate name resolution, and archive members don't override weak aliases, eager resolution would incorrectly skip it.