[llvm-branch-commits] [lld] [LLD][COFF] Don't dllimport from static libraries (#134443) (PR #138354)
Alexandre Ganea via llvm-branch-commits
llvm-branch-commits at lists.llvm.org
Fri May 2 16:29:07 PDT 2025
https://github.com/aganea updated https://github.com/llvm/llvm-project/pull/138354
>From 902cc177fe89f13ce41f76372157d96b304d585f Mon Sep 17 00:00:00 2001
From: Alexandre Ganea <alex_toresh at yahoo.fr>
Date: Mon, 7 Apr 2025 11:34:24 -0400
Subject: [PATCH 1/2] [LLD][COFF] Don't dllimport from static libraries
(#134443)
This reverts commit 6a1bdd9 and re-instate behavior that matches what
MSVC link.exe does, that is, error out when trying to dllimport a symbol
from a static library.
A hint is now displayed in stdout, mentioning that we should rather dllimport the symbol
from a import library.
Fixes https://github.com/llvm/llvm-project/issues/131807
---
lld/COFF/Driver.cpp | 6 ++--
lld/COFF/SymbolTable.cpp | 20 ++++++-----
lld/COFF/SymbolTable.h | 5 +--
.../COFF/imports-static-lib-indirect.test | 26 +++++++++++++++
lld/test/COFF/imports-static-lib.test | 33 +++++++++++++++++++
lld/test/COFF/undefined_lazy.test | 26 ---------------
6 files changed, 74 insertions(+), 42 deletions(-)
create mode 100644 lld/test/COFF/imports-static-lib-indirect.test
create mode 100644 lld/test/COFF/imports-static-lib.test
delete mode 100644 lld/test/COFF/undefined_lazy.test
diff --git a/lld/COFF/Driver.cpp b/lld/COFF/Driver.cpp
index ac3ac57bd17f4..f50ca529df4d7 100644
--- a/lld/COFF/Driver.cpp
+++ b/lld/COFF/Driver.cpp
@@ -2639,10 +2639,8 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
createECExportThunks();
// Resolve remaining undefined symbols and warn about imported locals.
- ctx.forEachSymtab([&](SymbolTable &symtab) {
- while (symtab.resolveRemainingUndefines())
- run();
- });
+ ctx.forEachSymtab(
+ [&](SymbolTable &symtab) { symtab.resolveRemainingUndefines(); });
if (errorCount())
return;
diff --git a/lld/COFF/SymbolTable.cpp b/lld/COFF/SymbolTable.cpp
index 307bd4a0c9411..8448d47d505f6 100644
--- a/lld/COFF/SymbolTable.cpp
+++ b/lld/COFF/SymbolTable.cpp
@@ -232,6 +232,17 @@ static void reportUndefinedSymbol(COFFLinkerContext &ctx,
}
if (numDisplayedRefs < numRefs)
diag << "\n>>> referenced " << numRefs - numDisplayedRefs << " more times";
+
+ // Hints
+ StringRef name = undefDiag.sym->getName();
+ if (name.consume_front("__imp_")) {
+ Symbol *imp = find(name);
+ if (imp && imp->isLazy()) {
+ diag << "\nNOTE: a relevant symbol '" << imp->getName()
+ << "' is available in " << toString(imp->getFile())
+ << " but cannot be used because it is not an import library.";
+ }
+ }
}
void SymbolTable::loadMinGWSymbols() {
@@ -432,11 +443,10 @@ void SymbolTable::reportUnresolvable() {
reportProblemSymbols(undefs, /*localImports=*/nullptr, true);
}
-bool SymbolTable::resolveRemainingUndefines() {
+void SymbolTable::resolveRemainingUndefines() {
llvm::TimeTraceScope timeScope("Resolve remaining undefined symbols");
SmallPtrSet<Symbol *, 8> undefs;
DenseMap<Symbol *, Symbol *> localImports;
- bool foundLazy = false;
for (auto &i : symMap) {
Symbol *sym = i.second;
@@ -481,11 +491,6 @@ bool SymbolTable::resolveRemainingUndefines() {
imp = findLocalSym(*mangledName);
}
}
- if (imp && imp->isLazy()) {
- forceLazy(imp);
- foundLazy = true;
- continue;
- }
if (imp && isa<Defined>(imp)) {
auto *d = cast<Defined>(imp);
replaceSymbol<DefinedLocalImport>(sym, ctx, name, d);
@@ -513,7 +518,6 @@ bool SymbolTable::resolveRemainingUndefines() {
reportProblemSymbols(
undefs, ctx.config.warnLocallyDefinedImported ? &localImports : nullptr,
false);
- return foundLazy;
}
std::pair<Symbol *, bool> SymbolTable::insert(StringRef name) {
diff --git a/lld/COFF/SymbolTable.h b/lld/COFF/SymbolTable.h
index ff6e8487f0734..2916c23d95c87 100644
--- a/lld/COFF/SymbolTable.h
+++ b/lld/COFF/SymbolTable.h
@@ -58,10 +58,7 @@ class SymbolTable {
// Try to resolve any undefined symbols and update the symbol table
// accordingly, then print an error message for any remaining undefined
// symbols and warn about imported local symbols.
- // Returns whether more files might need to be linked in to resolve lazy
- // symbols, in which case the caller is expected to call the function again
- // after linking those files.
- bool resolveRemainingUndefines();
+ void resolveRemainingUndefines();
// Load lazy objects that are needed for MinGW automatic import and for
// doing stdcall fixups.
diff --git a/lld/test/COFF/imports-static-lib-indirect.test b/lld/test/COFF/imports-static-lib-indirect.test
new file mode 100644
index 0000000000000..beda0d7a31afd
--- /dev/null
+++ b/lld/test/COFF/imports-static-lib-indirect.test
@@ -0,0 +1,26 @@
+# REQUIRES: x86
+
+# Pulling in on both a dllimport symbol and a static symbol should only warn.
+# RUN: split-file %s %t.dir
+# RUN: llvm-mc --filetype=obj -triple=x86_64-windows-msvc %t.dir/other.s -o %t.other.obj
+# RUN: llvm-mc --filetype=obj -triple=x86_64-windows-msvc %t.dir/main.s -o %t.main.obj
+# RUN: llvm-lib %t.other.obj -out:%t.other.lib
+# RUN: lld-link %t.other.lib %t.main.obj -out:%t.dll -dll 2>&1 | FileCheck %s
+
+CHECK: warning: {{.*}} locally defined symbol imported: foo {{.*}} [LNK4217]
+
+#--- other.s
+.text
+.globl other
+.globl foo
+other:
+ ret
+foo:
+ ret
+#--- main.s
+.text
+.global _DllMainCRTStartup
+_DllMainCRTStartup:
+ call *other(%rip)
+ call *__imp_foo(%rip)
+ ret
diff --git a/lld/test/COFF/imports-static-lib.test b/lld/test/COFF/imports-static-lib.test
new file mode 100644
index 0000000000000..8e9525dab5284
--- /dev/null
+++ b/lld/test/COFF/imports-static-lib.test
@@ -0,0 +1,33 @@
+# REQUIRES: x86
+
+# Ensure that we don't import dllimport symbols from static (non-import) libraries
+# RUN: split-file %s %t.dir
+# RUN: llvm-mc --filetype=obj -triple=x86_64-windows-msvc %t.dir/foo.s -o %t.foo.obj
+# RUN: llvm-mc --filetype=obj -triple=x86_64-windows-msvc %t.dir/main.s -o %t.main.obj
+# RUN: llvm-lib %t.foo.obj -out:%t.foo.lib
+# RUN: not lld-link %t.foo.lib %t.main.obj -out:%t.dll -dll 2>&1 | FileCheck %s
+
+CHECK: error: undefined symbol: __declspec(dllimport) foo
+CHECK: NOTE: a relevant symbol 'foo' is available in {{.*}}.foo.lib but cannot be used because it is not an import library.
+
+# Now do the same thing, but import the symbol from a import library.
+# RUN: llvm-mc --filetype=obj -triple=x86_64-windows-msvc %t.dir/foo_dll_main.s -o %t.foo_dll_main.obj
+# RUN: lld-link /out:%t.dll /dll %t.foo.obj %t.foo_dll_main.obj /export:foo /implib:%t.foo.imp.lib
+# RUN: lld-link %t.main.obj %t.foo.imp.lib -out:%t.exe -dll
+
+#--- foo.s
+.text
+.globl foo
+foo:
+ ret
+#--- foo_dll_main.s
+.text
+.global _DllMainCRTStartup
+_DllMainCRTStartup:
+ ret
+#--- main.s
+.text
+.global _DllMainCRTStartup
+_DllMainCRTStartup:
+ call *__imp_foo(%rip)
+ ret
diff --git a/lld/test/COFF/undefined_lazy.test b/lld/test/COFF/undefined_lazy.test
deleted file mode 100644
index ed5cd358b5cd9..0000000000000
--- a/lld/test/COFF/undefined_lazy.test
+++ /dev/null
@@ -1,26 +0,0 @@
-# REQUIRES: x86
-
-# RUN: split-file %s %t.dir
-# RUN: llvm-mc --filetype=obj -triple=x86_64-windows-msvc %t.dir/foo.s -o %t.foo.obj
-# RUN: llvm-mc --filetype=obj -triple=x86_64-windows-msvc %t.dir/bar.s -o %t.bar.obj
-# RUN: llvm-mc --filetype=obj -triple=x86_64-windows-msvc %t.dir/qux.s -o %t.qux.obj
-# RUN: llvm-lib %t.foo.obj -out:%t.foo.lib
-# RUN: llvm-lib %t.bar.obj -out:%t.bar.lib
-# RUN: lld-link %t.foo.lib %t.bar.lib %t.qux.obj -out:%t.dll -dll
-#
-#--- foo.s
-.text
-.globl foo
-foo:
- call bar
-#--- bar.s
-.text
-.globl bar
-bar:
- ret
-#--- qux.s
-.text
-.global _DllMainCRTStartup
-_DllMainCRTStartup:
- call *__imp_foo(%rip)
- ret
>From c101b9d3549876a0033b0855986c5643061cdc8d Mon Sep 17 00:00:00 2001
From: Alexandre Ganea <alex_toresh at yahoo.fr>
Date: Fri, 2 May 2025 19:28:23 -0400
Subject: [PATCH 2/2] Fix lld build.
---
lld/COFF/SymbolTable.cpp | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/lld/COFF/SymbolTable.cpp b/lld/COFF/SymbolTable.cpp
index 8448d47d505f6..a146e5211736e 100644
--- a/lld/COFF/SymbolTable.cpp
+++ b/lld/COFF/SymbolTable.cpp
@@ -214,7 +214,8 @@ struct UndefinedDiag {
std::vector<File> files;
};
-static void reportUndefinedSymbol(COFFLinkerContext &ctx,
+static void reportUndefinedSymbol(SymbolTable *symTab,
+ COFFLinkerContext &ctx,
const UndefinedDiag &undefDiag) {
auto diag = errorOrWarn(ctx);
diag << "undefined symbol: " << undefDiag.sym;
@@ -236,7 +237,7 @@ static void reportUndefinedSymbol(COFFLinkerContext &ctx,
// Hints
StringRef name = undefDiag.sym->getName();
if (name.consume_front("__imp_")) {
- Symbol *imp = find(name);
+ Symbol *imp = symTab->find(name);
if (imp && imp->isLazy()) {
diag << "\nNOTE: a relevant symbol '" << imp->getName()
<< "' is available in " << toString(imp->getFile())
@@ -413,7 +414,7 @@ void SymbolTable::reportProblemSymbols(
processFile(file, file->getSymbols());
for (const UndefinedDiag &undefDiag : undefDiags)
- reportUndefinedSymbol(ctx, undefDiag);
+ reportUndefinedSymbol(this, ctx, undefDiag);
}
void SymbolTable::reportUnresolvable() {
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