[lld][wasm] Allow stub libraries to depend on optional linker symbols - #215112
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[lld][wasm] Allow stub libraries to depend on optional linker symbols#215112ANAMASGARD wants to merge 3 commits into
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@llvm/pr-subscribers-lld Author: Gauarv Chaudhary (ANAMASGARD) ChangesFixes #180632 Summary
Test plan
Full diff: https://github.com/llvm/llvm-project/pull/215112.diff 12 Files Affected:
diff --git a/lld/test/wasm/Inputs/libstub-dso-handle.so b/lld/test/wasm/Inputs/libstub-dso-handle.so
new file mode 100644
index 0000000000000..bb500f885468c
--- /dev/null
+++ b/lld/test/wasm/Inputs/libstub-dso-handle.so
@@ -0,0 +1,2 @@
+#STUB
+foo_import: __dso_handle
diff --git a/lld/test/wasm/Inputs/libstub-first-page-end.so b/lld/test/wasm/Inputs/libstub-first-page-end.so
new file mode 100644
index 0000000000000..55cc723835afb
--- /dev/null
+++ b/lld/test/wasm/Inputs/libstub-first-page-end.so
@@ -0,0 +1,2 @@
+#STUB
+foo_import: __wasm_first_page_end
diff --git a/lld/test/wasm/Inputs/libstub-heap-base.so b/lld/test/wasm/Inputs/libstub-heap-base.so
new file mode 100644
index 0000000000000..d0c2f37f023ff
--- /dev/null
+++ b/lld/test/wasm/Inputs/libstub-heap-base.so
@@ -0,0 +1,2 @@
+#STUB
+foo_import: __heap_base
diff --git a/lld/test/wasm/Inputs/libstub-memory-base.so b/lld/test/wasm/Inputs/libstub-memory-base.so
new file mode 100644
index 0000000000000..740e683da8d46
--- /dev/null
+++ b/lld/test/wasm/Inputs/libstub-memory-base.so
@@ -0,0 +1,2 @@
+#STUB
+foo_import: __memory_base
diff --git a/lld/test/wasm/Inputs/stub-optional-absent.s b/lld/test/wasm/Inputs/stub-optional-absent.s
new file mode 100644
index 0000000000000..4b412cbf91698
--- /dev/null
+++ b/lld/test/wasm/Inputs/stub-optional-absent.s
@@ -0,0 +1,8 @@
+.functype foo () -> ()
+.import_name foo, foo_import
+
+.globl _start
+_start:
+ .functype _start () -> ()
+ call foo
+ end_function
diff --git a/lld/test/wasm/Inputs/stub-optional-memory.s b/lld/test/wasm/Inputs/stub-optional-memory.s
new file mode 100644
index 0000000000000..4b412cbf91698
--- /dev/null
+++ b/lld/test/wasm/Inputs/stub-optional-memory.s
@@ -0,0 +1,8 @@
+.functype foo () -> ()
+.import_name foo, foo_import
+
+.globl _start
+_start:
+ .functype _start () -> ()
+ call foo
+ end_function
diff --git a/lld/test/wasm/Inputs/stub-optional-undef.s b/lld/test/wasm/Inputs/stub-optional-undef.s
new file mode 100644
index 0000000000000..eede83f8dcc35
--- /dev/null
+++ b/lld/test/wasm/Inputs/stub-optional-undef.s
@@ -0,0 +1,10 @@
+.functype foo () -> ()
+.import_name foo, foo_import
+
+.globl _start
+_start:
+ .functype _start () -> ()
+ i32.const __heap_base@GOT
+ drop
+ call foo
+ end_function
diff --git a/lld/test/wasm/Inputs/stub-optional-user-heap.s b/lld/test/wasm/Inputs/stub-optional-user-heap.s
new file mode 100644
index 0000000000000..ed051470deac9
--- /dev/null
+++ b/lld/test/wasm/Inputs/stub-optional-user-heap.s
@@ -0,0 +1,11 @@
+.functype foo () -> ()
+.import_name foo, foo_import
+
+.globaltype __heap_base, i32, immutable
+__heap_base:
+
+.globl _start
+_start:
+ .functype _start () -> ()
+ call foo
+ end_function
diff --git a/lld/test/wasm/stub-library-optional-symbol.s b/lld/test/wasm/stub-library-optional-symbol.s
new file mode 100644
index 0000000000000..d882d5dd660a6
--- /dev/null
+++ b/lld/test/wasm/stub-library-optional-symbol.s
@@ -0,0 +1,76 @@
+## Test stub library dependencies on optional linker-created symbols.
+## See https://github.com/llvm/llvm-project/issues/180632
+
+# --- Case 1: __heap_base completely absent from object (exact #180632 bug) ---
+# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown -o %t-absent.o %S/Inputs/stub-optional-absent.s
+# RUN: wasm-ld %t-absent.o %S/Inputs/libstub-heap-base.so -o %t-absent.wasm
+# RUN: obj2yaml %t-absent.wasm | FileCheck %s --check-prefix=CHECK-ABSENT
+
+# --- Case 2: __heap_base already Undefined in object (subtle v2 bug) ---
+# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown -o %t-undef.o %S/Inputs/stub-optional-undef.s
+# RUN: wasm-ld %t-undef.o %S/Inputs/libstub-heap-base.so -o %t-undef.wasm
+# RUN: obj2yaml %t-undef.wasm | FileCheck %s --check-prefix=CHECK-UNDEF
+
+# --- Case 3: unknown stub dependency still errors ---
+# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown -o %t.o %S/Inputs/stub-optional-absent.s
+# RUN: not wasm-ld %t.o %p/Inputs/libstub-missing-dep.so -o %t.wasm 2>&1 | FileCheck %s --check-prefix=CHECK-MISSING
+# CHECK-MISSING: libstub-missing-dep.so: undefined symbol: missing_dep. Required by foo
+
+# --- Case 5: user-defined __heap_base — linker must not override ---
+# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown -o %t-user.o %S/Inputs/stub-optional-user-heap.s
+# RUN: wasm-ld %t-user.o %S/Inputs/libstub-heap-base.so -o %t-user.wasm
+# RUN: obj2yaml %t-user.wasm | FileCheck %s --check-prefix=CHECK-USER
+
+# --- Case 6: __memory_base optional global path (non-PIC) ---
+# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown -o %t-mem.o %S/Inputs/stub-optional-memory.s
+# RUN: wasm-ld %t-mem.o %S/Inputs/libstub-memory-base.so -o %t-mem.wasm
+# RUN: obj2yaml %t-mem.wasm | FileCheck %s --check-prefix=CHECK-MEM
+
+# CHECK-ABSENT: Field: foo_import
+# CHECK-ABSENT: - Type: GLOBAL
+# CHECK-ABSENT: InitExpr:
+# CHECK-ABSENT-NEXT: Opcode: I32_CONST
+# CHECK-ABSENT-NEXT: Value: 65536
+# CHECK-ABSENT: - Name: __heap_base
+# CHECK-ABSENT-NEXT: Kind: GLOBAL
+
+# CHECK-UNDEF: Field: foo_import
+# CHECK-UNDEF: - Type: GLOBAL
+# CHECK-UNDEF: InitExpr:
+# CHECK-UNDEF-NEXT: Opcode: I32_CONST
+# CHECK-UNDEF-NEXT: Value: 65536
+# CHECK-UNDEF: - Name: __heap_base
+# CHECK-UNDEF-NEXT: Kind: GLOBAL
+
+# CHECK-USER: - Name: __heap_base
+# CHECK-USER-NEXT: Kind: GLOBAL
+
+# CHECK-MEM: Field: foo_import
+# CHECK-MEM: - Name: __memory_base
+# CHECK-MEM-NEXT: Kind: GLOBAL
+
+# --- Case 7: PIC __dso_handle stub dependency (must be created) ---
+# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown -o %t-pic-dso.o %S/Inputs/stub-optional-absent.s
+# RUN: wasm-ld --experimental-pic -pie --import-memory %t-pic-dso.o %S/Inputs/libstub-dso-handle.so -o %t-pic-dso.wasm
+# RUN: obj2yaml %t-pic-dso.wasm | FileCheck %s --check-prefix=CHECK-PIC-DSO
+
+# --- Case 8: PIC __wasm_first_page_end stub dependency (must be created) ---
+# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown -o %t-pic-fpe.o %S/Inputs/stub-optional-absent.s
+# RUN: wasm-ld --experimental-pic -pie --import-memory %t-pic-fpe.o %S/Inputs/libstub-first-page-end.so -o %t-pic-fpe.wasm
+# RUN: obj2yaml %t-pic-fpe.wasm | FileCheck %s --check-prefix=CHECK-PIC-FPE
+
+# --- Case 9: PIC __heap_base stub dependency (must NOT be linker-created) ---
+# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown -o %t-pic-heap.o %S/Inputs/stub-optional-absent.s
+# RUN: not wasm-ld --experimental-pic -pie --import-memory %t-pic-heap.o %S/Inputs/libstub-heap-base.so -o %t-pic-heap.wasm 2>&1 | FileCheck %s --check-prefix=CHECK-PIC-HEAP-FAIL
+
+# CHECK-PIC-DSO: Field: foo_import
+# CHECK-PIC-DSO: - Name: __dso_handle
+# CHECK-PIC-DSO-NEXT: Kind: GLOBAL
+
+# CHECK-PIC-FPE: InitExpr:
+# CHECK-PIC-FPE-NEXT: Opcode: I32_CONST
+# CHECK-PIC-FPE-NEXT: Value: 65536
+# CHECK-PIC-FPE: - Name: __wasm_first_page_end
+# CHECK-PIC-FPE-NEXT: Kind: GLOBAL
+
+# CHECK-PIC-HEAP-FAIL: undefined symbol: __heap_base
diff --git a/lld/wasm/Driver.cpp b/lld/wasm/Driver.cpp
index 740e8878c6e03..3f26c7dcf32d4 100644
--- a/lld/wasm/Driver.cpp
+++ b/lld/wasm/Driver.cpp
@@ -922,9 +922,143 @@ static DefinedGlobal *createGlobalVariable(StringRef name, bool isMutable,
return symtab->addSyntheticGlobal(name, flags, g);
}
-static DefinedGlobal *createOptionalGlobal(StringRef name, bool isMutable) {
+static DefinedGlobal *createOptionalGlobal(StringRef name, bool isMutable,
+ bool force = false) {
+ if (Symbol *s = symtab->find(name)) {
+ if (s->isDefined())
+ return dyn_cast<DefinedGlobal>(s);
+ }
InputGlobal *g = createGlobal(name, isMutable);
- return symtab->addOptionalGlobalSymbol(name, g);
+ return symtab->addOptionalGlobalSymbol(name, g, force);
+}
+
+static DefinedData *materializeOptionalDataSymbol(StringRef name,
+ DefinedData *&slot,
+ bool force) {
+ if (slot)
+ return slot;
+ if (DefinedData *d = symtab->addOptionalDataSymbol(name, 0, force))
+ slot = d;
+ else if (Symbol *s = symtab->find(name))
+ slot = dyn_cast<DefinedData>(s);
+ return slot;
+}
+
+static DefinedData *materializeOptionalDataLayoutSymbol(StringRef name,
+ DefinedData *&slot,
+ bool force) {
+ if (slot)
+ return slot;
+ if (ctx.isPic) {
+ ctx.arg.allowUndefinedSymbols.insert(name);
+ return nullptr;
+ }
+ return materializeOptionalDataSymbol(name, slot, force);
+}
+
+// Materialize a known optional linker-created symbol when required by a stub
+// library dependency. Returns a defined symbol, or nullptr if the name is not
+// a known optional linker symbol (or cannot be created in the current config).
+static Symbol *resolveStubDependency(StringRef name) {
+ if (ctx.arg.relocatable)
+ return nullptr;
+
+ if (name == "__dso_handle") {
+ materializeOptionalDataSymbol(name, ctx.sym.dsoHandle, true);
+ return symtab->find(name);
+ }
+ if (name == "__data_end") {
+ materializeOptionalDataLayoutSymbol(name, ctx.sym.dataEnd, true);
+ return symtab->find(name);
+ }
+ if (name == "__rodata_start") {
+ materializeOptionalDataLayoutSymbol(name, ctx.sym.rodataStart, true);
+ return symtab->find(name);
+ }
+ if (name == "__rodata_end") {
+ materializeOptionalDataLayoutSymbol(name, ctx.sym.rodataEnd, true);
+ return symtab->find(name);
+ }
+ if (name == "__stack_low") {
+ materializeOptionalDataLayoutSymbol(name, ctx.sym.stackLow, true);
+ return symtab->find(name);
+ }
+ if (name == "__stack_high") {
+ materializeOptionalDataLayoutSymbol(name, ctx.sym.stackHigh, true);
+ return symtab->find(name);
+ }
+ if (name == "__global_base") {
+ materializeOptionalDataLayoutSymbol(name, ctx.sym.globalBase, true);
+ return symtab->find(name);
+ }
+ if (name == "__heap_base") {
+ materializeOptionalDataLayoutSymbol(name, ctx.sym.heapBase, true);
+ return symtab->find(name);
+ }
+ if (name == "__heap_end") {
+ materializeOptionalDataLayoutSymbol(name, ctx.sym.heapEnd, true);
+ return symtab->find(name);
+ }
+ if (name == "__memory_base" && !ctx.isPic) {
+ if (!ctx.sym.memoryBase)
+ ctx.sym.memoryBase = createOptionalGlobal(name, false, true);
+ return symtab->find(name);
+ }
+ if (name == "__table_base" && !ctx.isPic) {
+ if (!ctx.sym.tableBase)
+ ctx.sym.tableBase = createOptionalGlobal(name, false, true);
+ return symtab->find(name);
+ }
+ if (name == "__wasm_first_page_end") {
+ materializeOptionalDataSymbol(name, ctx.sym.firstPageEnd, true);
+ if (ctx.sym.firstPageEnd)
+ ctx.sym.firstPageEnd->setVA(ctx.arg.pageSize);
+ return symtab->find(name);
+ }
+ if (name == "__tls_base" && !ctx.sym.tlsBase) {
+ ctx.sym.tlsBase = createOptionalGlobal(name, false, true);
+ return symtab->find(name);
+ }
+ return nullptr;
+}
+
+static void createOptionalSymbols() {
+ if (ctx.arg.relocatable)
+ return;
+
+ if (!ctx.sym.dsoHandle)
+ materializeOptionalDataSymbol("__dso_handle", ctx.sym.dsoHandle, false);
+
+ materializeOptionalDataLayoutSymbol("__data_end", ctx.sym.dataEnd, false);
+ materializeOptionalDataLayoutSymbol("__rodata_start", ctx.sym.rodataStart, false);
+ materializeOptionalDataLayoutSymbol("__rodata_end", ctx.sym.rodataEnd, false);
+ materializeOptionalDataLayoutSymbol("__stack_low", ctx.sym.stackLow, false);
+ materializeOptionalDataLayoutSymbol("__stack_high", ctx.sym.stackHigh, false);
+ materializeOptionalDataLayoutSymbol("__global_base", ctx.sym.globalBase, false);
+ materializeOptionalDataLayoutSymbol("__heap_base", ctx.sym.heapBase, false);
+ materializeOptionalDataLayoutSymbol("__heap_end", ctx.sym.heapEnd, false);
+
+ // for pic, __memory_base and __table_base are handled in
+ // createSyntheticSymbols.
+ if (!ctx.isPic) {
+ if (!ctx.sym.memoryBase)
+ ctx.sym.memoryBase = createOptionalGlobal("__memory_base", false);
+ if (!ctx.sym.tableBase)
+ ctx.sym.tableBase = createOptionalGlobal("__table_base", false);
+ }
+
+ if (!ctx.sym.firstPageEnd)
+ materializeOptionalDataSymbol("__wasm_first_page_end", ctx.sym.firstPageEnd, false);
+ if (ctx.sym.firstPageEnd)
+ ctx.sym.firstPageEnd->setVA(ctx.arg.pageSize);
+
+ // TLS object files may be linked into single-threaded programs, so
+ // __tls_base must always be defined. In this case it is immutable and points
+ // directly to the start of the `.tdata` segment. __tls_size and __tls_align
+ // are omitted since they are only used by __wasm_init_tls, which is not
+ // created in this case.
+ if (!ctx.sym.tlsBase)
+ ctx.sym.tlsBase = createOptionalGlobal("__tls_base", false);
}
// Create ABI-defined synthetic symbols
@@ -1008,52 +1142,6 @@ static void createSyntheticSymbols() {
}
}
-static void createOptionalSymbols() {
- if (ctx.arg.relocatable)
- return;
-
- ctx.sym.dsoHandle = symtab->addOptionalDataSymbol("__dso_handle");
-
- auto addDataLayoutSymbol = [&](StringRef s) -> DefinedData * {
- // Data layout symbols are either defined by lld, or (in the case
- // of PIC code) defined by the dynamic linker / embedder.
- if (ctx.isPic) {
- ctx.arg.allowUndefinedSymbols.insert(s);
- return nullptr;
- } else {
- return symtab->addOptionalDataSymbol(s);
- }
- };
-
- ctx.sym.dataEnd = addDataLayoutSymbol("__data_end");
- ctx.sym.rodataStart = addDataLayoutSymbol("__rodata_start");
- ctx.sym.rodataEnd = addDataLayoutSymbol("__rodata_end");
- ctx.sym.stackLow = addDataLayoutSymbol("__stack_low");
- ctx.sym.stackHigh = addDataLayoutSymbol("__stack_high");
- ctx.sym.globalBase = addDataLayoutSymbol("__global_base");
- ctx.sym.heapBase = addDataLayoutSymbol("__heap_base");
- ctx.sym.heapEnd = addDataLayoutSymbol("__heap_end");
-
- // for pic, __memory_base and __table_base are handled in
- // createSyntheticSymbols.
- if (!ctx.isPic) {
- ctx.sym.memoryBase = createOptionalGlobal("__memory_base", false);
- ctx.sym.tableBase = createOptionalGlobal("__table_base", false);
- }
-
- ctx.sym.firstPageEnd = symtab->addOptionalDataSymbol("__wasm_first_page_end");
- if (ctx.sym.firstPageEnd)
- ctx.sym.firstPageEnd->setVA(ctx.arg.pageSize);
-
- // TLS object files may be linked into single-threaded programs, so
- // __tls_base must always be defined. In this case it is immutable and points
- // directly to the start of the `.tdata` segment. __tls_size and __tls_align
- // are omitted since they are only used by __wasm_init_tls, which is not
- // created in this case.
- if (!ctx.sym.tlsBase)
- ctx.sym.tlsBase = createOptionalGlobal("__tls_base", false);
-}
-
static void processStubLibrariesPreLTO() {
log("-- processStubLibrariesPreLTO");
for (auto &stub_file : ctx.stubFiles) {
@@ -1102,6 +1190,8 @@ static bool addStubSymbolDeps(const StubFile *stub_file, Symbol *sym,
bool depsAdded = false;
for (const auto dep : deps) {
auto *needed = symtab->find(dep);
+ if (!needed || needed->isUndefined())
+ needed = resolveStubDependency(dep);
if (!needed) {
error(toString(stub_file) + ": undefined symbol: " + dep +
". Required by " + toString(*sym));
diff --git a/lld/wasm/SymbolTable.cpp b/lld/wasm/SymbolTable.cpp
index 88ac54302c286..5b1b0b3c51507 100644
--- a/lld/wasm/SymbolTable.cpp
+++ b/lld/wasm/SymbolTable.cpp
@@ -267,10 +267,10 @@ DefinedFunction *SymbolTable::addSyntheticFunction(StringRef name,
// added if there is an undefine reference to it, or if it is explicitly
// exported via the --export flag. Otherwise we don't add the symbol and return
// nullptr.
-DefinedData *SymbolTable::addOptionalDataSymbol(StringRef name,
- uint64_t value) {
+DefinedData *SymbolTable::addOptionalDataSymbol(StringRef name, uint64_t value,
+ bool force) {
Symbol *s = find(name);
- if (!s && (ctx.arg.exportAll || ctx.arg.exportedSymbols.contains(name)))
+ if (!s && (force || ctx.arg.exportAll || ctx.arg.exportedSymbols.contains(name)))
s = insertName(name).first;
else if (!s || s->isDefined())
return nullptr;
@@ -301,9 +301,10 @@ DefinedGlobal *SymbolTable::addSyntheticGlobal(StringRef name, uint32_t flags,
}
DefinedGlobal *SymbolTable::addOptionalGlobalSymbol(StringRef name,
- InputGlobal *global) {
+ InputGlobal *global,
+ bool force) {
Symbol *s = find(name);
- if (!s && (ctx.arg.exportAll || ctx.arg.exportedSymbols.contains(name)))
+ if (!s && (force || ctx.arg.exportAll || ctx.arg.exportedSymbols.contains(name)))
s = insertName(name).first;
else if (!s || s->isDefined())
return nullptr;
diff --git a/lld/wasm/SymbolTable.h b/lld/wasm/SymbolTable.h
index 0667cedecdb4f..f89390e88e6b7 100644
--- a/lld/wasm/SymbolTable.h
+++ b/lld/wasm/SymbolTable.h
@@ -97,8 +97,10 @@ class SymbolTable {
InputGlobal *global);
DefinedFunction *addSyntheticFunction(StringRef name, uint32_t flags,
InputFunction *function);
- DefinedData *addOptionalDataSymbol(StringRef name, uint64_t value = 0);
- DefinedGlobal *addOptionalGlobalSymbol(StringRef name, InputGlobal *global);
+ DefinedData *addOptionalDataSymbol(StringRef name, uint64_t value = 0,
+ bool force = false);
+ DefinedGlobal *addOptionalGlobalSymbol(StringRef name, InputGlobal *global,
+ bool force = false);
DefinedTable *addSyntheticTable(StringRef name, uint32_t flags,
InputTable *global);
|
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@llvm/pr-subscribers-lld-wasm Author: Gauarv Chaudhary (ANAMASGARD) ChangesFixes #180632 Summary
Test plan
Full diff: https://github.com/llvm/llvm-project/pull/215112.diff 12 Files Affected:
diff --git a/lld/test/wasm/Inputs/libstub-dso-handle.so b/lld/test/wasm/Inputs/libstub-dso-handle.so
new file mode 100644
index 0000000000000..bb500f885468c
--- /dev/null
+++ b/lld/test/wasm/Inputs/libstub-dso-handle.so
@@ -0,0 +1,2 @@
+#STUB
+foo_import: __dso_handle
diff --git a/lld/test/wasm/Inputs/libstub-first-page-end.so b/lld/test/wasm/Inputs/libstub-first-page-end.so
new file mode 100644
index 0000000000000..55cc723835afb
--- /dev/null
+++ b/lld/test/wasm/Inputs/libstub-first-page-end.so
@@ -0,0 +1,2 @@
+#STUB
+foo_import: __wasm_first_page_end
diff --git a/lld/test/wasm/Inputs/libstub-heap-base.so b/lld/test/wasm/Inputs/libstub-heap-base.so
new file mode 100644
index 0000000000000..d0c2f37f023ff
--- /dev/null
+++ b/lld/test/wasm/Inputs/libstub-heap-base.so
@@ -0,0 +1,2 @@
+#STUB
+foo_import: __heap_base
diff --git a/lld/test/wasm/Inputs/libstub-memory-base.so b/lld/test/wasm/Inputs/libstub-memory-base.so
new file mode 100644
index 0000000000000..740e683da8d46
--- /dev/null
+++ b/lld/test/wasm/Inputs/libstub-memory-base.so
@@ -0,0 +1,2 @@
+#STUB
+foo_import: __memory_base
diff --git a/lld/test/wasm/Inputs/stub-optional-absent.s b/lld/test/wasm/Inputs/stub-optional-absent.s
new file mode 100644
index 0000000000000..4b412cbf91698
--- /dev/null
+++ b/lld/test/wasm/Inputs/stub-optional-absent.s
@@ -0,0 +1,8 @@
+.functype foo () -> ()
+.import_name foo, foo_import
+
+.globl _start
+_start:
+ .functype _start () -> ()
+ call foo
+ end_function
diff --git a/lld/test/wasm/Inputs/stub-optional-memory.s b/lld/test/wasm/Inputs/stub-optional-memory.s
new file mode 100644
index 0000000000000..4b412cbf91698
--- /dev/null
+++ b/lld/test/wasm/Inputs/stub-optional-memory.s
@@ -0,0 +1,8 @@
+.functype foo () -> ()
+.import_name foo, foo_import
+
+.globl _start
+_start:
+ .functype _start () -> ()
+ call foo
+ end_function
diff --git a/lld/test/wasm/Inputs/stub-optional-undef.s b/lld/test/wasm/Inputs/stub-optional-undef.s
new file mode 100644
index 0000000000000..eede83f8dcc35
--- /dev/null
+++ b/lld/test/wasm/Inputs/stub-optional-undef.s
@@ -0,0 +1,10 @@
+.functype foo () -> ()
+.import_name foo, foo_import
+
+.globl _start
+_start:
+ .functype _start () -> ()
+ i32.const __heap_base@GOT
+ drop
+ call foo
+ end_function
diff --git a/lld/test/wasm/Inputs/stub-optional-user-heap.s b/lld/test/wasm/Inputs/stub-optional-user-heap.s
new file mode 100644
index 0000000000000..ed051470deac9
--- /dev/null
+++ b/lld/test/wasm/Inputs/stub-optional-user-heap.s
@@ -0,0 +1,11 @@
+.functype foo () -> ()
+.import_name foo, foo_import
+
+.globaltype __heap_base, i32, immutable
+__heap_base:
+
+.globl _start
+_start:
+ .functype _start () -> ()
+ call foo
+ end_function
diff --git a/lld/test/wasm/stub-library-optional-symbol.s b/lld/test/wasm/stub-library-optional-symbol.s
new file mode 100644
index 0000000000000..d882d5dd660a6
--- /dev/null
+++ b/lld/test/wasm/stub-library-optional-symbol.s
@@ -0,0 +1,76 @@
+## Test stub library dependencies on optional linker-created symbols.
+## See https://github.com/llvm/llvm-project/issues/180632
+
+# --- Case 1: __heap_base completely absent from object (exact #180632 bug) ---
+# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown -o %t-absent.o %S/Inputs/stub-optional-absent.s
+# RUN: wasm-ld %t-absent.o %S/Inputs/libstub-heap-base.so -o %t-absent.wasm
+# RUN: obj2yaml %t-absent.wasm | FileCheck %s --check-prefix=CHECK-ABSENT
+
+# --- Case 2: __heap_base already Undefined in object (subtle v2 bug) ---
+# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown -o %t-undef.o %S/Inputs/stub-optional-undef.s
+# RUN: wasm-ld %t-undef.o %S/Inputs/libstub-heap-base.so -o %t-undef.wasm
+# RUN: obj2yaml %t-undef.wasm | FileCheck %s --check-prefix=CHECK-UNDEF
+
+# --- Case 3: unknown stub dependency still errors ---
+# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown -o %t.o %S/Inputs/stub-optional-absent.s
+# RUN: not wasm-ld %t.o %p/Inputs/libstub-missing-dep.so -o %t.wasm 2>&1 | FileCheck %s --check-prefix=CHECK-MISSING
+# CHECK-MISSING: libstub-missing-dep.so: undefined symbol: missing_dep. Required by foo
+
+# --- Case 5: user-defined __heap_base — linker must not override ---
+# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown -o %t-user.o %S/Inputs/stub-optional-user-heap.s
+# RUN: wasm-ld %t-user.o %S/Inputs/libstub-heap-base.so -o %t-user.wasm
+# RUN: obj2yaml %t-user.wasm | FileCheck %s --check-prefix=CHECK-USER
+
+# --- Case 6: __memory_base optional global path (non-PIC) ---
+# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown -o %t-mem.o %S/Inputs/stub-optional-memory.s
+# RUN: wasm-ld %t-mem.o %S/Inputs/libstub-memory-base.so -o %t-mem.wasm
+# RUN: obj2yaml %t-mem.wasm | FileCheck %s --check-prefix=CHECK-MEM
+
+# CHECK-ABSENT: Field: foo_import
+# CHECK-ABSENT: - Type: GLOBAL
+# CHECK-ABSENT: InitExpr:
+# CHECK-ABSENT-NEXT: Opcode: I32_CONST
+# CHECK-ABSENT-NEXT: Value: 65536
+# CHECK-ABSENT: - Name: __heap_base
+# CHECK-ABSENT-NEXT: Kind: GLOBAL
+
+# CHECK-UNDEF: Field: foo_import
+# CHECK-UNDEF: - Type: GLOBAL
+# CHECK-UNDEF: InitExpr:
+# CHECK-UNDEF-NEXT: Opcode: I32_CONST
+# CHECK-UNDEF-NEXT: Value: 65536
+# CHECK-UNDEF: - Name: __heap_base
+# CHECK-UNDEF-NEXT: Kind: GLOBAL
+
+# CHECK-USER: - Name: __heap_base
+# CHECK-USER-NEXT: Kind: GLOBAL
+
+# CHECK-MEM: Field: foo_import
+# CHECK-MEM: - Name: __memory_base
+# CHECK-MEM-NEXT: Kind: GLOBAL
+
+# --- Case 7: PIC __dso_handle stub dependency (must be created) ---
+# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown -o %t-pic-dso.o %S/Inputs/stub-optional-absent.s
+# RUN: wasm-ld --experimental-pic -pie --import-memory %t-pic-dso.o %S/Inputs/libstub-dso-handle.so -o %t-pic-dso.wasm
+# RUN: obj2yaml %t-pic-dso.wasm | FileCheck %s --check-prefix=CHECK-PIC-DSO
+
+# --- Case 8: PIC __wasm_first_page_end stub dependency (must be created) ---
+# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown -o %t-pic-fpe.o %S/Inputs/stub-optional-absent.s
+# RUN: wasm-ld --experimental-pic -pie --import-memory %t-pic-fpe.o %S/Inputs/libstub-first-page-end.so -o %t-pic-fpe.wasm
+# RUN: obj2yaml %t-pic-fpe.wasm | FileCheck %s --check-prefix=CHECK-PIC-FPE
+
+# --- Case 9: PIC __heap_base stub dependency (must NOT be linker-created) ---
+# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown -o %t-pic-heap.o %S/Inputs/stub-optional-absent.s
+# RUN: not wasm-ld --experimental-pic -pie --import-memory %t-pic-heap.o %S/Inputs/libstub-heap-base.so -o %t-pic-heap.wasm 2>&1 | FileCheck %s --check-prefix=CHECK-PIC-HEAP-FAIL
+
+# CHECK-PIC-DSO: Field: foo_import
+# CHECK-PIC-DSO: - Name: __dso_handle
+# CHECK-PIC-DSO-NEXT: Kind: GLOBAL
+
+# CHECK-PIC-FPE: InitExpr:
+# CHECK-PIC-FPE-NEXT: Opcode: I32_CONST
+# CHECK-PIC-FPE-NEXT: Value: 65536
+# CHECK-PIC-FPE: - Name: __wasm_first_page_end
+# CHECK-PIC-FPE-NEXT: Kind: GLOBAL
+
+# CHECK-PIC-HEAP-FAIL: undefined symbol: __heap_base
diff --git a/lld/wasm/Driver.cpp b/lld/wasm/Driver.cpp
index 740e8878c6e03..3f26c7dcf32d4 100644
--- a/lld/wasm/Driver.cpp
+++ b/lld/wasm/Driver.cpp
@@ -922,9 +922,143 @@ static DefinedGlobal *createGlobalVariable(StringRef name, bool isMutable,
return symtab->addSyntheticGlobal(name, flags, g);
}
-static DefinedGlobal *createOptionalGlobal(StringRef name, bool isMutable) {
+static DefinedGlobal *createOptionalGlobal(StringRef name, bool isMutable,
+ bool force = false) {
+ if (Symbol *s = symtab->find(name)) {
+ if (s->isDefined())
+ return dyn_cast<DefinedGlobal>(s);
+ }
InputGlobal *g = createGlobal(name, isMutable);
- return symtab->addOptionalGlobalSymbol(name, g);
+ return symtab->addOptionalGlobalSymbol(name, g, force);
+}
+
+static DefinedData *materializeOptionalDataSymbol(StringRef name,
+ DefinedData *&slot,
+ bool force) {
+ if (slot)
+ return slot;
+ if (DefinedData *d = symtab->addOptionalDataSymbol(name, 0, force))
+ slot = d;
+ else if (Symbol *s = symtab->find(name))
+ slot = dyn_cast<DefinedData>(s);
+ return slot;
+}
+
+static DefinedData *materializeOptionalDataLayoutSymbol(StringRef name,
+ DefinedData *&slot,
+ bool force) {
+ if (slot)
+ return slot;
+ if (ctx.isPic) {
+ ctx.arg.allowUndefinedSymbols.insert(name);
+ return nullptr;
+ }
+ return materializeOptionalDataSymbol(name, slot, force);
+}
+
+// Materialize a known optional linker-created symbol when required by a stub
+// library dependency. Returns a defined symbol, or nullptr if the name is not
+// a known optional linker symbol (or cannot be created in the current config).
+static Symbol *resolveStubDependency(StringRef name) {
+ if (ctx.arg.relocatable)
+ return nullptr;
+
+ if (name == "__dso_handle") {
+ materializeOptionalDataSymbol(name, ctx.sym.dsoHandle, true);
+ return symtab->find(name);
+ }
+ if (name == "__data_end") {
+ materializeOptionalDataLayoutSymbol(name, ctx.sym.dataEnd, true);
+ return symtab->find(name);
+ }
+ if (name == "__rodata_start") {
+ materializeOptionalDataLayoutSymbol(name, ctx.sym.rodataStart, true);
+ return symtab->find(name);
+ }
+ if (name == "__rodata_end") {
+ materializeOptionalDataLayoutSymbol(name, ctx.sym.rodataEnd, true);
+ return symtab->find(name);
+ }
+ if (name == "__stack_low") {
+ materializeOptionalDataLayoutSymbol(name, ctx.sym.stackLow, true);
+ return symtab->find(name);
+ }
+ if (name == "__stack_high") {
+ materializeOptionalDataLayoutSymbol(name, ctx.sym.stackHigh, true);
+ return symtab->find(name);
+ }
+ if (name == "__global_base") {
+ materializeOptionalDataLayoutSymbol(name, ctx.sym.globalBase, true);
+ return symtab->find(name);
+ }
+ if (name == "__heap_base") {
+ materializeOptionalDataLayoutSymbol(name, ctx.sym.heapBase, true);
+ return symtab->find(name);
+ }
+ if (name == "__heap_end") {
+ materializeOptionalDataLayoutSymbol(name, ctx.sym.heapEnd, true);
+ return symtab->find(name);
+ }
+ if (name == "__memory_base" && !ctx.isPic) {
+ if (!ctx.sym.memoryBase)
+ ctx.sym.memoryBase = createOptionalGlobal(name, false, true);
+ return symtab->find(name);
+ }
+ if (name == "__table_base" && !ctx.isPic) {
+ if (!ctx.sym.tableBase)
+ ctx.sym.tableBase = createOptionalGlobal(name, false, true);
+ return symtab->find(name);
+ }
+ if (name == "__wasm_first_page_end") {
+ materializeOptionalDataSymbol(name, ctx.sym.firstPageEnd, true);
+ if (ctx.sym.firstPageEnd)
+ ctx.sym.firstPageEnd->setVA(ctx.arg.pageSize);
+ return symtab->find(name);
+ }
+ if (name == "__tls_base" && !ctx.sym.tlsBase) {
+ ctx.sym.tlsBase = createOptionalGlobal(name, false, true);
+ return symtab->find(name);
+ }
+ return nullptr;
+}
+
+static void createOptionalSymbols() {
+ if (ctx.arg.relocatable)
+ return;
+
+ if (!ctx.sym.dsoHandle)
+ materializeOptionalDataSymbol("__dso_handle", ctx.sym.dsoHandle, false);
+
+ materializeOptionalDataLayoutSymbol("__data_end", ctx.sym.dataEnd, false);
+ materializeOptionalDataLayoutSymbol("__rodata_start", ctx.sym.rodataStart, false);
+ materializeOptionalDataLayoutSymbol("__rodata_end", ctx.sym.rodataEnd, false);
+ materializeOptionalDataLayoutSymbol("__stack_low", ctx.sym.stackLow, false);
+ materializeOptionalDataLayoutSymbol("__stack_high", ctx.sym.stackHigh, false);
+ materializeOptionalDataLayoutSymbol("__global_base", ctx.sym.globalBase, false);
+ materializeOptionalDataLayoutSymbol("__heap_base", ctx.sym.heapBase, false);
+ materializeOptionalDataLayoutSymbol("__heap_end", ctx.sym.heapEnd, false);
+
+ // for pic, __memory_base and __table_base are handled in
+ // createSyntheticSymbols.
+ if (!ctx.isPic) {
+ if (!ctx.sym.memoryBase)
+ ctx.sym.memoryBase = createOptionalGlobal("__memory_base", false);
+ if (!ctx.sym.tableBase)
+ ctx.sym.tableBase = createOptionalGlobal("__table_base", false);
+ }
+
+ if (!ctx.sym.firstPageEnd)
+ materializeOptionalDataSymbol("__wasm_first_page_end", ctx.sym.firstPageEnd, false);
+ if (ctx.sym.firstPageEnd)
+ ctx.sym.firstPageEnd->setVA(ctx.arg.pageSize);
+
+ // TLS object files may be linked into single-threaded programs, so
+ // __tls_base must always be defined. In this case it is immutable and points
+ // directly to the start of the `.tdata` segment. __tls_size and __tls_align
+ // are omitted since they are only used by __wasm_init_tls, which is not
+ // created in this case.
+ if (!ctx.sym.tlsBase)
+ ctx.sym.tlsBase = createOptionalGlobal("__tls_base", false);
}
// Create ABI-defined synthetic symbols
@@ -1008,52 +1142,6 @@ static void createSyntheticSymbols() {
}
}
-static void createOptionalSymbols() {
- if (ctx.arg.relocatable)
- return;
-
- ctx.sym.dsoHandle = symtab->addOptionalDataSymbol("__dso_handle");
-
- auto addDataLayoutSymbol = [&](StringRef s) -> DefinedData * {
- // Data layout symbols are either defined by lld, or (in the case
- // of PIC code) defined by the dynamic linker / embedder.
- if (ctx.isPic) {
- ctx.arg.allowUndefinedSymbols.insert(s);
- return nullptr;
- } else {
- return symtab->addOptionalDataSymbol(s);
- }
- };
-
- ctx.sym.dataEnd = addDataLayoutSymbol("__data_end");
- ctx.sym.rodataStart = addDataLayoutSymbol("__rodata_start");
- ctx.sym.rodataEnd = addDataLayoutSymbol("__rodata_end");
- ctx.sym.stackLow = addDataLayoutSymbol("__stack_low");
- ctx.sym.stackHigh = addDataLayoutSymbol("__stack_high");
- ctx.sym.globalBase = addDataLayoutSymbol("__global_base");
- ctx.sym.heapBase = addDataLayoutSymbol("__heap_base");
- ctx.sym.heapEnd = addDataLayoutSymbol("__heap_end");
-
- // for pic, __memory_base and __table_base are handled in
- // createSyntheticSymbols.
- if (!ctx.isPic) {
- ctx.sym.memoryBase = createOptionalGlobal("__memory_base", false);
- ctx.sym.tableBase = createOptionalGlobal("__table_base", false);
- }
-
- ctx.sym.firstPageEnd = symtab->addOptionalDataSymbol("__wasm_first_page_end");
- if (ctx.sym.firstPageEnd)
- ctx.sym.firstPageEnd->setVA(ctx.arg.pageSize);
-
- // TLS object files may be linked into single-threaded programs, so
- // __tls_base must always be defined. In this case it is immutable and points
- // directly to the start of the `.tdata` segment. __tls_size and __tls_align
- // are omitted since they are only used by __wasm_init_tls, which is not
- // created in this case.
- if (!ctx.sym.tlsBase)
- ctx.sym.tlsBase = createOptionalGlobal("__tls_base", false);
-}
-
static void processStubLibrariesPreLTO() {
log("-- processStubLibrariesPreLTO");
for (auto &stub_file : ctx.stubFiles) {
@@ -1102,6 +1190,8 @@ static bool addStubSymbolDeps(const StubFile *stub_file, Symbol *sym,
bool depsAdded = false;
for (const auto dep : deps) {
auto *needed = symtab->find(dep);
+ if (!needed || needed->isUndefined())
+ needed = resolveStubDependency(dep);
if (!needed) {
error(toString(stub_file) + ": undefined symbol: " + dep +
". Required by " + toString(*sym));
diff --git a/lld/wasm/SymbolTable.cpp b/lld/wasm/SymbolTable.cpp
index 88ac54302c286..5b1b0b3c51507 100644
--- a/lld/wasm/SymbolTable.cpp
+++ b/lld/wasm/SymbolTable.cpp
@@ -267,10 +267,10 @@ DefinedFunction *SymbolTable::addSyntheticFunction(StringRef name,
// added if there is an undefine reference to it, or if it is explicitly
// exported via the --export flag. Otherwise we don't add the symbol and return
// nullptr.
-DefinedData *SymbolTable::addOptionalDataSymbol(StringRef name,
- uint64_t value) {
+DefinedData *SymbolTable::addOptionalDataSymbol(StringRef name, uint64_t value,
+ bool force) {
Symbol *s = find(name);
- if (!s && (ctx.arg.exportAll || ctx.arg.exportedSymbols.contains(name)))
+ if (!s && (force || ctx.arg.exportAll || ctx.arg.exportedSymbols.contains(name)))
s = insertName(name).first;
else if (!s || s->isDefined())
return nullptr;
@@ -301,9 +301,10 @@ DefinedGlobal *SymbolTable::addSyntheticGlobal(StringRef name, uint32_t flags,
}
DefinedGlobal *SymbolTable::addOptionalGlobalSymbol(StringRef name,
- InputGlobal *global) {
+ InputGlobal *global,
+ bool force) {
Symbol *s = find(name);
- if (!s && (ctx.arg.exportAll || ctx.arg.exportedSymbols.contains(name)))
+ if (!s && (force || ctx.arg.exportAll || ctx.arg.exportedSymbols.contains(name)))
s = insertName(name).first;
else if (!s || s->isDefined())
return nullptr;
diff --git a/lld/wasm/SymbolTable.h b/lld/wasm/SymbolTable.h
index 0667cedecdb4f..f89390e88e6b7 100644
--- a/lld/wasm/SymbolTable.h
+++ b/lld/wasm/SymbolTable.h
@@ -97,8 +97,10 @@ class SymbolTable {
InputGlobal *global);
DefinedFunction *addSyntheticFunction(StringRef name, uint32_t flags,
InputFunction *function);
- DefinedData *addOptionalDataSymbol(StringRef name, uint64_t value = 0);
- DefinedGlobal *addOptionalGlobalSymbol(StringRef name, InputGlobal *global);
+ DefinedData *addOptionalDataSymbol(StringRef name, uint64_t value = 0,
+ bool force = false);
+ DefinedGlobal *addOptionalGlobalSymbol(StringRef name, InputGlobal *global,
+ bool force = false);
DefinedTable *addSyntheticTable(StringRef name, uint32_t flags,
InputTable *global);
|
|
✅ With the latest revision this PR passed the C/C++ code formatter. |
sbc100
reviewed
Aug 9, 2026
| @@ -0,0 +1,11 @@ | |||
| .functype foo () -> () | |||
Contributor
There was a problem hiding this comment.
Rather than adding all these small Input files you can put them all in test file and use the split-file tool.
Stub library dependency resolution runs before createOptionalSymbols() and rejects missing or undefined deps. Materialize known optional linker-created symbols on demand when a stub library requires them. Fixes llvm#180632 Signed-off-by: Gaurav Chaudhary <chaudharygaurav2004@gmail.com>
Split materializeOptionalDataSymbol into generic and PIC-gated data-layout helpers so __dso_handle and __wasm_first_page_end are created in PIC mode while __heap_base and other data-layout symbols are not. Add PIC stub regression tests. Part of fix for llvm#180632 Signed-off-by: Gaurav Chaudhary <chaudharygaurav2004@gmail.com>
Remove ctx.sym.* fallback to user-defined symbols. Consolidate tests into split-file layout. Add __tls_base and __start_foo probe cases. Apply clang-format. Addresses llvm#180632 Signed-off-by: Gaurav Chaudhary <chaudharygaurav2004@gmail.com>
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Summary
Test plan
Addresses #180632
Note: _start/_stop stub deps are not yet supported (case 11 documents current limitation).