[WebAssembly] Error on relocations against undefined data symbols.
We can't (currently) meaningfully resolve certain types of relocations
against undefined data symbols. Previously when `--allow-undefined` was
used we were treating such relocation much like weak data symbols and
simply inserting zeros. This change turns such use cases in to an
error.
This means that `--allow-undefined` is no longer effective for data
symbols.
Fixes https://bugs.llvm.org/show_bug.cgi?id=40364
Differential Revision: https://reviews.llvm.org/D60882
llvm-svn: 358899
diff --git a/lld/test/wasm/undefined-data.ll b/lld/test/wasm/undefined-data.ll
index 635dccd..c3928bc 100644
--- a/lld/test/wasm/undefined-data.ll
+++ b/lld/test/wasm/undefined-data.ll
@@ -1,6 +1,7 @@
; RUN: llc -filetype=obj %s -o %t.o
; RUN: not wasm-ld -o %t.wasm %t.o 2>&1 | FileCheck %s -check-prefix=UNDEF
-; RUN: not wasm-ld --shared -o %t.wasm %t.o 2>&1 | FileCheck %s -check-prefix=BADRELOC
+; RUN: not wasm-ld --allow-undefined -o %t.wasm %t.o 2>&1 | FileCheck %s -check-prefix=ALLOW
+; RUN: not wasm-ld --shared -o %t.wasm %t.o 2>&1 | FileCheck %s -check-prefix=SHARED
target triple = "wasm32-unknown-unknown"
@@ -13,4 +14,5 @@
}
; UNDEF: undefined symbol: data_external
-; BADRELOC: undefined-data.ll.tmp.o: relocation R_WASM_MEMORY_ADDR_LEB cannot be used againt symbol data_external; recompile with -fPIC
+; ALLOW: undefined-data.ll.tmp.o: cannot resolve relocation of type R_WASM_MEMORY_ADDR_LEB against undefined (non-weak) data symbol: data_external
+; SHARED: undefined-data.ll.tmp.o: relocation R_WASM_MEMORY_ADDR_LEB cannot be used againt symbol data_external; recompile with -fPIC
diff --git a/lld/wasm/InputFiles.cpp b/lld/wasm/InputFiles.cpp
index 2929379..807651a 100644
--- a/lld/wasm/InputFiles.cpp
+++ b/lld/wasm/InputFiles.cpp
@@ -141,6 +141,30 @@
// Translate from the relocation's index into the final linked output value.
uint32_t ObjFile::calcNewValue(const WasmRelocation &Reloc) const {
+ const Symbol* Sym = nullptr;
+ if (Reloc.Type != R_WASM_TYPE_INDEX_LEB) {
+ Sym = Symbols[Reloc.Index];
+
+ // We can end up with relocations against non-live symbols. For example
+ // in debug sections.
+ if ((isa<FunctionSymbol>(Sym) || isa<DataSymbol>(Sym)) && !Sym->isLive())
+ return 0;
+
+ // Special handling for undefined data symbols. Most relocations against
+ // such symbols cannot be resolved.
+ if (isa<DataSymbol>(Sym) && Sym->isUndefined()) {
+ if (Sym->isWeak() || Config->Relocatable)
+ return 0;
+ if (Config->Shared && Reloc.Type == R_WASM_MEMORY_ADDR_I32)
+ return 0;
+ if (Reloc.Type != R_WASM_GLOBAL_INDEX_LEB) {
+ llvm_unreachable(
+ ("invalid relocation against undefined data symbol: " + toString(*Sym))
+ .c_str());
+ }
+ }
+ }
+
switch (Reloc.Type) {
case R_WASM_TABLE_INDEX_I32:
case R_WASM_TABLE_INDEX_SLEB:
@@ -150,28 +174,22 @@
case R_WASM_MEMORY_ADDR_I32:
case R_WASM_MEMORY_ADDR_LEB:
case R_WASM_MEMORY_ADDR_REL_SLEB:
- if (auto *Sym = dyn_cast<DefinedData>(getDataSymbol(Reloc.Index)))
- if (Sym->isLive())
- return Sym->getVirtualAddress() + Reloc.Addend;
- return 0;
+ return cast<DefinedData>(Sym)->getVirtualAddress() + Reloc.Addend;
case R_WASM_TYPE_INDEX_LEB:
return TypeMap[Reloc.Index];
case R_WASM_FUNCTION_INDEX_LEB:
return getFunctionSymbol(Reloc.Index)->getFunctionIndex();
- case R_WASM_GLOBAL_INDEX_LEB: {
- const Symbol* Sym = Symbols[Reloc.Index];
+ case R_WASM_GLOBAL_INDEX_LEB:
if (auto GS = dyn_cast<GlobalSymbol>(Sym))
return GS->getGlobalIndex();
return Sym->getGOTIndex();
- } case R_WASM_EVENT_INDEX_LEB:
+ case R_WASM_EVENT_INDEX_LEB:
return getEventSymbol(Reloc.Index)->getEventIndex();
- case R_WASM_FUNCTION_OFFSET_I32:
- if (auto *Sym = dyn_cast<DefinedFunction>(getFunctionSymbol(Reloc.Index))) {
- if (Sym->isLive())
- return Sym->Function->OutputOffset +
- Sym->Function->getFunctionCodeOffset() + Reloc.Addend;
- }
- return 0;
+ case R_WASM_FUNCTION_OFFSET_I32: {
+ auto *F = cast<DefinedFunction>(Sym);
+ return F->Function->OutputOffset + F->Function->getFunctionCodeOffset() +
+ Reloc.Addend;
+ }
case R_WASM_SECTION_OFFSET_I32:
return getSectionSymbol(Reloc.Index)->Section->OutputOffset + Reloc.Addend;
default:
diff --git a/lld/wasm/Writer.cpp b/lld/wasm/Writer.cpp
index 6a835ce..d4014d7 100644
--- a/lld/wasm/Writer.cpp
+++ b/lld/wasm/Writer.cpp
@@ -1170,6 +1170,20 @@
Sym->setGOTIndex(NumImportedGlobals++);
GOTSymbols.push_back(Sym);
}
+ break;
+ }
+ case R_WASM_MEMORY_ADDR_SLEB:
+ case R_WASM_MEMORY_ADDR_LEB:
+ case R_WASM_MEMORY_ADDR_REL_SLEB: {
+ if (!Config->Relocatable) {
+ auto* Sym = File->getSymbols()[Reloc.Index];
+ if (Sym->isUndefined() && !Sym->isWeak()) {
+ error(toString(File) + ": cannot resolve relocation of type " +
+ relocTypeToString(Reloc.Type) +
+ " against undefined (non-weak) data symbol: " + toString(*Sym));
+ }
+ }
+ break;
}
}