[WebAssembly] Add support for -emit-relocs
This can be useful for post-link tools and for testing. Sometimes
it can be useful to produces a regular executable but with relocations
preserved.
Differential Revision: https://reviews.llvm.org/D62378
llvm-svn: 361635
diff --git a/lld/test/wasm/emit-relocs.ll b/lld/test/wasm/emit-relocs.ll
new file mode 100644
index 0000000..cdf492a
--- /dev/null
+++ b/lld/test/wasm/emit-relocs.ll
@@ -0,0 +1,39 @@
+; RUN: llc -filetype=obj %s -o %t.o
+; RUN: llc -filetype=obj %p/Inputs/ret32.ll -o %t.ret32.o
+; RUN: wasm-ld --emit-relocs -o %t.wasm %t.o %t.ret32.o
+; RUN: obj2yaml %t.wasm | FileCheck %s
+
+target triple = "wasm32-unknown-unknown"
+
+declare i32 @ret32(float)
+
+define void @unused_function() {
+ ret void
+}
+
+define hidden void @_start() local_unnamed_addr #0 {
+entry:
+ call i32 @ret32(float 0.0)
+ ret void
+}
+
+; CHECK: - Type: CODE
+; CHECK-NEXT: Relocations:
+; CHECK-NEXT: - Type: R_WASM_FUNCTION_INDEX_LEB
+; CHECK-NEXT: Index: 1
+; CHECK-NEXT: Offset: 0x00000009
+
+; CHECK: - Type: CUSTOM
+; CHECK-NEXT: Name: linking
+; CHECK-NEXT: Version: 2
+; CHECK-NEXT: SymbolTable:
+; CHECK-NEXT: - Index: 0
+; CHECK-NEXT: Kind: FUNCTION
+; CHECK-NEXT: Name: _start
+; CHECK-NEXT: Flags: [ ]
+; CHECK-NEXT: Function: 0
+; CHECK-NEXT: - Index: 1
+; CHECK-NEXT: Kind: FUNCTION
+; CHECK-NEXT: Name: ret32
+; CHECK-NEXT: Flags: [ VISIBILITY_HIDDEN ]
+; CHECK-NEXT: Function: 1
diff --git a/lld/wasm/Config.h b/lld/wasm/Config.h
index 7881d015..6650e9e 100644
--- a/lld/wasm/Config.h
+++ b/lld/wasm/Config.h
@@ -27,6 +27,7 @@
bool CompressRelocations;
bool Demangle;
bool DisableVerify;
+ bool EmitRelocs;
bool ExportAll;
bool ExportDynamic;
bool ExportTable;
diff --git a/lld/wasm/Driver.cpp b/lld/wasm/Driver.cpp
index 0bea11f..06868f3 100644
--- a/lld/wasm/Driver.cpp
+++ b/lld/wasm/Driver.cpp
@@ -302,6 +302,7 @@
Config->CompressRelocations = Args.hasArg(OPT_compress_relocations);
Config->Demangle = Args.hasFlag(OPT_demangle, OPT_no_demangle, true);
Config->DisableVerify = Args.hasArg(OPT_disable_verify);
+ Config->EmitRelocs = Args.hasArg(OPT_emit_relocs);
Config->Entry = getEntry(Args);
Config->ExportAll = Args.hasArg(OPT_export_all);
Config->ExportDynamic = Args.hasFlag(OPT_export_dynamic,
diff --git a/lld/wasm/Options.td b/lld/wasm/Options.td
index a7760e8..b95d9de 100644
--- a/lld/wasm/Options.td
+++ b/lld/wasm/Options.td
@@ -31,6 +31,8 @@
"Demangle symbol names",
"Do not demangle symbol names">;
+def emit_relocs: F<"emit-relocs">, HelpText<"Generate relocations in output">;
+
defm export_dynamic: B<"export-dynamic",
"Put symbols in the dynamic symbol table",
"Do not put symbols in the dynamic symbol table (default)">;
diff --git a/lld/wasm/SyntheticSections.h b/lld/wasm/SyntheticSections.h
index ccd6632..9f52661 100644
--- a/lld/wasm/SyntheticSections.h
+++ b/lld/wasm/SyntheticSections.h
@@ -246,7 +246,9 @@
const std::vector<OutputSegment *> &DataSegments)
: SyntheticSection(llvm::wasm::WASM_SEC_CUSTOM, "linking"),
InitFunctions(InitFunctions), DataSegments(DataSegments) {}
- bool isNeeded() const override { return Config->Relocatable; }
+ bool isNeeded() const override {
+ return Config->Relocatable || Config->EmitRelocs;
+ }
void writeBody() override;
void addToSymtab(Symbol *Sym);
diff --git a/lld/wasm/Writer.cpp b/lld/wasm/Writer.cpp
index f43191c..5df364f 100644
--- a/lld/wasm/Writer.cpp
+++ b/lld/wasm/Writer.cpp
@@ -129,7 +129,7 @@
LLVM_DEBUG(dbgs() << "createCustomSection: " << Name << "\n");
OutputSection *Sec = make<CustomSection>(Name, Pair.second);
- if (Config->Relocatable) {
+ if (Config->Relocatable || Config->EmitRelocs) {
auto *Sym = make<OutputSectionSymbol>(Sec);
Out.LinkingSec->addToSymtab(Sym);
Sec->SectionSym = Sym;
@@ -330,7 +330,7 @@
createCustomSections();
addSection(Out.LinkingSec);
- if (Config->Relocatable) {
+ if (Config->EmitRelocs || Config->Relocatable) {
createRelocSections();
}
@@ -493,17 +493,17 @@
}
void Writer::populateSymtab() {
- if (!Config->Relocatable)
+ if (!Config->Relocatable && !Config->EmitRelocs)
return;
for (Symbol *Sym : Symtab->getSymbols())
- if (Sym->IsUsedInRegularObj)
+ if (Sym->IsUsedInRegularObj && Sym->isLive())
Out.LinkingSec->addToSymtab(Sym);
for (ObjFile *File : Symtab->ObjectFiles) {
LLVM_DEBUG(dbgs() << "Local symtab entries: " << File->getName() << "\n");
for (Symbol *Sym : File->getSymbols())
- if (Sym->isLocal() && !isa<SectionSymbol>(Sym))
+ if (Sym->isLocal() && !isa<SectionSymbol>(Sym) && Sym->isLive())
Out.LinkingSec->addToSymtab(Sym);
}
}
