Revert "[WebAssembly] Error on mismatched function signature in final output"

This caused a lot of issues on the WebAssembly waterfall.
In particular, until with the signature of `main`.  We
probably want a better solution for main before we re-land.

Reverts rL335192

llvm-svn: 335355

lld/test/wasm/fatal-warnings.ll

@@ -9,11 +9,6 @@
 target triple = "wasm32-unknown-unknown"
 
 define hidden void @_start() local_unnamed_addr #0 {
-entry:
-  ret void
-}
-
-define hidden void @_call_ret32() local_unnamed_addr #0 {
 entry:
   %call = tail call i32 @ret32(i32 1, i64 2, i32 3) #2
   ret void

lld/test/wasm/signature-mismatch-weak.ll

@@ -1,7 +1,7 @@
 ; RUN: llc -filetype=obj %p/Inputs/weak-symbol1.ll -o %t.weak.o
 ; RUN: llc -filetype=obj %p/Inputs/strong-symbol.ll -o %t.strong.o
 ; RUN: llc -filetype=obj %s -o %t.o
-; RUN: not wasm-ld -o %t.wasm %t.o %t.strong.o %t.weak.o 2>&1 | FileCheck %s
+; RUN: wasm-ld -o %t.wasm %t.o %t.strong.o %t.weak.o 2>&1 | FileCheck %s
 
 target triple = "wasm32-unknown-unknown"
 
@@ -16,4 +16,3 @@ entry:
 ; CHECK: warning: function signature mismatch: weakFn
 ; CHECK-NEXT: >>> defined as () -> I32 in {{.*}}signature-mismatch-weak.ll.tmp.o
 ; CHECK-NEXT: >>> defined as () -> I64 in {{.*}}signature-mismatch-weak.ll.tmp.strong.o
-; CHECK: error: function signature mismatch: weakFn

lld/test/wasm/signature-mismatch.ll

@@ -1,11 +1,10 @@
 ; RUN: llc -filetype=obj %p/Inputs/ret32.ll -o %t.ret32.o
 ; RUN: llc -filetype=obj %s -o %t.main.o
-; RUN: not wasm-ld -o %t.wasm %t.main.o %t.ret32.o 2>&1 | FileCheck %s
-; RUN: not wasm-ld --no-gc-sections -o %t.wasm %t.main.o %t.ret32.o 2>&1 | FileCheck %s -check-prefix=NO-GC
+; RUN: not wasm-ld --fatal-warnings -o %t.wasm %t.main.o %t.ret32.o 2>&1 | FileCheck %s
 ; Run the test again by with the object files in the other order to verify
 ; the check works when the undefined symbol is resolved by an existing defined
 ; one.
-; RUN: not wasm-ld -o %t.wasm %t.ret32.o %t.main.o 2>&1 | FileCheck %s -check-prefix=REVERSE
+; RUN: not wasm-ld --fatal-warnings -o %t.wasm %t.ret32.o %t.main.o 2>&1 | FileCheck %s -check-prefix=REVERSE
 
 target triple = "wasm32-unknown-unknown"
 
@@ -18,16 +17,10 @@ entry:
 
 declare i32 @ret32(i32, i64, i32) local_unnamed_addr #1
 
-; CHECK: warning: function signature mismatch: ret32
+; CHECK: error: function signature mismatch: ret32
 ; CHECK-NEXT: >>> defined as (I32, I64, I32) -> I32 in {{.*}}.main.o
 ; CHECK-NEXT: >>> defined as (F32) -> I32 in {{.*}}.ret32.o
-; CHECK: error: function signature mismatch: ret32
 
-; NO-GC: error: function signature mismatch: ret32
-; NO-GC-NEXT: >>> defined as (I32, I64, I32) -> I32 in {{.*}}.main.o
-; NO-GC-NEXT: >>> defined as (F32) -> I32 in {{.*}}.ret32.o
-
-; REVERSE: warning: function signature mismatch: ret32
+; REVERSE: error: function signature mismatch: ret32
 ; REVERSE-NEXT: >>> defined as (F32) -> I32 in {{.*}}.ret32.o
 ; REVERSE-NEXT: >>> defined as (I32, I64, I32) -> I32 in {{.*}}.main.o
-; REVERSE: error: function signature mismatch: ret32

lld/wasm/Driver.cpp

@@ -483,8 +483,7 @@ void LinkerDriver::link(ArrayRef<const char *> ArgsArr) {
     return;
 
   // Do size optimizations: garbage collection
-  if (Config->GcSections)
-    markLive();
+  markLive();
 
   // Write the result to the file.
   writeResult();

lld/wasm/MarkLive.cpp

@@ -34,6 +34,9 @@ using namespace lld;
 using namespace lld::wasm;
 
 void lld::wasm::markLive() {
+  if (!Config->GcSections)
+    return;
+
   LLVM_DEBUG(dbgs() << "markLive\n");
   SmallVector<InputChunk *, 256> Q;
 
@@ -42,8 +45,6 @@ void lld::wasm::markLive() {
       return;
     LLVM_DEBUG(dbgs() << "markLive: " << Sym->getName() << "\n");
     Sym->markLive();
-    if (Sym->SignatureMismatch)
-      error("function signature mismatch: " + Sym->getName());
     if (InputChunk *Chunk = Sym->getChunk())
       Q.push_back(Chunk);
   };

lld/wasm/SymbolTable.cpp

@@ -106,7 +106,7 @@ static void reportTypeError(const Symbol *Existing, const InputFile *File,
         " in " + toString(File));
 }
 
-static void checkFunctionType(Symbol *Existing, const InputFile *File,
+static void checkFunctionType(const Symbol *Existing, const InputFile *File,
                               const WasmSignature *NewSig) {
   auto ExistingFunction = dyn_cast<FunctionSymbol>(Existing);
   if (!ExistingFunction) {
@@ -114,27 +114,12 @@ static void checkFunctionType(Symbol *Existing, const InputFile *File,
     return;
   }
 
-
   const WasmSignature *OldSig = ExistingFunction->getFunctionType();
   if (OldSig && NewSig && *NewSig != *OldSig) {
-    // Don't generate more than one warning per symbol.
-    if (Existing->SignatureMismatch)
-      return;
-    Existing->SignatureMismatch = true;
-
-    std::string msg = ("function signature mismatch: " + Existing->getName() +
-                       "\n>>> defined as " + toString(*OldSig) + " in " +
-                       toString(Existing->getFile()) + "\n>>> defined as " +
-                       toString(*NewSig) + " in " + toString(File))
-                          .str();
-    // A function signature mismatch is only really problem if the mismatched
-    // symbol is included in the final output, and gc-sections can remove the
-    // offending uses.  Therefore we delay reporting this as an error when
-    // section GC is enabled.
-    if (Config->GcSections)
-      warn(msg);
-    else
-      error(msg);
+    warn("function signature mismatch: " + Existing->getName() +
+         "\n>>> defined as " + toString(*OldSig) + " in " +
+         toString(Existing->getFile()) + "\n>>> defined as " +
+         toString(*NewSig) + " in " + toString(File));
   }
 }
 

lld/wasm/Symbols.h

@@ -93,12 +93,11 @@ public:
 
   // True if this symbol was referenced by a regular (non-bitcode) object.
   unsigned IsUsedInRegularObj : 1;
-  unsigned SignatureMismatch : 1;
 
 protected:
   Symbol(StringRef Name, Kind K, uint32_t Flags, InputFile *F)
-      : IsUsedInRegularObj(false), SignatureMismatch(false), Name(Name),
-        SymbolKind(K), Flags(Flags), File(F), Referenced(!Config->GcSections) {}
+      : IsUsedInRegularObj(false), Name(Name), SymbolKind(K), Flags(Flags),
+        File(F), Referenced(!Config->GcSections) {}
 
   StringRef Name;
   Kind SymbolKind;
@@ -341,7 +340,6 @@ T *replaceSymbol(Symbol *S, ArgT &&... Arg) {
 
   T *S2 = new (S) T(std::forward<ArgT>(Arg)...);
   S2->IsUsedInRegularObj = SymCopy.IsUsedInRegularObj;
-  S2->SignatureMismatch = SymCopy.SignatureMismatch;
   return S2;
 }