[WebAssembly] Support bitcasted function addresses with varargs.

Generalize FixFunctionBitcasts to handle varargs functions. This in
particular fixes the case where clang bitcasts away a varargs when
calling a K&R-style function.

This avoids interacting with tricky ABI details because it operates
at the LLVM IR level before varargs ABI details are exposed.

This fixes PR35385.

llvm-svn: 319186

diff --git a/llvm/lib/MC/WasmObjectWriter.cpp b/llvm/lib/MC/WasmObjectWriter.cpp
index 2297084..6e9088b 100644 (file)
--- a/llvm/lib/MC/WasmObjectWriter.cpp
+++ b/llvm/lib/MC/WasmObjectWriter.cpp
@@ -1040,12 +1040,15 @@ void WasmObjectWriter::writeObject(MCAssembler &Asm,
   for (const MCSymbol &S : Asm.symbols()) {
     const auto &WS = static_cast<const MCSymbolWasm &>(S);
 
-    if (WS.isTemporary())
-      continue;
-
+    // Register types for all functions, including those with private linkage
+    // (making them
+    // because wasm always needs a type signature.
     if (WS.isFunction())
       registerFunctionType(WS);
 
+    if (WS.isTemporary())
+      continue;
+
     // If the symbol is not defined in this translation unit, import it.
     if (!WS.isDefined(/*SetUsed=*/false)) {
       WasmImport Import;

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyFixFunctionBitcasts.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyFixFunctionBitcasts.cpp
index 19df75c..6473a2b 100644 (file)
--- a/llvm/lib/Target/WebAssembly/WebAssemblyFixFunctionBitcasts.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyFixFunctionBitcasts.cpp
@@ -107,9 +107,10 @@ static Function *CreateWrapper(Function *F, FunctionType *Ty) {
   // Determine what arguments to pass.
   SmallVector<Value *, 4> Args;
   Function::arg_iterator AI = Wrapper->arg_begin();
+  Function::arg_iterator AE = Wrapper->arg_end();
   FunctionType::param_iterator PI = F->getFunctionType()->param_begin();
   FunctionType::param_iterator PE = F->getFunctionType()->param_end();
-  for (; AI != Wrapper->arg_end() && PI != PE; ++AI, ++PI) {
+  for (; AI != AE && PI != PE; ++AI, ++PI) {
     if (AI->getType() != *PI) {
       Wrapper->eraseFromParent();
       return nullptr;
@@ -118,6 +119,9 @@ static Function *CreateWrapper(Function *F, FunctionType *Ty) {
   }
   for (; PI != PE; ++PI)
     Args.push_back(UndefValue::get(*PI));
+  if (F->isVarArg())
+    for (; AI != AE; ++AI)
+      Args.push_back(&*AI);
 
   CallInst *Call = CallInst::Create(F, Args, "", BB);
 
@@ -158,11 +162,6 @@ bool FixFunctionBitcasts::runOnModule(Module &M) {
     if (!Ty)
       continue;
 
-    // Wasm varargs are not ABI-compatible with non-varargs. Just ignore
-    // such casts for now.
-    if (Ty->isVarArg() || F->isVarArg())
-      continue;
-
     auto Pair = Wrappers.insert(std::make_pair(std::make_pair(F, Ty), nullptr));
     if (Pair.second)
       Pair.first->second = CreateWrapper(F, Ty);

diff --git a/llvm/test/CodeGen/WebAssembly/call.ll b/llvm/test/CodeGen/WebAssembly/call.ll
index dfa0cf5..74c9fb6 100644 (file)
--- a/llvm/test/CodeGen/WebAssembly/call.ll
+++ b/llvm/test/CodeGen/WebAssembly/call.ll
@@ -153,7 +153,7 @@ define void @coldcc_tail_call_void_nullary() {
 ; CHECK-LABEL: call_constexpr:
 ; CHECK-NEXT: i32.const $push[[L0:[0-9]+]]=, 2{{$}}
 ; CHECK-NEXT: i32.const $push[[L1:[0-9]+]]=, 3{{$}}
-; CHECK-NEXT: call vararg_func@FUNCTION, $pop[[L0]], $pop[[L1]]{{$}}
+; CHECK-NEXT: call .Lbitcast@FUNCTION, $pop[[L0]], $pop[[L1]]{{$}}
 ; CHECK-NEXT: call other_void_nullary@FUNCTION{{$}}
 ; CHECK-NEXT: call void_nullary@FUNCTION{{$}}
 ; CHECK-NEXT: return{{$}}

diff --git a/llvm/test/CodeGen/WebAssembly/function-bitcasts-varargs.ll b/llvm/test/CodeGen/WebAssembly/function-bitcasts-varargs.ll
new file mode 100644 (file)
index 0000000..c08fe8f
--- /dev/null
+++ b/llvm/test/CodeGen/WebAssembly/function-bitcasts-varargs.ll
@@ -0,0 +1,31 @@
+; RUN: llc < %s -asm-verbose=false | FileCheck %s
+
+; Test that function pointer casts casting away varargs are replaced with
+; wrappers.
+
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown-wasm"
+
+define void @callWithArgs() {
+entry:
+  call void bitcast (void (...)* @underspecified to void (i32, i32)*)(i32 0, i32 1)
+  call void(...) bitcast (void (i32, i32)* @specified to void (...)*)(i32 0, i32 1)
+  ret void
+}
+
+declare void @underspecified(...)
+declare void @specified(i32, i32)
+
+; CHECK: callWithArgs:
+; CHECK: i32.const     $push1=, 0
+; CHECK-NEXT: i32.const        $push0=, 1
+; CHECK-NEXT: call     .Lbitcast@FUNCTION, $pop1, $pop0
+; CHECK: call          .Lbitcast.1@FUNCTION, $pop{{[0-9]+$}}
+
+; CHECK: .Lbitcast:
+; CHECK-NEXT: .param   i32, i32{{$}}
+; CHECK: call          underspecified@FUNCTION, $pop{{[0-9]+$}}
+
+; CHECK: .Lbitcast.1:
+; CHECK-NEXT: .param   i32{{$}}
+; CHECK: call          specified@FUNCTION, $pop{{[0-9]+}}, $pop{{[0-9]+$}}

diff --git a/llvm/test/CodeGen/WebAssembly/function-bitcasts.ll b/llvm/test/CodeGen/WebAssembly/function-bitcasts.ll
index 3e796e3..17843a2 100644 (file)
--- a/llvm/test/CodeGen/WebAssembly/function-bitcasts.ll
+++ b/llvm/test/CodeGen/WebAssembly/function-bitcasts.ll
@@ -20,13 +20,13 @@ declare void @foo3()
 ; CHECK-NEXT: call        .Lbitcast@FUNCTION{{$}}
 ; CHECK-NEXT: call        .Lbitcast.1@FUNCTION{{$}}
 ; CHECK-NEXT: i32.const   $push[[L0:[0-9]+]]=, 0
-; CHECK-NEXT: call        .Lbitcast.2@FUNCTION, $pop[[L0]]{{$}}
+; CHECK-NEXT: call        .Lbitcast.4@FUNCTION, $pop[[L0]]{{$}}
 ; CHECK-NEXT: i32.const   $push[[L1:[0-9]+]]=, 0
-; CHECK-NEXT: call        .Lbitcast.2@FUNCTION, $pop[[L1]]{{$}}
+; CHECK-NEXT: call        .Lbitcast.4@FUNCTION, $pop[[L1]]{{$}}
 ; CHECK-NEXT: i32.const   $push[[L2:[0-9]+]]=, 0
-; CHECK-NEXT: call        .Lbitcast.2@FUNCTION, $pop[[L2]]{{$}}
+; CHECK-NEXT: call        .Lbitcast.4@FUNCTION, $pop[[L2]]{{$}}
 ; CHECK-NEXT: call        foo0@FUNCTION
-; CHECK-NEXT: i32.call    $drop=, .Lbitcast.3@FUNCTION{{$}}
+; CHECK-NEXT: i32.call    $drop=, .Lbitcast.5@FUNCTION{{$}}
 ; CHECK-NEXT: call        foo2@FUNCTION{{$}}
 ; CHECK-NEXT: call        foo1@FUNCTION{{$}}
 ; CHECK-NEXT: call        foo3@FUNCTION{{$}}
@@ -54,10 +54,10 @@ entry:
 ; CHECK-LABEL: test_varargs:
 ; CHECK:      set_global
 ; CHECK:      i32.const   $push[[L3:[0-9]+]]=, 0{{$}}
-; CHECK-NEXT: call        vararg@FUNCTION, $pop[[L3]]{{$}}
+; CHECK-NEXT: call        .Lbitcast.2@FUNCTION, $pop[[L3]]{{$}}
 ; CHECK-NEXT: i32.const   $push[[L4:[0-9]+]]=, 0{{$}}
 ; CHECK-NEXT: i32.store   0($[[L5:[0-9]+]]), $pop[[L4]]{{$}}
-; CHECK-NEXT: call        plain@FUNCTION, $[[L5]]{{$}}
+; CHECK-NEXT: call        .Lbitcast.3@FUNCTION, $[[L5]]{{$}}
 define void @test_varargs() {
   call void bitcast (void (...)* @vararg to void (i32)*)(i32 0)
   call void (...) bitcast (void (i32)* @plain to void (...)*)(i32 0)
@@ -147,11 +147,19 @@ end:
 ; CHECK-NEXT: end_function
 
 ; CHECK-LABEL: .Lbitcast.2:
+; CHECK: call        vararg@FUNCTION, $1{{$}}
+; CHECK: end_function
+
+; CHECK-LABEL: .Lbitcast.3:
+; CHECK: call        plain@FUNCTION, $1{{$}}
+; CHECK: end_function
+
+; CHECK-LABEL: .Lbitcast.4:
 ; CHECK-NEXT: .param      i32
 ; CHECK-NEXT: call        foo0@FUNCTION{{$}}
 ; CHECK-NEXT: end_function
 
-; CHECK-LABEL: .Lbitcast.3:
+; CHECK-LABEL: .Lbitcast.5:
 ; CHECK-NEXT: .result     i32
 ; CHECK-NEXT: call        foo1@FUNCTION{{$}}
 ; CHECK-NEXT: copy_local  $push0=, $0