[WebAssembly] Refactor WasmSignature and use it for MCSymbolWasm

MCContext does not destroy MCSymbols on shutdown. So, rather than putting
SmallVectors (which may heap-allocate) inside MCSymbolWasm, use unowned pointer
to a WasmSignature instead. The signatures are now owned by the AsmPrinter.
Also uses WasmSignature instead of param and result vectors in TargetStreamer,
and leaves some TODOs for further simplification.

 Differential Revision: https://reviews.llvm.org/D52580

llvm-svn: 343733

1 files changed, 20 insertions, 6 deletions

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.cpp
index e511e574050..073706e567e 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.cpp
@@ -43,20 +43,34 @@ void llvm::ComputeLegalValueVTs(const Function &F, const TargetMachine &TM,
   }
 }
 
-void llvm::ComputeSignatureVTs(const Function &F, const TargetMachine &TM,
+void llvm::ComputeSignatureVTs(const FunctionType *Ty, const Function &F,
+                               const TargetMachine &TM,
                                SmallVectorImpl<MVT> &Params,
                                SmallVectorImpl<MVT> &Results) {
-  ComputeLegalValueVTs(F, TM, F.getReturnType(), Results);
+  ComputeLegalValueVTs(F, TM, Ty->getReturnType(), Results);
 
+  MVT PtrVT = MVT::getIntegerVT(TM.createDataLayout().getPointerSizeInBits());
   if (Results.size() > 1) {
     // WebAssembly currently can't lower returns of multiple values without
     // demoting to sret (see WebAssemblyTargetLowering::CanLowerReturn). So
     // replace multiple return values with a pointer parameter.
     Results.clear();
-    Params.push_back(
-        MVT::getIntegerVT(TM.createDataLayout().getPointerSizeInBits()));
+    Params.push_back(PtrVT);
   }
 
-  for (auto &Arg : F.args())
-    ComputeLegalValueVTs(F, TM, Arg.getType(), Params);
+  for (auto *Param : Ty->params())
+    ComputeLegalValueVTs(F, TM, Param, Params);
+  if (Ty->isVarArg())
+    Params.push_back(PtrVT);
+}
+
+std::unique_ptr<wasm::WasmSignature>
+llvm::SignatureFromMVTs(const SmallVectorImpl<MVT> &Results,
+                        const SmallVectorImpl<MVT> &Params) {
+  auto Sig = make_unique<wasm::WasmSignature>();
+  for (MVT Ty : Results)
+    Sig->Returns.push_back(WebAssembly::toValType(Ty));
+  for (MVT Ty : Params)
+    Sig->Params.push_back(WebAssembly::toValType(Ty));
+  return Sig;
 }