[WebAssemby] Implement block signatures.

Per spec changes, this implements block signatures, and adds just enough
logic to produce correct block signatures at the ends of functions.

Differential Revision: https://reviews.llvm.org/D25144

llvm-svn: 283503

1 files changed, 37 insertions, 0 deletions

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.cpp
index 225c5d32cb5..ccf6a18b32e 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.cpp
@@ -14,6 +14,9 @@
 //===----------------------------------------------------------------------===//
 
 #include "WebAssemblyMachineFunctionInfo.h"
+#include "WebAssemblyISelLowering.h"
+#include "WebAssemblySubtarget.h"
+#include "llvm/CodeGen/Analysis.h"
 using namespace llvm;
 
 WebAssemblyFunctionInfo::~WebAssemblyFunctionInfo() {}
@@ -23,3 +26,37 @@ void WebAssemblyFunctionInfo::initWARegs() {
   unsigned Reg = UnusedReg;
   WARegs.resize(MF.getRegInfo().getNumVirtRegs(), Reg);
 }
+
+void llvm::ComputeLegalValueVTs(const Function &F, const TargetMachine &TM,
+                                Type *Ty, SmallVectorImpl<MVT> &ValueVTs) {
+  const DataLayout &DL(F.getParent()->getDataLayout());
+  const WebAssemblyTargetLowering &TLI =
+      *TM.getSubtarget<WebAssemblySubtarget>(F).getTargetLowering();
+  SmallVector<EVT, 4> VTs;
+  ComputeValueVTs(TLI, DL, Ty, VTs);
+
+  for (EVT VT : VTs) {
+    unsigned NumRegs = TLI.getNumRegisters(F.getContext(), VT);
+    MVT RegisterVT = TLI.getRegisterType(F.getContext(), VT);
+    for (unsigned i = 0; i != NumRegs; ++i)
+      ValueVTs.push_back(RegisterVT);
+  }
+}
+
+void llvm::ComputeSignatureVTs(const Function &F, const TargetMachine &TM,
+                               SmallVectorImpl<MVT> &Params,
+                               SmallVectorImpl<MVT> &Results) {
+  ComputeLegalValueVTs(F, TM, F.getReturnType(), Results);
+
+  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()));
+  }
+
+  for (auto &Arg : F.args())
+    ComputeLegalValueVTs(F, TM, Arg.getType(), Params);
+}