WebAssembly: print basic integer assembly.

Summary:
This prints assembly for int32 integer operations defined in WebAssemblyInstrInteger.td only, with major caveats:

  - The operation names are currently incorrect.
  - Other integer and floating-point types will be added later.
  - The printer isn't factored out to handle recursive AST code yet, since it can't even handle control flow anyways.
  - The assembly format isn't full s-expressions yet either, this will be added later.
  - This currently disables PrologEpilogCodeInserter as well as MachineCopyPropagation becasue they don't like virtual registers, which WebAssembly likes quite a bit. This will be fixed by factoring out NVPTX's change (currently a fork of PrologEpilogCodeInserter).

Reviewers: sunfish

Subscribers: llvm-commits, jfb

Differential Revision: http://reviews.llvm.org/D11671

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@243763 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp

@@ -38,9 +38,11 @@ using namespace llvm;
 namespace {
 
 class WebAssemblyAsmPrinter final : public AsmPrinter {
+  const WebAssemblyInstrInfo *TII;
+
 public:
   WebAssemblyAsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer)
-      : AsmPrinter(TM, std::move(Streamer)) {}
+      : AsmPrinter(TM, std::move(Streamer)), TII(nullptr) {}
 
 private:
   const char *getPassName() const override {
@@ -55,8 +57,10 @@ private:
     AsmPrinter::getAnalysisUsage(AU);
   }
 
-  bool runOnMachineFunction(MachineFunction &F) override {
-    return AsmPrinter::runOnMachineFunction(F);
+  bool runOnMachineFunction(MachineFunction &MF) override {
+    TII = static_cast<const WebAssemblyInstrInfo *>(
+        MF.getSubtarget().getInstrInfo());
+    return AsmPrinter::runOnMachineFunction(MF);
   }
 
   //===------------------------------------------------------------------===//
@@ -74,13 +78,43 @@ void WebAssemblyAsmPrinter::EmitInstruction(const MachineInstr *MI) {
   SmallString<128> Str;
   raw_svector_ostream OS(Str);
 
+  unsigned NumDefs = MI->getDesc().getNumDefs();
+  assert(NumDefs <= 1 &&
+         "Instructions with multiple result values not implemented");
+
+  if (NumDefs != 0) {
+    const MachineOperand &MO = MI->getOperand(0);
+    unsigned Reg = MO.getReg();
+    OS << "(setlocal @" << TargetRegisterInfo::virtReg2Index(Reg) << ' ';
+  }
+
+  OS << '(';
+
+  bool PrintOperands = true;
   switch (MI->getOpcode()) {
+  case WebAssembly::ARGUMENT:
+    OS << "argument " << MI->getOperand(1).getImm();
+    PrintOperands = false;
+    break;
   default:
-    DEBUG(MI->print(dbgs()));
-    llvm_unreachable("Unhandled instruction");
+    OS << TII->getName(MI->getOpcode());
     break;
   }
 
+  if (PrintOperands)
+    for (const MachineOperand &MO : MI->uses()) {
+      if (MO.isReg() && MO.isImplicit())
+        continue;
+      unsigned Reg = MO.getReg();
+      OS << " @" << TargetRegisterInfo::virtReg2Index(Reg);
+    }
+  OS << ')';
+
+  if (NumDefs != 0)
+    OS << ')';
+
+  OS << '\n';
+
   OutStreamer->EmitRawText(OS.str());
 }
 

lib/Target/WebAssembly/WebAssemblyISelLowering.cpp

@@ -141,8 +141,13 @@ SDValue WebAssemblyTargetLowering::LowerReturn(
   assert(Outs.size() <= 1 && "WebAssembly can only return up to one value");
   if (CallConv != CallingConv::C)
     fail(DL, DAG, "WebAssembly doesn't support non-C calling conventions");
+  if (IsVarArg)
+    fail(DL, DAG, "WebAssembly doesn't support varargs yet");
 
-  // FIXME: Implement LowerReturn.
+  SmallVector<SDValue, 4> RetOps(1, Chain);
+  RetOps.append(OutVals.begin(), OutVals.end());
+  const SDValue Ops[] = {Chain, OutVals.front()};
+  Chain = DAG.getNode(WebAssemblyISD::RETURN, DL, MVT::Other, Ops);
 
   return Chain;
 }
@@ -160,9 +165,38 @@ SDValue WebAssemblyTargetLowering::LowerFormalArguments(
   if (MF.getFunction()->hasStructRetAttr())
     fail(DL, DAG, "WebAssembly doesn't support struct return yet");
 
-  // FIXME: Implement LowerFormalArguments.
-  for (const ISD::InputArg &In : Ins)
-    InVals.push_back(DAG.getNode(ISD::UNDEF, DL, In.VT));
+  unsigned ArgNo = 0;
+  for (const ISD::InputArg &In : Ins) {
+    if (In.Flags.isZExt())
+      fail(DL, DAG, "WebAssembly hasn't implemented zext arguments");
+    if (In.Flags.isSExt())
+      fail(DL, DAG, "WebAssembly hasn't implemented sext arguments");
+    if (In.Flags.isInReg())
+      fail(DL, DAG, "WebAssembly hasn't implemented inreg arguments");
+    if (In.Flags.isSRet())
+      fail(DL, DAG, "WebAssembly hasn't implemented sret arguments");
+    if (In.Flags.isByVal())
+      fail(DL, DAG, "WebAssembly hasn't implemented byval arguments");
+    if (In.Flags.isInAlloca())
+      fail(DL, DAG, "WebAssembly hasn't implemented inalloca arguments");
+    if (In.Flags.isNest())
+      fail(DL, DAG, "WebAssembly hasn't implemented nest arguments");
+    if (In.Flags.isReturned())
+      fail(DL, DAG, "WebAssembly hasn't implemented returned arguments");
+    if (In.Flags.isInConsecutiveRegs())
+      fail(DL, DAG, "WebAssembly hasn't implemented cons regs arguments");
+    if (In.Flags.isInConsecutiveRegsLast())
+      fail(DL, DAG, "WebAssembly hasn't implemented cons regs last arguments");
+    if (In.Flags.isSplit())
+      fail(DL, DAG, "WebAssembly hasn't implemented split arguments");
+    if (In.VT != MVT::i32)
+      fail(DL, DAG, "WebAssembly hasn't implemented non-i32 arguments");
+    if (!In.Used)
+      fail(DL, DAG, "WebAssembly hasn't implemented unused arguments");
+    // FIXME Do something with In.getOrigAlign()?
+    InVals.push_back(DAG.getNode(WebAssemblyISD::ARGUMENT, DL, In.VT,
+                                 DAG.getTargetConstant(ArgNo++, DL, MVT::i32)));
+  }
 
   return Chain;
 }

lib/Target/WebAssembly/WebAssemblyISelLowering.h

@@ -24,6 +24,8 @@ namespace WebAssemblyISD {
 
 enum {
   FIRST_NUMBER = ISD::BUILTIN_OP_END,
+  RETURN,
+  ARGUMENT,
 
   // add memory opcodes starting at ISD::FIRST_TARGET_MEMORY_OPCODE here...
 };

lib/Target/WebAssembly/WebAssemblyInstrControl.td

@@ -0,0 +1,33 @@
+//===- WebAssemblyInstrControl.td-WebAssembly control-flow ------*- tablegen -*-
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// \brief WebAssembly control-flow code-gen constructs.
+///
+//===----------------------------------------------------------------------===//
+
+/*
+ * TODO(jfb): Add the following.
+ *
+ * block: a fixed-length sequence of statements
+ * if: if statement
+ * do_while: do while statement, basically a loop with a conditional branch
+ * forever: infinite loop statement (like while (1)), basically an unconditional
+ *          branch (back to the top of the loop)
+ * continue: continue to start of nested loop
+ * break: break to end from nested loop or block
+ * switch: switch statement with fallthrough
+ */
+
+let hasSideEffects = 1, isReturn = 1, isTerminator = 1, hasCtrlDep = 1,
+    isBarrier = 1 in {
+//FIXME return more than just int32.
+def RETURN : I<(outs), (ins Int32:$val), [(WebAssemblyreturn Int32:$val)]>;
+} // hasSideEffects = 1, isReturn = 1, isTerminator = 1, hasCtrlDep = 1,
+  // isBarrier = 1

lib/Target/WebAssembly/WebAssemblyInstrInfo.td

@@ -25,10 +25,19 @@ def HasSIMD128 : Predicate<"Subtarget->hasSIMD128()">,
 // WebAssembly-specific DAG Node Types.
 //===----------------------------------------------------------------------===//
 
+def SDT_WebAssemblyArgument : SDTypeProfile<1, 1, [SDTCisVT<1, i32>]>;
+def SDT_WebAssemblyReturn   : SDTypeProfile<0, 1, []>;
+
 //===----------------------------------------------------------------------===//
 // WebAssembly-specific DAG Nodes.
 //===----------------------------------------------------------------------===//
 
+def WebAssemblyargument : SDNode<"WebAssemblyISD::ARGUMENT",
+                                 SDT_WebAssemblyArgument>;
+def WebAssemblyreturn   : SDNode<"WebAssemblyISD::RETURN",
+                                 SDT_WebAssemblyReturn,
+                                 [SDNPHasChain, SDNPSideEffect]>;
+
 //===----------------------------------------------------------------------===//
 // WebAssembly-specific Operands.
 //===----------------------------------------------------------------------===//
@@ -46,12 +55,16 @@ def HasSIMD128 : Predicate<"Subtarget->hasSIMD128()">,
 
 include "WebAssemblyInstrFormats.td"
 
+def ARGUMENT : I<(outs Int32:$res), (ins i32imm:$argno),
+                 [(set Int32:$res, (WebAssemblyargument timm:$argno))]>;
+
 //===----------------------------------------------------------------------===//
 // Additional sets of instructions.
 //===----------------------------------------------------------------------===//
 
 include "WebAssemblyInstrMemory.td"
 include "WebAssemblyInstrCall.td"
+include "WebAssemblyInstrControl.td"
 include "WebAssemblyInstrInteger.td"
 include "WebAssemblyInstrFloat.td"
 include "WebAssemblyInstrConv.td"

lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp

@@ -166,7 +166,15 @@ void WebAssemblyPassConfig::addPreRegAlloc() {}
 
 void WebAssemblyPassConfig::addRegAllocPasses(bool Optimized) {}
 
-void WebAssemblyPassConfig::addPostRegAlloc() {}
+void WebAssemblyPassConfig::addPostRegAlloc() {
+  // FIXME: the following passes dislike virtual registers. Disable them for now
+  //        so that basic tests can pass. Future patches will remedy this.
+  //
+  // Fails with: Regalloc must assign all vregs.
+  disablePass(&PrologEpilogCodeInserterID);
+  // Fails with: should be run after register allocation.
+  disablePass(&MachineCopyPropagationID);
+}
 
 void WebAssemblyPassConfig::addPreSched2() {}