From cf4748f18000ac24fb9d07d493be59cf035c8d68 Mon Sep 17 00:00:00 2001
From: Dan Gohman <dan433584@gmail.com>
Date: Thu, 12 Nov 2015 17:04:33 +0000
Subject: [WebAssembly] Reapply r252858, with svn add for the new file.

Switch to MC for instruction printing.

This encompasses several changes which are all interconnected:
 - Use the MC framework for printing almost all instructions.
 - AsmStrings are now live.
 - This introduces an indirection between LLVM vregs and WebAssembly registers,
   and a new pass, WebAssemblyRegNumbering, for computing a basic the mapping.
   This addresses some basic issues with argument registers and unused registers.
 - The way ARGUMENT instructions are handled no longer generates redundant
   get_local+set_local for every argument.

This also changes the assembly syntax somewhat; most notably, MC's printing
does not use sigils on label names, so those are no longer present, and
push/pop now have a sigil to keep them unambiguous.

The usage of set_local/get_local/$push/$pop will continue to evolve
significantly. This patch is just one step of a larger change.

llvm-svn: 252910
---
 .../InstPrinter/WebAssemblyInstPrinter.cpp         | 46 ++++++++++++++++------
 1 file changed, 34 insertions(+), 12 deletions(-)

(limited to 'llvm/lib/Target/WebAssembly/InstPrinter/WebAssemblyInstPrinter.cpp')

diff --git a/llvm/lib/Target/WebAssembly/InstPrinter/WebAssemblyInstPrinter.cpp b/llvm/lib/Target/WebAssembly/InstPrinter/WebAssemblyInstPrinter.cpp
index bb10f20fd6d..cc77f56dce3 100644
--- a/llvm/lib/Target/WebAssembly/InstPrinter/WebAssemblyInstPrinter.cpp
+++ b/llvm/lib/Target/WebAssembly/InstPrinter/WebAssemblyInstPrinter.cpp
@@ -36,28 +36,50 @@ WebAssemblyInstPrinter::WebAssemblyInstPrinter(const MCAsmInfo &MAI,
 
 void WebAssemblyInstPrinter::printRegName(raw_ostream &OS,
                                           unsigned RegNo) const {
-  if (TargetRegisterInfo::isPhysicalRegister(RegNo))
-    OS << getRegisterName(RegNo);
-  else
-    OS << TargetRegisterInfo::virtReg2Index(RegNo);
+  // FIXME: Revisit whether we actually print the get_local explicitly.
+  OS << "(get_local " << RegNo << ")";
 }
 
 void WebAssemblyInstPrinter::printInst(const MCInst *MI, raw_ostream &OS,
                                        StringRef Annot,
                                        const MCSubtargetInfo &STI) {
   printInstruction(MI, OS);
+
+  const MCInstrDesc &Desc = MII.get(MI->getOpcode());
+  if (Desc.isVariadic())
+    for (unsigned i = Desc.getNumOperands(), e = MI->getNumOperands(); i < e;
+         ++i) {
+      OS << ", ";
+      printOperand(MI, i, OS);
+    }
+
   printAnnotation(OS, Annot);
 
   unsigned NumDefs = MII.get(MI->getOpcode()).getNumDefs();
   assert(NumDefs <= 1 &&
          "Instructions with multiple result values not implemented");
 
-  if (NumDefs != 0) {
+  // FIXME: Revisit whether we actually print the set_local explicitly.
+  if (NumDefs != 0)
     OS << "\n"
-          "\t" "set_local ";
-    printRegName(OS, MI->getOperand(0).getReg());
-    OS << ", pop";
-  }
+          "\t" "set_local " << MI->getOperand(0).getReg() << ", $pop";
+}
+
+static std::string toString(const APFloat &FP) {
+  static const size_t BufBytes = 128;
+  char buf[BufBytes];
+  if (FP.isNaN())
+    assert((FP.bitwiseIsEqual(APFloat::getQNaN(FP.getSemantics())) ||
+            FP.bitwiseIsEqual(
+                APFloat::getQNaN(FP.getSemantics(), /*Negative=*/true))) &&
+           "convertToHexString handles neither SNaN nor NaN payloads");
+  // Use C99's hexadecimal floating-point representation.
+  auto Written = FP.convertToHexString(
+      buf, /*hexDigits=*/0, /*upperCase=*/false, APFloat::rmNearestTiesToEven);
+  (void)Written;
+  assert(Written != 0);
+  assert(Written < BufBytes);
+  return buf;
 }
 
 void WebAssemblyInstPrinter::printOperand(const MCInst *MI, unsigned OpNo,
@@ -65,13 +87,13 @@ void WebAssemblyInstPrinter::printOperand(const MCInst *MI, unsigned OpNo,
   const MCOperand &Op = MI->getOperand(OpNo);
   if (Op.isReg()) {
     if (OpNo < MII.get(MI->getOpcode()).getNumDefs())
-      O << "push";
+      O << "$push";
     else
       printRegName(O, Op.getReg());
   } else if (Op.isImm())
-    O << '#' << Op.getImm();
+    O << Op.getImm();
   else if (Op.isFPImm())
-    O << '#' << Op.getFPImm();
+    O << toString(APFloat(Op.getFPImm()));
   else {
     assert(Op.isExpr() && "unknown operand kind in printOperand");
     Op.getExpr()->print(O, &MAI);
-- 
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