[WebAssembly] 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
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: 252858

1 files changed, 21 insertions, 8 deletions

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyMCInstLower.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyMCInstLower.cpp
index 59acbdb..4226a53 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyMCInstLower.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyMCInstLower.cpp
@@ -14,11 +14,13 @@
 //===----------------------------------------------------------------------===//
 
 #include "WebAssemblyMCInstLower.h"
+#include "WebAssemblyMachineFunctionInfo.h"
 #include "llvm/ADT/SmallString.h"
-#include "llvm/IR/Constants.h"
 #include "llvm/CodeGen/AsmPrinter.h"
 #include "llvm/CodeGen/MachineBasicBlock.h"
+#include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/IR/Constants.h"
 #include "llvm/MC/MCAsmInfo.h"
 #include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCExpr.h"
@@ -55,25 +57,36 @@ void WebAssemblyMCInstLower::Lower(const MachineInstr *MI,
     default:
       MI->dump();
       llvm_unreachable("unknown operand type");
-    case MachineOperand::MO_Register:
+    case MachineOperand::MO_Register: {
       // Ignore all implicit register operands.
       if (MO.isImplicit())
         continue;
-      MCOp = MCOperand::createReg(MO.getReg());
+      // TODO: Handle physical registers.
+      const WebAssemblyFunctionInfo &MFI =
+          *MI->getParent()->getParent()->getInfo<WebAssemblyFunctionInfo>();
+      unsigned WAReg = MFI.getWAReg(MO.getReg());
+      MCOp = MCOperand::createReg(WAReg);
       break;
+    }
     case MachineOperand::MO_Immediate:
       MCOp = MCOperand::createImm(MO.getImm());
       break;
-    case MachineOperand::MO_FPImmediate:
-      MCOp = MCOperand::createFPImm(
-          MO.getFPImm()->getValueAPF().convertToDouble());
+    case MachineOperand::MO_FPImmediate: {
+      // TODO: MC converts all floating point immediate operands to double.
+      // This is fine for numeric values, but may cause NaNs to change bits.
+      const ConstantFP *Imm = MO.getFPImm();
+      if (Imm->getType()->isFloatTy())
+        MCOp = MCOperand::createFPImm(Imm->getValueAPF().convertToFloat());
+      else if (Imm->getType()->isDoubleTy())
+        MCOp = MCOperand::createFPImm(Imm->getValueAPF().convertToDouble());
+      else
+        llvm_unreachable("unknown floating point immediate type");
       break;
+    }
     case MachineOperand::MO_MachineBasicBlock:
       MCOp = MCOperand::createExpr(
           MCSymbolRefExpr::create(MO.getMBB()->getSymbol(), Ctx));
       break;
-    case MachineOperand::MO_RegisterMask:
-      continue;
     case MachineOperand::MO_GlobalAddress:
       MCOp = LowerSymbolOperand(MO, GetGlobalAddressSymbol(MO));
       break;