[WebAssembly] Fixed disassembler not knowing about new brlist operand

Summary:
The previously introduced new operand type for br_table didn't have
a disassembler implementation, causing an assert.

Reviewers: dschuff, aheejin

Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D56227

llvm-svn: 350366

llvm/lib/Target/WebAssembly/Disassembler/WebAssemblyDisassembler.cpp

@@ -151,7 +151,8 @@ MCDisassembler::DecodeStatus WebAssemblyDisassembler::getInstruction(
   MI.setOpcode(WasmInst->Opcode);
   // Parse any operands.
   for (uint8_t OPI = 0; OPI < WasmInst->NumOperands; OPI++) {
-    switch (OperandTable[WasmInst->OperandStart + OPI]) {
+    auto OT = OperandTable[WasmInst->OperandStart + OPI];
+    switch (OT) {
     // ULEB operands:
     case WebAssembly::OPERAND_BASIC_BLOCK:
     case WebAssembly::OPERAND_LOCAL:
@@ -210,6 +211,19 @@ MCDisassembler::DecodeStatus WebAssemblyDisassembler::getInstruction(
         return MCDisassembler::Fail;
       break;
     }
+    case WebAssembly::OPERAND_BRLIST: {
+      int64_t TargetTableLen;
+      if (!nextLEB(TargetTableLen, Bytes, Size, false))
+        return MCDisassembler::Fail;
+      for (int64_t I = 0; I < TargetTableLen; I++) {
+        if (!parseLEBImmediate(MI, Size, Bytes, false))
+          return MCDisassembler::Fail;
+      }
+      // Default case.
+      if (!parseLEBImmediate(MI, Size, Bytes, false))
+        return MCDisassembler::Fail;
+      break;
+    }
     case MCOI::OPERAND_REGISTER:
       // The tablegen header currently does not have any register operands since
       // we use only the stack (_S) instructions.

llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.h

@@ -79,6 +79,8 @@ enum OperandType {
   OPERAND_TYPEINDEX,
   /// Event index.
   OPERAND_EVENT,
+  /// A list of branch targets for br_list.
+  OPERAND_BRLIST,
 };
 } // end namespace WebAssembly
 

llvm/lib/Target/WebAssembly/WebAssemblyInstrControl.td

@@ -36,10 +36,14 @@ def : Pat<(brcond (i32 (seteq I32:$cond, 0)), bb:$dst),
 // A list of branch targets enclosed in {} and separated by comma.
 // Used by br_table only.
 def BrListAsmOperand : AsmOperandClass { let Name = "BrList"; }
+let OperandNamespace = "WebAssembly" in {
+let OperandType = "OPERAND_BRLIST" in {
 def brlist : Operand<i32> {
   let ParserMatchClass = BrListAsmOperand;
   let PrintMethod = "printBrList";
 }
+}  // OPERAND_BRLIST
+}  // OperandNamespace = "WebAssembly"
 
 // TODO: SelectionDAG's lowering insists on using a pointer as the index for
 // jump tables, so in practice we don't ever use BR_TABLE_I64 in wasm32 mode

llvm/test/MC/Disassembler/WebAssembly/wasm.txt

@@ -44,3 +44,7 @@
 # CHECK: i64x2.any_true
 # CHECK-NOT: i64.div_u
 0xFD 0x85 0x81 0x80 0x80 0x80 0x80 0x00
+
+# Check br_table, which has its own operand type.
+# CHECK: br_table {0, 1, 2}
+0x0E 0x02 0x00 0x01 0x02

llvm/utils/TableGen/WebAssemblyDisassemblerEmitter.cpp

@@ -92,6 +92,7 @@ void emitWebAssemblyDisassemblerTables(
         // Collect operand types for storage in a shared list.
         CurOperandList.clear();
         for (auto &Op : CGI.Operands.OperandList) {
+          assert(Op.OperandType != "MCOI::OPERAND_UNKNOWN");
           CurOperandList.push_back(Op.OperandType);
         }
         // See if we already have stored this sequence before. This is not