[llvm] r346465 - [WebAssembly] Read prefixed opcodes as ULEB128s

[Thomas Lively via llvm-commits]

Author: tlively
Date: Thu Nov  8 17:57:00 2018
New Revision: 346465

URL: http://llvm.org/viewvc/llvm-project?rev=346465&view=rev
Log:
[WebAssembly] Read prefixed opcodes as ULEB128s

Summary: Depends on D54126.

Reviewers: aheejin, dschuff, aardappel

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

Differential Revision: https://reviews.llvm.org/D54138

Modified:
    llvm/trunk/lib/Target/WebAssembly/Disassembler/WebAssemblyDisassembler.cpp
    llvm/trunk/test/MC/Disassembler/WebAssembly/wasm.txt
    llvm/trunk/utils/TableGen/WebAssemblyDisassemblerEmitter.cpp

Modified: llvm/trunk/lib/Target/WebAssembly/Disassembler/WebAssemblyDisassembler.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/Disassembler/WebAssemblyDisassembler.cpp?rev=346465&r1=346464&r2=346465&view=diff
==============================================================================
--- llvm/trunk/lib/Target/WebAssembly/Disassembler/WebAssemblyDisassembler.cpp (original)
+++ llvm/trunk/lib/Target/WebAssembly/Disassembler/WebAssemblyDisassembler.cpp Thu Nov  8 17:57:00 2018
@@ -66,7 +66,7 @@ extern "C" void LLVMInitializeWebAssembl
                                          createWebAssemblyDisassembler);
 }
 
-static int nextByte(ArrayRef<uint8_t> Bytes, uint64_t &Size) {
+static uint8_t nextByte(ArrayRef<uint8_t> Bytes, uint64_t &Size) {
   if (Size >= Bytes.size())
     return -1;
   auto V = Bytes[Size];
@@ -74,18 +74,26 @@ static int nextByte(ArrayRef<uint8_t> By
   return V;
 }
 
-static bool parseLEBImmediate(MCInst &MI, uint64_t &Size,
-                              ArrayRef<uint8_t> Bytes, bool Signed) {
+static bool nextLEB(int64_t &Val, ArrayRef<uint8_t> Bytes, uint64_t &Size,
+                    bool Signed = false) {
   unsigned N = 0;
   const char *Error = nullptr;
-  auto Val = Signed ? decodeSLEB128(Bytes.data() + Size, &N,
-                                    Bytes.data() + Bytes.size(), &Error)
-                    : static_cast<int64_t>(
-                          decodeULEB128(Bytes.data() + Size, &N,
-                                        Bytes.data() + Bytes.size(), &Error));
+  Val = Signed ? decodeSLEB128(Bytes.data() + Size, &N,
+                               Bytes.data() + Bytes.size(), &Error)
+               : static_cast<int64_t>(decodeULEB128(Bytes.data() + Size, &N,
+                                                    Bytes.data() + Bytes.size(),
+                                                    &Error));
   if (Error)
     return false;
   Size += N;
+  return true;
+}
+
+static bool parseLEBImmediate(MCInst &MI, uint64_t &Size,
+                              ArrayRef<uint8_t> Bytes, bool Signed) {
+  int64_t Val;
+  if (!nextLEB(Val, Bytes, Size, Signed))
+    return false;
   MI.addOperand(MCOperand::createImm(Val));
   return true;
 }
@@ -127,10 +135,12 @@ MCDisassembler::DecodeStatus WebAssembly
     }
     if (!WasmInst)
       return MCDisassembler::Fail;
-    Opc = nextByte(Bytes, Size);
-    if (Opc < 0)
+    int64_t PrefixedOpc;
+    if (!nextLEB(PrefixedOpc, Bytes, Size))
+      return MCDisassembler::Fail;
+    if (PrefixedOpc < 0 || PrefixedOpc >= WebAssemblyInstructionTableSize)
       return MCDisassembler::Fail;
-    WasmInst += Opc;
+    WasmInst += PrefixedOpc;
   }
   if (WasmInst->ET == ET_Unused)
     return MCDisassembler::Fail;

Modified: llvm/trunk/test/MC/Disassembler/WebAssembly/wasm.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/Disassembler/WebAssembly/wasm.txt?rev=346465&r1=346464&r2=346465&view=diff
==============================================================================
--- llvm/trunk/test/MC/Disassembler/WebAssembly/wasm.txt (original)
+++ llvm/trunk/test/MC/Disassembler/WebAssembly/wasm.txt Thu Nov  8 17:57:00 2018
@@ -37,3 +37,12 @@
 
 # CHECK: v8x16.shuffle 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
 0xFD 0x03 0x00 0x01 0x02 0x03 0x04 0x05 0x06 0x07 0x08 0x09 0x0A 0x0B 0x0C 0x0D 0x0E 0x0F
+
+# Check LEB128 encoding of SIMD instructions
+# CHECK: i64x2.all_true
+0xFD 0x86 0x01
+
+# Including non-canonical LEB128 encodings
+# CHECK: i64x2.any_true
+# CHECK-NOT: i64.div_u
+0xFD 0x85 0x81 0x80 0x80 0x80 0x80 0x00

Modified: llvm/trunk/utils/TableGen/WebAssemblyDisassemblerEmitter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/utils/TableGen/WebAssemblyDisassemblerEmitter.cpp?rev=346465&r1=346464&r2=346465&view=diff
==============================================================================
--- llvm/trunk/utils/TableGen/WebAssemblyDisassemblerEmitter.cpp (original)
+++ llvm/trunk/utils/TableGen/WebAssemblyDisassemblerEmitter.cpp Thu Nov  8 17:57:00 2018
@@ -19,6 +19,8 @@
 
 namespace llvm {
 
+static constexpr int WebAssemblyInstructionTableSize = 256;
+
 void emitWebAssemblyDisassemblerTables(
     raw_ostream &OS,
     const ArrayRef<const CodeGenInstruction *> &NumberedInstructions) {
@@ -59,6 +61,8 @@ void emitWebAssemblyDisassemblerTables(
   OS << "#include \"MCTargetDesc/WebAssemblyMCTargetDesc.h\"\n";
   OS << "\n";
   OS << "namespace llvm {\n\n";
+  OS << "static constexpr int WebAssemblyInstructionTableSize = ";
+  OS << WebAssemblyInstructionTableSize << ";\n\n";
   OS << "enum EntryType : uint8_t { ";
   OS << "ET_Unused, ET_Prefix, ET_Instruction };\n\n";
   OS << "struct WebAssemblyInstruction {\n";
@@ -74,7 +78,7 @@ void emitWebAssemblyDisassemblerTables(
       continue;
     OS << "WebAssemblyInstruction InstructionTable" << PrefixPair.first;
     OS << "[] = {\n";
-    for (unsigned I = 0; I <= 0xFF; I++) {
+    for (unsigned I = 0; I < WebAssemblyInstructionTableSize; I++) {
       auto InstIt = PrefixPair.second.find(I);
       if (InstIt != PrefixPair.second.end()) {
         // Regular instruction.