[wasm] Rename LookupBlockType to Validate

For consistency with the existing Validate/Complete methodology.

Drive-by: Use it in {PrintRawWasmCode}.

R=titzer@chromium.org

Bug: v8:7754
Change-Id: I6f08ad7456ded2bdb9b06bb9f288e2609d4010e7
Reviewed-on: https://chromium-review.googlesource.com/1109793Reviewed-by: Ben Titzer <titzer@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53922}

src/wasm/function-body-decoder-impl.h

@@ -940,8 +940,9 @@ class WasmDecoder : public Decoder {
   inline bool Validate(const byte* pc,
                        Simd8x16ShuffleImmediate<validate>& imm) {
     uint8_t max_lane = 0;
-    for (uint32_t i = 0; i < kSimd128Size; ++i)
+    for (uint32_t i = 0; i < kSimd128Size; ++i) {
       max_lane = std::max(max_lane, imm.shuffle[i]);
+    }
     // Shuffle indices must be in [0..31] for a 16 lane shuffle.
     if (!VALIDATE(max_lane <= 2 * kSimd128Size)) {
       error(pc_ + 2, "invalid shuffle mask");
@@ -950,6 +951,24 @@ class WasmDecoder : public Decoder {
     return true;
   }
 
+  inline bool Complete(BlockTypeImmediate<validate>& imm) {
+    if (imm.type != kWasmVar) return true;
+    if (!VALIDATE((module_ && imm.sig_index < module_->signatures.size()))) {
+      return false;
+    }
+    imm.sig = module_->signatures[imm.sig_index];
+    return true;
+  }
+
+  inline bool Validate(BlockTypeImmediate<validate>& imm) {
+    if (!Complete(imm)) {
+      errorf(pc_, "block type index %u out of bounds (%zu signatures)",
+             imm.sig_index, module_ ? module_->signatures.size() : 0);
+      return false;
+    }
+    return true;
+  }
+
   static unsigned OpcodeLength(Decoder* decoder, const byte* pc) {
     WasmOpcode opcode = static_cast<WasmOpcode>(*pc);
     switch (opcode) {
@@ -1410,7 +1429,7 @@ class WasmFullDecoder : public WasmDecoder<validate> {
             break;
           case kExprBlock: {
             BlockTypeImmediate<validate> imm(this, this->pc_);
-            if (!LookupBlockType(&imm)) break;
+            if (!this->Validate(imm)) break;
             PopArgs(imm.sig);
             auto* block = PushBlock();
             SetBlockType(block, imm);
@@ -1439,7 +1458,7 @@ class WasmFullDecoder : public WasmDecoder<validate> {
           case kExprTry: {
             CHECK_PROTOTYPE_OPCODE(eh);
             BlockTypeImmediate<validate> imm(this, this->pc_);
-            if (!LookupBlockType(&imm)) break;
+            if (!this->Validate(imm)) break;
             PopArgs(imm.sig);
             auto* try_block = PushTry();
             SetBlockType(try_block, imm);
@@ -1492,7 +1511,7 @@ class WasmFullDecoder : public WasmDecoder<validate> {
           }
           case kExprLoop: {
             BlockTypeImmediate<validate> imm(this, this->pc_);
-            if (!LookupBlockType(&imm)) break;
+            if (!this->Validate(imm)) break;
             PopArgs(imm.sig);
             auto* block = PushLoop();
             SetBlockType(&control_.back(), imm);
@@ -1503,7 +1522,7 @@ class WasmFullDecoder : public WasmDecoder<validate> {
           }
           case kExprIf: {
             BlockTypeImmediate<validate> imm(this, this->pc_);
-            if (!LookupBlockType(&imm)) break;
+            if (!this->Validate(imm)) break;
             auto cond = Pop(0, kWasmI32);
             PopArgs(imm.sig);
             if (!VALIDATE(this->ok())) break;
@@ -2006,22 +2025,6 @@ class WasmFullDecoder : public WasmDecoder<validate> {
     current->reachability = kUnreachable;
   }
 
-  bool LookupBlockType(BlockTypeImmediate<validate>* imm) {
-    if (imm->type == kWasmVar) {
-      if (!VALIDATE(this->module_ &&
-                    imm->sig_index < this->module_->signatures.size())) {
-        this->errorf(
-            this->pc_, "block type index %u out of bounds (%d signatures)",
-            imm->sig_index,
-            static_cast<int>(this->module_ ? this->module_->signatures.size()
-                                           : 0));
-        return false;
-      }
-      imm->sig = this->module_->signatures[imm->sig_index];
-    }
-    return true;
-  }
-
   template<typename func>
   void InitMerge(Merge<Value>* merge, uint32_t arity, func get_val) {
     merge->arity = arity;

src/wasm/function-body-decoder.cc

@@ -1017,8 +1017,10 @@ bool PrintRawWasmCode(AccountingAllocator* allocator, const FunctionBody& body,
       case kExprTry: {
         BlockTypeImmediate<Decoder::kNoValidate> imm(&i, i.pc());
         os << "   // @" << i.pc_offset();
-        for (unsigned i = 0; i < imm.out_arity(); i++) {
-          os << " " << ValueTypes::TypeName(imm.out_type(i));
+        if (decoder.Complete(imm)) {
+          for (unsigned i = 0; i < imm.out_arity(); i++) {
+            os << " " << ValueTypes::TypeName(imm.out_type(i));
+          }
         }
         control_depth++;
         break;