[wasm] Put the condition last in kExprBrIf.

src/wasm/ast-decoder.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/base/platform/elapsed-timer.h"
 #include "src/signature.h"
 
 #include "src/bit-vector.h"
 #include "src/flags.h"
 #include "src/handles.h"
@@ skipping 980 matching lines @@
         }
         break;
       }
       case kExprBr: {
         BreakDepthOperand operand(this, p->pc());
         CHECK(Validate(p->pc(), operand, blocks_));
         ReduceBreakToExprBlock(p, operand.target);
         break;
       }
       case kExprBrIf: {
-        if (p->index == 1) {
+        if (p->done()) {
           TypeCheckLast(p, kAstI32);
-        } else if (p->done()) {
           BreakDepthOperand operand(this, p->pc());
           CHECK(Validate(p->pc(), operand, blocks_));
           SsaEnv* fenv = ssa_env_;
           SsaEnv* tenv = Split(fenv);
-          BUILD(Branch, p->tree->children[0]->node, &tenv->control,
+          BUILD(Branch, p->tree->children[1]->node, &tenv->control,
                 &fenv->control);
           ssa_env_ = tenv;
-          ReduceBreakToExprBlock(p, operand.target);
+          ReduceBreakToExprBlock(p, operand.target, p->tree->children[0]);
           ssa_env_ = fenv;
         }
         break;
       }
       case kExprTableSwitch: {
         if (p->index == 1) {
           // Switch key finished.
           TypeCheckLast(p, kAstI32);
           if (failed()) break;
 
@@ skipping 190 matching lines @@
           p->tree->node = builder_->CallIndirect(operand.index, buffer);
         }
         break;
       }
       default:
         break;
     }
   }
 
   void ReduceBreakToExprBlock(Production* p, Block* block) {
+    ReduceBreakToExprBlock(p, block, p->tree->count > 0 ? p->last() : nullptr);
+  }
+
+  void ReduceBreakToExprBlock(Production* p, Block* block, Tree* val) {
     if (block->stack_depth < 0) {
       // This is the inner loop block, which does not have a value.
       Goto(ssa_env_, block->ssa_env);
     } else {
       // Merge the value into the production for the block.
       Production* bp = &stack_[block->stack_depth];
-      MergeIntoProduction(bp, block->ssa_env, p->last());
+      MergeIntoProduction(bp, block->ssa_env, val);
     }
   }
 
   void MergeIntoProduction(Production* p, SsaEnv* target, Tree* expr) {
     if (!ssa_env_->go()) return;
 
     bool first = target->state == SsaEnv::kUnreachable;
     Goto(ssa_env_, target);
-    if (expr->type == kAstEnd) return;
+    if (expr == nullptr || expr->type == kAstEnd) return;
 
     if (first) {
       // first merge to this environment; set the type and the node.
       p->tree->type = expr->type;
       p->tree->node = expr->node;
     } else {
       // merge with the existing value for this block.
       LocalType type = p->tree->type;
       if (expr->type != type) {
         type = kAstStmt;
@@ skipping 406 matching lines @@
 
 BitVector* AnalyzeLoopAssignmentForTesting(Zone* zone, FunctionEnv* env,
                                            const byte* start, const byte* end) {
   LoopAssignmentAnalyzer analyzer(zone, env);
   return analyzer.Analyze(start, end);
 }
 
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8