[wasm] Do not unroll unreachable loops

Bug: v8:11298, v8:13292
Change-Id: Ifabcbb64889012778439fb14e22a7cf885965b1e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3905724
Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83363}

src/compiler/pipeline.cc

@@ -19,6 +19,7 @@
 #include "src/codegen/reloc-info.h"
 #include "src/common/high-allocation-throughput-scope.h"
 #include "src/compiler/add-type-assertions-reducer.h"
+#include "src/compiler/all-nodes.h"
 #include "src/compiler/backend/code-generator.h"
 #include "src/compiler/backend/frame-elider.h"
 #include "src/compiler/backend/instruction-selector.h"
@@ -1699,8 +1700,11 @@ struct WasmLoopUnrollingPhase {
 
   void Run(PipelineData* data, Zone* temp_zone,
            std::vector<compiler::WasmLoopInfo>* loop_infos) {
+    if (loop_infos->empty()) return;
+    AllNodes all_nodes(temp_zone, data->graph(), data->graph()->end());
     for (WasmLoopInfo& loop_info : *loop_infos) {
-      if (loop_info.can_be_innermost) {
+      if (!loop_info.can_be_innermost) continue;
+      if (!all_nodes.IsReachable(loop_info.header)) continue;
       ZoneUnorderedSet<Node*>* loop =
           LoopFinder::FindSmallInnermostLoopFromHeader(
               loop_info.header, temp_zone,
@@ -1708,10 +1712,9 @@ struct WasmLoopUnrollingPhase {
               // size for its depth.
               maximum_unrollable_size(loop_info.nesting_depth), true);
       if (loop == nullptr) continue;
-        UnrollLoop(loop_info.header, loop, loop_info.nesting_depth,
-                   data->graph(), data->common(), temp_zone,
-                   data->source_positions(), data->node_origins());
-      }
+      UnrollLoop(loop_info.header, loop, loop_info.nesting_depth, data->graph(),
+                 data->common(), temp_zone, data->source_positions(),
+                 data->node_origins());
     }
 
     EliminateLoopExits(loop_infos);