[cleanup] Add named constant SafepointEntry::kNoTrampolinePC

.. instead of implicitly using -1 as a marker in a few spots.

Bug: chromium:1161357
Change-Id: Icfb9a2b81dbda844c8405c57454d63ae89dfe4f9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2606336
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Auto-Submit: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72037}

src/codegen/safepoint-table.h

@@ -21,7 +21,8 @@ class WasmCode;
 
 class SafepointEntry {
  public:
-  SafepointEntry() : deopt_index_(0), bits_(nullptr), trampoline_pc_(-1) {}
+  SafepointEntry()
+      : deopt_index_(0), bits_(nullptr), trampoline_pc_(kNoTrampolinePC) {}
 
   SafepointEntry(unsigned deopt_index, uint8_t* bits, int trampoline_pc)
       : deopt_index_(deopt_index), bits_(bits), trampoline_pc_(trampoline_pc) {
@@ -42,6 +43,7 @@ class SafepointEntry {
   int trampoline_pc() { return trampoline_pc_; }
 
   static const unsigned kNoDeoptIndex = kMaxUInt32;
+  static constexpr int kNoTrampolinePC = -1;
 
   int deoptimization_index() const {
     DCHECK(is_valid() && has_deoptimization_index());
@@ -96,8 +98,9 @@ class SafepointTable {
     unsigned deopt_index =
         base::Memory<uint32_t>(GetEncodedInfoLocation(index));
     uint8_t* bits = &base::Memory<uint8_t>(entries() + (index * entry_size_));
-    int trampoline_pc =
-        has_deopt_ ? base::Memory<int>(GetTrampolineLocation(index)) : -1;
+    int trampoline_pc = has_deopt_
+                            ? base::Memory<int>(GetTrampolineLocation(index))
+                            : SafepointEntry::kNoTrampolinePC;
     return SafepointEntry(deopt_index, bits, trampoline_pc);
   }
 

src/deoptimizer/deoptimizer.cc

@@ -267,6 +267,7 @@ class ActivationsFinder : public ThreadVisitor {
           SafepointEntry safepoint = code.GetSafepointEntry(it.frame()->pc());
           int trampoline_pc = safepoint.trampoline_pc();
           DCHECK_IMPLIES(code == topmost_, safe_to_deopt_);
+          STATIC_ASSERT(SafepointEntry::kNoTrampolinePC == -1);
           CHECK_GE(trampoline_pc, 0);
           // Replace the current pc on the stack with the trampoline.
           // TODO(v8:10026): avoid replacing a signed pointer.

src/wasm/wasm-code-manager.cc

@@ -413,7 +413,7 @@ void WasmCode::Disassemble(const char* name, std::ostream& os,
       table.PrintEntry(i, os);
       os << " (sp -> fp)";
       SafepointEntry entry = table.GetEntry(i);
-      if (entry.trampoline_pc() != -1) {
+      if (entry.trampoline_pc() != SafepointEntry::kNoTrampolinePC) {
         os << " trampoline: " << std::hex << entry.trampoline_pc() << std::dec;
       }
       if (entry.has_deoptimization_index()) {