ARM: Fix deoptimizer for two-word call sites.

src/arm/deoptimizer-arm.cc

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@@ skipping 75 matching lines @@
     }
 #endif
     last_pc_offset = pc_offset;
     if (deoptimization_index != Safepoint::kNoDeoptimizationIndex) {
       last_pc_offset += gap_code_size;
       CodePatcher patcher(code->instruction_start() + last_pc_offset,
                           call_size_in_words);
       Address deoptimization_entry = Deoptimizer::GetDeoptimizationEntry(
           deoptimization_index, Deoptimizer::LAZY);
       patcher.masm()->Call(deoptimization_entry, RelocInfo::NONE);
+#ifdef DEBUG

[Kevin Millikin (Chromium), 2011/08/05 15:10:16]

There must be a better fix than this.  The patcher is designed to treat an
existing code object like a macro assembler buffer, and overwrite exactly N
bytes.

The assert is that we overwrote too few bytes.  This fix just disables the
assert at this site.

Is it possible to change patch_size() to give the correct answer in this case?

[Michael Starzinger, 2011/08/08 09:31:25]

I think making patch_size() giving the correct answer is not possible, because
the size depends on the call target, and that target is not known when the
compiler generates the original (i.e. to-be-patched) code. So it returns the
maximum size (i.e. 3 words) of a call site.

But what we can do, is get the correct size before instantiating a CodePatcher
for each safe-point. See the recent patch set for my proposal.

+      while (patcher.masm()->pc_offset() < patch_size()) {
+        patcher.masm()->bkpt(0);
+      }
+      ASSERT(patcher.masm()->pc_offset() == patch_size());
+#endif
       last_pc_offset += patch_size();
     }
   }
 
 
 #ifdef DEBUG
   // Destroy the code which is not supposed to be run again.
   int instructions =
       (code->safepoint_table_offset() - last_pc_offset) / Assembler::kInstrSize;
   CodePatcher destroyer(code->instruction_start() + last_pc_offset,
@@ skipping 656 matching lines @@
     __ push(ip);
     __ b(&done);
     ASSERT(masm()->pc_offset() - start == table_entry_size_);
   }
   __ bind(&done);
 }
 
 #undef __
 
 } }  // namespace v8::internal