ARM: Fix deoptimizer for two-word call sites.

src/arm/deoptimizer-arm.cc

Index: src/arm/deoptimizer-arm.cc
diff --git a/src/arm/deoptimizer-arm.cc b/src/arm/deoptimizer-arm.cc
index cd70e6de8242f4d6638bdc0c8f645288c50ffcde..80b77732963dcd58fa9bb129f3ce753dd80110e9 100644
--- a/src/arm/deoptimizer-arm.cc
+++ b/src/arm/deoptimizer-arm.cc
@@ -93,6 +93,12 @@ void Deoptimizer::DeoptimizeFunction(JSFunction* function) {
       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();
     }
   }