commit bb245d199a5240b4c520263fd2c8c10dba79eadc
author Aart Bik <ajcbik@google.com> Mon Oct 19 11:05:03 2015 -0700
committer Aart Bik <ajcbik@google.com> Mon Oct 19 11:12:11 2015 -0700
tree e16b37485e3e0e34c24e35a71cc8e6986d1e2e70
parent d5a69fc429f57bf528aa061618d3ae94ee8deb24

Generalize codegen and simplification of deopt.

Rationale: the de-opt instruction is very similar to an if,
           so the existing assumption that it always has a
           conditional "under the hood" is very unsafe, since
           optimizations may have replaced conditionals with
           actual values; this CL generalizes handling of deopt.

Change-Id: I1c6cb71fdad2af869fa4714b38417dceed676459

compiler/optimizing/instruction_simplifier.cc

diff --git a/compiler/optimizing/instruction_simplifier.cc b/compiler/optimizing/instruction_simplifier.cc
index d468540..7814eb9 100644
--- a/compiler/optimizing/instruction_simplifier.cc
+++ b/compiler/optimizing/instruction_simplifier.cc
@@ -73,6 +73,7 @@
   void VisitInstanceOf(HInstanceOf* instruction) OVERRIDE;
   void VisitFakeString(HFakeString* fake_string) OVERRIDE;
   void VisitInvoke(HInvoke* invoke) OVERRIDE;
+  void VisitDeoptimize(HDeoptimize* deoptimize) OVERRIDE;
 
   bool CanEnsureNotNullAt(HInstruction* instr, HInstruction* at) const;
 
@@ -1151,4 +1152,16 @@
   }
 }
 
+void InstructionSimplifierVisitor::VisitDeoptimize(HDeoptimize* deoptimize) {
+  HInstruction* cond = deoptimize->InputAt(0);
+  if (cond->IsConstant()) {
+    if (cond->AsIntConstant()->IsZero()) {
+      // Never deopt: instruction can be removed.
+      deoptimize->GetBlock()->RemoveInstruction(deoptimize);
+    } else {
+      // Always deopt.
+    }
+  }
+}
+
 }  // namespace art