Fix null check elimination

The existing null check elimination mechanism suffered from the same
limitation as the SSA renaming: it took shortcuts that were valid in
a trace compilation world, but not in a method compilation world.

This CL replaces the old mechanism, and additionally takes advantage
of some the fact that "this" is always non-null, as are objects returned
from OP_NEW_* (thanks Ian!).

Two test cases added.  The one for ensuring that unnecessary null checks
are elminated requires manual inspection.  The other - that we don't
eliminate a necessary null check - is disabled until exceptions are working.

Change-Id: I2a9b72741f56617bf609e4d7c20244796c988f28

1 files changed, 0 insertions, 2 deletions

diff --git a/src/compiler/codegen/CodegenFactory.cc b/src/compiler/codegen/CodegenFactory.cc
index 5a75cee80b..14c7e5722f 100644
--- a/src/compiler/codegen/CodegenFactory.cc
+++ b/src/compiler/codegen/CodegenFactory.cc
@@ -127,7 +127,6 @@ static void storeValue(CompilationUnit* cUnit, RegLocation rlDest,
     LIR* defEnd;
     assert(!rlDest.wide);
     assert(!rlSrc.wide);
-    oatKillNullCheckedLoc(cUnit, rlDest);
     rlSrc = oatUpdateLoc(cUnit, rlSrc);
     rlDest = oatUpdateLoc(cUnit, rlDest);
     if (rlSrc.location == kLocPhysReg) {
@@ -190,7 +189,6 @@ static void storeValueWide(CompilationUnit* cUnit, RegLocation rlDest,
     assert(FPREG(rlSrc.lowReg)==FPREG(rlSrc.highReg));
     assert(rlDest.wide);
     assert(rlSrc.wide);
-    oatKillNullCheckedLoc(cUnit, rlDest);
     if (rlSrc.location == kLocPhysReg) {
         if (oatIsLive(cUnit, rlSrc.lowReg) ||
             oatIsLive(cUnit, rlSrc.highReg) ||