commit 510c605443e8b0f28ba7c434142b9f1498664606
author buzbee <buzbee@google.com> Thu Oct 27 10:47:20 2011 -0700
committer buzbee <buzbee@google.com> Thu Oct 27 11:02:31 2011 -0700
tree 8d39d304cfa299c351995bce6e78b2ed75b610a6
parent 9fdfc1808f2a3845ee7e890a4e5d22a10f2ee93d

Workaround for cfg building failure

Currently the compiler expects well-formed control flow graphs -
no dead code (though infinate loops are allowed).  This is the
case for all dx output (but might not be for custom tools).
However, when the verifier replaces an instruction with
OP_THROW_VERIFICATION_ERROR, it can create dead code from a
previously well-formed graph.  This CL works around that
problem by not treating OP_THROW_VERIFICATION_ERROR as a
direct branch.

A future CL will alter the CFG builder to be resiliant in the face
of dead code.

Also, removes a spurious DCHECK, and adds a few where they are
needed.

Change-Id: I68554a2a8b88e857faeff3300f2ebbf2d0323693

src/compiler/Frontend.cc

diff --git a/src/compiler/Frontend.cc b/src/compiler/Frontend.cc
index a0e7713..f8f985d 100644
--- a/src/compiler/Frontend.cc
+++ b/src/compiler/Frontend.cc
@@ -675,11 +675,13 @@
                                                      /* create */
                                                      true);
             /*
-             * OP_THROW and OP_THROW_VERIFICATION_ERROR are unconditional
-             * branches.
+             * OP_THROW is an unconditional branch.  NOTE:
+             * OP_THROW_VERIFICATION_ERROR is also an unconditional
+             * branch, but we shouldn't treat it as such until we have
+             * a dead code elimination pass (which won't be important
+             * until inlining w/ constant propogation is implemented.
              */
-            if (insn->dalvikInsn.opcode != OP_THROW_VERIFICATION_ERROR &&
-                insn->dalvikInsn.opcode != OP_THROW) {
+            if (insn->dalvikInsn.opcode != OP_THROW) {
                 curBlock->fallThrough = fallthroughBlock;
                 oatSetBit(fallthroughBlock->predecessors, curBlock->id);
             }

src/compiler/codegen/arm/MethodCodegenDriver.cc

diff --git a/src/compiler/codegen/arm/MethodCodegenDriver.cc b/src/compiler/codegen/arm/MethodCodegenDriver.cc
index 366a6d3..7ea7d69 100644
--- a/src/compiler/codegen/arm/MethodCodegenDriver.cc
+++ b/src/compiler/codegen/arm/MethodCodegenDriver.cc
@@ -483,7 +483,6 @@
                            DecodedInstruction* dInsn, int state,
                            ArmLIR* rollback)
 {
-    DCHECK(rollback == NULL);
     RegLocation rlArg;
     ArmLIR* skipBranch;
     ArmLIR* skipTarget;
@@ -583,6 +582,7 @@
                                  DecodedInstruction* dInsn, int state,
                                  ArmLIR* rollback)
 {
+    DCHECK(rollback == NULL);
     switch(state) {
         case 0: // Load trampoline target
             loadWordDisp(cUnit, rSELF,
@@ -659,7 +659,6 @@
                                DecodedInstruction* dInsn, int state,
                                ArmLIR* rollback)
 {
-    DCHECK(rollback == NULL);
     RegLocation rlArg;
     ArmLIR* skipBranch;
     ArmLIR* skipTarget;