From cbd6d44c0a94f3d26671b5325aa21bbf1335ffe8 Mon Sep 17 00:00:00 2001
From: buzbee <buzbee@google.com>
Date: Sat, 17 Nov 2012 14:11:25 -0800
Subject: C++'ification of Quick compiler's casts

 o Eliminate old useless LIR casts.
 o Replace remaining C-style casts with new C++ versions.
 o Unified instruction encoding enum
 o Expand usage of the auto-generated ostream helpers for enum LOG messages.
 o Replaced all usages of intptr_t with uintptr_t.
 o Fixed bug in removeRedundantBranches, and moved to common code

Change-Id: I53211c0de1be913f958c8fde915296ac08345b7e
---
 src/compiler/codegen/local_optimizations.cc | 56 +++++++++++++++++++++++------
 1 file changed, 46 insertions(+), 10 deletions(-)

(limited to 'src/compiler/codegen/local_optimizations.cc')

diff --git a/src/compiler/codegen/local_optimizations.cc b/src/compiler/codegen/local_optimizations.cc
index e485f03a36..03f9463324 100644
--- a/src/compiler/codegen/local_optimizations.cc
+++ b/src/compiler/codegen/local_optimizations.cc
@@ -50,7 +50,7 @@ void convertMemOpIntoMove(CompilationUnit* cUnit, LIR* origLIR, int dest,
    * will need to be re-checked (eg the new dest clobbers the src used in
    * thisLIR).
    */
-  oatInsertLIRAfter((LIR*) origLIR, (LIR*) moveLIR);
+  oatInsertLIRAfter(origLIR, moveLIR);
 }
 
 /*
@@ -240,15 +240,14 @@ void applyLoadStoreElimination(CompilationUnit* cUnit, LIR* headLIR,
         DEBUG_OPT(dumpDependentInsnPair(thisLIR, checkLIR, "REG CLOBBERED"));
         /* Only sink store instructions */
         if (sinkDistance && !isThisLIRLoad) {
-          LIR* newStoreLIR =
-              (LIR* ) oatNew(cUnit, sizeof(LIR), true, kAllocLIR);
+          LIR* newStoreLIR = static_cast<LIR*>(oatNew(cUnit, sizeof(LIR), true, kAllocLIR));
           *newStoreLIR = *thisLIR;
           /*
            * Stop point found - insert *before* the checkLIR
            * since the instruction list is scanned in the
            * top-down order.
            */
-          oatInsertLIRBefore((LIR*) checkLIR, (LIR*) newStoreLIR);
+          oatInsertLIRBefore(checkLIR, newStoreLIR);
           thisLIR->flags.isNop = true;
         }
         break;
@@ -429,14 +428,13 @@ void applyLoadHoisting(CompilationUnit* cUnit, LIR* headLIR, LIR* tailLIR)
       /* Found a slot to hoist to */
       if (slot >= 0) {
         LIR* curLIR = prevInstList[slot];
-        LIR* newLoadLIR = (LIR* ) oatNew(cUnit, sizeof(LIR),
-                             true, kAllocLIR);
+        LIR* newLoadLIR = static_cast<LIR*>(oatNew(cUnit, sizeof(LIR), true, kAllocLIR));
         *newLoadLIR = *thisLIR;
         /*
          * Insertion is guaranteed to succeed since checkLIR
          * is never the first LIR on the list
          */
-        oatInsertLIRBefore((LIR*) curLIR, (LIR*) newLoadLIR);
+        oatInsertLIRBefore(curLIR, newLoadLIR);
         thisLIR->flags.isNop = true;
       }
     }
@@ -447,11 +445,49 @@ void oatApplyLocalOptimizations(CompilationUnit* cUnit, LIR* headLIR,
                     LIR* tailLIR)
 {
   if (!(cUnit->disableOpt & (1 << kLoadStoreElimination))) {
-    applyLoadStoreElimination(cUnit, (LIR* ) headLIR,
-                  (LIR* ) tailLIR);
+    applyLoadStoreElimination(cUnit, headLIR, tailLIR);
   }
   if (!(cUnit->disableOpt & (1 << kLoadHoisting))) {
-    applyLoadHoisting(cUnit, (LIR* ) headLIR, (LIR* ) tailLIR);
+    applyLoadHoisting(cUnit, headLIR, tailLIR);
+  }
+}
+
+/*
+ * Nop any unconditional branches that go to the next instruction.
+ * Note: new redundant branches may be inserted later, and we'll
+ * use a check in final instruction assembly to nop those out.
+ */
+void removeRedundantBranches(CompilationUnit* cUnit)
+{
+  LIR* thisLIR;
+
+  for (thisLIR = cUnit->firstLIRInsn; thisLIR != cUnit->lastLIRInsn; thisLIR = NEXT_LIR(thisLIR)) {
+
+    /* Branch to the next instruction */
+    if (branchUnconditional(thisLIR)) {
+      LIR* nextLIR = thisLIR;
+
+      while (true) {
+        nextLIR = NEXT_LIR(nextLIR);
+
+        /*
+         * Is the branch target the next instruction?
+         */
+        if (nextLIR == thisLIR->target) {
+          thisLIR->flags.isNop = true;
+          break;
+        }
+
+        /*
+         * Found real useful stuff between the branch and the target.
+         * Need to explicitly check the lastLIRInsn here because it
+         * might be the last real instruction.
+         */
+        if (!isPseudoOpcode(nextLIR->opcode) ||
+          (nextLIR == cUnit->lastLIRInsn))
+          break;
+      }
+    }
   }
 }
 
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