Subzero: Add branch optimization.

src/IceTargetLoweringX8632.cpp

Index: src/IceTargetLoweringX8632.cpp
diff --git a/src/IceTargetLoweringX8632.cpp b/src/IceTargetLoweringX8632.cpp
index 464a2e88a91260686a086eb91a6016eb1cf92dcc..ad687c82533940d68bb5ec946ed66c4e201548f9 100644
--- a/src/IceTargetLoweringX8632.cpp
+++ b/src/IceTargetLoweringX8632.cpp
@@ -399,6 +399,12 @@ void TargetX8632::translateO2() {
   if (shouldDoNopInsertion()) {
     Func->doNopInsertion();
   }
+
+  // Branch optimization.  This needs to be done just before code

[jvoung (off chromium), 2014/09/18 03:56:02]

Should this be before nop insertion? I don't think that will reorder or insert
CfgNodes, but if before then you will at least not need to iterate over the nops
to find the branches.

[Jim Stichnoth, 2014/09/18 11:45:51]

Good point, done.

+  // emission.  In particular, no transformations that insert or
+  // reorder CfgNodes should be done after branch optimization.
+  Func->doBranchOpt();
+  Func->dump("After branch optimization");
 }
 
 void TargetX8632::translateOm1() {
@@ -444,6 +450,12 @@ void TargetX8632::translateOm1() {
   }
 }
 
+void TargetX8632::doBranchOpt(Inst *I, const CfgNode *NextNode) {
+  if (InstX8632Br *Br = llvm::dyn_cast<InstX8632Br>(I)) {
+    Br->optimizeBranch(NextNode);
+  }
+}
+
 IceString TargetX8632::RegNames[] = {
 #define X(val, init, name, name16, name8, scratch, preserved, stackptr,        \
           frameptr, isI8, isInt, isFP)                                         \