cpu: Eliminate the unused hasBranchTarget method in StaticInst.

This was once used to implement GDB single stepping back when it was
reimplemented for each ISA, but has not been used since 2014 when that
code was refactored.

Change-Id: If37ccfec2c43a33320d753c68892aa6fefd16b4f
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/51531
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Reviewed-by: ZHENGRONG WANG <seanyukigeek@gmail.com>

src/cpu/static_inst.cc

@@ -33,23 +33,6 @@
 namespace gem5
 {
 
-bool
-StaticInst::hasBranchTarget(const TheISA::PCState &pc, ThreadContext *tc,
-                            TheISA::PCState &tgt) const
-{
-    if (isDirectCtrl()) {
-        tgt = branchTarget(pc);
-        return true;
-    }
-
-    if (isIndirectCtrl()) {
-        tgt = branchTarget(tc);
-        return true;
-    }
-
-    return false;
-}
-
 StaticInstPtr
 StaticInst::fetchMicroop(MicroPC upc) const
 {

src/cpu/static_inst.hh

@@ -351,13 +351,6 @@ class StaticInst : public RefCounted, public StaticInstFlags
      */
     virtual TheISA::PCState branchTarget(ThreadContext *tc) const;
 
-    /**
-     * Return true if the instruction is a control transfer, and if so,
-     * return the target address as well.
-     */
-    bool hasBranchTarget(const TheISA::PCState &pc, ThreadContext *tc,
-            TheISA::PCState &tgt) const;
-
     /**
      * Return string representation of disassembled instruction.
      * The default version of this function will call the internal