* i386 optimization - remove the test/or %y, %y instruction in the sequence:

  shl/sal/shr/sar $x, %y
  test/or %y, %y
  jz/jnz/setz/setnz/cmovz/cmovnz ...

git-svn-id: trunk@25881 -

compiler/i386/popt386.pas

@@ -2226,7 +2226,7 @@ See test/tgadint64 in the test suite.
                        (taicpu(hp2).opcode = A_Jcc) or
                        (taicpu(hp2).opcode = A_CMOVcc)) then
                      case taicpu(hp1).opcode Of
-                       A_ADD, A_SUB, A_OR, A_XOR, A_AND{, A_SHL, A_SHR}:
+                       A_ADD, A_SUB, A_OR, A_XOR, A_AND:
                          begin
                            if OpsEqual(taicpu(hp1).oper[1]^,taicpu(p).oper[0]^) and
                              { does not work in case of overflow for G(E)/L(E)/C_O/C_NO }
@@ -2242,6 +2242,25 @@ See test/tgadint64 in the test suite.
                                continue
                              end;
                          end;
+                       A_SHL, A_SAL, A_SHR, A_SAR:
+                         begin
+                           if OpsEqual(taicpu(hp1).oper[1]^,taicpu(p).oper[0]^) and
+                             { SHL/SAL/SHR/SAR with a value of 0 do not change the flags }
+                             { therefore, it's only safe to do this optimization for     }
+                             { shifts by a (nonzero) constant                            }
+                              (taicpu(hp1).oper[0]^.typ = top_const) and
+                              (taicpu(hp1).oper[0]^.val <> 0) and
+                             { does not work in case of overflow for G(E)/L(E)/C_O/C_NO }
+                             { and in case of carry for A(E)/B(E)/C/NC                  }
+                              (taicpu(hp2).condition in [C_Z,C_NZ,C_E,C_NE]) then
+                             begin
+                               hp1 := tai(p.next);
+                               asml.remove(p);
+                               p.free;
+                               p := tai(hp1);
+                               continue
+                             end;
+                         end;
                        A_DEC, A_INC, A_NEG:
                          begin
                            if OpsEqual(taicpu(hp1).oper[0]^,taicpu(p).oper[0]^) and