arm.c (arm_emit_coreregs_64bit_shift): Clear the result register only if "in" and...

2016-10-19  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        * config/arm/arm.c (arm_emit_coreregs_64bit_shift): Clear the result
        register only if "in" and "out" are different registers.

From-SVN: r241348

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index be2521e..e4840df 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2016-10-19  Bernd Edlinger  <bernd.edlinger@hotmail.de>
+
+       * config/arm/arm.c (arm_emit_coreregs_64bit_shift): Clear the result
+       register only if "in" and "out" are different registers.
+
 2016-10-19  Eric Botcazou  <ebotcazou@adacore.com>
 
        * omp-low.c (pass_oacc_device_lower::gate): New method.

diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index a758839..022c1d7 100644 (file)
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -29218,8 +29218,10 @@ arm_emit_coreregs_64bit_shift (enum rtx_code code, rtx out, rtx in,
 
          /* Clearing the out register in DImode first avoids lots
             of spilling and results in less stack usage.
-            Later this redundant insn is completely removed.  */
-         emit_insn (SET (out, const0_rtx));
+            Later this redundant insn is completely removed.
+            Do that only if "in" and "out" are different registers.  */
+         if (REG_P (out) && REG_P (in) && REGNO (out) != REGNO (in))
+           emit_insn (SET (out, const0_rtx));
          emit_insn (SET (out_down, LSHIFT (code, in_down, amount)));
          emit_insn (SET (out_down,
                          ORR (REV_LSHIFT (code, in_up, reverse_amount),
@@ -29231,11 +29233,14 @@ arm_emit_coreregs_64bit_shift (enum rtx_code code, rtx out, rtx in,
          /* Shifts by a constant greater than 31.  */
          rtx adj_amount = GEN_INT (INTVAL (amount) - 32);
 
-         emit_insn (SET (out, const0_rtx));
+         if (REG_P (out) && REG_P (in) && REGNO (out) != REGNO (in))
+           emit_insn (SET (out, const0_rtx));
          emit_insn (SET (out_down, SHIFT (code, in_up, adj_amount)));
          if (code == ASHIFTRT)
            emit_insn (gen_ashrsi3 (out_up, in_up,
                                    GEN_INT (31)));
+         else
+           emit_insn (SET (out_up, const0_rtx));
        }
     }
   else