[gcc r10-8793] aarch64: Do not alter value on a force_reg returned rtx expanding __jcvt

[Andrea Corallo <akrl@gcc.gnu.org>]

https://gcc.gnu.org/g:aa47c987340946034fe9e32832bd1eb49d6287f3

commit r10-8793-gaa47c987340946034fe9e32832bd1eb49d6287f3
Author: Andrea Corallo <andrea.corallo@arm.com>
Date:   Thu Sep 17 17:17:52 2020 +0100

    aarch64: Do not alter value on a force_reg returned rtx expanding __jcvt
    
    2020-09-17  Andrea Corallo  <andrea.corallo@arm.com>
    
            * config/aarch64/aarch64-builtins.c
            (aarch64_general_expand_builtin): Use expand machinery not to
            alter the value of an rtx returned by force_reg.
    
    (cherry picked from commit 2c62952f8160bdc8d4111edb34a4bc75096c1e05)

Diff:
---
 gcc/config/aarch64/aarch64-builtins.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/gcc/config/aarch64/aarch64-builtins.c b/gcc/config/aarch64/aarch64-builtins.c
index 8407a34b594..b8d301f00e2 100644
--- a/gcc/config/aarch64/aarch64-builtins.c
+++ b/gcc/config/aarch64/aarch64-builtins.c
@@ -1976,14 +1976,14 @@ aarch64_general_expand_builtin (unsigned int fcode, tree exp, rtx target,
       return target;
 
     case AARCH64_JSCVT:
-      arg0 = CALL_EXPR_ARG (exp, 0);
-      op0 = force_reg (DFmode, expand_normal (arg0));
-      if (!target)
-	target = gen_reg_rtx (SImode);
-      else
-	target = force_reg (SImode, target);
-      emit_insn (GEN_FCN (CODE_FOR_aarch64_fjcvtzs) (target, op0));
-      return target;
+      {
+	expand_operand ops[2];
+	create_output_operand (&ops[0], target, SImode);
+	op0 = expand_normal (CALL_EXPR_ARG (exp, 0));
+	create_input_operand (&ops[1], op0, DFmode);
+	expand_insn (CODE_FOR_aarch64_fjcvtzs, 2, ops);
+	return ops[0].value;
+      }
 
     case AARCH64_SIMD_BUILTIN_FCMLA_LANEQ0_V2SF:
     case AARCH64_SIMD_BUILTIN_FCMLA_LANEQ90_V2SF: