gcc: xtensa: fix PR target/105879

split_double operates with the 'word that comes first in memory in the
target' terminology, while gen_lowpart operates with the 'value
representing some low-order bits of X' terminology. They are not
equivalent and must be dealt with differently on little- and big-endian
targets.

gcc/
	PR target/105879
	* config/xtensa/xtensa.md (movdi): Rename 'first' and 'second'
	to 'lowpart' and 'highpart' so that they match 'gen_lowpart' and
	'gen_highpart' bitwise semantics and fix order of highpart and
	lowpart depending on target endianness.

(cherry picked from commit e94c6dbfb57a862dd8a8685eabc4886ad1aaea25)

diff --git a/gcc/config/xtensa/xtensa.md b/gcc/config/xtensa/xtensa.md
index 3b61e5d..2554235 100644 (file)
--- a/gcc/config/xtensa/xtensa.md
+++ b/gcc/config/xtensa/xtensa.md
@@ -754,11 +754,14 @@
         because of offering further optimization opportunities.  */
       if (register_operand (operands[0], DImode))
        {
-         rtx first, second;
-
-         split_double (operands[1], &first, &second);
-         emit_insn (gen_movsi (gen_lowpart (SImode, operands[0]), first));
-         emit_insn (gen_movsi (gen_highpart (SImode, operands[0]), second));
+         rtx lowpart, highpart;
+
+         if (TARGET_BIG_ENDIAN)
+           split_double (operands[1], &highpart, &lowpart);
+         else
+           split_double (operands[1], &lowpart, &highpart);
+         emit_insn (gen_movsi (gen_lowpart (SImode, operands[0]), lowpart));
+         emit_insn (gen_movsi (gen_highpart (SImode, operands[0]), highpart));
          DONE;
        }