https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77308
--- Comment #5 from Bernd Edlinger <bernd.edlinger at hotmail dot de> ---
Now I try to clear the out register when the shift < 32
Index: gcc/config/arm/arm.c
===================================================================
--- gcc/config/arm/arm.c (revision 239624)
+++ gcc/config/arm/arm.c (working copy)
@@ -29159,6 +29159,7 @@ arm_emit_coreregs_64bit_shift (enum rtx_code code,
/* Shifts by a constant less than 32. */
rtx reverse_amount = GEN_INT (32 - INTVAL (amount));
+ 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),
@@ -29170,12 +29171,11 @@ arm_emit_coreregs_64bit_shift (enum rtx_code code,
/* Shifts by a constant greater than 31. */
rtx adj_amount = GEN_INT (INTVAL (amount) - 32);
+ 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
result: the stack use goes down from 2960 to 2320
note: this SET is simply redundant, but it makes the out
well-defined from the beginning.
