https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99930
--- Comment #7 from Hongtao.liu <crazylht at gmail dot com> ---
i'm testing
1 file changed, 30 insertions(+)
gcc/combine.c | 30 ++++++++++++++++++++++++++++++
modified gcc/combine.c
@@ -1811,6 +1811,33 @@ set_nonzero_bits_and_sign_copies (rtx x, const_rtx set,
void *data)
}
}
}
+
+/* Return true is reg is only defined by loading from constant pool. */
+static int
+single_ref_from_constant_pool (rtx reg)
+{
+ gcc_assert (REG_P (reg));
+ rtx_insn* insn;
+ rtx src, set;
+
+ if (DF_REG_DEF_COUNT (REGNO (reg)) != 1)
+ return 0;
+ insn = DF_REF_INSN (DF_REG_DEF_CHAIN (REGNO (reg)));
+ if (!insn)
+ return 0;
+ set = single_set (insn);
+ if (!set)
+ return 0;
+ src = SET_SRC (set);
+
+ /* Constant pool. */
+ if (!MEM_P (src)
+ || !SYMBOL_REF_P (XEXP (src, 0))
+ || !CONSTANT_POOL_ADDRESS_P (XEXP (src, 0)))
+ return 0;
+
+ return 1;
+}
/* See if INSN can be combined into I3. PRED, PRED2, SUCC and SUCC2 are
optionally insns that were previously combined into I3 or that will be
@@ -1895,7 +1922,10 @@ can_combine_p (rtx_insn *insn, rtx_insn *i3, rtx_insn
*pred ATTRIBUTE_UNUSED,
something to tell them apart, e.g. different modes. For
now, we forgo such complicated tests and simply disallow
combining of USES of pseudo registers with any other USE. */
+ /* If the USE in INSN is only defined by loading from constant
+ pool, it must have identical value. */
if (REG_P (XEXP (elt, 0))
+ && !single_ref_from_constant_pool (XEXP (elt, 0))
&& GET_CODE (PATTERN (i3)) == PARALLEL)
{
rtx i3pat = PATTERN (i3);
