https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120090
--- Comment #7 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #6)
>
> But nowhere in simplify-rtx.cc checks that gen_lowpart_no_emit will return
> CLOBBER. Or should we wrap gen_lowpart_for_combine and return NULL when it
> is a clobber ...
>
That is this:
```
diff --git a/gcc/combine.cc b/gcc/combine.cc
index 67cf0447607..366886020e7 100644
--- a/gcc/combine.cc
+++ b/gcc/combine.cc
@@ -458,6 +458,7 @@ static rtx simplify_shift_const (rtx, enum rtx_code,
machine_mode, rtx,
int);
static int recog_for_combine (rtx *, rtx_insn *, rtx *, unsigned = 0, unsigned
= 0);
static rtx gen_lowpart_for_combine (machine_mode, rtx);
+static rtx gen_lowpart_for_combine_no_emit (machine_mode, rtx);
static enum rtx_code simplify_compare_const (enum rtx_code, machine_mode,
rtx *, rtx *);
static enum rtx_code simplify_comparison (enum rtx_code, rtx *, rtx *);
@@ -491,7 +492,7 @@ static rtx gen_lowpart_or_truncate (machine_mode, rtx);
/* Our implementation of gen_lowpart never emits a new pseudo. */
#undef RTL_HOOKS_GEN_LOWPART_NO_EMIT
-#define RTL_HOOKS_GEN_LOWPART_NO_EMIT gen_lowpart_for_combine
+#define RTL_HOOKS_GEN_LOWPART_NO_EMIT gen_lowpart_for_combine_no_emit
#undef RTL_HOOKS_REG_NONZERO_REG_BITS
#define RTL_HOOKS_REG_NONZERO_REG_BITS reg_nonzero_bits_for_combine
@@ -11890,6 +11891,16 @@ gen_lowpart_for_combine (machine_mode omode, rtx x)
fail:
return gen_rtx_CLOBBER (omode, const0_rtx);
}
+
+static rtx
+gen_lowpart_for_combine_no_emit (machine_mode omode, rtx x)
+{
+ rtx tem = gen_lowpart_for_combine (omode, x);
+ if (!tem || GET_CODE (tem) == CLOBBER)
+ return NULL_RTX;
+ return tem;
+}
+
^L
/* Try to simplify a comparison between OP0 and a constant OP1,
where CODE is the comparison code that will be tested, into a
```
