Hi Renlin, all,
On 20/09/13 15:30, Renlin Li wrote:
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -7016,10 +7016,10 @@ arm_legitimize_reload_address (rtx *p,
/* Reload the high part into a base reg; leave the low part
in the mem. */
- *p = gen_rtx_PLUS (GET_MODE (*p),
- gen_rtx_PLUS (GET_MODE (*p), XEXP (*p, 0),
- GEN_INT (high)),
- GEN_INT (low));
+ *p = plus_constant (GET_MODE (*p),
+ plus_constant (GET_MODE (*p), XEXP (*p, 0),
+ high),
+ low);
push_reload (XEXP (*p, 0), NULL_RTX, &XEXP (*p, 0), NULL,
MODE_BASE_REG_CLASS (mode), GET_MODE (*p),
VOIDmode, 0, 0, opnum, (enum reload_type) type);
We have to be careful with this hunk. plus_constant performs automatic constant
folding on its arguments, whereas gen_rtx_PLUS does not. This means that with
this patch, *p will be of the form:
(plus (reg) (const))
while currently it is:
(plus
(plus (reg)
(const1))
const2)
While constant folding is in general a good thing, in this case the next line
(push_reload) accesses XEXP (*p, 0) which is now different between the two
revisions. This is a similar bug to what was in your AArch64 patch
(http://gcc.gnu.org/ml/gcc-patches/2013-09/msg01536.html ) that caused
regressions there.
Therefore I suggest this hunk is removed from the patch.
What do the maintainers think?
Kyrill
