Hi All,
Previously GCC's no-op detection could would consider something a no-op even
when the
mode change is not directly possible. This caused subregs that shouldn't be
removed
to be treated as a no-op and deleted.
Regtested on armeb-none-eabi and no regressions.
Bootstrapped on arm-none-linux-gnueabihf and no issues.
Ok for trunk? and for backport to GCC 8?
Thanks,
Tamar
gcc/
2018-06-19 Tamar Christina <tamar.christ...@arm.com>
PR target/84711
* rtlanal.c (set_noop_p): Constrain on mode change,
include hard-reg-set.h
--
diff --git a/gcc/rtlanal.c b/gcc/rtlanal.c
index ac3662de3ce0c9fcb58a042138f461c538fc1522..7af516378b38e043849cc2e1326a43837856ae4d 100644
--- a/gcc/rtlanal.c
+++ b/gcc/rtlanal.c
@@ -35,6 +35,7 @@ along with GCC; see the file COPYING3. If not see
#include "recog.h"
#include "addresses.h"
#include "rtl-iter.h"
+#include "hard-reg-set.h"
/* Forward declarations */
static void set_of_1 (rtx, const_rtx, void *);
@@ -1620,8 +1621,9 @@ set_noop_p (const_rtx set)
if (INTVAL (XVECEXP (par, 0, i)) != c0 + i)
return 0;
return
- simplify_subreg_regno (REGNO (src0), GET_MODE (src0),
- offset, GET_MODE (dst)) == (int) REGNO (dst);
+ REG_CAN_CHANGE_MODE_P (REGNO (dst), GET_MODE (src0), GET_MODE (dst))
+ && simplify_subreg_regno (REGNO (src0), GET_MODE (src0),
+ offset, GET_MODE (dst)) == (int) REGNO (dst);
}
return (REG_P (src) && REG_P (dst)
