For h8300-elf, gcc.dg/pr114768.c fails when compiled with -O2 -msx since
cselib_redundant_set_p returns true when called with
(gdb) call debug (set)
(set (mem:HI (reg/f:SI 0 r0 [orig:21 p ] [21]) [1 *p_3(D)+0 S2 A16])
(mem/v:HI (reg/f:SI 0 r0 [orig:21 p ] [21]) [1 MEM[(volatile int
*)p_3(D)]+0 S2 A16]))
(gdb)
from reload_cse_regs. Update cselib_redundant_set_p to return false for
volatile memory source or destination.
gcc/
PR target/122343
* cselib.cc (cselib_redundant_set_p): Return false for volatile
memory source or destination.
gcc/testsuite/
PR target/122343
* gcc.dg/pr122343-1.c: New test.
--
H.J.
From 7b6aa7c61740abca75d4922340b516d2d64c74a2 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <[email protected]>
Date: Wed, 17 Dec 2025 12:18:15 +0800
Subject: [PATCH] cse: Check volatile memory in cselib_redundant_set_p
For h8300-elf, gcc.dg/pr114768.c fails when compiled with -O2 -msx since
cselib_redundant_set_p returns true when called with
(gdb) call debug (set)
(set (mem:HI (reg/f:SI 0 r0 [orig:21 p ] [21]) [1 *p_3(D)+0 S2 A16])
(mem/v:HI (reg/f:SI 0 r0 [orig:21 p ] [21]) [1 MEM[(volatile int *)p_3(D)]+0 S2 A16]))
(gdb)
from reload_cse_regs. Update cselib_redundant_set_p to return false for
volatile memory source or destination.
gcc/
PR target/122343
* cselib.cc (cselib_redundant_set_p): Return false for volatile
memory source or destination.
gcc/testsuite/
PR target/122343
* gcc.dg/pr122343-1.c: New test.
Signed-off-by: H.J. Lu <[email protected]>
---
gcc/cselib.cc | 8 ++++++--
gcc/testsuite/gcc.dg/pr122343-1.c | 9 +++++++++
2 files changed, 15 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/pr122343-1.c
diff --git a/gcc/cselib.cc b/gcc/cselib.cc
index 930357409bc..5d78675c4ba 100644
--- a/gcc/cselib.cc
+++ b/gcc/cselib.cc
@@ -1194,7 +1194,9 @@ cselib_redundant_set_p (rtx set)
if (cselib_reg_set_mode (dest) != GET_MODE (dest))
return false;
- if (!rtx_equal_for_cselib_p (dest, SET_SRC (set)))
+ rtx src = SET_SRC (set);
+ if ((MEM_P (src) && MEM_VOLATILE_P (src))
+ || !rtx_equal_for_cselib_p (dest, src))
return false;
while (GET_CODE (dest) == SUBREG
@@ -1205,6 +1207,9 @@ cselib_redundant_set_p (rtx set)
if (!flag_strict_aliasing || !MEM_P (dest))
return true;
+ if (MEM_VOLATILE_P (dest))
+ return false;
+
/* For a store we need to check that suppressing it will not change
the effective alias set. */
rtx dest_addr = XEXP (dest, 0);
@@ -1242,7 +1247,6 @@ cselib_redundant_set_p (rtx set)
/* We failed to find a recorded value in the cselib history, so try
the source of this set; this catches cases such as *p = *q when p
and q have the same value. */
- rtx src = SET_SRC (set);
while (GET_CODE (src) == SUBREG)
src = XEXP (src, 0);
diff --git a/gcc/testsuite/gcc.dg/pr122343-1.c b/gcc/testsuite/gcc.dg/pr122343-1.c
new file mode 100644
index 00000000000..b1fd0f0abc2
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr122343-1.c
@@ -0,0 +1,9 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-rtl-final" } */
+/* { dg-final { scan-rtl-dump "\\\(mem/v:" "final" } } */
+
+void
+foo (int *p)
+{
+ *(volatile int *) p = *p;
+}
--
2.52.0
