Hi!
abs_hwi asserts that the argument is not HOST_WIDE_INT_MIN and as the
(invalid) testcase shows, the function can be called with such an offset.
The following patch is IMHO minimal fix, absu_hwi unlike abs_hwi allows even
that value and will return (unsigned HOST_WIDE_INT) HOST_WIDE_INT_MIN
in that case. The function then uses moffset in two spots which wouldn't
care if the value is (unsigned HOST_WIDE_INT) HOST_WIDE_INT_MIN or
HOST_WIDE_INT_MIN and wouldn't accept it (!moffset and
aarch64_uimm12_shift (moffset)), then in one spot where the signedness of
moffset does matter and using unsigned is the right thing -
moffset < 0x1000000 - and finally has code which will handle even this
value right; the assembler doesn't really care for DImode immediates if
mov x1, -9223372036854775808
or
mov x1, 9223372036854775808
is used and similarly it doesn't matter if we add or sub it in DImode.
Bootstrapped/regtested on aarch64-linux, ok for trunk?
2020-03-10 Jakub Jelinek <ja...@redhat.com>
PR target/94121
* config/aarch64/aarch64.c (aarch64_add_offset_1): Use absu_hwi
instead of abs_hwi, change moffset type to unsigned HOST_WIDE_INT.
* gcc.dg/pr94121.c: New test.
--- gcc/config/aarch64/aarch64.c.jj 2020-02-28 17:33:03.414258503 +0100
+++ gcc/config/aarch64/aarch64.c 2020-03-10 17:01:39.435302124 +0100
@@ -3713,7 +3713,7 @@ aarch64_add_offset_1 (scalar_int_mode mo
gcc_assert (emit_move_imm || temp1 != NULL_RTX);
gcc_assert (temp1 == NULL_RTX || !reg_overlap_mentioned_p (temp1, src));
- HOST_WIDE_INT moffset = abs_hwi (offset);
+ unsigned HOST_WIDE_INT moffset = absu_hwi (offset);
rtx_insn *insn;
if (!moffset)
--- gcc/testsuite/gcc.dg/pr94121.c.jj 2020-03-10 16:58:40.246974306 +0100
+++ gcc/testsuite/gcc.dg/pr94121.c 2020-03-10 16:58:40.246974306 +0100
@@ -0,0 +1,16 @@
+/* PR target/94121 */
+/* { dg-do compile { target pie } } */
+/* { dg-options "-O2 -fpie -w" } */
+
+#define DIFF_MAX __PTRDIFF_MAX__
+#define DIFF_MIN (-DIFF_MAX - 1)
+
+extern void foo (char *);
+extern char v[];
+
+void
+bar (void)
+{
+ char *p = v;
+ foo (&p[DIFF_MIN]);
+}
Jakub
