Hi!
The following patch ensures we don't access bytes beyond the original MEM,
those might not be mapped etc., or for big endian the offset computation
computes the offset incorrectly.
Bootstrapped/regtested on powerpc64{,-le}-linux, Wilco has tested it on
aarch64_be-*, preapproved by Segher in the PR, committed to trunk.
2019-02-05 Jakub Jelinek <ja...@redhat.com>
PR rtl-optimization/89195
* combine.c (make_extraction): For MEMs, don't extract bytes outside
of the original MEM.
* gcc.c-torture/execute/pr89195.c: New test.
--- gcc/combine.c.jj 2019-02-01 23:52:24.701025057 +0100
+++ gcc/combine.c 2019-02-05 12:51:17.813658725 +0100
@@ -7687,6 +7687,7 @@ make_extraction (machine_mode mode, rtx
/* We can't do this if we are widening INNER_MODE (it
may not be aligned, for one thing). */
&& !paradoxical_subreg_p (tmode, inner_mode)
+ && known_le (pos + len, GET_MODE_PRECISION (is_mode))
&& (inner_mode == tmode
|| (! mode_dependent_address_p (XEXP (inner, 0),
MEM_ADDR_SPACE (inner))
--- gcc/testsuite/gcc.c-torture/execute/pr89195.c.jj 2019-02-05
12:55:40.856362136 +0100
+++ gcc/testsuite/gcc.c-torture/execute/pr89195.c 2019-02-05
12:55:09.920853996 +0100
@@ -0,0 +1,22 @@
+/* PR rtl-optimization/89195 */
+/* { dg-require-effective-target int32plus } */
+
+struct S { unsigned i : 24; };
+
+volatile unsigned char x;
+
+__attribute__((noipa)) int
+foo (struct S d)
+{
+ return d.i & x;
+}
+
+int
+main ()
+{
+ struct S d = { 0x123456 };
+ x = 0x75;
+ if (foo (d) != (0x56 & 0x75))
+ __builtin_abort ();
+ return 0;
+}
Jakub
