Hi!
The following testcase ICEs in the combiner, because we try to optimize
HImode SUBREG of SImode LSHIFTRT with shift count 80, so width is -48,
and in the end we call smallest_mode_for_size (-48, MODE_INT) and
that function has unsigned int as first argument; most of the ports don't
have modes with 4Gbits yet.
Bootstrapped/regtested on x86_64-linux and i686-linux, pre-approved by
Segher on IRC, committed to trunk.
2016-11-25 Jakub Jelinek <ja...@redhat.com>
PR rtl-optimization/78527
* combine.c (make_compound_operation_int): Ignore LSHIFTRT with
out of bounds shift count.
* gcc.c-torture/compile/pr78527.c: New test.
--- gcc/combine.c.jj 2016-11-25 09:49:50.000000000 +0100
+++ gcc/combine.c 2016-11-25 13:42:43.628487136 +0100
@@ -8091,6 +8091,8 @@ make_compound_operation_int (machine_mod
if (GET_CODE (inner) == LSHIFTRT
&& CONST_INT_P (XEXP (inner, 1))
&& GET_MODE_SIZE (mode) < GET_MODE_SIZE (GET_MODE (inner))
+ && (UINTVAL (XEXP (inner, 1))
+ < GET_MODE_PRECISION (GET_MODE (inner)))
&& subreg_lowpart_p (x))
{
new_rtx = make_compound_operation (XEXP (inner, 0), next_code);
--- gcc/testsuite/gcc.c-torture/compile/pr78527.c.jj 2016-11-25
13:44:53.806825477 +0100
+++ gcc/testsuite/gcc.c-torture/compile/pr78527.c 2016-11-25
13:44:35.000000000 +0100
@@ -0,0 +1,21 @@
+/* PR rtl-optimization/78527 */
+
+unsigned a;
+short b, e;
+int *c;
+char d;
+
+int
+main ()
+{
+ int f = 80;
+ for (;;) {
+ if (f > 432)
+ *c = a;
+ while (b)
+ if (d)
+ e = -(a >> f);
+ c = &f;
+ b = e;
+ }
+}
Jakub
