Hi!
The following testcase is lowered by the bitint lowering pass, then
vectorizer vectorizes one of the loops in it, so we have
vect__18.6_34 = VIEW_CONVERT_EXPR<vector(4) unsigned long>(x_35(D));
_8 = BIT_FIELD_REF <vect__18.6_34, 64, 0>;
...
_18 = BIT_FIELD_REF <vect__18.6_34, 64, 64>;
etc. where x_35(D) is _BitInt(256) argument. That is valid BIT_FIELD_REF,
the first argument is a vector and it extracts the vector elements from it.
Then comes forwprop4 and simplifies that using match.pd into
_8 = (unsigned long) x_35(D);
...
_18 = BIT_FIELD_REF <x_35(D), 64, 64>;
and tree-cfg verification ICEs on the latter (though, even the first cast
is kind of undesirable after bitint lowering, we want large/huge bitints
lowered). The ICE is because if BIT_FIELD_REFs first argument has
INTEGRAL_TYPE_P, we require type_has_mode_precision_p, but that is not the
case of _BitInt(256), it has BLKmode.
The following patch fixes it by doing the BIT_FIELD_REF with VCE to
BIT_FIELD_REF simplification only if the result is valid.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2023-11-23 Jakub Jelinek <ja...@redhat.com>
PR tree-optimization/112673
* match.pd (bit_field_ref (vce @0) -> bit_field_ref @0): Only simplify
if either @0 doesn't have scalar integral type or if it has mode
precision.
* gcc.dg/pr112673.c: New test.
--- gcc/match.pd.jj 2023-11-17 15:10:43.306043972 +0100
+++ gcc/match.pd 2023-11-23 18:09:22.538414897 +0100
@@ -8285,7 +8285,9 @@ (define_operator_list SYNC_FETCH_AND_AND
(simplify
(BIT_FIELD_REF (view_convert @0) @1 @2)
- (BIT_FIELD_REF @0 @1 @2))
+ (if (! INTEGRAL_TYPE_P (TREE_TYPE (@0))
+ || type_has_mode_precision_p (TREE_TYPE (@0)))
+ (BIT_FIELD_REF @0 @1 @2)))
(simplify
(BIT_FIELD_REF @0 @1 integer_zerop)
--- gcc/testsuite/gcc.dg/pr112673.c.jj 2023-11-23 18:29:44.540260525 +0100
+++ gcc/testsuite/gcc.dg/pr112673.c 2023-11-23 18:31:31.863765381 +0100
@@ -0,0 +1,10 @@
+/* PR tree-optimization/112673 */
+/* { dg-do compile { target bitint575 } } */
+/* { dg-options "-O3" } */
+/* { dg-additional-options "-mavx2" { target i?86-*-* x86_64-*-* } } */
+
+int
+foo (_BitInt(256) x)
+{
+ return __builtin_ctzg ((unsigned _BitInt(512)) x);
+}
Jakub
