Richard Biener <richard.guent...@gmail.com> writes:
> On December 2, 2019 5:27:05 PM GMT+01:00, Richard Sandiford
> <richard.sandif...@arm.com> wrote:
>>In this PR, IPA-CP was misled into using NOP_EXPR rather than
>>VIEW_CONVERT_EXPR to reinterpret a vector of 4 shorts as a vector
>>of 2 ints. This tripped the tree-cfg.c assert I'd added in r278245.
>>
>>Tested on aarch64-linux-gnu and x86_64-linux-gnu. OK to install?
>
> Hmm, but then it may create such conversion without verifying the target
> supports it?
This doesn't seem like the right place to check that though.
E.g. tree-vect-generic.c could lower conversions if necessary, just
like for any other vector op. AIUI fold_convertible_p is just checking
whether the conversion satisfies the tree/gimple semantics of NOP_EXPR.
Note that in the IPA-CP case, we should never generate a vector NOP_EXPR
that isn't also tree_nop_conversion_p, see comment 4 in the PR. It's
possible we might want to rewrite the IPA-CP (and other IPA conditions)
to be more explicit about this, but I think we want the patch either way.
All it does is disallow cases that were previously (wrongly) allowed.
Thanks,
Richard
>
> Richard.
>
>>Richard
>>
>>
>>2019-12-02 Richard Sandiford <richard.sandif...@arm.com>
>>
>>gcc/
>> PR middle-end/92741
>> * fold-const.c (fold_convertible_p): Check vector types more
>> thoroughly.
>>
>>gcc/testsuite/
>> PR middle-end/92741
>> * gcc.dg/pr92741.c: New test.
>>
>>Index: gcc/fold-const.c
>>===================================================================
>>--- gcc/fold-const.c 2019-11-18 15:27:36.053367794 +0000
>>+++ gcc/fold-const.c 2019-12-02 16:25:02.662405351 +0000
>>@@ -2375,10 +2375,15 @@ fold_convertible_p (const_tree type, con
>>
>> case REAL_TYPE:
>> case FIXED_POINT_TYPE:
>>- case VECTOR_TYPE:
>> case VOID_TYPE:
>> return TREE_CODE (type) == TREE_CODE (orig);
>>
>>+ case VECTOR_TYPE:
>>+ return (VECTOR_TYPE_P (orig)
>>+ && known_eq (TYPE_VECTOR_SUBPARTS (type),
>>+ TYPE_VECTOR_SUBPARTS (orig))
>>+ && fold_convertible_p (TREE_TYPE (type), TREE_TYPE (orig)));
>>+
>> default:
>> return false;
>> }
>>Index: gcc/testsuite/gcc.dg/pr92741.c
>>===================================================================
>>--- /dev/null 2019-09-17 11:41:18.176664108 +0100
>>+++ gcc/testsuite/gcc.dg/pr92741.c 2019-12-02 16:25:02.662405351 +0000
>>@@ -0,0 +1,19 @@
>>+/* { dg-options "-O2 -fexceptions -fnon-call-exceptions -fno-inline" }
>>*/
>>+
>>+typedef int vh __attribute__ ((__vector_size__ (2 * sizeof (int))));
>>+typedef short int cq __attribute__ ((__vector_size__ (4 * sizeof
>>(short int))));
>>+
>>+static void
>>+id (int *r8, vh *tu)
>>+{
>>+ *(vh *) r8 = *tu;
>>+}
>>+
>>+void
>>+mr (void)
>>+{
>>+ int r8;
>>+ cq he = { 0, };
>>+
>>+ id (&r8, (vh *) &he);
>>+}
