Hi!
The following testcase is miscompiled, because the variable shift left
operand, { -1, -1, -1, -1 } is represented as a VECTOR_CST with
VECTOR_CST_NPATTERNS 1 and VECTOR_CST_NELTS_PER_PATTERN 1, so when
we call builder.new_unary_operation, builder.encoded_nelts () will be just 1
and thus we encode the resulting vector as if all the elements were the
same.
For non-masked is_vshift, we could perhaps call builder.new_binary_operation
(TREE_TYPE (args[0]), args[0], args[1], false), but then there are masked
shifts, for non-is_vshift we could perhaps call it too but with args[2]
instead of args[1], but there is no builder.new_ternary_operation.
All this stuff is primarily for aarch64 anyway, on x86 we don't have any
variable length vectors, and it is not a big deal to compute all elements
and just let builder.finalize () find the most efficient VECTOR_CST
representation of the vector. So, instead of doing too much, this just
keeps using new_unary_operation only if only one VECTOR_CST is involved
(i.e. non-masked shift by constant) and for the rest just compute all elts.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2020-01-28 Jakub Jelinek <ja...@redhat.com>
PR target/93418
* config/i386/i386.c (ix86_fold_builtin) <do_shift>: If mask is not
-1 or is_vshift is true, use new_vector with number of elts npatterns
rather than new_unary_operation.
* gcc.target/i386/avx2-pr93418.c: New test.
--- gcc/config/i386/i386.c.jj 2020-01-22 09:49:27.375413362 +0100
+++ gcc/config/i386/i386.c 2020-01-27 18:22:34.986577375 +0100
@@ -17278,8 +17278,13 @@ ix86_fold_builtin (tree fndecl, int n_ar
countt = build_int_cst (integer_type_node, count);
}
tree_vector_builder builder;
- builder.new_unary_operation (TREE_TYPE (args[0]), args[0],
- false);
+ if (mask != HOST_WIDE_INT_M1U || is_vshift)
+ builder.new_vector (TREE_TYPE (args[0]),
+ TYPE_VECTOR_SUBPARTS (TREE_TYPE (args[0])),
+ 1);
+ else
+ builder.new_unary_operation (TREE_TYPE (args[0]), args[0],
+ false);
unsigned int cnt = builder.encoded_nelts ();
for (unsigned int i = 0; i < cnt; ++i)
{
--- gcc/testsuite/gcc.target/i386/avx2-pr93418.c.jj 2020-01-27
18:27:53.461799372 +0100
+++ gcc/testsuite/gcc.target/i386/avx2-pr93418.c 2020-01-27
18:26:11.592327685 +0100
@@ -0,0 +1,20 @@
+/* PR target/93418 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -mavx2 -fdump-tree-optimized" } */
+/* { dg-final { scan-tree-dump-not "link_error" "optimized" } } */
+
+#include <x86intrin.h>
+
+void link_error (void);
+
+void
+foo (void)
+{
+ __m128i a = _mm_set1_epi32 (0xffffffffU);
+ __m128i b = _mm_setr_epi32 (16, 31, -34, 3);
+ __m128i c = _mm_sllv_epi32 (a, b);
+ __v4su d = (__v4su) c;
+ if (d[0] != 0xffff0000U || d[1] != 0x80000000U
+ || d[2] != 0 || d[3] != 0xfffffff8U)
+ link_error ();
+}
Jakub
