tree-optimization/107686 - fix bitfield ref through vec_unpack optimization

The following propely restricts the bitfield access to integral types
when we look through VEC_UNPACK with the intent to emit a widening
conversion.

	PR tree-optimization/107686
	* tree-ssa-forwprop.cc (optimize_vector_load): Restrict
	VEC_UNPACK support to integral typed bitfield refs.

	* gcc.dg/pr107686.c: New testcase.

(cherry picked from commit 246bbdaa5f536b7a199dda9860c473137f40d622)

diff --git a/gcc/testsuite/gcc.dg/pr107686.c b/gcc/testsuite/gcc.dg/pr107686.c
new file mode 100644 (file)
index 0000000..2378103
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr107686.c
@@ -0,0 +1,16 @@
+/* { dg-do compile { target { dfp && longlong64 } } } */
+/* { dg-options "-O" } */
+/* { dg-additional-options "-mavx2" { target x86_64-*-* i?86-*-* } } */
+
+typedef _Decimal64 __attribute__((__vector_size__ (64))) D;
+typedef __INT32_TYPE__ __attribute__((__vector_size__ (32))) U;
+typedef __INT64_TYPE__ __attribute__((__vector_size__ (64))) V;
+
+U u;
+D d;
+
+void
+foo (void)
+{
+  d = d < (D) __builtin_convertvector (u, V);
+}

diff --git a/gcc/tree-ssa-forwprop.cc b/gcc/tree-ssa-forwprop.cc
index 484491fa1c50653780adc37fe92c9d5c6bbec1d9..260d5dac83bc560895b4317ffeead4c17b38ea28 100644 (file)
--- a/gcc/tree-ssa-forwprop.cc
+++ b/gcc/tree-ssa-forwprop.cc
@@ -3118,7 +3118,11 @@ optimize_vector_load (gimple_stmt_iterator *gsi)
              && (def == lhs
                  || (known_eq (bit_field_size (use_rhs), def_eltsize)
                      && constant_multiple_p (bit_field_offset (use_rhs),
-                                             def_eltsize))))
+                                             def_eltsize)
+                     /* We can simulate the VEC_UNPACK_{HI,LO}_EXPR
+                        via a NOP_EXPR only for integral types.
+                        ???  Support VEC_UNPACK_FLOAT_{HI,LO}_EXPR.  */
+                     && INTEGRAL_TYPE_P (TREE_TYPE (use_rhs)))))
            {
              bf_stmts.safe_push (use_stmt);
              continue;