tree-optimization/106934 - avoid BIT_FIELD_REF of bitfields

The following avoids creating BIT_FIELD_REF of bitfields in
update-address-taken.  The patch doesn't implement punning to
a full precision integer type but leaves a comment according to
that.

	PR tree-optimization/106934
	* tree-ssa.cc (non_rewritable_mem_ref_base): Avoid BIT_FIELD_REFs
	of bitfields.
	(maybe_rewrite_mem_ref_base): Likewise.

	* gfortran.dg/pr106934.f90: New testcase.

(cherry picked from commit 05f5c42cb42c5088187d44cc45a5f671d19ad8c5)

diff --git a/gcc/testsuite/gfortran.dg/pr106934.f90 b/gcc/testsuite/gfortran.dg/pr106934.f90
new file mode 100644 (file)
index 0000000..ac58a3e
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr106934.f90
@@ -0,0 +1,7 @@
+! { dg-do compile }
+! { dg-options "-O" }
+subroutine s
+   logical(1) :: a = .true.
+   logical(2) :: b
+   a = transfer(b, a)
+end

diff --git a/gcc/tree-ssa.cc b/gcc/tree-ssa.cc
index a362a0a9ea63be609da459998045243c07cbc173..ab8b1c27ed43ce9d184e61f03623f51b52537fc2 100644 (file)
--- a/gcc/tree-ssa.cc
+++ b/gcc/tree-ssa.cc
@@ -1459,6 +1459,8 @@ maybe_rewrite_mem_ref_base (tree *tp, bitmap suitable_for_renaming)
               && (! INTEGRAL_TYPE_P (TREE_TYPE (*tp)) 
                   || (wi::to_offset (TYPE_SIZE (TREE_TYPE (*tp)))
                       == TYPE_PRECISION (TREE_TYPE (*tp))))
+              && (! INTEGRAL_TYPE_P (TREE_TYPE (sym))
+                  || type_has_mode_precision_p (TREE_TYPE (sym)))
               && wi::umod_trunc (wi::to_offset (TYPE_SIZE (TREE_TYPE (*tp))),
                                  BITS_PER_UNIT) == 0)
        {
@@ -1531,6 +1533,10 @@ non_rewritable_mem_ref_base (tree ref)
          && (! INTEGRAL_TYPE_P (TREE_TYPE (base))
              || (wi::to_offset (TYPE_SIZE (TREE_TYPE (base)))
                  == TYPE_PRECISION (TREE_TYPE (base))))
+         /* ???  Likewise for extracts from bitfields, we'd have
+            to pun the base object to a size precision mode first.  */
+         && (! INTEGRAL_TYPE_P (TREE_TYPE (decl))
+             || type_has_mode_precision_p (TREE_TYPE (decl)))
          && wi::umod_trunc (wi::to_offset (TYPE_SIZE (TREE_TYPE (base))),
                             BITS_PER_UNIT) == 0)
        return NULL_TREE;