[gcc r13-2657] tree-optimization/106934 - avoid BIT_FIELD_REF of bitfields

[Richard Biener <rguenth@gcc.gnu.org>]

https://gcc.gnu.org/g:05f5c42cb42c5088187d44cc45a5f671d19ad8c5

commit r13-2657-g05f5c42cb42c5088187d44cc45a5f671d19ad8c5
Author: Richard Biener <rguenther@suse.de>
Date:   Wed Sep 14 09:00:35 2022 +0200

    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.

Diff:
---
 gcc/testsuite/gfortran.dg/pr106934.f90 | 7 +++++++
 gcc/tree-ssa.cc                        | 6 ++++++
 2 files changed, 13 insertions(+)

diff --git a/gcc/testsuite/gfortran.dg/pr106934.f90 b/gcc/testsuite/gfortran.dg/pr106934.f90
new file mode 100644
index 00000000000..ac58a3e82e3
--- /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 6507348e793..1a93ffdbd64 100644
--- 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;