From: Richard Biener <rguenther@suse.de>
Date: Wed, 14 Sep 2022 07:00:35 +0000 (+0200)
Subject: tree-optimization/106934 - avoid BIT_FIELD_REF of bitfields
X-Git-Tag: release-12.2.mpacbti-rel1~373
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c3119f575a04845fbbebbf90b5cdea88d5d76156;p=thirdparty%2Fgcc.git

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
index 000000000000..ac58a3e82e3b
--- /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 a362a0a9ea63..ab8b1c27ed43 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;