From: Richard Biener <rguenther@suse.de>
Date: Thu, 11 Jul 2019 07:32:04 +0000 (+0000)
Subject: re PR middle-end/91131 (Bad bitfield coalescing)
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=3e66e7b0d1efa3f78a5598884e2d5d526894833e;p=gcc.git

re PR middle-end/91131 (Bad bitfield coalescing)

2019-07-11  Richard Biener  <rguenther@suse.de>

	PR middle-end/91131
	* gimplify.c (gimplify_compound_literal_expr): Force a temporary
	when the object is volatile and we have not cleared it even though
	there are no nonzero elements.

	* gcc.target/i386/pr91131.c: New testcase.

From-SVN: r273376
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index e5c05e5e88d..ee70694afeb 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2019-07-11  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/91131
+	* gimplify.c (gimplify_compound_literal_expr): Force a temporary
+	when the object is volatile and we have not cleared it even though
+	there are no nonzero elements.
+
 2019-07-10  Michael Meissner  <meissner@linux.ibm.com>
 
 	* config/rs6000/predicates.md (cint34_operand): Update
diff --git a/gcc/gimplify.c b/gcc/gimplify.c
index 239988b56ac..146a86ce588 100644
--- a/gcc/gimplify.c
+++ b/gcc/gimplify.c
@@ -5005,7 +5005,7 @@ gimplify_init_constructor (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p,
 	   one field to assign, initialize the target from a temporary.  */
 	if (TREE_THIS_VOLATILE (object)
 	    && !TREE_ADDRESSABLE (type)
-	    && num_nonzero_elements > 0
+	    && (num_nonzero_elements > 0 || !cleared)
 	    && vec_safe_length (elts) > 1)
 	  {
 	    tree temp = create_tmp_var (TYPE_MAIN_VARIANT (type));
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 7172061a835..efebc7260a5 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2019-07-11  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/91131
+	* gcc.target/i386/pr91131.c: New testcase.
+
 2019-07-10  Martin Sebor  <msebor@redhat.com>
 
 	PR testsuite/91132
diff --git a/gcc/testsuite/gcc.target/i386/pr91131.c b/gcc/testsuite/gcc.target/i386/pr91131.c
new file mode 100644
index 00000000000..85008ff8a8b
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr91131.c
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* { dg-options "-O" } */
+
+struct Reg_T {
+    unsigned int a : 3;
+    unsigned int b : 1;
+    unsigned int c : 4;
+};
+
+volatile struct Reg_T Reg_A;
+
+int
+main ()
+{
+  Reg_A = (struct Reg_T){ .a = 0, .b = 0, .c = 0 };
+  return 0;
+}
+
+/* { dg-final { scan-assembler-times "mov\[^\r\n\]*Reg_A" 1 } } */