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 e5c05e5e88d0210ace5c3c4f24146548b390aadf..ee70694afebc52affe6de0c58bb5ccbead4ed84b 100644 (file)
--- 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 239988b56acb977b5ad08c0c5301242a530f0b32..146a86ce5883c5faafabfc8120b47573db408268 100644 (file)
--- 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 7172061a835abe2630394471b8bae88b9905a933..efebc7260a51ced26a6b2730f79aced49a433316 100644 (file)
--- 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 (file)
index 0000000..85008ff
--- /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 } } */