From: Richard Biener <rguenther@suse.de>
Date: Fri, 11 Nov 2016 12:53:36 +0000 (+0000)
Subject: re PR middle-end/78295 (Spurious -Wuninitialized warning for vector element assignment)
X-Git-Tag: basepoints/gcc-8~3235
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=d07f8c591acf1ed2f99873464093b8729a8da0f2;p=thirdparty%2Fgcc.git

re PR middle-end/78295 (Spurious -Wuninitialized warning for vector element assignment)

2016-11-11  Richard Biener  <rguenther@suse.de>

	PR middle-end/78295
	* tree-ssa-uninit.c (warn_uninitialized_vars): Do not warn
	about uninitialized destination arg of BIT_INSERT_EXPR.

	* gcc.dg/uninit-pr78295.c: New testcase.

From-SVN: r242068
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 5cbc53d45b73..5ca356d7b139 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2016-11-11  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/78295
+	* tree-ssa-uninit.c (warn_uninitialized_vars): Do not warn
+	about uninitialized destination arg of BIT_INSERT_EXPR.
+
 2016-11-10  Sandra Loosemore  <sandra@codesourcery.com>
 
 	PR c/37998
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index e16fdde8db96..acec6d953438 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2016-11-11  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/78295
+	* gcc.dg/uninit-pr78295.c: New testcase.
+
 2016-11-10  Fritz O. Reese <fritzoreese@gmail.com>
 
 	PR fortran/78277
diff --git a/gcc/testsuite/gcc.dg/uninit-pr78295.c b/gcc/testsuite/gcc.dg/uninit-pr78295.c
new file mode 100644
index 000000000000..ae0b21469b0b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/uninit-pr78295.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -Wall" } */
+
+typedef double vectype __attribute__ ((__vector_size__ (16)));
+
+vectype
+f (double x)
+{
+  vectype t;
+  for (int i = 0; i < 2; i++)
+    t[i] = x; /* { dg-bogus "uninitialized" } */
+  return t;
+}
diff --git a/gcc/tree-ssa-uninit.c b/gcc/tree-ssa-uninit.c
index 13448548e0e0..dfee0ea72d1a 100644
--- a/gcc/tree-ssa-uninit.c
+++ b/gcc/tree-ssa-uninit.c
@@ -212,6 +212,14 @@ warn_uninitialized_vars (bool warn_possibly_uninitialized)
 	     can warn about.  */
 	  FOR_EACH_SSA_USE_OPERAND (use_p, stmt, op_iter, SSA_OP_USE)
 	    {
+	      /* BIT_INSERT_EXPR first operand should not be considered
+	         a use for the purpose of uninit warnings.  */
+	      if (gassign *ass = dyn_cast <gassign *> (stmt))
+		{
+		  if (gimple_assign_rhs_code (ass) == BIT_INSERT_EXPR
+		      && use_p->use == gimple_assign_rhs1_ptr (ass))
+		    continue;
+		}
 	      use = USE_FROM_PTR (use_p);
 	      if (always_executed)
 		warn_uninit (OPT_Wuninitialized, use, SSA_NAME_VAR (use),