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[PATCH] Fix PR39246: -Wuninitialized for partially initialized complex


Warning for use of a partially initialized complex is displayed on the wrong line (the one where the partial initialization is done) and is not consistent between target (or even within a given target, for instance between hardfloat and softfloat on arm-none-eabi target). This patch correctly retains the line location when expanding a complex move, stop warning when a COMPLEX_EXPR is constructed but instead warn when it is used, and for cases where a branch is involved, get the line location from the phi argument involved as a fallback. This fixes PR39246.

The ChangeLog are as follows:

*** gcc/ChangeLog ***

2014-05-04  Thomas Preud'homme  <thomas.preudhomme@arm.com>

	PR middle-end/39246
	* tree-complex.c (expand_complex_move): Keep line info when expanding
	complex move.
	* tree-ssa-uninit.c (warn_uninit): New argument. Ignore assignment of
	complex expression. Use new argument to display correct location for
	values coming from phi statement.
	(warn_uninitialized_vars): Adapt to new signature of warn_uninit.
	(warn_uninitialized_phi): Pass location of phi argument to warn_uninit.
	* tree-ssa.c (ssa_undefined_value_p): For SSA_NAME initialized by a
	COMPLEX_EXPR, recurse on each part of the COMPLEX_EXPR.


*** gcc/testsuite/ChangeLog ***

2014-05-04  Thomas Preud'homme  <thomas.preudhomme@arm.com>

	* gcc.dg/uninit-13.c: Move warning on the actual source line where the
	uninitialized complex is used.
	* gcc.dg/uninit-17.c: New test to check partial initialization of
	complex with branches.
	* gcc.dg/uninit-17-O0.c: Likewise.

Bootstrapped on x86_64-linux-gnu with no regression in the testsuite. Also tested a cross-build of gcc for arm-none-eabi target and run the regression testsuite in qemu for cortex-m3 without any regression and the uninit-13.c test fixed.

Ok for stage1? Patch with proper formatting in attachment.

diff --git a/gcc/testsuite/gcc.dg/uninit-13.c b/gcc/testsuite/gcc.dg/uninit-13.c
index 631e8de..5e88a8a 100644
--- a/gcc/testsuite/gcc.dg/uninit-13.c
+++ b/gcc/testsuite/gcc.dg/uninit-13.c
@@ -5,6 +5,6 @@ typedef _Complex float C;
 C foo()
 {
   C f;
-  __imag__ f = 0;	/* { dg-warning "is used" "unconditional" } */
-  return f;
+  __imag__ f = 0;
+  return f;	/* { dg-warning "is used" "unconditional" } */
 }
diff --git a/gcc/testsuite/gcc.dg/uninit-17-O0.c b/gcc/testsuite/gcc.dg/uninit-17-O0.c
new file mode 100644
index 0000000..0eaef05
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/uninit-17-O0.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-Wuninitialized" } */
+
+typedef _Complex float C;
+C foo(int cond)
+{
+  C f;
+  __imag__ f = 0;
+  if (cond)
+    {
+      __real__ f = 1;
+      return f;
+    }
+  return f;
+}
diff --git a/gcc/testsuite/gcc.dg/uninit-17.c b/gcc/testsuite/gcc.dg/uninit-17.c
new file mode 100644
index 0000000..8a95f15
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/uninit-17.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-O -Wuninitialized" } */
+
+typedef _Complex float C;
+C foo(int cond)
+{
+  C f;
+  __imag__ f = 0;
+  if (cond)
+    {
+      __real__ f = 1;
+      return f;
+    }
+  return f;	/* { dg-warning "may be used" "unconditional" } */
+}
diff --git a/gcc/tree-complex.c b/gcc/tree-complex.c
index a97aaf9..2286e2e 100644
--- a/gcc/tree-complex.c
+++ b/gcc/tree-complex.c
@@ -831,12 +831,15 @@ expand_complex_move (gimple_stmt_iterator *gsi, tree type)
     {
       tree x;
       gimple t;
+      location_t loc;
 
+      loc = gimple_location (stmt);
       r = extract_component (gsi, rhs, 0, false);
       i = extract_component (gsi, rhs, 1, false);
 
       x = build1 (REALPART_EXPR, inner_type, unshare_expr (lhs));
       t = gimple_build_assign (x, r);
+      gimple_set_location (t, loc);
       gsi_insert_before (gsi, t, GSI_SAME_STMT);
 
       if (stmt == gsi_stmt (*gsi))
@@ -849,6 +852,7 @@ expand_complex_move (gimple_stmt_iterator *gsi, tree type)
 	{
 	  x = build1 (IMAGPART_EXPR, inner_type, unshare_expr (lhs));
 	  t = gimple_build_assign (x, i);
+	  gimple_set_location (t, loc);
 	  gsi_insert_before (gsi, t, GSI_SAME_STMT);
 
 	  stmt = gsi_stmt (*gsi);
diff --git a/gcc/tree-ssa-uninit.c b/gcc/tree-ssa-uninit.c
index ae251cc..4310e7e 100644
--- a/gcc/tree-ssa-uninit.c
+++ b/gcc/tree-ssa-uninit.c
@@ -123,17 +123,25 @@ uninit_undefined_value_p (tree t) {
 
 /* Emit a warning for EXPR based on variable VAR at the point in the
    program T, an SSA_NAME, is used being uninitialized.  The exact
-   warning text is in MSGID and LOCUS may contain a location or be null.
-   WC is the warning code.  */
+   warning text is in MSGID and DATA is the gimple stmt with info about
+   the location in source code. When DATA is a GIMPLE_PHI, PHIARG_IDX
+   gives which argument of the phi node to take the location from.  WC
+   is the warning code.  */
 
 static void
-warn_uninit (enum opt_code wc, tree t,
-	     tree expr, tree var, const char *gmsgid, void *data)
+warn_uninit (enum opt_code wc, tree t, tree expr, tree var,
+	     const char *gmsgid, void *data, location_t phiarg_loc)
 {
   gimple context = (gimple) data;
   location_t location, cfun_loc;
   expanded_location xloc, floc;
 
+  /* Ignore COMPLEX_EXPR as initializing only a part of a complex
+     turns in a COMPLEX_EXPR with the not initialized part being
+     set to its previous (undefined) value.  */
+  if (is_gimple_assign (context)
+      && gimple_assign_rhs_code (context) == COMPLEX_EXPR)
+    return;
   if (!has_undefined_value_p (t))
     return;
 
@@ -146,9 +154,12 @@ warn_uninit (enum opt_code wc, tree t,
       || TREE_NO_WARNING (expr))
     return;
 
-  location = (context != NULL && gimple_has_location (context))
-	     ? gimple_location (context)
-	     : DECL_SOURCE_LOCATION (var);
+  if (context != NULL && gimple_has_location (context))
+    location = gimple_location (context);
+  else if (phiarg_loc != UNKNOWN_LOCATION)
+    location = phiarg_loc;
+  else
+    location = DECL_SOURCE_LOCATION (var);
   location = linemap_resolve_location (line_table, location,
 				       LRK_SPELLING_LOCATION,
 				       NULL);
@@ -200,12 +211,12 @@ warn_uninitialized_vars (bool warn_possibly_uninitialized)
 		warn_uninit (OPT_Wuninitialized, use,
 			     SSA_NAME_VAR (use), SSA_NAME_VAR (use),
 			     "%qD is used uninitialized in this function",
-			     stmt);
+			     stmt, UNKNOWN_LOCATION);
 	      else if (warn_possibly_uninitialized)
 		warn_uninit (OPT_Wmaybe_uninitialized, use,
 			     SSA_NAME_VAR (use), SSA_NAME_VAR (use),
 			     "%qD may be used uninitialized in this function",
-			     stmt);
+			     stmt, UNKNOWN_LOCATION);
 	    }
 
 	  /* For memory the only cheap thing we can do is see if we
@@ -236,12 +247,12 @@ warn_uninitialized_vars (bool warn_possibly_uninitialized)
 		warn_uninit (OPT_Wuninitialized, use,
 			     gimple_assign_rhs1 (stmt), base,
 			     "%qE is used uninitialized in this function",
-			     stmt);
+			     stmt, UNKNOWN_LOCATION);
 	      else if (warn_possibly_uninitialized)
 		warn_uninit (OPT_Wmaybe_uninitialized, use,
 			     gimple_assign_rhs1 (stmt), base,
 			     "%qE may be used uninitialized in this function",
-			     stmt);
+			     stmt, UNKNOWN_LOCATION);
 	    }
 	}
     }
@@ -2247,6 +2258,8 @@ warn_uninitialized_phi (gimple phi, vec<gimple> *worklist,
   unsigned uninit_opnds;
   gimple uninit_use_stmt = 0;
   tree uninit_op;
+  int phiarg_index;
+  location_t loc;
 
   /* Don't look at virtual operands.  */
   if (virtual_operand_p (gimple_phi_result (phi)))
@@ -2271,13 +2284,18 @@ warn_uninitialized_phi (gimple phi, vec<gimple> *worklist,
   if (!uninit_use_stmt)
     return;
 
-  uninit_op = gimple_phi_arg_def (phi, MASK_FIRST_SET_BIT (uninit_opnds));
+  phiarg_index = MASK_FIRST_SET_BIT (uninit_opnds);
+  uninit_op = gimple_phi_arg_def (phi, phiarg_index);
   if (SSA_NAME_VAR (uninit_op) == NULL_TREE)
     return;
+  if (gimple_phi_arg_has_location (phi, phiarg_index))
+    loc = gimple_phi_arg_location (phi, phiarg_index);
+  else
+    loc = UNKNOWN_LOCATION;
   warn_uninit (OPT_Wmaybe_uninitialized, uninit_op, SSA_NAME_VAR (uninit_op),
 	       SSA_NAME_VAR (uninit_op),
                "%qD may be used uninitialized in this function",
-               uninit_use_stmt);
+               uninit_use_stmt, loc);
 
 }
 
diff --git a/gcc/tree-ssa.c b/gcc/tree-ssa.c
index 1ea639d..499bd06 100644
--- a/gcc/tree-ssa.c
+++ b/gcc/tree-ssa.c
@@ -1246,6 +1246,7 @@ tree_ssa_strip_useless_type_conversions (tree exp)
 bool
 ssa_undefined_value_p (tree t)
 {
+  gimple def_stmt;
   tree var = SSA_NAME_VAR (t);
 
   if (!var)
@@ -1262,7 +1263,22 @@ ssa_undefined_value_p (tree t)
     return false;
 
   /* The value is undefined iff its definition statement is empty.  */
-  return gimple_nop_p (SSA_NAME_DEF_STMT (t));
+  def_stmt = SSA_NAME_DEF_STMT (t);
+  if (gimple_nop_p (def_stmt))
+    return true;
+
+  /* Check if the complex was not only partially defined.  */
+  if (is_gimple_assign (def_stmt)
+      && gimple_assign_rhs_code (def_stmt) == COMPLEX_EXPR)
+    {
+      tree rhs1, rhs2;
+
+      rhs1 = gimple_assign_rhs1 (def_stmt);
+      rhs2 = gimple_assign_rhs2 (def_stmt);
+      return (TREE_CODE (rhs1) == SSA_NAME && ssa_undefined_value_p (rhs1))
+	     || (TREE_CODE (rhs2) == SSA_NAME && ssa_undefined_value_p (rhs2));
+    }
+  return false;
 }
 

Attachment: gcc32rm-91.1.1.diff
Description: Binary data


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