re PR target/88234 (UBsan and runtime error: signed integer overflow using unsigned vector)

	PR target/88234
	* config/rs6000/rs6000.c (rs6000_gimple_fold_builtin): For
	vec_add and vec_sub builtins, perform PLUS_EXPR or MINUS_EXPR
	in unsigned_type_for instead of vector integral type where overflow
	doesn't wrap.

	* gcc.dg/ubsan/pr88234.c: New test.

From-SVN: r266619

gcc/ChangeLog

+2018-11-29  Jakub Jelinek  <jakub@redhat.com>
+
+	PR target/88234
+	* config/rs6000/rs6000.c (rs6000_gimple_fold_builtin): For
+	vec_add and vec_sub builtins, perform PLUS_EXPR or MINUS_EXPR
+	in unsigned_type_for instead of vector integral type where overflow
+	doesn't wrap.
+
 2018-11-29  Michael Ploujnikov  <michael.ploujnikov@oracle.com>
 
 	There can be at most one .resolver clone per function

gcc/config/rs6000/rs6000.c

@@ -15371,6 +15371,7 @@ rs6000_gimple_fold_builtin (gimple_stmt_iterator *gsi)
   enum rs6000_builtins fn_code
     = (enum rs6000_builtins) DECL_FUNCTION_CODE (fndecl);
   tree arg0, arg1, lhs, temp;
+  enum tree_code bcode;
   gimple *g;
 
   size_t uns_fncode = (size_t) fn_code;
@@ -15409,10 +15410,32 @@ rs6000_gimple_fold_builtin (gimple_stmt_iterator *gsi)
     case P8V_BUILTIN_VADDUDM:
     case ALTIVEC_BUILTIN_VADDFP:
     case VSX_BUILTIN_XVADDDP:
+      bcode = PLUS_EXPR;
+    do_binary:
       arg0 = gimple_call_arg (stmt, 0);
       arg1 = gimple_call_arg (stmt, 1);
       lhs = gimple_call_lhs (stmt);
-      g = gimple_build_assign (lhs, PLUS_EXPR, arg0, arg1);
+      if (INTEGRAL_TYPE_P (TREE_TYPE (TREE_TYPE (lhs)))
+	  && !TYPE_OVERFLOW_WRAPS (TREE_TYPE (TREE_TYPE (lhs))))
+	{
+	  /* Ensure the binary operation is performed in a type
+	     that wraps if it is integral type.  */
+	  gimple_seq stmts = NULL;
+	  tree type = unsigned_type_for (TREE_TYPE (lhs));
+	  tree uarg0 = gimple_build (&stmts, VIEW_CONVERT_EXPR,
+				     type, arg0);
+	  tree uarg1 = gimple_build (&stmts, VIEW_CONVERT_EXPR,
+				     type, arg1);
+	  tree res = gimple_build (&stmts, gimple_location (stmt), bcode,
+				   type, uarg0, uarg1);
+	  gsi_insert_seq_before (gsi, stmts, GSI_SAME_STMT);
+	  g = gimple_build_assign (lhs, VIEW_CONVERT_EXPR,
+				   build1 (VIEW_CONVERT_EXPR,
+					   TREE_TYPE (lhs), res));
+	  gsi_replace (gsi, g, true);
+	  return true;
+	}
+      g = gimple_build_assign (lhs, bcode, arg0, arg1);
       gimple_set_location (g, gimple_location (stmt));
       gsi_replace (gsi, g, true);
       return true;
@@ -15424,13 +15447,8 @@ rs6000_gimple_fold_builtin (gimple_stmt_iterator *gsi)
     case P8V_BUILTIN_VSUBUDM:
     case ALTIVEC_BUILTIN_VSUBFP:
     case VSX_BUILTIN_XVSUBDP:
-      arg0 = gimple_call_arg (stmt, 0);
-      arg1 = gimple_call_arg (stmt, 1);
-      lhs = gimple_call_lhs (stmt);
-      g = gimple_build_assign (lhs, MINUS_EXPR, arg0, arg1);
-      gimple_set_location (g, gimple_location (stmt));
-      gsi_replace (gsi, g, true);
-      return true;
+      bcode = MINUS_EXPR;
+      goto do_binary;
     case VSX_BUILTIN_XVMULSP:
     case VSX_BUILTIN_XVMULDP:
       arg0 = gimple_call_arg (stmt, 0);

gcc/testsuite/ChangeLog

+2018-11-29  Jakub Jelinek  <jakub@redhat.com>
+
+	PR target/88234
+	* gcc.dg/ubsan/pr88234.c: New test.
+
 2018-11-29  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/88243

gcc/testsuite/gcc.dg/ubsan/pr88234.c

+/* PR target/88234 */
+/* { dg-do run { target { powerpc*-*-* && vmx_hw } } } */
+/* { dg-require-effective-target powerpc_altivec_ok } */
+/* { dg-options "-fsanitize=signed-integer-overflow -fno-sanitize-recover=signed-integer-overflow -O2 -maltivec" } */
+
+#include <altivec.h>
+
+__attribute__((noipa)) vector unsigned int
+f1 (vector unsigned int x, vector unsigned int y)
+{
+  return vec_add (x, y);
+}
+
+__attribute__((noipa)) vector unsigned int
+f2 (vector unsigned int x, vector unsigned int y)
+{
+  return vec_sub (x, y);
+}
+
+int
+main ()
+{
+  vector unsigned int x = { __INT_MAX__, -__INT_MAX__, __INT_MAX__ - 3, -__INT_MAX__ + 4 };
+  vector unsigned int y = { 1, -1, 4, -5 };
+  vector unsigned int z = f1 (x, y);
+  f2 (z, x);
+  f2 (z, y);
+  return 0;
+}