Re: C++ PATCH to tweak cp_fully_fold (PR c++/84590)

[Jason Merrill]

Ok.

On Mar 1, 2018 4:38 PM, "Marek Polacek"  wrote:

> On Thu, Mar 01, 2018 at 02:29:47PM -0500, Jason Merrill wrote:
> > I think this should happen in the block with maybe_constant_value;
> > cp_fold_rvalue doesn't do this.
>
> This, then:
>
> Bootstrapped/regtested on x86_64-linux, ok for trunk?
>
> 2018-03-01  Marek Polacek  
>
> PR c++/84590
> * cp-gimplify.c (cp_fully_fold): Unwrap TARGET_EXPR or a
> CONSTRUCTOR
> wrapped in VIEW_CONVERT_EXPR.
>
> * c-c++-common/ubsan/shift-11.c: New test.
>
> diff --git gcc/cp/cp-gimplify.c gcc/cp/cp-gimplify.c
> index 55a9d278dbe..0ddd435454c 100644
> --- gcc/cp/cp-gimplify.c
> +++ gcc/cp/cp-gimplify.c
> @@ -2037,7 +2037,17 @@ cp_fully_fold (tree x)
>/* FIXME cp_fold ought to be a superset of maybe_constant_value so we
> don't
>   have to call both.  */
>if (cxx_dialect >= cxx11)
> -x = maybe_constant_value (x);
> +{
> +  x = maybe_constant_value (x);
> +  /* Sometimes we are given a CONSTRUCTOR but the call above wraps it
> into
> +a TARGET_EXPR; undo that here.  */
> +  if (TREE_CODE (x) == TARGET_EXPR)
> +   x = TARGET_EXPR_INITIAL (x);
> +  else if (TREE_CODE (x) == VIEW_CONVERT_EXPR
> +  && TREE_CODE (TREE_OPERAND (x, 0)) == CONSTRUCTOR
> +  && TREE_TYPE (TREE_OPERAND (x, 0)) == TREE_TYPE (x))
> +   x = TREE_OPERAND (x, 0);
> +}
>return cp_fold_rvalue (x);
>  }
>
> diff --git gcc/testsuite/c-c++-common/ubsan/shift-11.c
> gcc/testsuite/c-c++-common/ubsan/shift-11.c
> index e69de29bb2d..03a72e217a2 100644
> --- gcc/testsuite/c-c++-common/ubsan/shift-11.c
> +++ gcc/testsuite/c-c++-common/ubsan/shift-11.c
> @@ -0,0 +1,13 @@
> +/* PR c++/84590 */
> +/* { dg-do compile } */
> +/* { dg-options "-fsanitize=shift" } */
> +
> +struct S {
> +  int b;
> +};
> +
> +void
> +fn (void)
> +{
> +  struct S c1 = { 1 << -1 }; /* { dg-warning "left shift" } */
> +}
>
> Marek
>

Re: C++ PATCH to tweak cp_fully_fold (PR c++/84590)

[Marek Polacek]

On Thu, Mar 01, 2018 at 02:29:47PM -0500, Jason Merrill wrote:
> I think this should happen in the block with maybe_constant_value;
> cp_fold_rvalue doesn't do this.

This, then:

Bootstrapped/regtested on x86_64-linux, ok for trunk?

2018-03-01  Marek Polacek  

PR c++/84590
* cp-gimplify.c (cp_fully_fold): Unwrap TARGET_EXPR or a CONSTRUCTOR
wrapped in VIEW_CONVERT_EXPR.

* c-c++-common/ubsan/shift-11.c: New test.

diff --git gcc/cp/cp-gimplify.c gcc/cp/cp-gimplify.c
index 55a9d278dbe..0ddd435454c 100644
--- gcc/cp/cp-gimplify.c
+++ gcc/cp/cp-gimplify.c
@@ -2037,7 +2037,17 @@ cp_fully_fold (tree x)
   /* FIXME cp_fold ought to be a superset of maybe_constant_value so we don't
  have to call both.  */
   if (cxx_dialect >= cxx11)
-x = maybe_constant_value (x);
+{
+  x = maybe_constant_value (x);
+  /* Sometimes we are given a CONSTRUCTOR but the call above wraps it into
+a TARGET_EXPR; undo that here.  */
+  if (TREE_CODE (x) == TARGET_EXPR)
+   x = TARGET_EXPR_INITIAL (x);
+  else if (TREE_CODE (x) == VIEW_CONVERT_EXPR
+  && TREE_CODE (TREE_OPERAND (x, 0)) == CONSTRUCTOR
+  && TREE_TYPE (TREE_OPERAND (x, 0)) == TREE_TYPE (x))
+   x = TREE_OPERAND (x, 0);
+}
   return cp_fold_rvalue (x);
 }
 
diff --git gcc/testsuite/c-c++-common/ubsan/shift-11.c 
gcc/testsuite/c-c++-common/ubsan/shift-11.c
index e69de29bb2d..03a72e217a2 100644
--- gcc/testsuite/c-c++-common/ubsan/shift-11.c
+++ gcc/testsuite/c-c++-common/ubsan/shift-11.c
@@ -0,0 +1,13 @@
+/* PR c++/84590 */
+/* { dg-do compile } */
+/* { dg-options "-fsanitize=shift" } */
+
+struct S {
+  int b;
+};
+
+void
+fn (void)
+{
+  struct S c1 = { 1 << -1 }; /* { dg-warning "left shift" } */
+}

Marek

Re: C++ PATCH to tweak cp_fully_fold (PR c++/84590)

[Jason Merrill]

On Thu, Mar 1, 2018 at 2:12 PM, Marek Polacek  wrote:
> In this testcase we find ourselves in split_nonconstant_init:
>
>init = cp_fully_fold (init);
>code = push_stmt_list ();
>if (split_nonconstant_init_1 (dest, init))
>
> where initially INIT was a CONSTRUCTOR, but cp_fully_fold returned
> a TARGET_EXPR.  This confuses split_nonconstant_init_1 which only expects
> a CONSTRUCTOR or a VECTOR_CST.  Jason suggested stripping TARGET_EXPRs /
> VIEW_CONVERT_EXPRs, so here it is.
>
> Bootstrapped/regtested on x86_64-linux, ok for trunk?
>
> 2018-03-01  Marek Polacek  
>
> PR c++/84590
> * cp-gimplify.c (cp_fully_fold): Unwrap TARGET_EXPR or a CONSTRUCTOR
> wrapped in VIEW_CONVERT_EXPR.
>
> * c-c++-common/ubsan/shift-11.c: New test.
>
> diff --git gcc/cp/cp-gimplify.c gcc/cp/cp-gimplify.c
> index 55a9d278dbe..1fa9c466e6b 100644
> --- gcc/cp/cp-gimplify.c
> +++ gcc/cp/cp-gimplify.c
> @@ -2038,7 +2038,18 @@ cp_fully_fold (tree x)
>   have to call both.  */
>if (cxx_dialect >= cxx11)
>  x = maybe_constant_value (x);
> -  return cp_fold_rvalue (x);
> +  x = cp_fold_rvalue (x);
> +
> +  /* Sometimes we are given a CONSTRUCTOR but 
> cxx_eval_outermost_constant_expr
> + wraps it into a TARGET_EXPR; undo that here.  */
> +  if (TREE_CODE (x) == TARGET_EXPR)
> +x = TARGET_EXPR_INITIAL (x);
> +  else if (TREE_CODE (x) == VIEW_CONVERT_EXPR
> +  && TREE_CODE (TREE_OPERAND (x, 0)) == CONSTRUCTOR
> +  && TREE_TYPE (TREE_OPERAND (x, 0)) == TREE_TYPE (x))
> +x = TREE_OPERAND (x, 0);

I think this should happen in the block with maybe_constant_value;
cp_fold_rvalue doesn't do this.

Jason

C++ PATCH to tweak cp_fully_fold (PR c++/84590)

[Marek Polacek]

In this testcase we find ourselves in split_nonconstant_init:

   init = cp_fully_fold (init);
   code = push_stmt_list ();
   if (split_nonconstant_init_1 (dest, init))

where initially INIT was a CONSTRUCTOR, but cp_fully_fold returned
a TARGET_EXPR.  This confuses split_nonconstant_init_1 which only expects
a CONSTRUCTOR or a VECTOR_CST.  Jason suggested stripping TARGET_EXPRs /
VIEW_CONVERT_EXPRs, so here it is.

Bootstrapped/regtested on x86_64-linux, ok for trunk?

2018-03-01  Marek Polacek  

PR c++/84590
* cp-gimplify.c (cp_fully_fold): Unwrap TARGET_EXPR or a CONSTRUCTOR
wrapped in VIEW_CONVERT_EXPR.

* c-c++-common/ubsan/shift-11.c: New test.

diff --git gcc/cp/cp-gimplify.c gcc/cp/cp-gimplify.c
index 55a9d278dbe..1fa9c466e6b 100644
--- gcc/cp/cp-gimplify.c
+++ gcc/cp/cp-gimplify.c
@@ -2038,7 +2038,18 @@ cp_fully_fold (tree x)
  have to call both.  */
   if (cxx_dialect >= cxx11)
 x = maybe_constant_value (x);
-  return cp_fold_rvalue (x);
+  x = cp_fold_rvalue (x);
+
+  /* Sometimes we are given a CONSTRUCTOR but cxx_eval_outermost_constant_expr
+ wraps it into a TARGET_EXPR; undo that here.  */
+  if (TREE_CODE (x) == TARGET_EXPR)
+x = TARGET_EXPR_INITIAL (x);
+  else if (TREE_CODE (x) == VIEW_CONVERT_EXPR
+  && TREE_CODE (TREE_OPERAND (x, 0)) == CONSTRUCTOR
+  && TREE_TYPE (TREE_OPERAND (x, 0)) == TREE_TYPE (x))
+x = TREE_OPERAND (x, 0);
+
+  return x;
 }
 
 /* c-common interface to cp_fold.  If IN_INIT, this is in a static initializer
diff --git gcc/testsuite/c-c++-common/ubsan/shift-11.c 
gcc/testsuite/c-c++-common/ubsan/shift-11.c
index e69de29bb2d..03a72e217a2 100644
--- gcc/testsuite/c-c++-common/ubsan/shift-11.c
+++ gcc/testsuite/c-c++-common/ubsan/shift-11.c
@@ -0,0 +1,13 @@
+/* PR c++/84590 */
+/* { dg-do compile } */
+/* { dg-options "-fsanitize=shift" } */
+
+struct S {
+  int b;
+};
+
+void
+fn (void)
+{
+  struct S c1 = { 1 << -1 }; /* { dg-warning "left shift" } */
+}

Marek