[RFA(tree)] c++: source position of lambda captures [PR84471]
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Commit Message
Tested x86_64-pc-linux-gnu, OK for trunk?
-- 8< --
If the DECL_VALUE_EXPR of a VAR_DECL has EXPR_LOCATION set, then any use of
that variable looks like it has that location, which leads to the debugger
jumping back and forth for both lambdas and structured bindings.
Rather than fix all the uses, it seems simplest to remove any EXPR_LOCATION
when setting DECL_VALUE_EXPR. So the cp/ hunks aren't necessary, but it
seems cleaner not to work to add a location that will immediately get
stripped.
PR c++/84471
PR c++/107504
gcc/cp/ChangeLog:
* coroutines.cc (transform_local_var_uses): Don't
specify a location for DECL_VALUE_EXPR.
* decl.cc (cp_finish_decomp): Likewise.
gcc/ChangeLog:
* tree.cc (decl_value_expr_insert): Clear EXPR_LOCATION.
gcc/testsuite/ChangeLog:
* g++.dg/tree-ssa/value-expr1.C: New test.
* g++.dg/tree-ssa/value-expr2.C: New test.
* g++.dg/analyzer/pr93212.C: Move warning.
---
gcc/cp/coroutines.cc | 4 ++--
gcc/cp/decl.cc | 12 +++-------
gcc/testsuite/g++.dg/analyzer/pr93212.C | 4 ++--
gcc/testsuite/g++.dg/tree-ssa/value-expr1.C | 16 +++++++++++++
gcc/testsuite/g++.dg/tree-ssa/value-expr2.C | 26 +++++++++++++++++++++
gcc/tree.cc | 3 +++
6 files changed, 52 insertions(+), 13 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/tree-ssa/value-expr1.C
create mode 100644 gcc/testsuite/g++.dg/tree-ssa/value-expr2.C
base-commit: 70596a0fb2a2ec072e1e97e37616e05041dfa4e5
Comments
Ping.
On 12/2/22 10:45, Jason Merrill wrote:
> Tested x86_64-pc-linux-gnu, OK for trunk?
>
> -- 8< --
>
> If the DECL_VALUE_EXPR of a VAR_DECL has EXPR_LOCATION set, then any use of
> that variable looks like it has that location, which leads to the debugger
> jumping back and forth for both lambdas and structured bindings.
>
> Rather than fix all the uses, it seems simplest to remove any EXPR_LOCATION
> when setting DECL_VALUE_EXPR. So the cp/ hunks aren't necessary, but it
> seems cleaner not to work to add a location that will immediately get
> stripped.
>
> PR c++/84471
> PR c++/107504
>
> gcc/cp/ChangeLog:
>
> * coroutines.cc (transform_local_var_uses): Don't
> specify a location for DECL_VALUE_EXPR.
> * decl.cc (cp_finish_decomp): Likewise.
>
> gcc/ChangeLog:
>
> * tree.cc (decl_value_expr_insert): Clear EXPR_LOCATION.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/tree-ssa/value-expr1.C: New test.
> * g++.dg/tree-ssa/value-expr2.C: New test.
> * g++.dg/analyzer/pr93212.C: Move warning.
> ---
> gcc/cp/coroutines.cc | 4 ++--
> gcc/cp/decl.cc | 12 +++-------
> gcc/testsuite/g++.dg/analyzer/pr93212.C | 4 ++--
> gcc/testsuite/g++.dg/tree-ssa/value-expr1.C | 16 +++++++++++++
> gcc/testsuite/g++.dg/tree-ssa/value-expr2.C | 26 +++++++++++++++++++++
> gcc/tree.cc | 3 +++
> 6 files changed, 52 insertions(+), 13 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/tree-ssa/value-expr1.C
> create mode 100644 gcc/testsuite/g++.dg/tree-ssa/value-expr2.C
>
> diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
> index 01a3e831ee5..a72bd6bbef0 100644
> --- a/gcc/cp/coroutines.cc
> +++ b/gcc/cp/coroutines.cc
> @@ -2047,8 +2047,8 @@ transform_local_var_uses (tree *stmt, int *do_subtree, void *d)
> = lookup_member (lvd->coro_frame_type, local_var.field_id,
> /*protect=*/1, /*want_type=*/0,
> tf_warning_or_error);
> - tree fld_idx = build3_loc (lvd->loc, COMPONENT_REF, TREE_TYPE (lvar),
> - lvd->actor_frame, fld_ref, NULL_TREE);
> + tree fld_idx = build3 (COMPONENT_REF, TREE_TYPE (lvar),
> + lvd->actor_frame, fld_ref, NULL_TREE);
> local_var.field_idx = fld_idx;
> SET_DECL_VALUE_EXPR (lvar, fld_idx);
> DECL_HAS_VALUE_EXPR_P (lvar) = true;
> diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
> index 7af0b05d5f8..59e21581503 100644
> --- a/gcc/cp/decl.cc
> +++ b/gcc/cp/decl.cc
> @@ -9133,9 +9133,7 @@ cp_finish_decomp (tree decl, tree first, unsigned int count)
> if (processing_template_decl)
> continue;
> tree t = unshare_expr (dexp);
> - t = build4_loc (DECL_SOURCE_LOCATION (v[i]), ARRAY_REF,
> - eltype, t, size_int (i), NULL_TREE,
> - NULL_TREE);
> + t = build4 (ARRAY_REF, eltype, t, size_int (i), NULL_TREE, NULL_TREE);
> SET_DECL_VALUE_EXPR (v[i], t);
> DECL_HAS_VALUE_EXPR_P (v[i]) = 1;
> }
> @@ -9154,9 +9152,7 @@ cp_finish_decomp (tree decl, tree first, unsigned int count)
> if (processing_template_decl)
> continue;
> tree t = unshare_expr (dexp);
> - t = build1_loc (DECL_SOURCE_LOCATION (v[i]),
> - i ? IMAGPART_EXPR : REALPART_EXPR, eltype,
> - t);
> + t = build1 (i ? IMAGPART_EXPR : REALPART_EXPR, eltype, t);
> SET_DECL_VALUE_EXPR (v[i], t);
> DECL_HAS_VALUE_EXPR_P (v[i]) = 1;
> }
> @@ -9180,9 +9176,7 @@ cp_finish_decomp (tree decl, tree first, unsigned int count)
> tree t = unshare_expr (dexp);
> convert_vector_to_array_for_subscript (DECL_SOURCE_LOCATION (v[i]),
> &t, size_int (i));
> - t = build4_loc (DECL_SOURCE_LOCATION (v[i]), ARRAY_REF,
> - eltype, t, size_int (i), NULL_TREE,
> - NULL_TREE);
> + t = build4 (ARRAY_REF, eltype, t, size_int (i), NULL_TREE, NULL_TREE);
> SET_DECL_VALUE_EXPR (v[i], t);
> DECL_HAS_VALUE_EXPR_P (v[i]) = 1;
> }
> diff --git a/gcc/testsuite/g++.dg/analyzer/pr93212.C b/gcc/testsuite/g++.dg/analyzer/pr93212.C
> index 41507e2b837..1029e8d547b 100644
> --- a/gcc/testsuite/g++.dg/analyzer/pr93212.C
> +++ b/gcc/testsuite/g++.dg/analyzer/pr93212.C
> @@ -4,8 +4,8 @@
> auto lol()
> {
> int aha = 3;
> - return [&aha] { // { dg-warning "dereferencing pointer '.*' to within stale stack frame" }
> - return aha;
> + return [&aha] {
> + return aha; // { dg-warning "dereferencing pointer '.*' to within stale stack frame" }
> };
> /* TODO: may be worth special-casing the reporting of dangling
> references from lambdas, to highlight the declaration, and maybe fix
> diff --git a/gcc/testsuite/g++.dg/tree-ssa/value-expr1.C b/gcc/testsuite/g++.dg/tree-ssa/value-expr1.C
> new file mode 100644
> index 00000000000..946ccc3bd97
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/tree-ssa/value-expr1.C
> @@ -0,0 +1,16 @@
> +// PR c++/84471
> +// { dg-do compile { target c++11 } }
> +// { dg-additional-options -fdump-tree-gimple-lineno }
> +// { dg-final { scan-tree-dump-not {value-expr: \[} "gimple" } }
> +
> +int main(int argc, char**)
> +{
> + int x = 1;
> + auto f = [&x, &argc](const char* i) {
> + i += x;
> + i -= argc;
> + i += argc - x;
> + return i;
> + };
> + f(" ");
> +}
> diff --git a/gcc/testsuite/g++.dg/tree-ssa/value-expr2.C b/gcc/testsuite/g++.dg/tree-ssa/value-expr2.C
> new file mode 100644
> index 00000000000..4d00498f214
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/tree-ssa/value-expr2.C
> @@ -0,0 +1,26 @@
> +// PR c++/107504
> +// { dg-do compile { target c++17 } }
> +// { dg-additional-options -fdump-tree-gimple-lineno }
> +// { dg-final { scan-tree-dump-not {value-expr: \[} "gimple" } }
> +
> +struct S
> +{
> + void* i;
> + int j;
> +};
> +
> +S f(char* p)
> +{
> + return {p, 1};
> +}
> +
> +int main()
> +{
> + char buf[1];
> + auto [x, y] = f(buf);
> + if (x != buf)
> + throw 1;
> + if (y != 1)
> + throw 2;
> + return 0;
> +}
> diff --git a/gcc/tree.cc b/gcc/tree.cc
> index 254b2373dcf..836c51cd4d5 100644
> --- a/gcc/tree.cc
> +++ b/gcc/tree.cc
> @@ -5862,6 +5862,9 @@ decl_value_expr_insert (tree from, tree to)
> {
> struct tree_decl_map *h;
>
> + /* Uses of FROM shouldn't look like they happen at the location of TO. */
> + protected_set_expr_location (to, UNKNOWN_LOCATION);
> +
> h = ggc_alloc<tree_decl_map> ();
> h->base.from = from;
> h->to = to;
>
> base-commit: 70596a0fb2a2ec072e1e97e37616e05041dfa4e5
On 12/2/22 10:45, Jason Merrill wrote:
> Tested x86_64-pc-linux-gnu, OK for trunk?
>
> -- 8< --
>
> If the DECL_VALUE_EXPR of a VAR_DECL has EXPR_LOCATION set, then any use of
> that variable looks like it has that location, which leads to the debugger
> jumping back and forth for both lambdas and structured bindings.
>
> Rather than fix all the uses, it seems simplest to remove any EXPR_LOCATION
> when setting DECL_VALUE_EXPR. So the cp/ hunks aren't necessary, but it
> seems cleaner not to work to add a location that will immediately get
> stripped.
>
> PR c++/84471
> PR c++/107504
>
> gcc/cp/ChangeLog:
>
> * coroutines.cc (transform_local_var_uses): Don't
> specify a location for DECL_VALUE_EXPR.
> * decl.cc (cp_finish_decomp): Likewise.
>
> gcc/ChangeLog:
>
> * tree.cc (decl_value_expr_insert): Clear EXPR_LOCATION.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/tree-ssa/value-expr1.C: New test.
> * g++.dg/tree-ssa/value-expr2.C: New test.
> * g++.dg/analyzer/pr93212.C: Move warning.
> ---
> gcc/cp/coroutines.cc | 4 ++--
> gcc/cp/decl.cc | 12 +++-------
> gcc/testsuite/g++.dg/analyzer/pr93212.C | 4 ++--
> gcc/testsuite/g++.dg/tree-ssa/value-expr1.C | 16 +++++++++++++
> gcc/testsuite/g++.dg/tree-ssa/value-expr2.C | 26 +++++++++++++++++++++
> gcc/tree.cc | 3 +++
> 6 files changed, 52 insertions(+), 13 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/tree-ssa/value-expr1.C
> create mode 100644 gcc/testsuite/g++.dg/tree-ssa/value-expr2.C
>
> diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
> index 01a3e831ee5..a72bd6bbef0 100644
> --- a/gcc/cp/coroutines.cc
> +++ b/gcc/cp/coroutines.cc
> @@ -2047,8 +2047,8 @@ transform_local_var_uses (tree *stmt, int *do_subtree, void *d)
> = lookup_member (lvd->coro_frame_type, local_var.field_id,
> /*protect=*/1, /*want_type=*/0,
> tf_warning_or_error);
> - tree fld_idx = build3_loc (lvd->loc, COMPONENT_REF, TREE_TYPE (lvar),
> - lvd->actor_frame, fld_ref, NULL_TREE);
> + tree fld_idx = build3 (COMPONENT_REF, TREE_TYPE (lvar),
> + lvd->actor_frame, fld_ref, NULL_TREE);
> local_var.field_idx = fld_idx;
> SET_DECL_VALUE_EXPR (lvar, fld_idx);
> DECL_HAS_VALUE_EXPR_P (lvar) = true;
> diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
> index 7af0b05d5f8..59e21581503 100644
> --- a/gcc/cp/decl.cc
> +++ b/gcc/cp/decl.cc
> @@ -9133,9 +9133,7 @@ cp_finish_decomp (tree decl, tree first, unsigned int count)
> if (processing_template_decl)
> continue;
> tree t = unshare_expr (dexp);
> - t = build4_loc (DECL_SOURCE_LOCATION (v[i]), ARRAY_REF,
> - eltype, t, size_int (i), NULL_TREE,
> - NULL_TREE);
> + t = build4 (ARRAY_REF, eltype, t, size_int (i), NULL_TREE, NULL_TREE);
> SET_DECL_VALUE_EXPR (v[i], t);
> DECL_HAS_VALUE_EXPR_P (v[i]) = 1;
> }
> @@ -9154,9 +9152,7 @@ cp_finish_decomp (tree decl, tree first, unsigned int count)
> if (processing_template_decl)
> continue;
> tree t = unshare_expr (dexp);
> - t = build1_loc (DECL_SOURCE_LOCATION (v[i]),
> - i ? IMAGPART_EXPR : REALPART_EXPR, eltype,
> - t);
> + t = build1 (i ? IMAGPART_EXPR : REALPART_EXPR, eltype, t);
> SET_DECL_VALUE_EXPR (v[i], t);
> DECL_HAS_VALUE_EXPR_P (v[i]) = 1;
> }
> @@ -9180,9 +9176,7 @@ cp_finish_decomp (tree decl, tree first, unsigned int count)
> tree t = unshare_expr (dexp);
> convert_vector_to_array_for_subscript (DECL_SOURCE_LOCATION (v[i]),
> &t, size_int (i));
> - t = build4_loc (DECL_SOURCE_LOCATION (v[i]), ARRAY_REF,
> - eltype, t, size_int (i), NULL_TREE,
> - NULL_TREE);
> + t = build4 (ARRAY_REF, eltype, t, size_int (i), NULL_TREE, NULL_TREE);
> SET_DECL_VALUE_EXPR (v[i], t);
> DECL_HAS_VALUE_EXPR_P (v[i]) = 1;
> }
> diff --git a/gcc/testsuite/g++.dg/analyzer/pr93212.C b/gcc/testsuite/g++.dg/analyzer/pr93212.C
> index 41507e2b837..1029e8d547b 100644
> --- a/gcc/testsuite/g++.dg/analyzer/pr93212.C
> +++ b/gcc/testsuite/g++.dg/analyzer/pr93212.C
> @@ -4,8 +4,8 @@
> auto lol()
> {
> int aha = 3;
> - return [&aha] { // { dg-warning "dereferencing pointer '.*' to within stale stack frame" }
> - return aha;
> + return [&aha] {
> + return aha; // { dg-warning "dereferencing pointer '.*' to within stale stack frame" }
> };
> /* TODO: may be worth special-casing the reporting of dangling
> references from lambdas, to highlight the declaration, and maybe fix
> diff --git a/gcc/testsuite/g++.dg/tree-ssa/value-expr1.C b/gcc/testsuite/g++.dg/tree-ssa/value-expr1.C
> new file mode 100644
> index 00000000000..946ccc3bd97
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/tree-ssa/value-expr1.C
> @@ -0,0 +1,16 @@
> +// PR c++/84471
> +// { dg-do compile { target c++11 } }
> +// { dg-additional-options -fdump-tree-gimple-lineno }
> +// { dg-final { scan-tree-dump-not {value-expr: \[} "gimple" } }
> +
> +int main(int argc, char**)
> +{
> + int x = 1;
> + auto f = [&x, &argc](const char* i) {
> + i += x;
> + i -= argc;
> + i += argc - x;
> + return i;
> + };
> + f(" ");
> +}
> diff --git a/gcc/testsuite/g++.dg/tree-ssa/value-expr2.C b/gcc/testsuite/g++.dg/tree-ssa/value-expr2.C
> new file mode 100644
> index 00000000000..4d00498f214
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/tree-ssa/value-expr2.C
> @@ -0,0 +1,26 @@
> +// PR c++/107504
> +// { dg-do compile { target c++17 } }
> +// { dg-additional-options -fdump-tree-gimple-lineno }
> +// { dg-final { scan-tree-dump-not {value-expr: \[} "gimple" } }
> +
> +struct S
> +{
> + void* i;
> + int j;
> +};
> +
> +S f(char* p)
> +{
> + return {p, 1};
> +}
> +
> +int main()
> +{
> + char buf[1];
> + auto [x, y] = f(buf);
> + if (x != buf)
> + throw 1;
> + if (y != 1)
> + throw 2;
> + return 0;
> +}
> diff --git a/gcc/tree.cc b/gcc/tree.cc
> index 254b2373dcf..836c51cd4d5 100644
> --- a/gcc/tree.cc
> +++ b/gcc/tree.cc
> @@ -5862,6 +5862,9 @@ decl_value_expr_insert (tree from, tree to)
> {
> struct tree_decl_map *h;
>
> + /* Uses of FROM shouldn't look like they happen at the location of TO. */
> + protected_set_expr_location (to, UNKNOWN_LOCATION);
> +
> h = ggc_alloc<tree_decl_map> ();
> h->base.from = from;
> h->to = to;
>
> base-commit: 70596a0fb2a2ec072e1e97e37616e05041dfa4e5
On Fri, Dec 2, 2022 at 4:46 PM Jason Merrill via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> Tested x86_64-pc-linux-gnu, OK for trunk?
>
> -- 8< --
>
> If the DECL_VALUE_EXPR of a VAR_DECL has EXPR_LOCATION set, then any use of
> that variable looks like it has that location, which leads to the debugger
> jumping back and forth for both lambdas and structured bindings.
>
> Rather than fix all the uses, it seems simplest to remove any EXPR_LOCATION
> when setting DECL_VALUE_EXPR. So the cp/ hunks aren't necessary, but it
> seems cleaner not to work to add a location that will immediately get
> stripped.
>
> PR c++/84471
> PR c++/107504
>
> gcc/cp/ChangeLog:
>
> * coroutines.cc (transform_local_var_uses): Don't
> specify a location for DECL_VALUE_EXPR.
> * decl.cc (cp_finish_decomp): Likewise.
>
> gcc/ChangeLog:
>
> * tree.cc (decl_value_expr_insert): Clear EXPR_LOCATION.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/tree-ssa/value-expr1.C: New test.
> * g++.dg/tree-ssa/value-expr2.C: New test.
> * g++.dg/analyzer/pr93212.C: Move warning.
> ---
> gcc/cp/coroutines.cc | 4 ++--
> gcc/cp/decl.cc | 12 +++-------
> gcc/testsuite/g++.dg/analyzer/pr93212.C | 4 ++--
> gcc/testsuite/g++.dg/tree-ssa/value-expr1.C | 16 +++++++++++++
> gcc/testsuite/g++.dg/tree-ssa/value-expr2.C | 26 +++++++++++++++++++++
> gcc/tree.cc | 3 +++
> 6 files changed, 52 insertions(+), 13 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/tree-ssa/value-expr1.C
> create mode 100644 gcc/testsuite/g++.dg/tree-ssa/value-expr2.C
>
> diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
> index 01a3e831ee5..a72bd6bbef0 100644
> --- a/gcc/cp/coroutines.cc
> +++ b/gcc/cp/coroutines.cc
> @@ -2047,8 +2047,8 @@ transform_local_var_uses (tree *stmt, int *do_subtree, void *d)
> = lookup_member (lvd->coro_frame_type, local_var.field_id,
> /*protect=*/1, /*want_type=*/0,
> tf_warning_or_error);
> - tree fld_idx = build3_loc (lvd->loc, COMPONENT_REF, TREE_TYPE (lvar),
> - lvd->actor_frame, fld_ref, NULL_TREE);
> + tree fld_idx = build3 (COMPONENT_REF, TREE_TYPE (lvar),
> + lvd->actor_frame, fld_ref, NULL_TREE);
> local_var.field_idx = fld_idx;
> SET_DECL_VALUE_EXPR (lvar, fld_idx);
> DECL_HAS_VALUE_EXPR_P (lvar) = true;
> diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
> index 7af0b05d5f8..59e21581503 100644
> --- a/gcc/cp/decl.cc
> +++ b/gcc/cp/decl.cc
> @@ -9133,9 +9133,7 @@ cp_finish_decomp (tree decl, tree first, unsigned int count)
> if (processing_template_decl)
> continue;
> tree t = unshare_expr (dexp);
> - t = build4_loc (DECL_SOURCE_LOCATION (v[i]), ARRAY_REF,
> - eltype, t, size_int (i), NULL_TREE,
> - NULL_TREE);
> + t = build4 (ARRAY_REF, eltype, t, size_int (i), NULL_TREE, NULL_TREE);
> SET_DECL_VALUE_EXPR (v[i], t);
> DECL_HAS_VALUE_EXPR_P (v[i]) = 1;
> }
> @@ -9154,9 +9152,7 @@ cp_finish_decomp (tree decl, tree first, unsigned int count)
> if (processing_template_decl)
> continue;
> tree t = unshare_expr (dexp);
> - t = build1_loc (DECL_SOURCE_LOCATION (v[i]),
> - i ? IMAGPART_EXPR : REALPART_EXPR, eltype,
> - t);
> + t = build1 (i ? IMAGPART_EXPR : REALPART_EXPR, eltype, t);
> SET_DECL_VALUE_EXPR (v[i], t);
> DECL_HAS_VALUE_EXPR_P (v[i]) = 1;
> }
> @@ -9180,9 +9176,7 @@ cp_finish_decomp (tree decl, tree first, unsigned int count)
> tree t = unshare_expr (dexp);
> convert_vector_to_array_for_subscript (DECL_SOURCE_LOCATION (v[i]),
> &t, size_int (i));
> - t = build4_loc (DECL_SOURCE_LOCATION (v[i]), ARRAY_REF,
> - eltype, t, size_int (i), NULL_TREE,
> - NULL_TREE);
> + t = build4 (ARRAY_REF, eltype, t, size_int (i), NULL_TREE, NULL_TREE);
> SET_DECL_VALUE_EXPR (v[i], t);
> DECL_HAS_VALUE_EXPR_P (v[i]) = 1;
> }
> diff --git a/gcc/testsuite/g++.dg/analyzer/pr93212.C b/gcc/testsuite/g++.dg/analyzer/pr93212.C
> index 41507e2b837..1029e8d547b 100644
> --- a/gcc/testsuite/g++.dg/analyzer/pr93212.C
> +++ b/gcc/testsuite/g++.dg/analyzer/pr93212.C
> @@ -4,8 +4,8 @@
> auto lol()
> {
> int aha = 3;
> - return [&aha] { // { dg-warning "dereferencing pointer '.*' to within stale stack frame" }
> - return aha;
> + return [&aha] {
> + return aha; // { dg-warning "dereferencing pointer '.*' to within stale stack frame" }
> };
> /* TODO: may be worth special-casing the reporting of dangling
> references from lambdas, to highlight the declaration, and maybe fix
> diff --git a/gcc/testsuite/g++.dg/tree-ssa/value-expr1.C b/gcc/testsuite/g++.dg/tree-ssa/value-expr1.C
> new file mode 100644
> index 00000000000..946ccc3bd97
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/tree-ssa/value-expr1.C
> @@ -0,0 +1,16 @@
> +// PR c++/84471
> +// { dg-do compile { target c++11 } }
> +// { dg-additional-options -fdump-tree-gimple-lineno }
> +// { dg-final { scan-tree-dump-not {value-expr: \[} "gimple" } }
> +
> +int main(int argc, char**)
> +{
> + int x = 1;
> + auto f = [&x, &argc](const char* i) {
> + i += x;
> + i -= argc;
> + i += argc - x;
> + return i;
> + };
> + f(" ");
> +}
> diff --git a/gcc/testsuite/g++.dg/tree-ssa/value-expr2.C b/gcc/testsuite/g++.dg/tree-ssa/value-expr2.C
> new file mode 100644
> index 00000000000..4d00498f214
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/tree-ssa/value-expr2.C
> @@ -0,0 +1,26 @@
> +// PR c++/107504
> +// { dg-do compile { target c++17 } }
> +// { dg-additional-options -fdump-tree-gimple-lineno }
> +// { dg-final { scan-tree-dump-not {value-expr: \[} "gimple" } }
> +
> +struct S
> +{
> + void* i;
> + int j;
> +};
> +
> +S f(char* p)
> +{
> + return {p, 1};
> +}
> +
> +int main()
> +{
> + char buf[1];
> + auto [x, y] = f(buf);
> + if (x != buf)
> + throw 1;
> + if (y != 1)
> + throw 2;
> + return 0;
> +}
> diff --git a/gcc/tree.cc b/gcc/tree.cc
> index 254b2373dcf..836c51cd4d5 100644
> --- a/gcc/tree.cc
> +++ b/gcc/tree.cc
> @@ -5862,6 +5862,9 @@ decl_value_expr_insert (tree from, tree to)
> {
> struct tree_decl_map *h;
>
> + /* Uses of FROM shouldn't look like they happen at the location of TO. */
> + protected_set_expr_location (to, UNKNOWN_LOCATION);
> +
Doesn't that mean we'd eventually want unshare_expr_without_location
or similar here? Or rather maybe set the location of TO to that of
FROM? That said, this modifies FROM in place - we have
protected_set_expr_location_unshare (would need to be exported
from fold-const.cc) to avoid clobbering a possibly shared tree.
Maybe it would be easier to handle this in the consumers of the
DECL_VALUE_EXPR? gimplify_var_or_parm_decl does
/* If the decl is an alias for another expression, substitute it now. */
if (DECL_HAS_VALUE_EXPR_P (decl))
{
*expr_p = unshare_expr (DECL_VALUE_EXPR (decl));
return GS_OK;
it could also unshare without location.
> h = ggc_alloc<tree_decl_map> ();
> h->base.from = from;
> h->to = to;
>
> base-commit: 70596a0fb2a2ec072e1e97e37616e05041dfa4e5
> --
> 2.31.1
>
On 12/20/22 07:07, Richard Biener wrote:
> On Fri, Dec 2, 2022 at 4:46 PM Jason Merrill via Gcc-patches
> <gcc-patches@gcc.gnu.org> wrote:
>>
>> Tested x86_64-pc-linux-gnu, OK for trunk?
>>
>> -- 8< --
>>
>> If the DECL_VALUE_EXPR of a VAR_DECL has EXPR_LOCATION set, then any use of
>> that variable looks like it has that location, which leads to the debugger
>> jumping back and forth for both lambdas and structured bindings.
>>
>> Rather than fix all the uses, it seems simplest to remove any EXPR_LOCATION
>> when setting DECL_VALUE_EXPR. So the cp/ hunks aren't necessary, but it
>> seems cleaner not to work to add a location that will immediately get
>> stripped.
>>
>> PR c++/84471
>> PR c++/107504
>>
>> gcc/cp/ChangeLog:
>>
>> * coroutines.cc (transform_local_var_uses): Don't
>> specify a location for DECL_VALUE_EXPR.
>> * decl.cc (cp_finish_decomp): Likewise.
>>
>> gcc/ChangeLog:
>>
>> * tree.cc (decl_value_expr_insert): Clear EXPR_LOCATION.
>>
>> gcc/testsuite/ChangeLog:
>>
>> * g++.dg/tree-ssa/value-expr1.C: New test.
>> * g++.dg/tree-ssa/value-expr2.C: New test.
>> * g++.dg/analyzer/pr93212.C: Move warning.
>> ---
>> gcc/cp/coroutines.cc | 4 ++--
>> gcc/cp/decl.cc | 12 +++-------
>> gcc/testsuite/g++.dg/analyzer/pr93212.C | 4 ++--
>> gcc/testsuite/g++.dg/tree-ssa/value-expr1.C | 16 +++++++++++++
>> gcc/testsuite/g++.dg/tree-ssa/value-expr2.C | 26 +++++++++++++++++++++
>> gcc/tree.cc | 3 +++
>> 6 files changed, 52 insertions(+), 13 deletions(-)
>> create mode 100644 gcc/testsuite/g++.dg/tree-ssa/value-expr1.C
>> create mode 100644 gcc/testsuite/g++.dg/tree-ssa/value-expr2.C
>>
>> diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
>> index 01a3e831ee5..a72bd6bbef0 100644
>> --- a/gcc/cp/coroutines.cc
>> +++ b/gcc/cp/coroutines.cc
>> @@ -2047,8 +2047,8 @@ transform_local_var_uses (tree *stmt, int *do_subtree, void *d)
>> = lookup_member (lvd->coro_frame_type, local_var.field_id,
>> /*protect=*/1, /*want_type=*/0,
>> tf_warning_or_error);
>> - tree fld_idx = build3_loc (lvd->loc, COMPONENT_REF, TREE_TYPE (lvar),
>> - lvd->actor_frame, fld_ref, NULL_TREE);
>> + tree fld_idx = build3 (COMPONENT_REF, TREE_TYPE (lvar),
>> + lvd->actor_frame, fld_ref, NULL_TREE);
>> local_var.field_idx = fld_idx;
>> SET_DECL_VALUE_EXPR (lvar, fld_idx);
>> DECL_HAS_VALUE_EXPR_P (lvar) = true;
>> diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
>> index 7af0b05d5f8..59e21581503 100644
>> --- a/gcc/cp/decl.cc
>> +++ b/gcc/cp/decl.cc
>> @@ -9133,9 +9133,7 @@ cp_finish_decomp (tree decl, tree first, unsigned int count)
>> if (processing_template_decl)
>> continue;
>> tree t = unshare_expr (dexp);
>> - t = build4_loc (DECL_SOURCE_LOCATION (v[i]), ARRAY_REF,
>> - eltype, t, size_int (i), NULL_TREE,
>> - NULL_TREE);
>> + t = build4 (ARRAY_REF, eltype, t, size_int (i), NULL_TREE, NULL_TREE);
>> SET_DECL_VALUE_EXPR (v[i], t);
>> DECL_HAS_VALUE_EXPR_P (v[i]) = 1;
>> }
>> @@ -9154,9 +9152,7 @@ cp_finish_decomp (tree decl, tree first, unsigned int count)
>> if (processing_template_decl)
>> continue;
>> tree t = unshare_expr (dexp);
>> - t = build1_loc (DECL_SOURCE_LOCATION (v[i]),
>> - i ? IMAGPART_EXPR : REALPART_EXPR, eltype,
>> - t);
>> + t = build1 (i ? IMAGPART_EXPR : REALPART_EXPR, eltype, t);
>> SET_DECL_VALUE_EXPR (v[i], t);
>> DECL_HAS_VALUE_EXPR_P (v[i]) = 1;
>> }
>> @@ -9180,9 +9176,7 @@ cp_finish_decomp (tree decl, tree first, unsigned int count)
>> tree t = unshare_expr (dexp);
>> convert_vector_to_array_for_subscript (DECL_SOURCE_LOCATION (v[i]),
>> &t, size_int (i));
>> - t = build4_loc (DECL_SOURCE_LOCATION (v[i]), ARRAY_REF,
>> - eltype, t, size_int (i), NULL_TREE,
>> - NULL_TREE);
>> + t = build4 (ARRAY_REF, eltype, t, size_int (i), NULL_TREE, NULL_TREE);
>> SET_DECL_VALUE_EXPR (v[i], t);
>> DECL_HAS_VALUE_EXPR_P (v[i]) = 1;
>> }
>> diff --git a/gcc/testsuite/g++.dg/analyzer/pr93212.C b/gcc/testsuite/g++.dg/analyzer/pr93212.C
>> index 41507e2b837..1029e8d547b 100644
>> --- a/gcc/testsuite/g++.dg/analyzer/pr93212.C
>> +++ b/gcc/testsuite/g++.dg/analyzer/pr93212.C
>> @@ -4,8 +4,8 @@
>> auto lol()
>> {
>> int aha = 3;
>> - return [&aha] { // { dg-warning "dereferencing pointer '.*' to within stale stack frame" }
>> - return aha;
>> + return [&aha] {
>> + return aha; // { dg-warning "dereferencing pointer '.*' to within stale stack frame" }
>> };
>> /* TODO: may be worth special-casing the reporting of dangling
>> references from lambdas, to highlight the declaration, and maybe fix
>> diff --git a/gcc/testsuite/g++.dg/tree-ssa/value-expr1.C b/gcc/testsuite/g++.dg/tree-ssa/value-expr1.C
>> new file mode 100644
>> index 00000000000..946ccc3bd97
>> --- /dev/null
>> +++ b/gcc/testsuite/g++.dg/tree-ssa/value-expr1.C
>> @@ -0,0 +1,16 @@
>> +// PR c++/84471
>> +// { dg-do compile { target c++11 } }
>> +// { dg-additional-options -fdump-tree-gimple-lineno }
>> +// { dg-final { scan-tree-dump-not {value-expr: \[} "gimple" } }
>> +
>> +int main(int argc, char**)
>> +{
>> + int x = 1;
>> + auto f = [&x, &argc](const char* i) {
>> + i += x;
>> + i -= argc;
>> + i += argc - x;
>> + return i;
>> + };
>> + f(" ");
>> +}
>> diff --git a/gcc/testsuite/g++.dg/tree-ssa/value-expr2.C b/gcc/testsuite/g++.dg/tree-ssa/value-expr2.C
>> new file mode 100644
>> index 00000000000..4d00498f214
>> --- /dev/null
>> +++ b/gcc/testsuite/g++.dg/tree-ssa/value-expr2.C
>> @@ -0,0 +1,26 @@
>> +// PR c++/107504
>> +// { dg-do compile { target c++17 } }
>> +// { dg-additional-options -fdump-tree-gimple-lineno }
>> +// { dg-final { scan-tree-dump-not {value-expr: \[} "gimple" } }
>> +
>> +struct S
>> +{
>> + void* i;
>> + int j;
>> +};
>> +
>> +S f(char* p)
>> +{
>> + return {p, 1};
>> +}
>> +
>> +int main()
>> +{
>> + char buf[1];
>> + auto [x, y] = f(buf);
>> + if (x != buf)
>> + throw 1;
>> + if (y != 1)
>> + throw 2;
>> + return 0;
>> +}
>> diff --git a/gcc/tree.cc b/gcc/tree.cc
>> index 254b2373dcf..836c51cd4d5 100644
>> --- a/gcc/tree.cc
>> +++ b/gcc/tree.cc
>> @@ -5862,6 +5862,9 @@ decl_value_expr_insert (tree from, tree to)
>> {
>> struct tree_decl_map *h;
>>
>> + /* Uses of FROM shouldn't look like they happen at the location of TO. */
>> + protected_set_expr_location (to, UNKNOWN_LOCATION);
>> +
>
> Doesn't that mean we'd eventually want unshare_expr_without_location
> or similar here? Or rather maybe set the location of TO to that of
> FROM? That said, this modifies FROM in place - we have
> protected_set_expr_location_unshare (would need to be exported
> from fold-const.cc) to avoid clobbering a possibly shared tree.
I think these expressions aren't ever shared in practice, but I agree
it's safer to use the _unshare variant. OK with that change?
> Maybe it would be easier to handle this in the consumers of the
> DECL_VALUE_EXPR? gimplify_var_or_parm_decl does
I don't see how auditing all the (many) users of DECL_VALUE_EXPR would
be easier than doing it in this one place?
> /* If the decl is an alias for another expression, substitute it now. */
> if (DECL_HAS_VALUE_EXPR_P (decl))
> {
> *expr_p = unshare_expr (DECL_VALUE_EXPR (decl));
> return GS_OK;
>
> it could also unshare without location.
> Am 20.12.2022 um 18:38 schrieb Jason Merrill <jason@redhat.com>:
>
> On 12/20/22 07:07, Richard Biener wrote:
>>> On Fri, Dec 2, 2022 at 4:46 PM Jason Merrill via Gcc-patches
>>> <gcc-patches@gcc.gnu.org> wrote:
>>>
>>> Tested x86_64-pc-linux-gnu, OK for trunk?
>>>
>>> -- 8< --
>>>
>>> If the DECL_VALUE_EXPR of a VAR_DECL has EXPR_LOCATION set, then any use of
>>> that variable looks like it has that location, which leads to the debugger
>>> jumping back and forth for both lambdas and structured bindings.
>>>
>>> Rather than fix all the uses, it seems simplest to remove any EXPR_LOCATION
>>> when setting DECL_VALUE_EXPR. So the cp/ hunks aren't necessary, but it
>>> seems cleaner not to work to add a location that will immediately get
>>> stripped.
>>>
>>> PR c++/84471
>>> PR c++/107504
>>>
>>> gcc/cp/ChangeLog:
>>>
>>> * coroutines.cc (transform_local_var_uses): Don't
>>> specify a location for DECL_VALUE_EXPR.
>>> * decl.cc (cp_finish_decomp): Likewise.
>>>
>>> gcc/ChangeLog:
>>>
>>> * tree.cc (decl_value_expr_insert): Clear EXPR_LOCATION.
>>>
>>> gcc/testsuite/ChangeLog:
>>>
>>> * g++.dg/tree-ssa/value-expr1.C: New test.
>>> * g++.dg/tree-ssa/value-expr2.C: New test.
>>> * g++.dg/analyzer/pr93212.C: Move warning.
>>> ---
>>> gcc/cp/coroutines.cc | 4 ++--
>>> gcc/cp/decl.cc | 12 +++-------
>>> gcc/testsuite/g++.dg/analyzer/pr93212.C | 4 ++--
>>> gcc/testsuite/g++.dg/tree-ssa/value-expr1.C | 16 +++++++++++++
>>> gcc/testsuite/g++.dg/tree-ssa/value-expr2.C | 26 +++++++++++++++++++++
>>> gcc/tree.cc | 3 +++
>>> 6 files changed, 52 insertions(+), 13 deletions(-)
>>> create mode 100644 gcc/testsuite/g++.dg/tree-ssa/value-expr1.C
>>> create mode 100644 gcc/testsuite/g++.dg/tree-ssa/value-expr2.C
>>>
>>> diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
>>> index 01a3e831ee5..a72bd6bbef0 100644
>>> --- a/gcc/cp/coroutines.cc
>>> +++ b/gcc/cp/coroutines.cc
>>> @@ -2047,8 +2047,8 @@ transform_local_var_uses (tree *stmt, int *do_subtree, void *d)
>>> = lookup_member (lvd->coro_frame_type, local_var.field_id,
>>> /*protect=*/1, /*want_type=*/0,
>>> tf_warning_or_error);
>>> - tree fld_idx = build3_loc (lvd->loc, COMPONENT_REF, TREE_TYPE (lvar),
>>> - lvd->actor_frame, fld_ref, NULL_TREE);
>>> + tree fld_idx = build3 (COMPONENT_REF, TREE_TYPE (lvar),
>>> + lvd->actor_frame, fld_ref, NULL_TREE);
>>> local_var.field_idx = fld_idx;
>>> SET_DECL_VALUE_EXPR (lvar, fld_idx);
>>> DECL_HAS_VALUE_EXPR_P (lvar) = true;
>>> diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
>>> index 7af0b05d5f8..59e21581503 100644
>>> --- a/gcc/cp/decl.cc
>>> +++ b/gcc/cp/decl.cc
>>> @@ -9133,9 +9133,7 @@ cp_finish_decomp (tree decl, tree first, unsigned int count)
>>> if (processing_template_decl)
>>> continue;
>>> tree t = unshare_expr (dexp);
>>> - t = build4_loc (DECL_SOURCE_LOCATION (v[i]), ARRAY_REF,
>>> - eltype, t, size_int (i), NULL_TREE,
>>> - NULL_TREE);
>>> + t = build4 (ARRAY_REF, eltype, t, size_int (i), NULL_TREE, NULL_TREE);
>>> SET_DECL_VALUE_EXPR (v[i], t);
>>> DECL_HAS_VALUE_EXPR_P (v[i]) = 1;
>>> }
>>> @@ -9154,9 +9152,7 @@ cp_finish_decomp (tree decl, tree first, unsigned int count)
>>> if (processing_template_decl)
>>> continue;
>>> tree t = unshare_expr (dexp);
>>> - t = build1_loc (DECL_SOURCE_LOCATION (v[i]),
>>> - i ? IMAGPART_EXPR : REALPART_EXPR, eltype,
>>> - t);
>>> + t = build1 (i ? IMAGPART_EXPR : REALPART_EXPR, eltype, t);
>>> SET_DECL_VALUE_EXPR (v[i], t);
>>> DECL_HAS_VALUE_EXPR_P (v[i]) = 1;
>>> }
>>> @@ -9180,9 +9176,7 @@ cp_finish_decomp (tree decl, tree first, unsigned int count)
>>> tree t = unshare_expr (dexp);
>>> convert_vector_to_array_for_subscript (DECL_SOURCE_LOCATION (v[i]),
>>> &t, size_int (i));
>>> - t = build4_loc (DECL_SOURCE_LOCATION (v[i]), ARRAY_REF,
>>> - eltype, t, size_int (i), NULL_TREE,
>>> - NULL_TREE);
>>> + t = build4 (ARRAY_REF, eltype, t, size_int (i), NULL_TREE, NULL_TREE);
>>> SET_DECL_VALUE_EXPR (v[i], t);
>>> DECL_HAS_VALUE_EXPR_P (v[i]) = 1;
>>> }
>>> diff --git a/gcc/testsuite/g++.dg/analyzer/pr93212.C b/gcc/testsuite/g++.dg/analyzer/pr93212.C
>>> index 41507e2b837..1029e8d547b 100644
>>> --- a/gcc/testsuite/g++.dg/analyzer/pr93212.C
>>> +++ b/gcc/testsuite/g++.dg/analyzer/pr93212.C
>>> @@ -4,8 +4,8 @@
>>> auto lol()
>>> {
>>> int aha = 3;
>>> - return [&aha] { // { dg-warning "dereferencing pointer '.*' to within stale stack frame" }
>>> - return aha;
>>> + return [&aha] {
>>> + return aha; // { dg-warning "dereferencing pointer '.*' to within stale stack frame" }
>>> };
>>> /* TODO: may be worth special-casing the reporting of dangling
>>> references from lambdas, to highlight the declaration, and maybe fix
>>> diff --git a/gcc/testsuite/g++.dg/tree-ssa/value-expr1.C b/gcc/testsuite/g++.dg/tree-ssa/value-expr1.C
>>> new file mode 100644
>>> index 00000000000..946ccc3bd97
>>> --- /dev/null
>>> +++ b/gcc/testsuite/g++.dg/tree-ssa/value-expr1.C
>>> @@ -0,0 +1,16 @@
>>> +// PR c++/84471
>>> +// { dg-do compile { target c++11 } }
>>> +// { dg-additional-options -fdump-tree-gimple-lineno }
>>> +// { dg-final { scan-tree-dump-not {value-expr: \[} "gimple" } }
>>> +
>>> +int main(int argc, char**)
>>> +{
>>> + int x = 1;
>>> + auto f = [&x, &argc](const char* i) {
>>> + i += x;
>>> + i -= argc;
>>> + i += argc - x;
>>> + return i;
>>> + };
>>> + f(" ");
>>> +}
>>> diff --git a/gcc/testsuite/g++.dg/tree-ssa/value-expr2.C b/gcc/testsuite/g++.dg/tree-ssa/value-expr2.C
>>> new file mode 100644
>>> index 00000000000..4d00498f214
>>> --- /dev/null
>>> +++ b/gcc/testsuite/g++.dg/tree-ssa/value-expr2.C
>>> @@ -0,0 +1,26 @@
>>> +// PR c++/107504
>>> +// { dg-do compile { target c++17 } }
>>> +// { dg-additional-options -fdump-tree-gimple-lineno }
>>> +// { dg-final { scan-tree-dump-not {value-expr: \[} "gimple" } }
>>> +
>>> +struct S
>>> +{
>>> + void* i;
>>> + int j;
>>> +};
>>> +
>>> +S f(char* p)
>>> +{
>>> + return {p, 1};
>>> +}
>>> +
>>> +int main()
>>> +{
>>> + char buf[1];
>>> + auto [x, y] = f(buf);
>>> + if (x != buf)
>>> + throw 1;
>>> + if (y != 1)
>>> + throw 2;
>>> + return 0;
>>> +}
>>> diff --git a/gcc/tree.cc b/gcc/tree.cc
>>> index 254b2373dcf..836c51cd4d5 100644
>>> --- a/gcc/tree.cc
>>> +++ b/gcc/tree.cc
>>> @@ -5862,6 +5862,9 @@ decl_value_expr_insert (tree from, tree to)
>>> {
>>> struct tree_decl_map *h;
>>>
>>> + /* Uses of FROM shouldn't look like they happen at the location of TO. */
>>> + protected_set_expr_location (to, UNKNOWN_LOCATION);
>>> +
>> Doesn't that mean we'd eventually want unshare_expr_without_location
>> or similar here? Or rather maybe set the location of TO to that of
>> FROM? That said, this modifies FROM in place - we have
>> protected_set_expr_location_unshare (would need to be exported
>> from fold-const.cc) to avoid clobbering a possibly shared tree.
>
> I think these expressions aren't ever shared in practice, but I agree it's safer to use the _unshare variant. OK with that change?
>
>> Maybe it would be easier to handle this in the consumers of the
>> DECL_VALUE_EXPR? gimplify_var_or_parm_decl does
>
> I don't see how auditing all the (many) users of DECL_VALUE_EXPR would be easier than doing it in this one place
It might do less unsharing. But OK with the _unshare variant.
Thanks,
Richard
>> /* If the decl is an alias for another expression, substitute it now. */
>> if (DECL_HAS_VALUE_EXPR_P (decl))
>> {
>> *expr_p = unshare_expr (DECL_VALUE_EXPR (decl));
>> return GS_OK;
>> it could also unshare without location.
>
>
On 12/20/22 14:39, Richard Biener wrote:
>
>
>> Am 20.12.2022 um 18:38 schrieb Jason Merrill <jason@redhat.com>:
>>
>> On 12/20/22 07:07, Richard Biener wrote:
>>>> On Fri, Dec 2, 2022 at 4:46 PM Jason Merrill via Gcc-patches
>>>> <gcc-patches@gcc.gnu.org> wrote:
>>>>
>>>> Tested x86_64-pc-linux-gnu, OK for trunk?
>>>>
>>>> -- 8< --
>>>>
>>>> If the DECL_VALUE_EXPR of a VAR_DECL has EXPR_LOCATION set, then any use of
>>>> that variable looks like it has that location, which leads to the debugger
>>>> jumping back and forth for both lambdas and structured bindings.
>>>>
>>>> Rather than fix all the uses, it seems simplest to remove any EXPR_LOCATION
>>>> when setting DECL_VALUE_EXPR. So the cp/ hunks aren't necessary, but it
>>>> seems cleaner not to work to add a location that will immediately get
>>>> stripped.
>>>>
>>>> PR c++/84471
>>>> PR c++/107504
>>>>
>>>> gcc/cp/ChangeLog:
>>>>
>>>> * coroutines.cc (transform_local_var_uses): Don't
>>>> specify a location for DECL_VALUE_EXPR.
>>>> * decl.cc (cp_finish_decomp): Likewise.
>>>>
>>>> gcc/ChangeLog:
>>>>
>>>> * tree.cc (decl_value_expr_insert): Clear EXPR_LOCATION.
>>>>
>>>> gcc/testsuite/ChangeLog:
>>>>
>>>> * g++.dg/tree-ssa/value-expr1.C: New test.
>>>> * g++.dg/tree-ssa/value-expr2.C: New test.
>>>> * g++.dg/analyzer/pr93212.C: Move warning.
>>>> ---
>>>> gcc/cp/coroutines.cc | 4 ++--
>>>> gcc/cp/decl.cc | 12 +++-------
>>>> gcc/testsuite/g++.dg/analyzer/pr93212.C | 4 ++--
>>>> gcc/testsuite/g++.dg/tree-ssa/value-expr1.C | 16 +++++++++++++
>>>> gcc/testsuite/g++.dg/tree-ssa/value-expr2.C | 26 +++++++++++++++++++++
>>>> gcc/tree.cc | 3 +++
>>>> 6 files changed, 52 insertions(+), 13 deletions(-)
>>>> create mode 100644 gcc/testsuite/g++.dg/tree-ssa/value-expr1.C
>>>> create mode 100644 gcc/testsuite/g++.dg/tree-ssa/value-expr2.C
>>>>
>>>> diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
>>>> index 01a3e831ee5..a72bd6bbef0 100644
>>>> --- a/gcc/cp/coroutines.cc
>>>> +++ b/gcc/cp/coroutines.cc
>>>> @@ -2047,8 +2047,8 @@ transform_local_var_uses (tree *stmt, int *do_subtree, void *d)
>>>> = lookup_member (lvd->coro_frame_type, local_var.field_id,
>>>> /*protect=*/1, /*want_type=*/0,
>>>> tf_warning_or_error);
>>>> - tree fld_idx = build3_loc (lvd->loc, COMPONENT_REF, TREE_TYPE (lvar),
>>>> - lvd->actor_frame, fld_ref, NULL_TREE);
>>>> + tree fld_idx = build3 (COMPONENT_REF, TREE_TYPE (lvar),
>>>> + lvd->actor_frame, fld_ref, NULL_TREE);
>>>> local_var.field_idx = fld_idx;
>>>> SET_DECL_VALUE_EXPR (lvar, fld_idx);
>>>> DECL_HAS_VALUE_EXPR_P (lvar) = true;
>>>> diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
>>>> index 7af0b05d5f8..59e21581503 100644
>>>> --- a/gcc/cp/decl.cc
>>>> +++ b/gcc/cp/decl.cc
>>>> @@ -9133,9 +9133,7 @@ cp_finish_decomp (tree decl, tree first, unsigned int count)
>>>> if (processing_template_decl)
>>>> continue;
>>>> tree t = unshare_expr (dexp);
>>>> - t = build4_loc (DECL_SOURCE_LOCATION (v[i]), ARRAY_REF,
>>>> - eltype, t, size_int (i), NULL_TREE,
>>>> - NULL_TREE);
>>>> + t = build4 (ARRAY_REF, eltype, t, size_int (i), NULL_TREE, NULL_TREE);
>>>> SET_DECL_VALUE_EXPR (v[i], t);
>>>> DECL_HAS_VALUE_EXPR_P (v[i]) = 1;
>>>> }
>>>> @@ -9154,9 +9152,7 @@ cp_finish_decomp (tree decl, tree first, unsigned int count)
>>>> if (processing_template_decl)
>>>> continue;
>>>> tree t = unshare_expr (dexp);
>>>> - t = build1_loc (DECL_SOURCE_LOCATION (v[i]),
>>>> - i ? IMAGPART_EXPR : REALPART_EXPR, eltype,
>>>> - t);
>>>> + t = build1 (i ? IMAGPART_EXPR : REALPART_EXPR, eltype, t);
>>>> SET_DECL_VALUE_EXPR (v[i], t);
>>>> DECL_HAS_VALUE_EXPR_P (v[i]) = 1;
>>>> }
>>>> @@ -9180,9 +9176,7 @@ cp_finish_decomp (tree decl, tree first, unsigned int count)
>>>> tree t = unshare_expr (dexp);
>>>> convert_vector_to_array_for_subscript (DECL_SOURCE_LOCATION (v[i]),
>>>> &t, size_int (i));
>>>> - t = build4_loc (DECL_SOURCE_LOCATION (v[i]), ARRAY_REF,
>>>> - eltype, t, size_int (i), NULL_TREE,
>>>> - NULL_TREE);
>>>> + t = build4 (ARRAY_REF, eltype, t, size_int (i), NULL_TREE, NULL_TREE);
>>>> SET_DECL_VALUE_EXPR (v[i], t);
>>>> DECL_HAS_VALUE_EXPR_P (v[i]) = 1;
>>>> }
>>>> diff --git a/gcc/testsuite/g++.dg/analyzer/pr93212.C b/gcc/testsuite/g++.dg/analyzer/pr93212.C
>>>> index 41507e2b837..1029e8d547b 100644
>>>> --- a/gcc/testsuite/g++.dg/analyzer/pr93212.C
>>>> +++ b/gcc/testsuite/g++.dg/analyzer/pr93212.C
>>>> @@ -4,8 +4,8 @@
>>>> auto lol()
>>>> {
>>>> int aha = 3;
>>>> - return [&aha] { // { dg-warning "dereferencing pointer '.*' to within stale stack frame" }
>>>> - return aha;
>>>> + return [&aha] {
>>>> + return aha; // { dg-warning "dereferencing pointer '.*' to within stale stack frame" }
>>>> };
>>>> /* TODO: may be worth special-casing the reporting of dangling
>>>> references from lambdas, to highlight the declaration, and maybe fix
>>>> diff --git a/gcc/testsuite/g++.dg/tree-ssa/value-expr1.C b/gcc/testsuite/g++.dg/tree-ssa/value-expr1.C
>>>> new file mode 100644
>>>> index 00000000000..946ccc3bd97
>>>> --- /dev/null
>>>> +++ b/gcc/testsuite/g++.dg/tree-ssa/value-expr1.C
>>>> @@ -0,0 +1,16 @@
>>>> +// PR c++/84471
>>>> +// { dg-do compile { target c++11 } }
>>>> +// { dg-additional-options -fdump-tree-gimple-lineno }
>>>> +// { dg-final { scan-tree-dump-not {value-expr: \[} "gimple" } }
>>>> +
>>>> +int main(int argc, char**)
>>>> +{
>>>> + int x = 1;
>>>> + auto f = [&x, &argc](const char* i) {
>>>> + i += x;
>>>> + i -= argc;
>>>> + i += argc - x;
>>>> + return i;
>>>> + };
>>>> + f(" ");
>>>> +}
>>>> diff --git a/gcc/testsuite/g++.dg/tree-ssa/value-expr2.C b/gcc/testsuite/g++.dg/tree-ssa/value-expr2.C
>>>> new file mode 100644
>>>> index 00000000000..4d00498f214
>>>> --- /dev/null
>>>> +++ b/gcc/testsuite/g++.dg/tree-ssa/value-expr2.C
>>>> @@ -0,0 +1,26 @@
>>>> +// PR c++/107504
>>>> +// { dg-do compile { target c++17 } }
>>>> +// { dg-additional-options -fdump-tree-gimple-lineno }
>>>> +// { dg-final { scan-tree-dump-not {value-expr: \[} "gimple" } }
>>>> +
>>>> +struct S
>>>> +{
>>>> + void* i;
>>>> + int j;
>>>> +};
>>>> +
>>>> +S f(char* p)
>>>> +{
>>>> + return {p, 1};
>>>> +}
>>>> +
>>>> +int main()
>>>> +{
>>>> + char buf[1];
>>>> + auto [x, y] = f(buf);
>>>> + if (x != buf)
>>>> + throw 1;
>>>> + if (y != 1)
>>>> + throw 2;
>>>> + return 0;
>>>> +}
>>>> diff --git a/gcc/tree.cc b/gcc/tree.cc
>>>> index 254b2373dcf..836c51cd4d5 100644
>>>> --- a/gcc/tree.cc
>>>> +++ b/gcc/tree.cc
>>>> @@ -5862,6 +5862,9 @@ decl_value_expr_insert (tree from, tree to)
>>>> {
>>>> struct tree_decl_map *h;
>>>>
>>>> + /* Uses of FROM shouldn't look like they happen at the location of TO. */
>>>> + protected_set_expr_location (to, UNKNOWN_LOCATION);
>>>> +
>>> Doesn't that mean we'd eventually want unshare_expr_without_location
>>> or similar here? Or rather maybe set the location of TO to that of
>>> FROM? That said, this modifies FROM in place - we have
>>> protected_set_expr_location_unshare (would need to be exported
>>> from fold-const.cc) to avoid clobbering a possibly shared tree.
>>
>> I think these expressions aren't ever shared in practice, but I agree it's safer to use the _unshare variant. OK with that change?
>>
>>> Maybe it would be easier to handle this in the consumers of the
>>> DECL_VALUE_EXPR? gimplify_var_or_parm_decl does
>>
>> I don't see how auditing all the (many) users of DECL_VALUE_EXPR would be easier than doing it in this one place
>
> It might do less unsharing. But OK with the _unshare variant.
Thanks, here's what I pushed.
@@ -2047,8 +2047,8 @@ transform_local_var_uses (tree *stmt, int *do_subtree, void *d)
= lookup_member (lvd->coro_frame_type, local_var.field_id,
/*protect=*/1, /*want_type=*/0,
tf_warning_or_error);
- tree fld_idx = build3_loc (lvd->loc, COMPONENT_REF, TREE_TYPE (lvar),
- lvd->actor_frame, fld_ref, NULL_TREE);
+ tree fld_idx = build3 (COMPONENT_REF, TREE_TYPE (lvar),
+ lvd->actor_frame, fld_ref, NULL_TREE);
local_var.field_idx = fld_idx;
SET_DECL_VALUE_EXPR (lvar, fld_idx);
DECL_HAS_VALUE_EXPR_P (lvar) = true;
@@ -9133,9 +9133,7 @@ cp_finish_decomp (tree decl, tree first, unsigned int count)
if (processing_template_decl)
continue;
tree t = unshare_expr (dexp);
- t = build4_loc (DECL_SOURCE_LOCATION (v[i]), ARRAY_REF,
- eltype, t, size_int (i), NULL_TREE,
- NULL_TREE);
+ t = build4 (ARRAY_REF, eltype, t, size_int (i), NULL_TREE, NULL_TREE);
SET_DECL_VALUE_EXPR (v[i], t);
DECL_HAS_VALUE_EXPR_P (v[i]) = 1;
}
@@ -9154,9 +9152,7 @@ cp_finish_decomp (tree decl, tree first, unsigned int count)
if (processing_template_decl)
continue;
tree t = unshare_expr (dexp);
- t = build1_loc (DECL_SOURCE_LOCATION (v[i]),
- i ? IMAGPART_EXPR : REALPART_EXPR, eltype,
- t);
+ t = build1 (i ? IMAGPART_EXPR : REALPART_EXPR, eltype, t);
SET_DECL_VALUE_EXPR (v[i], t);
DECL_HAS_VALUE_EXPR_P (v[i]) = 1;
}
@@ -9180,9 +9176,7 @@ cp_finish_decomp (tree decl, tree first, unsigned int count)
tree t = unshare_expr (dexp);
convert_vector_to_array_for_subscript (DECL_SOURCE_LOCATION (v[i]),
&t, size_int (i));
- t = build4_loc (DECL_SOURCE_LOCATION (v[i]), ARRAY_REF,
- eltype, t, size_int (i), NULL_TREE,
- NULL_TREE);
+ t = build4 (ARRAY_REF, eltype, t, size_int (i), NULL_TREE, NULL_TREE);
SET_DECL_VALUE_EXPR (v[i], t);
DECL_HAS_VALUE_EXPR_P (v[i]) = 1;
}
@@ -4,8 +4,8 @@
auto lol()
{
int aha = 3;
- return [&aha] { // { dg-warning "dereferencing pointer '.*' to within stale stack frame" }
- return aha;
+ return [&aha] {
+ return aha; // { dg-warning "dereferencing pointer '.*' to within stale stack frame" }
};
/* TODO: may be worth special-casing the reporting of dangling
references from lambdas, to highlight the declaration, and maybe fix
new file mode 100644
@@ -0,0 +1,16 @@
+// PR c++/84471
+// { dg-do compile { target c++11 } }
+// { dg-additional-options -fdump-tree-gimple-lineno }
+// { dg-final { scan-tree-dump-not {value-expr: \[} "gimple" } }
+
+int main(int argc, char**)
+{
+ int x = 1;
+ auto f = [&x, &argc](const char* i) {
+ i += x;
+ i -= argc;
+ i += argc - x;
+ return i;
+ };
+ f(" ");
+}
new file mode 100644
@@ -0,0 +1,26 @@
+// PR c++/107504
+// { dg-do compile { target c++17 } }
+// { dg-additional-options -fdump-tree-gimple-lineno }
+// { dg-final { scan-tree-dump-not {value-expr: \[} "gimple" } }
+
+struct S
+{
+ void* i;
+ int j;
+};
+
+S f(char* p)
+{
+ return {p, 1};
+}
+
+int main()
+{
+ char buf[1];
+ auto [x, y] = f(buf);
+ if (x != buf)
+ throw 1;
+ if (y != 1)
+ throw 2;
+ return 0;
+}
@@ -5862,6 +5862,9 @@ decl_value_expr_insert (tree from, tree to)
{
struct tree_decl_map *h;
+ /* Uses of FROM shouldn't look like they happen at the location of TO. */
+ protected_set_expr_location (to, UNKNOWN_LOCATION);
+
h = ggc_alloc<tree_decl_map> ();
h->base.from = from;
h->to = to;