Hi Jason,
here is the fourth version of the patch.
I followed your suggestion and now make this
transformation sooner in pointer_int_sum.
I also added a check to only do this
transformation when the pointer is not a
VAR_DECL, which avoids it in the most
common cases where it is not necessary.
Looking for BIND_EXPR seems complicated
and I could not convince myself that it is
worth it. I also see the risk that this
makes potential failure cases even more
subtle. What do you think?
Bootstrapped and regression tested
on x86-64 for all languages.
Martin
Fix ICE when mixing VLAs and statement expressions [PR91038]
When returning VM-types from statement expressions, this can
lead to an ICE when declarations from the statement expression
are referred to later. Most of these issues can be addressed by
gimplifying the base expression earlier in gimplify_compound_lval.
Another issue is fixed by wrapping the pointer expression in
pointer_int_sum. This fixes PR91038 and some of the test cases
from PR29970 (structs with VLA members need further work).
2021-10-30 Martin Uecker <muec...@gwdg.de>
gcc/
PR c/91038
PR c/29970
* c-family/c-common.c (pointer_int_sum): Make sure
pointer expressions are evaluated first when the size
expression depends on for variably-modified types.
* gimplify.c (gimplify_var_or_parm_decl): Update comment.
(gimplify_compound_lval): Gimplify base expression first.
(gimplify_target_expr): Add comment.
gcc/testsuite/
PR c/91038
PR c/29970
* gcc.dg/vla-stexp-3.c: New test.
* gcc.dg/vla-stexp-4.c: New test.
* gcc.dg/vla-stexp-5.c: New test.
* gcc.dg/vla-stexp-6.c: New test.
* gcc.dg/vla-stexp-7.c: New test.
* gcc.dg/vla-stexp-8.c: New test.
* gcc.dg/vla-stexp-9.c: New test.
diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index 32c7e3e8972..a10b374dbed 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -3301,7 +3301,20 @@ pointer_int_sum (location_t loc, enum tree_code
resultcode,
TREE_TYPE (result_type)))
size_exp = integer_one_node;
else
- size_exp = size_in_bytes_loc (loc, TREE_TYPE (result_type));
+ {
+ size_exp = size_in_bytes_loc (loc, TREE_TYPE (result_type));
+ /* Wrap the pointer expression in a SAVE_EXPR to make sure it
+ * is evaluated first when the size expression may depend
+ * on it for VM types.
+ */
+ if (TREE_SIDE_EFFECTS (size_exp)
+ && variably_modified_type_p (TREE_TYPE (ptrop), NULL)
+ && (VAR_DECL != TREE_CODE (ptrop)))
+ {
+ ptrop = build1_loc (loc, SAVE_EXPR, TREE_TYPE (ptrop), ptrop);
+ size_exp = build2 (COMPOUND_EXPR, TREE_TYPE (intop), ptrop, size_exp);
+ }
+ }
/* We are manipulating pointer values, so we don't need to warn
about relying on undefined signed overflow. We disable the
diff --git a/gcc/gimplify.c b/gcc/gimplify.c
index 8bb54fd7481..7b6874a3142 100644
--- a/gcc/gimplify.c
+++ b/gcc/gimplify.c
@@ -2958,7 +2958,10 @@ gimplify_var_or_parm_decl (tree *expr_p)
declaration, for which we've already issued an error. It would
be really nice if the front end wouldn't leak these at all.
Currently the only known culprit is C++ destructors, as seen
- in g++.old-deja/g++.jason/binding.C. */
+ in g++.old-deja/g++.jason/binding.C.
+ Another possible culpit are size expressions for variably modified
+ types which are lost in the FE or not gimplified correctly.
+ */
if (VAR_P (decl)
&& !DECL_SEEN_IN_BIND_EXPR_P (decl)
&& !TREE_STATIC (decl) && !DECL_EXTERNAL (decl)
@@ -3103,16 +3106,22 @@ gimplify_compound_lval (tree *expr_p, gimple_seq
*pre_p, gimple_seq *post_p,
expression until we deal with any variable bounds, sizes, or
positions in order to deal with PLACEHOLDER_EXPRs.
- So we do this in three steps. First we deal with the annotations
- for any variables in the components, then we gimplify the base,
- then we gimplify any indices, from left to right. */
+ The base expression may contain a statement expression that
+ has declarations used in size expressions, so has to be
+ gimplified before gimplifying the size expressions.
+
+ So we do this in three steps. First we deal with variable
+ bounds, sizes, and positions, then we gimplify the base,
+ then we deal with the annotations for any variables in the
+ components and any indices, from left to right. */
+
for (i = expr_stack.length () - 1; i >= 0; i--)
{
tree t = expr_stack[i];
if (TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
{
- /* Gimplify the low bound and element type size and put them into
+ /* Deal with the low bound and element type size and put them into
the ARRAY_REF. If these values are set, they have already been
gimplified. */
if (TREE_OPERAND (t, 2) == NULL_TREE)
@@ -3121,18 +3130,8 @@ gimplify_compound_lval (tree *expr_p, gimple_seq *pre_p,
gimple_seq *post_p,
if (!is_gimple_min_invariant (low))
{
TREE_OPERAND (t, 2) = low;
- tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p,
- post_p, is_gimple_reg,
- fb_rvalue);
- ret = MIN (ret, tret);
}
}
- else
- {
- tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, post_p,
- is_gimple_reg, fb_rvalue);
- ret = MIN (ret, tret);
- }
if (TREE_OPERAND (t, 3) == NULL_TREE)
{
@@ -3149,18 +3148,8 @@ gimplify_compound_lval (tree *expr_p, gimple_seq *pre_p,
gimple_seq *post_p,
elmt_size, factor);
TREE_OPERAND (t, 3) = elmt_size;
- tret = gimplify_expr (&TREE_OPERAND (t, 3), pre_p,
- post_p, is_gimple_reg,
- fb_rvalue);
- ret = MIN (ret, tret);
}
}
- else
- {
- tret = gimplify_expr (&TREE_OPERAND (t, 3), pre_p, post_p,
- is_gimple_reg, fb_rvalue);
- ret = MIN (ret, tret);
- }
}
else if (TREE_CODE (t) == COMPONENT_REF)
{
@@ -3180,18 +3169,8 @@ gimplify_compound_lval (tree *expr_p, gimple_seq *pre_p,
gimple_seq *post_p,
offset, factor);
TREE_OPERAND (t, 2) = offset;
- tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p,
- post_p, is_gimple_reg,
- fb_rvalue);
- ret = MIN (ret, tret);
}
}
- else
- {
- tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, post_p,
- is_gimple_reg, fb_rvalue);
- ret = MIN (ret, tret);
- }
}
}
@@ -3202,21 +3181,34 @@ gimplify_compound_lval (tree *expr_p, gimple_seq
*pre_p, gimple_seq *post_p,
fallback | fb_lvalue);
ret = MIN (ret, tret);
- /* And finally, the indices and operands of ARRAY_REF. During this
- loop we also remove any useless conversions. */
+ /* Step 3: gimplify size expressions and the indices and operands of
+ ARRAY_REF. During this loop we also remove any useless conversions. */
+
for (; expr_stack.length () > 0; )
{
tree t = expr_stack.pop ();
if (TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
{
+ /* Gimplify the low bound and element type size. */
+ tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, post_p,
+ is_gimple_reg, fb_rvalue);
+ ret = MIN (ret, tret);
+
+ tret = gimplify_expr (&TREE_OPERAND (t, 3), pre_p, post_p,
+ is_gimple_reg, fb_rvalue);
+ ret = MIN (ret, tret);
+
/* Gimplify the dimension. */
- if (!is_gimple_min_invariant (TREE_OPERAND (t, 1)))
- {
- tret = gimplify_expr (&TREE_OPERAND (t, 1), pre_p, post_p,
- is_gimple_val, fb_rvalue);
- ret = MIN (ret, tret);
- }
+ tret = gimplify_expr (&TREE_OPERAND (t, 1), pre_p, post_p,
+ is_gimple_val, fb_rvalue);
+ ret = MIN (ret, tret);
+ }
+ else if (TREE_CODE (t) == COMPONENT_REF)
+ {
+ tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, post_p,
+ is_gimple_reg, fb_rvalue);
+ ret = MIN (ret, tret);
}
STRIP_USELESS_TYPE_CONVERSION (TREE_OPERAND (t, 0));
@@ -6914,6 +6906,8 @@ gimplify_target_expr (tree *expr_p, gimple_seq *pre_p,
gimple_seq *post_p)
{
if (!TYPE_SIZES_GIMPLIFIED (TREE_TYPE (temp)))
gimplify_type_sizes (TREE_TYPE (temp), pre_p);
+ /* FIXME: this is correct only when the size of the type does
+ not depend on expressions evaluated in init. */
gimplify_vla_decl (temp, pre_p);
}
else
diff --git a/gcc/testsuite/gcc.dg/vla-stexp-3.c
b/gcc/testsuite/gcc.dg/vla-stexp-3.c
new file mode 100644
index 00000000000..e663de1cd72
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vla-stexp-3.c
@@ -0,0 +1,11 @@
+/* PR91038 */
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+
+void bar(void)
+{
+ ({ int N = 2; int (*x)[9][N] = 0; x; })[1];
+ ({ int N = 2; int (*x)[9][N] = 0; x; })[0]; // should not ice
+}
+
diff --git a/gcc/testsuite/gcc.dg/vla-stexp-4.c
b/gcc/testsuite/gcc.dg/vla-stexp-4.c
new file mode 100644
index 00000000000..612b5a802fc
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vla-stexp-4.c
@@ -0,0 +1,94 @@
+/* PR29970, PR91038 */
+/* { dg-do run } */
+/* { dg-options "-O0 -Wunused-variable" } */
+
+int foo3b(void) // should not return 0
+{
+ int n = 0;
+ return sizeof *({ n = 10; int x[n]; &x; });
+}
+
+int foo4(void) // should not ICE
+{
+ return (*({
+ int n = 20;
+ char (*x)[n][n] = __builtin_malloc(n * n);
+ (*x)[12][1] = 1;
+ x;
+ }))[12][1];
+}
+
+int foo5(void) // should return 1, returns 0
+{
+ int n = 0;
+ return (*({
+ n = 20;
+ char (*x)[n][n] = __builtin_malloc(n * n);
+ (*x)[12][1] = 1;
+ (*x)[0][1] = 0;
+ x;
+ }))[12][1];
+}
+
+int foo5c(void) // should return 400
+{
+ int n = 0;
+ return sizeof(*({
+ n = 20;
+ char (*x)[n][n] = __builtin_malloc(n * n);
+ (*x)[12][1] = 1;
+ (*x)[0][1] = 0;
+ x;
+ }));
+}
+
+int foo5b(void) // should return 1, returns 0
+{
+ int n = 0; /* { dg-warning "unused variable" } */
+ return (*({
+ int n = 20;
+ char (*x)[n][n] = __builtin_malloc(n * n);
+ (*x)[12][1] = 1;
+ (*x)[0][1] = 0;
+ x;
+ }))[12][1];
+}
+
+int foo5a(void) // should return 1, returns 0
+{
+ return (*({
+ int n = 20;
+ char (*x)[n][n] = __builtin_malloc(n * n);
+ (*x)[12][1] = 1;
+ (*x)[0][1] = 0;
+ x;
+ }))[12][1];
+}
+
+
+
+
+int main()
+{
+ if (sizeof(int[10]) != foo3b())
+ __builtin_abort();
+
+ if (1 != foo4())
+ __builtin_abort();
+
+ if (400 != foo5c())
+ __builtin_abort();
+
+ if (1 != foo5a())
+ __builtin_abort();
+
+ if (1 != foo5b()) // -O0
+ __builtin_abort();
+
+ if (1 != foo5())
+ __builtin_abort();
+
+ return 0;
+}
+
+
diff --git a/gcc/testsuite/gcc.dg/vla-stexp-5.c
b/gcc/testsuite/gcc.dg/vla-stexp-5.c
new file mode 100644
index 00000000000..d6a7f2b34b8
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vla-stexp-5.c
@@ -0,0 +1,30 @@
+/* PR29970 */
+/* { dg-do run } */
+/* { dg-options "-Wunused-variable" } */
+
+
+
+
+int foo2a(void) // should not ICE
+{
+ return ({ int n = 20; struct { int x[n];} x; x.x[12] = 1; sizeof(x);
});
+}
+
+
+int foo2b(void) // should not ICE
+{
+ return sizeof *({ int n = 20; struct { int x[n];} x; x.x[12] = 1; &x;
});
+}
+
+int main()
+{
+ if (sizeof(struct { int x[20]; }) != foo2a())
+ __builtin_abort();
+
+ if (sizeof(struct { int x[20]; }) != foo2b())
+ __builtin_abort();
+
+ return 0;
+}
+
+
diff --git a/gcc/testsuite/gcc.dg/vla-stexp-6.c
b/gcc/testsuite/gcc.dg/vla-stexp-6.c
new file mode 100644
index 00000000000..3d96d38898b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vla-stexp-6.c
@@ -0,0 +1,94 @@
+/* PR29970, PR91038 */
+/* { dg-do run } */
+/* { dg-options "-O2 -Wunused-variable" } */
+
+int foo3b(void) // should not return 0
+{
+ int n = 0;
+ return sizeof *({ n = 10; int x[n]; &x; });
+}
+
+int foo4(void) // should not ICE
+{
+ return (*({
+ int n = 20;
+ char (*x)[n][n] = __builtin_malloc(n * n);
+ (*x)[12][1] = 1;
+ x;
+ }))[12][1];
+}
+
+int foo5(void) // should return 1, returns 0
+{
+ int n = 0;
+ return (*({
+ n = 20;
+ char (*x)[n][n] = __builtin_malloc(n * n);
+ (*x)[12][1] = 1;
+ (*x)[0][1] = 0;
+ x;
+ }))[12][1];
+}
+
+int foo5c(void) // should return 400
+{
+ int n = 0;
+ return sizeof(*({
+ n = 20;
+ char (*x)[n][n] = __builtin_malloc(n * n);
+ (*x)[12][1] = 1;
+ (*x)[0][1] = 0;
+ x;
+ }));
+}
+
+int foo5b(void) // should return 1, returns 0
+{
+ int n = 0; /* { dg-warning "unused variable" } */
+ return (*({
+ int n = 20;
+ char (*x)[n][n] = __builtin_malloc(n * n);
+ (*x)[12][1] = 1;
+ (*x)[0][1] = 0;
+ x;
+ }))[12][1];
+}
+
+int foo5a(void) // should return 1, returns 0
+{
+ return (*({
+ int n = 20;
+ char (*x)[n][n] = __builtin_malloc(n * n);
+ (*x)[12][1] = 1;
+ (*x)[0][1] = 0;
+ x;
+ }))[12][1];
+}
+
+
+
+
+int main()
+{
+ if (sizeof(int[10]) != foo3b())
+ __builtin_abort();
+
+ if (1 != foo4())
+ __builtin_abort();
+
+ if (400 != foo5c())
+ __builtin_abort();
+
+ if (1 != foo5a())
+ __builtin_abort();
+
+ if (1 != foo5b()) // -O0
+ __builtin_abort();
+
+ if (1 != foo5())
+ __builtin_abort();
+
+ return 0;
+}
+
+
diff --git a/gcc/testsuite/gcc.dg/vla-stexp-7.c
b/gcc/testsuite/gcc.dg/vla-stexp-7.c
new file mode 100644
index 00000000000..3091b9184c2
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vla-stexp-7.c
@@ -0,0 +1,44 @@
+/* PR91038 */
+/* { dg-do run } */
+/* { dg-options "-O2 -Wunused-variable" } */
+
+
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+
+struct lbm {
+
+ int D;
+ const int* DQ;
+
+} D2Q9 = { 2,
+ (const int*)&(const int[9][2]){
+ { 0, 0 },
+ { 1, 0 }, { 0, 1 }, { -1, 0 }, { 0, -1 },
+ { 1, 1 }, { -1, 1 }, { -1, -1 }, { 1, -1 },
+ }
+};
+
+void zouhe_left(void)
+{
+ __auto_type xx = (*({ int N = 2; struct lbm __x = D2Q9; ((const
int(*)[9][N])__x.DQ); }));
+
+ if (1 != xx[1][0])
+ __builtin_abort();
+
+ if (2 != ARRAY_SIZE(xx[1]))
+ __builtin_abort();
+
+ if (1 != (*({ int N = 2; struct lbm __x = D2Q9; ((const
int(*)[9][N])__x.DQ); }))[1][0])
+ __builtin_abort();
+
+ if (2 != ARRAY_SIZE(*({ int N = 2; struct lbm __x = D2Q9; ((const
int(*)[9][N])__x.DQ);
})[1]))
+ __builtin_abort();
+}
+
+int main()
+{
+ zouhe_left();
+ return 0;
+}
+
+
diff --git a/gcc/testsuite/gcc.dg/vla-stexp-8.c
b/gcc/testsuite/gcc.dg/vla-stexp-8.c
new file mode 100644
index 00000000000..5b475eb6cf2
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vla-stexp-8.c
@@ -0,0 +1,47 @@
+/* PR29970, PR91038 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -Wunused-variable" } */
+
+
+int foo0(void)
+{
+ int c = *(*(*({ int n = 10; int (*x)[n][n] = __builtin_malloc(sizeof
*x); x; }) + 5) + 5);
+ return c;
+}
+
+int foo1(void)
+{
+ int c = *(5 + *(5 + *({ int n = 10; int (*x)[n][n] =
__builtin_malloc(sizeof *x); x; })));
+ return c;
+}
+
+int bar2(void)
+{
+ int c = (*({ int n = 10; struct { int y[n]; int z; }* x =
__builtin_malloc(sizeof *x); x;
})).z;
+ return c;
+}
+
+int bar3(void)
+{
+ int n = 2; /* { dg-warning "unused variable" } */
+ int c = (*({ int n = 3; /* { dg-warning "unused variable" } */
+ ({ int n = 10; int (*x)[n][n] = __builtin_malloc(sizeof *x); x;
}); }))[5][5];
+ return c;
+}
+
+int bar3b(void)
+{
+ int n = 2; /* { dg-warning "unused variable" } */
+ int c = (*({ int n = 3; /* { dg-warning "unused variable" } */
+ ({ int n = 10; int (*x)[n][n] = __builtin_malloc(sizeof *x); x;
}); }))[0][0];
+ return c;
+}
+
+int bar4(void)
+{
+ int n = 2; /* { dg-warning "unused variable" } */
+ int c = *(5 + *( 5 + *({ int n = 3; /* { dg-warning "unused
variable" } */
+ ({ int n = 10; int (*x)[n][n] = __builtin_malloc(sizeof *x); x;
}); })));
+ return c;
+}
+
diff --git a/gcc/testsuite/gcc.dg/vla-stexp-9.c
b/gcc/testsuite/gcc.dg/vla-stexp-9.c
new file mode 100644
index 00000000000..3593a790785
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vla-stexp-9.c
@@ -0,0 +1,53 @@
+/* PR91038 */
+/* { dg-do run } */
+/* { dg-options "-O2 -Wunused-variable" } */
+
+
+
+void foo(void)
+{
+ if (2 * sizeof(int) != sizeof((*({ int N = 2; int (*x)[9][N] = 0; x;
})[1])))
+ __builtin_abort();
+}
+
+void bar(void)
+{
+ if (2 * sizeof(int) != sizeof((*({ int N = 2; int (*x)[9][N] = 0; x;
})[0])))
+ __builtin_abort();
+}
+
+void bar0(void)
+{
+ if (2 * 9 * sizeof(int) != sizeof((*({ int N = 2; int (*x)[9][N] = 0;
x; }))))
+ __builtin_abort();
+}
+
+void bar11(void)
+{
+ sizeof(*((*({ int N = 2; int (*x)[9][N] = 0; x; }) + 0)));
+}
+
+void bar12(void)
+{
+ if (2 * sizeof(int) != sizeof(*((*({ int N = 2; int (*x)[9][N] = 0; x;
}) ))))
+ __builtin_abort();
+}
+
+void bar1(void)
+{
+ if (2 * sizeof(int) != sizeof(*((*({ int N = 2; int (*x)[9][N] = 0; x;
}) + 0))))
+ __builtin_abort();
+}
+
+
+
+
+int main()
+{
+ foo();
+ bar0();
+ bar12();
+ bar1();
+ bar();
+}
+
