Improve/correct detection of overlapping aggregates [PR102238, PR102919].

Resolves:
PR tree-optimization/102238 - alias_offset in gimple-ssa-sprintf.c is broken
PR tree-optimization/102919 - spurious -Wrestrict warning for sprintf into the same member array as argument plus offset

gcc/ChangeLog:

	PR tree-optimization/102238
	PR tree-optimization/102919
	* gimple-ssa-sprintf.c (get_string_length): Add an argument.
	(array_elt_at_offset): Move to pointer-query.
	(set_aggregate_size_and_offset): New function.
	(field_at_offset):  Move to pointer-query.
	(get_origin_and_offset): Rename...
	(get_origin_and_offset_r): this.  Add an argument.  Make aggregate
	handling more robust.
	(get_origin_and_offset): New.
	(alias_offset): Add an argument.
	(format_string): Use subobject size determined by get_origin_and_offset.
	* pointer-query.cc (field_at_offset): Move from gimple-ssa-sprintf.c.
	Improve/correct handling of aggregates.
	(array_elt_at_offset): Same.
	* pointer-query.h (field_at_offset): Declare.
	(array_elt_at_offset): Declare.

gcc/testsuite/ChangeLog:

	PR tree-optimization/102238
	PR tree-optimization/102919
	* gcc.dg/tree-ssa/builtin-sprintf-warn-23.c: Remove warnings.
	* gcc.dg/Wrestrict-23.c: New test.

2 files changed, 159 insertions, 11 deletions

diff --git a/gcc/testsuite/gcc.dg/Wrestrict-23.c b/gcc/testsuite/gcc.dg/Wrestrict-23.c
new file mode 100644
index 0000000..c7a828b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/Wrestrict-23.c
@@ -0,0 +1,146 @@
+/* PR tree-optimization/102238 - missing -Wrestrict on sprintf formatting
+   a struct member into enclosing object
+   { dg-do compile }
+   { dg-options "-O2 -Wall -Wno-format-overflow" } */
+
+extern int sprintf (char*, const char*, ...);
+
+extern void sink (void*, ...);
+
+struct A
+{
+  char a[4];
+};
+
+struct B
+{
+  struct A a1, a2;
+};
+
+extern struct B eb;
+
+enum { B_a2_a_off = __builtin_offsetof (struct B, a2.a) };
+
+
+void test_warn_src_decl_plus (void)
+{
+  {
+    char *s = (char*)&eb + B_a2_a_off;
+    char *d = eb.a2.a;
+    sprintf (d, "%s", s);     // { dg-warning "overlaps" }
+  }
+
+  {
+    // If strlen (s) > 0 there is overlap with a[1].
+    char *s = (char*)&eb + B_a2_a_off + 1;
+    char *d = eb.a2.a;
+    sprintf (d, "%s", s);     // { dg-warning "may overlap" }
+  }
+
+  {
+    // strlen (s) must be at most 1 so there can be no overlap with a.
+    char *s = (char*)&eb + B_a2_a_off + 2;
+    char *d = eb.a2.a;
+    sprintf (d, "%s", s);     // { dg-bogus "-Wrestrict" }
+  }
+
+  {
+    // strlen (s) must be at most 0 so there can be no overlap with a.
+    char *s = (char*)&eb + B_a2_a_off + 3;
+    char *d = eb.a2.a;
+    sprintf (d, "%s", s);     // { dg-bogus "-Wrestrict" }
+  }
+}
+
+
+void test_warn_src_ptr_plus (struct B *p)
+{
+  {
+    char *s = (char*)p + B_a2_a_off;
+    char *d = p->a2.a;
+    sprintf (d, "%s", s);     // { dg-warning "overlaps" }
+  }
+
+  {
+    // If strlen (s) > 0 there is overlap with a[1].
+    char *s = (char*)p + B_a2_a_off + 1;
+    char *d = p->a2.a;
+    sprintf (d, "%s", s);     // { dg-warning "may overlap" }
+  }
+
+  {
+    // strlen (s) must be at most 1 so there can be no overlap with a.
+    char *s = (char*)p + B_a2_a_off + 2;
+    char *d = p->a2.a;
+    sprintf (d, "%s", s);     // { dg-bogus "-Wrestrict" }
+  }
+
+  {
+    // strlen (s) must be at most 0 so there can be no overlap with a.
+    char *s = (char*)p + B_a2_a_off + 3;
+    char *d = p->a2.a;
+    sprintf (d, "%s", s);     // { dg-bogus "-Wrestrict" }
+  }
+}
+
+
+void test_warn_dst_decl_plus (void)
+{
+  {
+    char *s = eb.a2.a;
+    char *d = (char*)&eb + B_a2_a_off;
+    sprintf (d, "%s", s);     // { dg-warning "overlaps" }
+  }
+
+  {
+    // If strlen (a) > 0 there is overlap with a[1].
+    char *s = eb.a2.a;
+    char *d = (char*)&eb + B_a2_a_off + 1;
+    sprintf (d, "%s", s);     // { dg-warning "may overlap" }
+  }
+
+  {
+    // If strlen (a) > 1 there is overlap with a[2].
+    char *s = eb.a2.a;
+    char *d = (char*)&eb + B_a2_a_off + 2;
+    sprintf (d, "%s", s);     // { dg-warning "may overlap" }
+  }
+
+  {
+    // If strlen (a) > 2 there is overlap with a[3].
+    char *s = eb.a2.a;
+    char *d = (char*)&eb + B_a2_a_off + 3;
+    sprintf (d, "%s", s);     // { dg-warning "may overlap" }
+  }
+}
+
+
+void test_warn_dst_ptr_plus (struct B *p)
+{
+  {
+    char *s = p->a2.a;
+    char *d = (char*)p + B_a2_a_off;
+    sprintf (d, "%s", s);     // { dg-warning "overlaps" }
+  }
+
+  {
+    // If strlen (a) > 0 there is overlap with a[1].
+    char *s = p->a2.a;
+    char *d = (char*)p + B_a2_a_off + 1;
+    sprintf (d, "%s", s);     // { dg-warning "may overlap" }
+  }
+
+  {
+    // If strlen (a) > 1 there is overlap with a[2].
+    char *s = p->a2.a;
+    char *d = (char*)p + B_a2_a_off + 2;
+    sprintf (d, "%s", s);     // { dg-warning "may overlap" }
+  }
+
+  {
+    // If strlen (a) > 2 there is overlap with a[3].
+    char *s = p->a2.a;
+    char *d = (char*)p + B_a2_a_off + 3;
+    sprintf (d, "%s", s);     // { dg-warning "may overlap" }
+  }
+}
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/builtin-sprintf-warn-23.c b/gcc/testsuite/gcc.dg/tree-ssa/builtin-sprintf-warn-23.c
index 7fb9651..112b08a 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/builtin-sprintf-warn-23.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/builtin-sprintf-warn-23.c
@@ -214,12 +214,14 @@ void test_struct_member_array (struct S3 *s3, int i)
   T (d, "%s", d);       /* { dg-warning "overlaps" } */
   T (d, "%s", d + 0);   /* { dg-warning "overlaps" } */
   T (d, "%s", d + 1);   /* { dg-warning "may overlap" } */
-  T (d, "%s", d + 2);   /* { dg-warning "may overlap" } */
+  /* Since d below points to char[4], strlen(d + 2) must be at most 1
+     and so the call cannot overlap. */
+  T (d, "%s", d + 2);
   T (d, "%s", d + i);   /* { dg-warning "may overlap" } */
 
   T (d, "%s", &d[0]);   /* { dg-warning "overlaps" } */
   T (d, "%s", &d[1]);   /* { dg-warning "may overlap" } */
-  T (d, "%s", &d[2]);   /* { dg-warning "may overlap" } */
+  T (d, "%s", &d[2]);
   T (d, "%s", &d[i]);   /* { dg-warning "may overlap" } */
 
   T (d + 0, "%s", d);   /* { dg-warning "overlaps" } */
@@ -236,7 +238,7 @@ void test_struct_member_array (struct S3 *s3, int i)
 
   T (d, "%s", s);       /* { dg-warning "overlaps" } */
   T (d, "%s", s + 1);   /* { dg-warning "may overlap" } */
-  T (d, "%s", s + 2);   /* { dg-warning "may overlap" } */
+  T (d, "%s", s + 2);
   T (d, "%s", s + i);   /* { dg-warning "may overlap" } */
 
   s = s3->s2_1.s_1.b;
@@ -324,7 +326,7 @@ void test_struct_member_array (struct S3 *s3, int i)
 
   T (d, "%s", s);       /* { dg-warning "overlaps" } */
   T (d, "%s", s + 1);   /* { dg-warning "may overlap" } */
-  T (d, "%s", s + 2);   /* { dg-warning "may overlap" } */
+  T (d, "%s", s + 2);
   T (d, "%s", s + i);   /* { dg-warning "may overlap" } */
 
   s = s3->s2_2.s_2.a;
@@ -368,7 +370,7 @@ void test_struct_member_array (struct S3 *s3, int i)
 
   T (d, "%s", s);       /* { dg-warning "overlaps" } */
   T (d, "%s", s + 1);   /* { dg-warning "may overlap" } */
-  T (d, "%s", s + 2);   /* { dg-warning "may overlap" } */
+  T (d, "%s", s + 2);
   T (d, "%s", s + i);   /* { dg-warning "may overlap" } */
 
   s = s3->s2_2.s_2.a;
@@ -394,12 +396,12 @@ void test_struct_member_array_array (struct S3 *s3, int i)
   T (d, "%s", s);       /* { dg-warning "overlaps" } */
   T (d, "%s", s + 0);   /* { dg-warning "overlaps" } */
   T (d, "%s", s + 1);   /* { dg-warning "may overlap" } */
-  T (d, "%s", s + 2);   /* { dg-warning "may overlap" } */
+  T (d, "%s", s + 2);
   T (d, "%s", s + i);   /* { dg-warning "may overlap" } */
 
   T (d, "%s", &s[0]);   /* { dg-warning "overlaps" } */
   T (d, "%s", &s[1]);   /* { dg-warning "may overlap" } */
-  T (d, "%s", &s[2]);   /* { dg-warning "may overlap" } */
+  T (d, "%s", &s[2]);
   T (d, "%s", &s[i]);   /* { dg-warning "may overlap" } */
 
   T (d + 0, "%s", s);   /* { dg-warning "overlaps" } */
@@ -566,12 +568,12 @@ void test_union_member_array (union U *un, int i)
   T (d, "%s", d);       /* { dg-warning "overlaps" } */
   T (d, "%s", d + 0);   /* { dg-warning "overlaps" } */
   T (d, "%s", d + 1);   /* { dg-warning "may overlap" } */
-  T (d, "%s", d + 2);   /* { dg-warning "may overlap" } */
+  T (d, "%s", d + 2);
   T (d, "%s", d + i);   /* { dg-warning "may overlap" } */
 
   T (d, "%s", &d[0]);   /* { dg-warning "overlaps" } */
   T (d, "%s", &d[1]);   /* { dg-warning "may overlap" } */
-  T (d, "%s", &d[2]);   /* { dg-warning "may overlap" } */
+  T (d, "%s", &d[2]);
   T (d, "%s", &d[i]);   /* { dg-warning "may overlap" } */
 
   T (d + 0, "%s", d);   /* { dg-warning "overlaps" } */
@@ -588,7 +590,7 @@ void test_union_member_array (union U *un, int i)
 
   T (d, "%s", s);       /* { dg-warning "overlaps" } */
   T (d, "%s", s + 1);   /* { dg-warning "may overlap" } */
-  T (d, "%s", s + 2);   /* { dg-warning "may overlap" } */
+  T (d, "%s", s + 2);
   T (d, "%s", s + i);   /* { dg-warning "may overlap" } */
 
   s = un->s2_1.s_1.b;
@@ -616,7 +618,7 @@ void test_union_member_array (union U *un, int i)
 
   T (d, "%s", s);       /* { dg-warning "overlaps" } */
   T (d, "%s", s + 1);   /* { dg-warning "may overlap" } */
-  T (d, "%s", s + 2);   /* { dg-warning "may overlap" } */
+  T (d, "%s", s + 2);
   T (d, "%s", s + i);   /* { dg-warning "may overlap" } */
 
   s = un->s2_2.s_1.b;