analyzer: fix direction of -Wanalyzer-out-of-bounds note [PR106626]

Fix a read/write typo.

Also, add more test coverage of -Wanalyzer-out-of-bounds to help
establish a baseline for experiments on tweaking the wording of
the warning (PR analyzer/106626).

gcc/analyzer/ChangeLog:
	PR analyzer/106626
	* region-model.cc (buffer_overread::emit): Fix copy&paste error in
	direction of the access in the note.

gcc/testsuite/ChangeLog:
	PR analyzer/106626
	* gcc.dg/analyzer/out-of-bounds-read-char-arr.c: New test.
	* gcc.dg/analyzer/out-of-bounds-read-int-arr.c: New test.
	* gcc.dg/analyzer/out-of-bounds-write-char-arr.c: New test.
	* gcc.dg/analyzer/out-of-bounds-write-int-arr.c: New test.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>

5 files changed, 220 insertions, 2 deletions

diff --git a/gcc/analyzer/region-model.cc b/gcc/analyzer/region-model.cc
index a58904c..b05b709 100644
--- a/gcc/analyzer/region-model.cc
+++ b/gcc/analyzer/region-model.cc
@@ -1447,11 +1447,11 @@ public:
 	print_dec (m_out_of_bounds_range.m_size_in_bytes,
 		   num_bytes_past_buf, UNSIGNED);
 	if (m_diag_arg)
-	  inform (rich_loc->get_loc (), "write is %s bytes past the end"
+	  inform (rich_loc->get_loc (), "read is %s bytes past the end"
 					" of %qE", num_bytes_past_buf,
 						    m_diag_arg);
 	else
-	  inform (rich_loc->get_loc (), "write is %s bytes past the end"
+	  inform (rich_loc->get_loc (), "read is %s bytes past the end"
 					"of the region",
 					num_bytes_past_buf);
       }
diff --git a/gcc/testsuite/gcc.dg/analyzer/out-of-bounds-read-char-arr.c b/gcc/testsuite/gcc.dg/analyzer/out-of-bounds-read-char-arr.c
new file mode 100644
index 0000000..61cbfc7
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/analyzer/out-of-bounds-read-char-arr.c
@@ -0,0 +1,55 @@
+char arr[10]; /* { dg-message "capacity is 10 bytes" } */
+
+char int_arr_read_element_before_start_far(void)
+{
+  return arr[-100]; /* { dg-warning "buffer underread" "warning" } */
+  /* { dg-message "out-of-bounds read at byte -100 but 'arr' starts at byte 0" "final event" { target *-*-* } .-1 } */
+}
+
+char int_arr_read_element_before_start_near(void)
+{
+  return arr[-2]; /* { dg-warning "buffer underread" "warning" } */
+  /* { dg-message "out-of-bounds read at byte -2 but 'arr' starts at byte 0" "final event" { target *-*-* } .-1 } */
+}
+
+char int_arr_read_element_before_start_off_by_one(void)
+{
+  return arr[-1]; /* { dg-warning "buffer underread" "warning" } */
+  /* { dg-message "out-of-bounds read at byte -1 but 'arr' starts at byte 0" "final event" { target *-*-* } .-1 } */
+}
+
+char int_arr_read_element_at_start(void)
+{
+  return arr[0];
+}
+
+char int_arr_read_element_at_end(void)
+{
+  return arr[9];
+}
+
+char int_arr_read_element_after_end_off_by_one(void)
+{
+  return arr[10]; /* { dg-warning "buffer overread" "warning" } */
+  /* { dg-message "out-of-bounds read at byte 10 but 'arr' ends at byte 10" "final event" { target *-*-* } .-1 } */
+  /* { dg-message "read is 1 bytes past the end of 'arr'" "note" { target *-*-* } .-2 } */
+  // FIXME(PR 106626): "1 bytes"
+}
+
+char int_arr_read_element_after_end_near(void)
+{
+  return arr[11]; /* { dg-warning "buffer overread" "warning" } */
+  /* { dg-message "out-of-bounds read at byte 11 but 'arr' ends at byte 10" "final event" { target *-*-* } .-1 } */
+  /* { dg-message "read is 1 bytes past the end of 'arr'" "note" { target *-*-* } .-2 } */
+  // FIXME(PR 106626): is the note correct?
+  // FIXME(PR 106626): "1 bytes"
+}
+
+char int_arr_read_element_after_end_far(void)
+{
+  return arr[100]; /* { dg-warning "buffer overread" "warning" } */
+  /* { dg-message "out-of-bounds read at byte 100 but 'arr' ends at byte 10" "final event" { target *-*-* } .-1 } */
+  /* { dg-message "read is 1 bytes past the end of 'arr'" "note" { target *-*-* } .-2 } */
+  // FIXME(PR 106626): the note seems incorrect (size of access is 1 byte, but magnitude beyond boundary is 90)
+  // FIXME(PR 106626): "1 bytes"
+}
diff --git a/gcc/testsuite/gcc.dg/analyzer/out-of-bounds-read-int-arr.c b/gcc/testsuite/gcc.dg/analyzer/out-of-bounds-read-int-arr.c
new file mode 100644
index 0000000..0bb30d2
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/analyzer/out-of-bounds-read-int-arr.c
@@ -0,0 +1,54 @@
+#include <stdint.h>
+
+int32_t arr[10]; /* { dg-message "capacity is 40 bytes" } */
+
+int32_t int_arr_read_element_before_start_far(void)
+{
+  return arr[-100]; /* { dg-warning "buffer underread" "warning" } */
+  /* { dg-message "out-of-bounds read from byte -400 till byte -397 but 'arr' starts at byte 0" "final event" { target *-*-* } .-1 } */
+}
+
+int32_t int_arr_read_element_before_start_near(void)
+{
+  return arr[-2]; /* { dg-warning "buffer underread" "warning" } */
+  /* { dg-message "out-of-bounds read from byte -8 till byte -5 but 'arr' starts at byte 0" "final event" { target *-*-* } .-1 } */
+}
+
+int32_t int_arr_read_element_before_start_off_by_one(void)
+{
+  return arr[-1]; /* { dg-warning "buffer underread" "warning" } */
+  /* { dg-message "out-of-bounds read from byte -4 till byte -1 but 'arr' starts at byte 0" "final event" { target *-*-* } .-1 } */
+}
+
+int32_t int_arr_read_element_at_start(void)
+{
+  return arr[0];
+}
+
+int32_t int_arr_read_element_at_end(void)
+{
+  return arr[9];
+}
+
+int32_t int_arr_read_element_after_end_off_by_one(void)
+{
+  return arr[10]; /* { dg-warning "buffer overread" "warning" } */
+  /* { dg-message "out-of-bounds read from byte 40 till byte 43 but 'arr' ends at byte 40" "final event" { target *-*-* } .-1 } */
+  /* { dg-message "read is 4 bytes past the end of 'arr'" "note" { target *-*-* } .-2 } */
+}
+
+int32_t int_arr_read_element_after_end_near(void)
+{
+  return arr[11]; /* { dg-warning "buffer overread" "warning" } */
+  /* { dg-message "out-of-bounds read from byte 44 till byte 47 but 'arr' ends at byte 40" "final event" { target *-*-* } .-1 } */
+  /* { dg-message "read is 4 bytes past the end of 'arr'" "note" { target *-*-* } .-2 } */
+  // FIXME(PR 106626): is the note correct?
+}
+
+int32_t int_arr_read_element_after_end_far(void)
+{
+  return arr[100]; /* { dg-warning "buffer overread" "warning" } */
+  /* { dg-message "out-of-bounds read from byte 400 till byte 403 but 'arr' ends at byte 40" "final event" { target *-*-* } .-1 } */
+  /* { dg-message "read is 4 bytes past the end of 'arr'" "note" { target *-*-* } .-2 } */
+  // FIXME(PR 106626): the note seems incorrect (size of access is 4 bytes, but magnitude beyond boundary is 390-393)
+}
diff --git a/gcc/testsuite/gcc.dg/analyzer/out-of-bounds-write-char-arr.c b/gcc/testsuite/gcc.dg/analyzer/out-of-bounds-write-char-arr.c
new file mode 100644
index 0000000..47fbc52
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/analyzer/out-of-bounds-write-char-arr.c
@@ -0,0 +1,55 @@
+char arr[10]; /* { dg-message "capacity is 10 bytes" } */
+
+void int_arr_write_element_before_start_far(char x)
+{
+  arr[-100] = x; /* { dg-warning "buffer underflow" "warning" } */
+  /* { dg-message "out-of-bounds write at byte -100 but 'arr' starts at byte 0" "final event" { target *-*-* } .-1 } */
+}
+
+void int_arr_write_element_before_start_near(char x)
+{
+  arr[-2] = x; /* { dg-warning "buffer underflow" "warning" } */
+  /* { dg-message "out-of-bounds write at byte -2 but 'arr' starts at byte 0" "final event" { target *-*-* } .-1 } */
+}
+
+void int_arr_write_element_before_start_off_by_one(char x)
+{
+  arr[-1] = x; /* { dg-warning "buffer underflow" "warning" } */
+  /* { dg-message "out-of-bounds write at byte -1 but 'arr' starts at byte 0" "final event" { target *-*-* } .-1 } */
+}
+
+void int_arr_write_element_at_start(char x)
+{
+  arr[0] = x;
+}
+
+void int_arr_write_element_at_end(char x)
+{
+  arr[9] = x;
+}
+
+void int_arr_write_element_after_end_off_by_one(char x)
+{
+  arr[10] = x; /* { dg-warning "buffer overflow" "warning" } */
+  /* { dg-message "out-of-bounds write at byte 10 but 'arr' ends at byte 10" "final event" { target *-*-* } .-1 } */
+  /* { dg-message "write is 1 bytes past the end of 'arr'" "note" { target *-*-* } .-2 } */
+  // FIXME(PR 106626): "1 bytes"
+}
+
+void int_arr_write_element_after_end_near(char x)
+{
+  arr[11] = x; /* { dg-warning "buffer overflow" "warning" } */
+  /* { dg-message "out-of-bounds write at byte 11 but 'arr' ends at byte 10" "final event" { target *-*-* } .-1 } */
+  /* { dg-message "write is 1 bytes past the end of 'arr'" "note" { target *-*-* } .-2 } */
+  // FIXME(PR 106626): is the note correct?
+  // FIXME(PR 106626): "1 bytes"
+}
+
+void int_arr_write_element_after_end_far(char x)
+{
+  arr[100] = x; /* { dg-warning "buffer overflow" "warning" } */
+  /* { dg-message "out-of-bounds write at byte 100 but 'arr' ends at byte 10" "final event" { target *-*-* } .-1 } */
+  /* { dg-message "write is 1 bytes past the end of 'arr'" "note" { target *-*-* } .-2 } */
+  // FIXME(PR 106626): the note seems incorrect (size of access is 1 byte, but magnitude beyond boundary is 90)
+  // FIXME(PR 106626): "1 bytes"
+}
diff --git a/gcc/testsuite/gcc.dg/analyzer/out-of-bounds-write-int-arr.c b/gcc/testsuite/gcc.dg/analyzer/out-of-bounds-write-int-arr.c
new file mode 100644
index 0000000..bf9760e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/analyzer/out-of-bounds-write-int-arr.c
@@ -0,0 +1,54 @@
+#include <stdint.h>
+
+int32_t arr[10]; /* { dg-message "capacity is 40 bytes" } */
+
+void int_arr_write_element_before_start_far(int32_t x)
+{
+  arr[-100] = x; /* { dg-warning "buffer underflow" "warning" } */
+  /* { dg-message "out-of-bounds write from byte -400 till byte -397 but 'arr' starts at byte 0" "final event" { target *-*-* } .-1 } */
+}
+
+void int_arr_write_element_before_start_near(int32_t x)
+{
+  arr[-2] = x; /* { dg-warning "buffer underflow" "warning" } */
+  /* { dg-message "out-of-bounds write from byte -8 till byte -5 but 'arr' starts at byte 0" "final event" { target *-*-* } .-1 } */
+}
+
+void int_arr_write_element_before_start_off_by_one(int32_t x)
+{
+  arr[-1] = x; /* { dg-warning "buffer underflow" "warning" } */
+  /* { dg-message "out-of-bounds write from byte -4 till byte -1 but 'arr' starts at byte 0" "final event" { target *-*-* } .-1 } */
+}
+
+void int_arr_write_element_at_start(int32_t x)
+{
+  arr[0] = x;
+}
+
+void int_arr_write_element_at_end(int32_t x)
+{
+  arr[9] = x;
+}
+
+void int_arr_write_element_after_end_off_by_one(int32_t x)
+{
+  arr[10] = x; /* { dg-warning "buffer overflow" "warning" } */
+  /* { dg-message "out-of-bounds write from byte 40 till byte 43 but 'arr' ends at byte 40" "final event" { target *-*-* } .-1 } */
+  /* { dg-message "write is 4 bytes past the end of 'arr'" "note" { target *-*-* } .-2 } */
+}
+
+void int_arr_write_element_after_end_near(int32_t x)
+{
+  arr[11] = x; /* { dg-warning "buffer overflow" "warning" } */
+  /* { dg-message "out-of-bounds write from byte 44 till byte 47 but 'arr' ends at byte 40" "final event" { target *-*-* } .-1 } */
+  /* { dg-message "write is 4 bytes past the end of 'arr'" "note" { target *-*-* } .-2 } */
+  // FIXME(PR 106626): is the note correct?
+}
+
+void int_arr_write_element_after_end_far(int32_t x)
+{
+  arr[100] = x; /* { dg-warning "buffer overflow" "warning" } */
+  /* { dg-message "out-of-bounds write from byte 400 till byte 403 but 'arr' ends at byte 40" "final event" { target *-*-* } .-1 } */
+  /* { dg-message "write is 4 bytes past the end of 'arr'" "note" { target *-*-* } .-2 } */
+  // FIXME(PR 106626): the note seems incorrect (size of access is 4 bytes, but magnitude beyond boundary is 390-393)
+}