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author | David Malcolm <dmalcolm@redhat.com> | 2017-01-07 21:33:59 +0000 |
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committer | David Malcolm <dmalcolm@gcc.gnu.org> | 2017-01-07 21:33:59 +0000 |
commit | 5ccf1d8d1073544f3d3c24e2168fc12e983dfa47 (patch) | |
tree | d50cf2a1d95d451c655a244f774cbcdbb459d9df /gcc | |
parent | ff98fa955b5dc98bb05e30ed79299155d2a2f97c (diff) | |
download | gcc-5ccf1d8d1073544f3d3c24e2168fc12e983dfa47.zip gcc-5ccf1d8d1073544f3d3c24e2168fc12e983dfa47.tar.gz gcc-5ccf1d8d1073544f3d3c24e2168fc12e983dfa47.tar.bz2 |
Fix linemap corruption after very wide source lines (PR c++/72803)
PR c++/72803 describes an issue where a fix-it hint is to be emitted at
column 512 of a 511-column source line, leading to an ICE.
The root cause is a bug in linemap_line_start, when transitioning from
lines >= 512 in width to narrow lines.
The wide line in the reproducer has a line map with:
m_column_and_range_bits = 15, m_range_bits = 5
giving 10 effective bits for representing columns, so that columns <= 1023
can be represented.
When parsing the following line,
linemap_line_start (..., ..., max_column_hint=0);
is called. This leads to the "add_map" logic, due to this condition:
|| (max_column_hint <= 80 && effective_column_bits >= 10)
i.e. the new line is sufficiently narrower than the old one to
potentially use a new linemap (so as to conserve values within the
location_t space).
It then attempts to avoid allocating a new line map. Part of the logic
to determine if we really need a new line map is this condition:
SOURCE_COLUMN (map, highest) >= (1U << column_bits)
The above condition is incorrect: we need to determine if the highest
column we've handed out will fit within the proposed *effective* column
bits, but "column_bits" here is the column plus the range bits, rather
than just the column bits.
Hence in this case linemap_line_start erroneously decides that we don't
need a new line map, and updates the column bits within the existing
line map, so any location_t values we've already handed out within it
that are offset from the start by
>= (1<<new_column_and_range_bits)
effectively change meaning, leading to incorrect line&column information
when decoding them, and various "interesting" ways for the linemap
code to fail.
The fix is to use the effective column bits in the above conditional.
gcc/ChangeLog:
PR c++/72803
* input.c (selftest::test_accessing_ordinary_linemaps): Verify
that the transition from a max line width >= 1<<10 to narrower
lines works correctly.
gcc/testsuite/ChangeLog:
PR c++/72803
* g++.dg/diagnostic/pr72803.C: New test case.
libcpp/ChangeLog:
PR c++/72803
* line-map.c (linemap_line_start): When determining if the highest
column given out so far will fit into a proposed change to the
current map, use the effective number of column bits, rather than
the total number of column + range bits.
From-SVN: r244199
Diffstat (limited to 'gcc')
-rw-r--r-- | gcc/ChangeLog | 7 | ||||
-rw-r--r-- | gcc/input.c | 12 | ||||
-rw-r--r-- | gcc/testsuite/ChangeLog | 5 | ||||
-rw-r--r-- | gcc/testsuite/g++.dg/diagnostic/pr72803.C | 9 |
4 files changed, 33 insertions, 0 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 9f7f090..38b6102 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,10 @@ +2017-01-07 David Malcolm <dmalcolm@redhat.com> + + PR c++/72803 + * input.c (selftest::test_accessing_ordinary_linemaps): Verify + that the transition from a max line width >= 1<<10 to narrower + lines works correctly. + 2017-01-07 Alexandre Oliva <aoliva@redhat.com> * doc/options.texi (PerFunction): New. diff --git a/gcc/input.c b/gcc/input.c index 195f72e..bbb6abb 100644 --- a/gcc/input.c +++ b/gcc/input.c @@ -1688,6 +1688,17 @@ test_accessing_ordinary_linemaps (const line_table_case &case_) linemap_line_start (line_table, 3, 2000); location_t loc_e = linemap_position_for_column (line_table, 700); + /* Transitioning back to a short line. */ + linemap_line_start (line_table, 4, 0); + location_t loc_back_to_short = linemap_position_for_column (line_table, 100); + + if (should_have_column_data_p (loc_back_to_short)) + { + /* Verify that we switched to short lines in the linemap. */ + line_map_ordinary *map = LINEMAPS_LAST_ORDINARY_MAP (line_table); + ASSERT_EQ (7, map->m_column_and_range_bits - map->m_range_bits); + } + linemap_add (line_table, LC_LEAVE, false, NULL, 0); /* Multiple files. */ @@ -1702,6 +1713,7 @@ test_accessing_ordinary_linemaps (const line_table_case &case_) assert_loceq ("foo.c", 2, 1, loc_c); assert_loceq ("foo.c", 2, 17, loc_d); assert_loceq ("foo.c", 3, 700, loc_e); + assert_loceq ("foo.c", 4, 100, loc_back_to_short); assert_loceq ("bar.c", 1, 150, loc_f); ASSERT_FALSE (is_location_from_builtin_token (loc_a)); diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 340ec41..1f6100b 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2017-01-07 David Malcolm <dmalcolm@redhat.com> + + PR c++/72803 + * g++.dg/diagnostic/pr72803.C: New test case. + 2017-01-07 Martin Sebor <msebor@redhat.com> * gcc.dg/attr-alloc_size-3.c: Remove regex made redundant by r243461. diff --git a/gcc/testsuite/g++.dg/diagnostic/pr72803.C b/gcc/testsuite/g++.dg/diagnostic/pr72803.C new file mode 100644 index 0000000..0a9a390 --- /dev/null +++ b/gcc/testsuite/g++.dg/diagnostic/pr72803.C @@ -0,0 +1,9 @@ +/* Long line, with a close brace at column 511, hence with the insertion + point for the missing semicolon at column 512. */ +class test { } +# 1 "" 1 +// The line directive appears to be necessary to trigger the ICE +// { dg-error "style of line directive is a GCC extension" "" { target *-*-* } .-2 } + +/* Verify that we get the correct line and column for the diagnostic. */ +// { dg-error "512: expected .;. after class definition" "" { target *-*-* } 3 } |