From: David Malcolm Date: Sat, 7 Jan 2017 21:33:59 +0000 (+0000) Subject: Fix linemap corruption after very wide source lines (PR c++/72803) X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=5ccf1d8d1073544f3d3c24e2168fc12e983dfa47;p=gcc.git 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<= 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 --- diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 9f7f0900bec..38b6102f3f7 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,10 @@ +2017-01-07 David Malcolm + + 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 * doc/options.texi (PerFunction): New. diff --git a/gcc/input.c b/gcc/input.c index 195f72e0619..bbb6abb8878 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 340ec410539..1f6100bd323 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2017-01-07 David Malcolm + + PR c++/72803 + * g++.dg/diagnostic/pr72803.C: New test case. + 2017-01-07 Martin Sebor * 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 00000000000..0a9a390b9c3 --- /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 } diff --git a/libcpp/ChangeLog b/libcpp/ChangeLog index e9055bb92a4..082291d5648 100644 --- a/libcpp/ChangeLog +++ b/libcpp/ChangeLog @@ -1,3 +1,11 @@ +2017-01-07 David Malcolm + + 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. + 2017-01-01 Jakub Jelinek Update copyright years. diff --git a/libcpp/line-map.c b/libcpp/line-map.c index 77beaffd5bf..b410c00e367 100644 --- a/libcpp/line-map.c +++ b/libcpp/line-map.c @@ -752,7 +752,7 @@ linemap_line_start (struct line_maps *set, linenum_type to_line, single line we can sometimes just increase its column_bits instead. */ if (line_delta < 0 || last_line != ORDINARY_MAP_STARTING_LINE_NUMBER (map) - || SOURCE_COLUMN (map, highest) >= (1U << column_bits) + || SOURCE_COLUMN (map, highest) >= (1U << (column_bits - range_bits)) || range_bits < map->m_range_bits) map = linemap_check_ordinary (const_cast