Hi!
Seems when Martin S. implemented this, he coded there strict reading
of the standard, which said that %lc with (wint_t) 0 argument is handled
as wchar_t[2] temp = { arg, 0 }; %ls with temp arg and so shouldn't print
any values. But, most of the libc implementations actually handled that
case like %c with '\0' argument, adding a single NUL character, the only
known exception is musl.
Recently, C23 changed this in response to GB-141 and POSIX in
https://austingroupbugs.net/view.php?id=1647
so that it should have the same behavior as %c with '\0'.
Because there is implementation divergence, the following patch uses
a range rather than hardcoding it to all 1s (i.e. the %c behavior),
though the likely case is still 1 (forward looking plus most of
implementations).
The res.knownrange = true; assignment removed is redundant due to
the same assignment done unconditionally before the if statement,
rest is formatting fixes.
I don't think the min >= 0 && min < 128 case is right either, I'd think
it should be min >= 0 && max < 128, otherwise it is just some possible
inputs are (maybe) ASCII and there can be others, but this code is a total
mess anyway, with the min, max, likely (somewhere in [min, max]?) and then
unlikely possibly larger than max, dunno, perhaps for at least some chars
in the ASCII range the likely case could be for the ascii case; so perhaps
just the one_2_one_ascii shouldn't set max to 1 and mayfail should be true
for max >= 128. Anyway, didn't feel I should touch that right now.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
Shall it go to 14.1, or wait for 14.2?
2024-04-30 Jakub Jelinek <ja...@redhat.com>
PR tree-optimization/114876
* gimple-ssa-sprintf.cc (format_character): For min == 0 && max == 0,
set max, likely and unlikely members to 1 rather than 0. Remove
useless res.knownrange = true;. Formatting fixes.
* gcc.dg/pr114876.c: New test.
* gcc.dg/tree-ssa/builtin-sprintf-warn-1.c: Adjust expected
diagnostics.
--- gcc/gimple-ssa-sprintf.cc.jj 2024-01-03 11:51:22.225860346 +0100
+++ gcc/gimple-ssa-sprintf.cc 2024-04-29 12:52:59.760668894 +0200
@@ -2177,8 +2177,7 @@ format_character (const directive &dir,
res.knownrange = true;
- if (dir.specifier == 'C'
- || dir.modifier == FMT_LEN_l)
+ if (dir.specifier == 'C' || dir.modifier == FMT_LEN_l)
{
/* A wide character can result in as few as zero bytes. */
res.range.min = 0;
@@ -2189,10 +2188,13 @@ format_character (const directive &dir,
{
if (min == 0 && max == 0)
{
- /* The NUL wide character results in no bytes. */
- res.range.max = 0;
- res.range.likely = 0;
- res.range.unlikely = 0;
+ /* In strict reading of older ISO C or POSIX, this required
+ no characters to be emitted. ISO C23 changes that, so
+ does POSIX, to match what has been implemented in most of the
+ implementations, namely emitting a single NUL character.
+ Let's use 0 for minimum and 1 for all the other values. */
+ res.range.max = 1;
+ res.range.likely = res.range.unlikely = 1;
}
else if (min >= 0 && min < 128)
{
@@ -2200,11 +2202,12 @@ format_character (const directive &dir,
is not a 1-to-1 mapping to the source character set or
if the source set is not ASCII. */
bool one_2_one_ascii
- = (target_to_host_charmap[0] == 1 && target_to_host ('a') ==
97);
+ = (target_to_host_charmap[0] == 1
+ && target_to_host ('a') == 97);
/* A wide character in the ASCII range most likely results
in a single byte, and only unlikely in up to MB_LEN_MAX. */
- res.range.max = one_2_one_ascii ? 1 : target_mb_len_max ();;
+ res.range.max = one_2_one_ascii ? 1 : target_mb_len_max ();
res.range.likely = 1;
res.range.unlikely = target_mb_len_max ();
res.mayfail = !one_2_one_ascii;
@@ -2235,7 +2238,6 @@ format_character (const directive &dir,
/* A plain '%c' directive. Its output is exactly 1. */
res.range.min = res.range.max = 1;
res.range.likely = res.range.unlikely = 1;
- res.knownrange = true;
}
/* Bump up the byte counters if WIDTH is greater. */
--- gcc/testsuite/gcc.dg/pr114876.c.jj 2024-04-29 12:26:45.774965158 +0200
+++ gcc/testsuite/gcc.dg/pr114876.c 2024-04-29 12:51:37.863777055 +0200
@@ -0,0 +1,34 @@
+/* PR tree-optimization/114876 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+/* { dg-final { scan-tree-dump-not "return \[01\];" "optimized" } } */
+/* { dg-final { scan-tree-dump "return 3;" "optimized" } } */
+/* { dg-final { scan-tree-dump "return 4;" "optimized" } } */
+
+int
+foo (void)
+{
+ char buf[64];
+ return __builtin_sprintf (buf, "%lc%lc%lc", (__WINT_TYPE__) 0,
(__WINT_TYPE__) 0, (__WINT_TYPE__) 0);
+}
+
+int
+bar (void)
+{
+ char buf[64];
+ return __builtin_sprintf (buf, "%c%c%c", 0, 0, 0);
+}
+
+int
+baz (void)
+{
+ char buf[64];
+ return __builtin_sprintf (buf, "%lc%lc%lca", (__WINT_TYPE__) 0,
(__WINT_TYPE__) 0, (__WINT_TYPE__) 0);
+}
+
+int
+qux (void)
+{
+ char buf[64];
+ return __builtin_sprintf (buf, "%c%c%ca", 0, 0, 0);
+}
--- gcc/testsuite/gcc.dg/tree-ssa/builtin-sprintf-warn-1.c.jj 2020-12-03
10:04:35.888092988 +0100
+++ gcc/testsuite/gcc.dg/tree-ssa/builtin-sprintf-warn-1.c 2024-04-29
12:49:14.452717581 +0200
@@ -200,11 +200,11 @@ void test_sprintf_chk_c_const (void)
T (3, "%c%c", '1', '2');
/* Wide characters. */
- T (0, "%lc", (wint_t)0); /* { dg-warning "nul past the end" } */
- T (1, "%lc", (wint_t)0);
- T (1, "%lc%lc", (wint_t)0, (wint_t)0);
+ T (0, "%lc", (wint_t)0); /* { dg-warning ".%lc. directive writing up
to 1 bytes into a region of size 0" } */
+ T (1, "%lc", (wint_t)0); /* { dg-warning "nul past the end" } */
+ T (1, "%lc%lc", (wint_t)0, (wint_t)0); /* { dg-warning ".%lc. directive
writing up to 1 bytes into a region of size between 0 and 1" } */
T (2, "%lc", (wint_t)0);
- T (2, "%lc%lc", (wint_t)0, (wint_t)0);
+ T (2, "%lc%lc", (wint_t)0, (wint_t)0); /* { dg-warning "nul past the end"
} */
/* The following could result in as few as no bytes and in as many as
MB_CUR_MAX, but since the MB_CUR_MAX value is a runtime property
@@ -1550,7 +1550,7 @@ void test_snprintf_c_const (char *d)
/* Wide characters. */
T (0, "%lc", (wint_t)0);
- T (1, "%lc", (wint_t)0);
+ T (1, "%lc", (wint_t)0); /* { dg-warning "output may be truncated
before the last format character" } */
T (2, "%lc", (wint_t)0);
/* The following could result in as few as a single byte and in as many
@@ -1603,7 +1603,7 @@ void test_snprintf_chk_c_const (void)
/* Wide characters. */
T (0, "%lc", (wint_t)0);
- T (1, "%lc", (wint_t)0);
+ T (1, "%lc", (wint_t)0); /* { dg-warning "output may be truncated
before the last format character" } */
T (2, "%lc", (wint_t)0);
/* The following could result in as few as a single byte and in as many
Jakub
