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| author | Carlos O'Donell <carlos@redhat.com> | 2018-02-01 20:40:48 +0000 |
|---|---|---|
| committer | Joseph Myers <joseph@codesourcery.com> | 2018-02-01 20:40:48 +0000 |
| commit | f1d7368196e27370dcb5dfa3319e102f33b9ad66 (patch) | |
| tree | f5cb96139f71bcacc420f32c7919fc1db97d59d8 /sysdeps/ieee754 | |
| parent | 086ee48eaeaba871a2300daf85469671cc14c7e9 (diff) | |
| download | glibc-f1d7368196e27370dcb5dfa3319e102f33b9ad66.tar.gz glibc-f1d7368196e27370dcb5dfa3319e102f33b9ad66.tar.xz glibc-f1d7368196e27370dcb5dfa3319e102f33b9ad66.zip | |
Fix -Os log1p, log1pf build (bug 21314).
As reported in bug 21314, building log1p and log1pf fails with -Os because of a spurious -Wmaybe-uninitialized warning (reported there for GCC 5 for MIPS, I see it also with GCC 7 for x86_64). This patch, based on the patches in the bug, fixes this using the DIAG_* macros. Tested for x86_64 with -Os that this eliminates those warnings and so allows the build to progress further. 2018-02-01 Carlos O'Donell <carlos@redhat.com> Ramin Seyed-Moussavi <lordrasmus@gmail.com> Joseph Myers <joseph@codesourcery.com> [BZ #21314] * sysdeps/ieee754/dbl-64/s_log1p.c: Include <libc-diag.h>. (__log1p): Disable -Wmaybe-uninitialized for -Os around computation using c. * sysdeps/ieee754/flt-32/s_log1pf.c: Include <libc-diag.h>. (__log1pf): Disable -Wmaybe-uninitialized for -Os around computation using c.
Diffstat (limited to 'sysdeps/ieee754')
| -rw-r--r-- | sysdeps/ieee754/dbl-64/s_log1p.c | 12 | ||||
| -rw-r--r-- | sysdeps/ieee754/flt-32/s_log1pf.c | 17 |
2 files changed, 26 insertions, 3 deletions
diff --git a/sysdeps/ieee754/dbl-64/s_log1p.c b/sysdeps/ieee754/dbl-64/s_log1p.c index 340f6377f7..b7cf5ce321 100644 --- a/sysdeps/ieee754/dbl-64/s_log1p.c +++ b/sysdeps/ieee754/dbl-64/s_log1p.c @@ -81,6 +81,7 @@ #include <float.h> #include <math.h> #include <math_private.h> +#include <libc-diag.h> static const double ln2_hi = 6.93147180369123816490e-01, /* 3fe62e42 fee00000 */ @@ -191,5 +192,14 @@ __log1p (double x) if (k == 0) return f - (hfsq - s * (hfsq + R)); else - return k * ln2_hi - ((hfsq - (s * (hfsq + R) + (k * ln2_lo + c))) - f); + { + /* With GCC 7 when compiling with -Os the compiler warns that c + might be used uninitialized. This can't be true because k + must be 0 for c to be uninitialized and we handled that + computation earlier without using c. */ + DIAG_PUSH_NEEDS_COMMENT; + DIAG_IGNORE_Os_NEEDS_COMMENT (7, "-Wmaybe-uninitialized"); + return k * ln2_hi - ((hfsq - (s * (hfsq + R) + (k * ln2_lo + c))) - f); + DIAG_POP_NEEDS_COMMENT; + } } diff --git a/sysdeps/ieee754/flt-32/s_log1pf.c b/sysdeps/ieee754/flt-32/s_log1pf.c index ade60a2e27..009084ee19 100644 --- a/sysdeps/ieee754/flt-32/s_log1pf.c +++ b/sysdeps/ieee754/flt-32/s_log1pf.c @@ -16,6 +16,7 @@ #include <float.h> #include <math.h> #include <math_private.h> +#include <libc-diag.h> static const float ln2_hi = 6.9313812256e-01, /* 0x3f317180 */ @@ -97,6 +98,18 @@ __log1pf(float x) s = f/((float)2.0+f); z = s*s; R = z*(Lp1+z*(Lp2+z*(Lp3+z*(Lp4+z*(Lp5+z*(Lp6+z*Lp7)))))); - if(k==0) return f-(hfsq-s*(hfsq+R)); else - return k*ln2_hi-((hfsq-(s*(hfsq+R)+(k*ln2_lo+c)))-f); + if (k == 0) + return f - (hfsq - s * (hfsq + R)); + else + { + /* With GCC 7 when compiling with -Os the compiler warns + that c might be used uninitialized. This can't be true + because k must be 0 for c to be uninitialized and we + handled that computation earlier without using c. */ + DIAG_PUSH_NEEDS_COMMENT; + DIAG_IGNORE_Os_NEEDS_COMMENT (7, "-Wmaybe-uninitialized"); + return k * ln2_hi - ((hfsq - (s * (hfsq + R) + + (k * ln2_lo + c))) - f); + DIAG_POP_NEEDS_COMMENT; + } } |