Message ID | 20180930155134.32524-1-Martin.Jansa@gmail.com |
---|---|
State | New |
Headers | show |
Series | [PATCHv3] sysdeps/ieee754: prevent maybe-uninitialized errors with -O [BZ #19444] | expand |
On Sun, 30 Sep 2018, Martin Jansa wrote: > + /* With GCC 8 (and older) when compiling with -O the compiler > + warns that the variable 'temp', may be used uninitialized. > + The switch above covers all possible values of n & 3 > + but GCC without VRP enabled isn't able to figure out the > + range of possible values is [0,3] as explained in: > + https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69230 > + so it's false possitive with -O1 and lower. */ "positive" (for all such comments). Also note there should be two spaces at the end of a comment between "." and the trailing "*/". Are you sure about the "and lower", or is this warning disabled for -O0? (glibc disallows building with -O0 at present, but I think we *should* fix things to be able to build with -O0, because being able to build with -O0 would be helpful for debugging - any particular pieces needing optimization should then just have it force-enabled, or functions declared as always_inline, or whatever is needed, locally.)
On Sun, Sep 30, 2018 at 04:52:56PM +0000, Joseph Myers wrote: > On Sun, 30 Sep 2018, Martin Jansa wrote: > > > + /* With GCC 8 (and older) when compiling with -O the compiler > > + warns that the variable 'temp', may be used uninitialized. > > + The switch above covers all possible values of n & 3 > > + but GCC without VRP enabled isn't able to figure out the > > + range of possible values is [0,3] as explained in: > > + https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69230 > > + so it's false possitive with -O1 and lower. */ > > "positive" (for all such comments). Also note there should be two spaces > at the end of a comment between "." and the trailing "*/". OK, will update. > Are you sure about the "and lower", or is this warning disabled for -O0? I'm pretty sure that -ftree-vrp isn't enabled with -O0, but will retry if it also shows this warning with -O0. > (glibc disallows building with -O0 at present, but I think we *should* fix > things to be able to build with -O0, because being able to build with -O0 > would be helpful for debugging - any particular pieces needing > optimization should then just have it force-enabled, or functions declared > as always_inline, or whatever is needed, locally.) I agree, but I'm not volunteering to fix all of -O0 issues reported in [BZ #19444], my motivation was just to fix debug builds in Yocto which is by default using -O (and issues with -Os which I'm using for some of my builds): http://lists.openembedded.org/pipermail/openembedded-core/2018-September/155693.html Fixing: https://sourceware.org/glibc/wiki/FAQ#Why_do_I_get:.60.23error_.22glibc_cannot_be_compiled_without_optimization.22.27.2C_when_trying_to_compile_GNU_libc_with_GNU_CC.3F is out of my league and time I'm willing to spend, I'll leave it to someone more knowledgable about glibc internals. Cheers,
On Sun, Sep 30, 2018 at 07:57:11PM +0200, Martin Jansa wrote: > On Sun, Sep 30, 2018 at 04:52:56PM +0000, Joseph Myers wrote: > > On Sun, 30 Sep 2018, Martin Jansa wrote: > > > > > + /* With GCC 8 (and older) when compiling with -O the compiler > > > + warns that the variable 'temp', may be used uninitialized. > > > + The switch above covers all possible values of n & 3 > > > + but GCC without VRP enabled isn't able to figure out the > > > + range of possible values is [0,3] as explained in: > > > + https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69230 > > > + so it's false possitive with -O1 and lower. */ > > > > "positive" (for all such comments). Also note there should be two spaces > > at the end of a comment between "." and the trailing "*/". > > OK, will update. > > > Are you sure about the "and lower", or is this warning disabled for -O0? > > I'm pretty sure that -ftree-vrp isn't enabled with -O0, but will retry > if it also shows this warning with -O0. You were right, it warning isn't triggered with -O0, I'll drop the " and lower" part in v4. docker-shr @ ~/build/oe-core/tmp-glibc/work/core2-64-oe-linux/glibc/2.28-r0/git/math $ x86_64-oe-linux-gcc -m64 -march=core2 -mtune=core2 -msse3 -mfpmath=sse --sysroot=/OE/build/oe-core/tmp-glibc/work/core2-64-oe-linux/glibc/2.28-r0/recipe-sysroot ../sysdeps/ieee754/ldbl-96/e_jnl.c -c -std=gnu11 -fgnu89-inline -O1 -pipe -g -feliminate-unused-debug-types -fdebug-prefix-map=/OE/build/oe-core/tmp-glibc/work/core2-64-oe-linux/glibc/2.28-r0=/usr/src/debug/glibc/2.28-r0 -fdebug-prefix-map=/OE/build/oe-core/tmp-glibc/work/core2-64-oe-linux/glibc/2.28-r0/recipe-sysroot= -fdebug-prefix-map=/OE/build/oe-core/tmp-glibc/work/core2-64-oe-linux/glibc/2.28-r0/recipe-sysroot-native= -Wall -Wwrite-strings -Wundef -Werror -fmerge-all-constants -frounding-math -fno-stack-protector -Wstrict-prototypes -Wold-style-definition -fno-math-errno -D__NO_MATH_INLINES -D__LIBC_INTERNAL_MATH_INLINES -I../include -I/OE/build/oe-core/tmp-glibc/work/core2-64-oe-linux/glibc/2.28-r0/build-x86_64-oe-linux/math -I/OE/build/oe-core/tmp-glibc/work/core2-64-oe-linux/glibc/2.28-r0/build-x86_64-oe-linux -I../sysdeps/unix/sysv/linux/x86_64/64 -I../sysdeps/unix/sysv/linux/x86_64 -I../sysdeps/unix/sysv/linux/x86/include -I../sysdeps/unix/sysv/linux/x86 -I../sysdeps/x86/nptl -I../sysdeps/unix/sysv/linux/wordsize-64 -I../sysdeps/x86_64/nptl -I../sysdeps/unix/sysv/linux/include -I../sysdeps/unix/sysv/linux -I../sysdeps/nptl -I../sysdeps/pthread -I../sysdeps/gnu -I../sysdeps/unix/inet -I../sysdeps/unix/sysv -I../sysdeps/unix/x86_64 -I../sysdeps/unix -I../sysdeps/posix -I../sysdeps/x86_64/64 -I../sysdeps/x86_64/fpu/multiarch -I../sysdeps/x86_64/fpu -I../sysdeps/x86/fpu/include -I../sysdeps/x86/fpu -I../sysdeps/x86_64/multiarch -I../sysdeps/x86_64 -I../sysdeps/x86 -I../sysdeps/ieee754/float128 -I../sysdeps/ieee754/ldbl-96/include -I../sysdeps/ieee754/ldbl-96 -I../sysdeps/ieee754/dbl-64/wordsize-64 -I../sysdeps/ieee754/dbl-64 -I../sysdeps/ieee754/flt-32 -I../sysdeps/wordsize-64 -I../sysdeps/ieee754 -I../sysdeps/generic -I.. -I../libio -I. -nostdinc -isystem /OE/build/oe-core/tmp-glibc/work/core2-64-oe-linux/glibc/2.28-r0/recipe-sysroot-native/usr/bin/x86_64-oe-linux.gcc-cross-initial-x86_64/../../lib/x86_64-oe-linux.gcc-cross-initial-x86_64/gcc/x86_64-oe-linux/8.2.0/include -isystem /OE/build/oe-core/tmp-glibc/work/core2-64-oe-linux/glibc/2.28-r0/recipe-sysroot-native/usr/bin/x86_64-oe-linux.gcc-cross-initial-x86_64/../../lib/x86_64-oe-linux.gcc-cross-initial-x86_64/gcc/x86_64-oe-linux/8.2.0/include-fixed -isystem /OE/build/oe-core/tmp-glibc/work/core2-64-oe-linux/glibc/2.28-r0/recipe-sysroot/usr/include -D_LIBC_REENTRANT -include /OE/build/oe-core/tmp-glibc/work/core2-64-oe-linux/glibc/2.28-r0/build-x86_64-oe-linux/libc-modules.h -DMODULE_NAME=libm -include ../include/libc-symbols.h -DTOP_NAMESPACE=glibc -I../soft-fp -o /OE/build/oe-core/tmp-glibc/work/core2-64-oe-linux/glibc/2.28-r0/build-x86_64-oe-linux/math/e_jnl.o -MD -MP -MF /OE/build/oe-core/tmp-glibc/work/core2-64-oe-linux/glibc/2.28-r0/build-x86_64-oe-linux/math/e_jnl.o.dt -MT /OE/build/oe-core/tmp-glibc/work/core2-64-oe-linux/glibc/2.28-r0/build-x86_64-oe-linux/math/e_jnl.o ../sysdeps/ieee754/ldbl-96/e_jnl.c: In function '__ieee754_jnl': ../sysdeps/ieee754/ldbl-96/e_jnl.c:147:20: error: 'temp' may be used uninitialized in this function [-Werror=maybe-uninitialized] b = invsqrtpi * temp / sqrtl (x); ~~~~~~~~~~^~~~~~ ../sysdeps/ieee754/ldbl-96/e_jnl.c: In function '__ieee754_ynl': ../sysdeps/ieee754/ldbl-96/e_jnl.c:376:16: error: 'temp' may be used uninitialized in this function [-Werror=maybe-uninitialized] b = invsqrtpi * temp / sqrtl (x); ~~~~~~~~~~^~~~~~ cc1: all warnings being treated as errors docker-shr @ ~/build/oe-core/tmp-glibc/work/core2-64-oe-linux/glibc/2.28-r0/git/math $ x86_64-oe-linux-gcc -m64 -march=core2 -mtune=core2 -msse3 -mfpmath=sse --sysroot=/OE/build/oe-core/tmp-glibc/work/core2-64-oe-linux/glibc/2.28-r0/recipe-sysroot ../sysdeps/ieee754/ldbl-96/e_jnl.c -c -std=gnu11 -fgnu89-inline -O0 -pipe -g -feliminate-unused-debug-types -fdebug-prefix-map=/OE/build/oe-core/tmp-glibc/work/core2-64-oe-linux/glibc/2.28-r0=/usr/src/debug/glibc/2.28-r0 -fdebug-prefix-map=/OE/build/oe-core/tmp-glibc/work/core2-64-oe-linux/glibc/2.28-r0/recipe-sysroot= -fdebug-prefix-map=/OE/build/oe-core/tmp-glibc/work/core2-64-oe-linux/glibc/2.28-r0/recipe-sysroot-native= -Wall -Wwrite-strings -Wundef -Werror -fmerge-all-constants -frounding-math -fno-stack-protector -Wstrict-prototypes -Wold-style-definition -fno-math-errno -D__NO_MATH_INLINES -D__LIBC_INTERNAL_MATH_INLINES -I../include -I/OE/build/oe-core/tmp-glibc/work/core2-64-oe-linux/glibc/2.28-r0/build-x86_64-oe-linux/math -I/OE/build/oe-core/tmp-glibc/work/core2-64-oe-linux/glibc/2.28-r0/build-x86_64-oe-linux -I../sysdeps/unix/sysv/linux/x86_64/64 -I../sysdeps/unix/sysv/linux/x86_64 -I../sysdeps/unix/sysv/linux/x86/include -I../sysdeps/unix/sysv/linux/x86 -I../sysdeps/x86/nptl -I../sysdeps/unix/sysv/linux/wordsize-64 -I../sysdeps/x86_64/nptl -I../sysdeps/unix/sysv/linux/include -I../sysdeps/unix/sysv/linux -I../sysdeps/nptl -I../sysdeps/pthread -I../sysdeps/gnu -I../sysdeps/unix/inet -I../sysdeps/unix/sysv -I../sysdeps/unix/x86_64 -I../sysdeps/unix -I../sysdeps/posix -I../sysdeps/x86_64/64 -I../sysdeps/x86_64/fpu/multiarch -I../sysdeps/x86_64/fpu -I../sysdeps/x86/fpu/include -I../sysdeps/x86/fpu -I../sysdeps/x86_64/multiarch -I../sysdeps/x86_64 -I../sysdeps/x86 -I../sysdeps/ieee754/float128 -I../sysdeps/ieee754/ldbl-96/include -I../sysdeps/ieee754/ldbl-96 -I../sysdeps/ieee754/dbl-64/wordsize-64 -I../sysdeps/ieee754/dbl-64 -I../sysdeps/ieee754/flt-32 -I../sysdeps/wordsize-64 -I../sysdeps/ieee754 -I../sysdeps/generic -I.. -I../libio -I. -nostdinc -isystem /OE/build/oe-core/tmp-glibc/work/core2-64-oe-linux/glibc/2.28-r0/recipe-sysroot-native/usr/bin/x86_64-oe-linux.gcc-cross-initial-x86_64/../../lib/x86_64-oe-linux.gcc-cross-initial-x86_64/gcc/x86_64-oe-linux/8.2.0/include -isystem /OE/build/oe-core/tmp-glibc/work/core2-64-oe-linux/glibc/2.28-r0/recipe-sysroot-native/usr/bin/x86_64-oe-linux.gcc-cross-initial-x86_64/../../lib/x86_64-oe-linux.gcc-cross-initial-x86_64/gcc/x86_64-oe-linux/8.2.0/include-fixed -isystem /OE/build/oe-core/tmp-glibc/work/core2-64-oe-linux/glibc/2.28-r0/recipe-sysroot/usr/include -D_LIBC_REENTRANT -include /OE/build/oe-core/tmp-glibc/work/core2-64-oe-linux/glibc/2.28-r0/build-x86_64-oe-linux/libc-modules.h -DMODULE_NAME=libm -include ../include/libc-symbols.h -DTOP_NAMESPACE=glibc -I../soft-fp -o /OE/build/oe-core/tmp-glibc/work/core2-64-oe-linux/glibc/2.28-r0/build-x86_64-oe-linux/math/e_jnl.o -MD -MP -MF /OE/build/oe-core/tmp-glibc/work/core2-64-oe-linux/glibc/2.28-r0/build-x86_64-oe-linux/math/e_jnl.o.dt -MT /OE/build/oe-core/tmp-glibc/work/core2-64-oe-linux/glibc/2.28-r0/build-x86_64-oe-linux/math/e_jnl.o > > (glibc disallows building with -O0 at present, but I think we *should* fix > > things to be able to build with -O0, because being able to build with -O0 > > would be helpful for debugging - any particular pieces needing > > optimization should then just have it force-enabled, or functions declared > > as always_inline, or whatever is needed, locally.) > > I agree, but I'm not volunteering to fix all of -O0 issues reported in > [BZ #19444], my motivation was just to fix debug builds in Yocto which > is by default using -O (and issues with -Os which I'm using for some of > my builds): > http://lists.openembedded.org/pipermail/openembedded-core/2018-September/155693.html > > Fixing: > https://sourceware.org/glibc/wiki/FAQ#Why_do_I_get:.60.23error_.22glibc_cannot_be_compiled_without_optimization.22.27.2C_when_trying_to_compile_GNU_libc_with_GNU_CC.3F > is out of my league and time I'm willing to spend, I'll leave it to > someone more knowledgable about glibc internals. > > Cheers, > -- > Martin 'JaMa' Jansa jabber: Martin.Jansa@gmail.com
diff --git a/ChangeLog b/ChangeLog index 07760299e6..4bafeefda5 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,10 @@ +2018-09-29 Martin Jansa <Martin.Jansa@gmail.com> + Partial fix for [BZ #23716] + * sysdeps/ieee754/dbl-96/e_jnl.c: Fix build with -O + * sysdeps/ieee754/ldbl-96/e_jnl.c: Likewise. + * sysdeps/ieee754/ldbl-128/e_jnl.c: Likewise. + * sysdeps/ieee754/ldbl-128ibm/e_jnl.c: Likewise. + 2018-09-28 Joseph Myers <joseph@codesourcery.com> * math/fromfp.h: Do not include <math_private.h>. diff --git a/sysdeps/ieee754/dbl-64/e_jn.c b/sysdeps/ieee754/dbl-64/e_jn.c index aff06ead16..2d8bafbcce 100644 --- a/sysdeps/ieee754/dbl-64/e_jn.c +++ b/sysdeps/ieee754/dbl-64/e_jn.c @@ -43,6 +43,7 @@ #include <math_private.h> #include <fenv_private.h> #include <math-underflow.h> +#include <libc-diag.h> static const double invsqrtpi = 5.64189583547756279280e-01, /* 0x3FE20DD7, 0x50429B6D */ @@ -110,7 +111,17 @@ __ieee754_jn (int n, double x) case 2: temp = -c - s; break; case 3: temp = c - s; break; } + /* With GCC 8 (and older) when compiling with -O the compiler + warns that the variable 'temp', may be used uninitialized. + The switch above covers all possible values of n & 3 + but GCC without VRP enabled isn't able to figure out the + range of possible values is [0,3] as explained in: + https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69230 + so it's false possitive with -O1 and lower. */ + DIAG_PUSH_NEEDS_COMMENT; + DIAG_IGNORE_NEEDS_COMMENT (8, "-Wmaybe-uninitialized"); b = invsqrtpi * temp / sqrt (x); + DIAG_POP_NEEDS_COMMENT; } else { @@ -317,7 +328,17 @@ __ieee754_yn (int n, double x) case 2: temp = -s + c; break; case 3: temp = s + c; break; } + /* With GCC 8 (and older) when compiling with -O the compiler + warns that the variable 'temp', may be used uninitialized. + The switch above covers all possible values of n & 3 + but GCC without VRP enabled isn't able to figure out the + range of possible values is [0,3] as explained in: + https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69230 + so it's false possitive with -O1 and lower. */ + DIAG_PUSH_NEEDS_COMMENT; + DIAG_IGNORE_NEEDS_COMMENT (8, "-Wmaybe-uninitialized"); b = invsqrtpi * temp / sqrt (x); + DIAG_POP_NEEDS_COMMENT; } else { diff --git a/sysdeps/ieee754/ldbl-128/e_jnl.c b/sysdeps/ieee754/ldbl-128/e_jnl.c index 7610d18c67..776da664dd 100644 --- a/sysdeps/ieee754/ldbl-128/e_jnl.c +++ b/sysdeps/ieee754/ldbl-128/e_jnl.c @@ -62,6 +62,7 @@ #include <math_private.h> #include <fenv_private.h> #include <math-underflow.h> +#include <libc-diag.h> static const _Float128 invsqrtpi = L(5.6418958354775628694807945156077258584405E-1), @@ -151,7 +152,17 @@ __ieee754_jnl (int n, _Float128 x) temp = c - s; break; } + /* With GCC 8 (and older) when compiling with -O the compiler + warns that the variable 'temp', may be used uninitialized. + The switch above covers all possible values of n & 3 + but GCC without VRP enabled isn't able to figure out the + range of possible values is [0,3] as explained in: + https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69230 + so it's false possitive with -O1 and lower. */ + DIAG_PUSH_NEEDS_COMMENT; + DIAG_IGNORE_NEEDS_COMMENT (8, "-Wmaybe-uninitialized"); b = invsqrtpi * temp / sqrtl (x); + DIAG_POP_NEEDS_COMMENT; } else { @@ -387,7 +398,17 @@ __ieee754_ynl (int n, _Float128 x) temp = s + c; break; } + /* With GCC 8 (and older) when compiling with -O the compiler + warns that the variable 'temp', may be used uninitialized. + The switch above covers all possible values of n & 3 + but GCC without VRP enabled isn't able to figure out the + range of possible values is [0,3] as explained in: + https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69230 + so it's false possitive with -O1 and lower. */ + DIAG_PUSH_NEEDS_COMMENT; + DIAG_IGNORE_NEEDS_COMMENT (8, "-Wmaybe-uninitialized"); b = invsqrtpi * temp / sqrtl (x); + DIAG_POP_NEEDS_COMMENT; } else { diff --git a/sysdeps/ieee754/ldbl-128ibm/e_jnl.c b/sysdeps/ieee754/ldbl-128ibm/e_jnl.c index 50b4558e74..fcc2e2fae6 100644 --- a/sysdeps/ieee754/ldbl-128ibm/e_jnl.c +++ b/sysdeps/ieee754/ldbl-128ibm/e_jnl.c @@ -62,6 +62,7 @@ #include <math_private.h> #include <fenv_private.h> #include <math-underflow.h> +#include <libc-diag.h> static const long double invsqrtpi = 5.6418958354775628694807945156077258584405E-1L, @@ -151,7 +152,17 @@ __ieee754_jnl (int n, long double x) temp = c - s; break; } + /* With GCC 8 (and older) when compiling with -O the compiler + warns that the variable 'temp', may be used uninitialized. + The switch above covers all possible values of n & 3 + but GCC without VRP enabled isn't able to figure out the + range of possible values is [0,3] as explained in: + https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69230 + so it's false possitive with -O1 and lower. */ + DIAG_PUSH_NEEDS_COMMENT; + DIAG_IGNORE_NEEDS_COMMENT (8, "-Wmaybe-uninitialized"); b = invsqrtpi * temp / sqrtl (x); + DIAG_POP_NEEDS_COMMENT; } else { @@ -387,7 +398,17 @@ __ieee754_ynl (int n, long double x) temp = s + c; break; } + /* With GCC 8 (and older) when compiling with -O the compiler + warns that the variable 'temp', may be used uninitialized. + The switch above covers all possible values of n & 3 + but GCC without VRP enabled isn't able to figure out the + range of possible values is [0,3] as explained in: + https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69230 + so it's false possitive with -O1 and lower. */ + DIAG_PUSH_NEEDS_COMMENT; + DIAG_IGNORE_NEEDS_COMMENT (8, "-Wmaybe-uninitialized"); b = invsqrtpi * temp / sqrtl (x); + DIAG_POP_NEEDS_COMMENT; } else { diff --git a/sysdeps/ieee754/ldbl-96/e_jnl.c b/sysdeps/ieee754/ldbl-96/e_jnl.c index 855190841b..650ff19539 100644 --- a/sysdeps/ieee754/ldbl-96/e_jnl.c +++ b/sysdeps/ieee754/ldbl-96/e_jnl.c @@ -62,6 +62,7 @@ #include <math_private.h> #include <fenv_private.h> #include <math-underflow.h> +#include <libc-diag.h> static const long double invsqrtpi = 5.64189583547756286948079e-1L, two = 2.0e0L, one = 1.0e0L; @@ -144,7 +145,17 @@ __ieee754_jnl (int n, long double x) temp = c - s; break; } + /* With GCC 8 (and older) when compiling with -O the compiler + warns that the variable 'temp', may be used uninitialized. + The switch above covers all possible values of n & 3 + but GCC without VRP enabled isn't able to figure out the + range of possible values is [0,3] as explained in: + https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69230 + so it's false possitive with -O1 and lower. */ + DIAG_PUSH_NEEDS_COMMENT; + DIAG_IGNORE_NEEDS_COMMENT (8, "-Wmaybe-uninitialized"); b = invsqrtpi * temp / sqrtl (x); + DIAG_POP_NEEDS_COMMENT; } else { @@ -373,7 +384,17 @@ __ieee754_ynl (int n, long double x) temp = s + c; break; } + /* With GCC 8 (and older) when compiling with -O the compiler + warns that the variable 'temp', may be used uninitialized. + The switch above covers all possible values of n & 3 + but GCC without VRP enabled isn't able to figure out the + range of possible values is [0,3] as explained in: + https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69230 + so it's false possitive with -O1 and lower. */ + DIAG_PUSH_NEEDS_COMMENT; + DIAG_IGNORE_NEEDS_COMMENT (8, "-Wmaybe-uninitialized"); b = invsqrtpi * temp / sqrtl (x); + DIAG_POP_NEEDS_COMMENT; } else {
With -O included in CFLAGS it fails to build with: ../sysdeps/ieee754/ldbl-96/e_jnl.c: In function '__ieee754_jnl': ../sysdeps/ieee754/ldbl-96/e_jnl.c:146:20: error: 'temp' may be used uninitialized in this function [-Werror=maybe-uninitialized] b = invsqrtpi * temp / sqrtl (x); ~~~~~~~~~~^~~~~~ ../sysdeps/ieee754/ldbl-96/e_jnl.c: In function '__ieee754_ynl': ../sysdeps/ieee754/ldbl-96/e_jnl.c:375:16: error: 'temp' may be used uninitialized in this function [-Werror=maybe-uninitialized] b = invsqrtpi * temp / sqrtl (x); ~~~~~~~~~~^~~~~~ ../sysdeps/ieee754/dbl-64/e_jn.c: In function '__ieee754_jn': ../sysdeps/ieee754/dbl-64/e_jn.c:113:20: error: 'temp' may be used uninitialized in this function [-Werror=maybe-uninitialized] b = invsqrtpi * temp / sqrt (x); ~~~~~~~~~~^~~~~~ ../sysdeps/ieee754/dbl-64/e_jn.c: In function '__ieee754_yn': ../sysdeps/ieee754/dbl-64/e_jn.c:320:16: error: 'temp' may be used uninitialized in this function [-Werror=maybe-uninitialized] b = invsqrtpi * temp / sqrt (x); ~~~~~~~~~~^~~~~~ Build tested with Yocto for ARM, AARCH64, X86, X86_64, PPC, MIPS, MIPS64 with -O, -O1, -Os. For soft-fp ARM it needs one more fix for -O1: https://sourceware.org/ml/libc-alpha/2018-09/msg00300.html For AARCH64 it needs one more fix in locale for -Os. [BZ #23716] * sysdeps/ieee754/dbl-96/e_jnl.c: Fix build with -O * sysdeps/ieee754/ldbl-96/e_jnl.c: Likewise. * sysdeps/ieee754/ldbl-128/e_jnl.c: Likewise. * sysdeps/ieee754/ldbl-128ibm/e_jnl.c: Likewise. Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com> --- ChangeLog | 7 +++++++ sysdeps/ieee754/dbl-64/e_jn.c | 21 +++++++++++++++++++++ sysdeps/ieee754/ldbl-128/e_jnl.c | 21 +++++++++++++++++++++ sysdeps/ieee754/ldbl-128ibm/e_jnl.c | 21 +++++++++++++++++++++ sysdeps/ieee754/ldbl-96/e_jnl.c | 21 +++++++++++++++++++++ 5 files changed, 91 insertions(+)