OK, this one is just too weird. It seems GCC turns off some heuristics.
It might be a better option to find out how to turn it back on on lower
optimization levels.
See this (command taken from make output, optimization moved to the very
end):
$ cd uspace/drv/bus/pci/pciintel
$ $CROSS_PREFIX/amd64-unknown-elf/bin/amd64-unknown-elf-gcc
-I../../../../lib/c/include -I../../../../lib/c/arch/amd64/include
-I../../../../../abi/include -imacros ../../../../../config.h -ffreestanding
-fno-builtin -nostdlib -nostdinc -fexec-charset=UTF-8 -finput-charset=UTF-8
-D__LE__ -Werror -fno-omit-frame-pointer -ffunction-sections -Wall -Wextra
-Wno-clobbered -Wno-unused-parameter -Wmissing-prototypes -std=gnu99
-Werror-implicit-function-declaration -Wwrite-strings -pipe
-mno-tls-direct-seg-refs -g -I../../../../lib/drv/include -c pci.c -o pci.o -O0
$ $CROSS_PREFIX/amd64-unknown-elf/bin/amd64-unknown-elf-gcc
-I../../../../lib/c/include -I../../../../lib/c/arch/amd64/include
-I../../../../../abi/include -imacros ../../../../../config.h -ffreestanding
-fno-builtin -nostdlib -nostdinc -fexec-charset=UTF-8 -finput-charset=UTF-8
-D__LE__ -Werror -fno-omit-frame-pointer -ffunction-sections -Wall -Wextra
-Wno-clobbered -Wno-unused-parameter -Wmissing-prototypes -std=gnu99
-Werror-implicit-function-declaration -Wwrite-strings -pipe
-mno-tls-direct-seg-refs -g -I../../../../lib/drv/include -c pci.c -o pci.o -O1
pci.c: In function 'pci_conf_write':
pci.c:322:7: error: 'val' may be used uninitialized in this function
[-Werror=maybe-uninitialized]
val &= ~(0xffU << ((reg & 3) * 8));
~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
$ $CROSS_PREFIX/amd64-unknown-elf/bin/amd64-unknown-elf-gcc
-I../../../../lib/c/include -I../../../../lib/c/arch/amd64/include
-I../../../../../abi/include -imacros ../../../../../config.h -ffreestanding
-fno-builtin -nostdlib -nostdinc -fexec-charset=UTF-8 -finput-charset=UTF-8
-D__LE__ -Werror -fno-omit-frame-pointer -ffunction-sections -Wall -Wextra
-Wno-clobbered -Wno-unused-parameter -Wmissing-prototypes -std=gnu99
-Werror-implicit-function-declaration -Wwrite-strings -pipe
-mno-tls-direct-seg-refs -g -I../../../../lib/drv/include -c pci.c -o pci.o -O2
$ $CROSS_PREFIX/amd64-unknown-elf/bin/amd64-unknown-elf-gcc
-I../../../../lib/c/include -I../../../../lib/c/arch/amd64/include
-I../../../../../abi/include -imacros ../../../../../config.h -ffreestanding
-fno-builtin -nostdlib -nostdinc -fexec-charset=UTF-8 -finput-charset=UTF-8
-D__LE__ -Werror -fno-omit-frame-pointer -ffunction-sections -Wall -Wextra
-Wno-clobbered -Wno-unused-parameter -Wmissing-prototypes -std=gnu99
-Werror-implicit-function-declaration -Wwrite-strings -pipe
-mno-tls-direct-seg-refs -g -I../../../../lib/drv/include -c pci.c -o pci.o -O3
$ $CROSS_PREFIX/amd64-unknown-elf/bin/amd64-unknown-elf-gcc
-I../../../../lib/c/include -I../../../../lib/c/arch/amd64/include
-I../../../../../abi/include -imacros ../../../../../config.h -ffreestanding
-fno-builtin -nostdlib -nostdinc -fexec-charset=UTF-8 -finput-charset=UTF-8
-D__LE__ -Werror -fno-omit-frame-pointer -ffunction-sections -Wall -Wextra
-Wno-clobbered -Wno-unused-parameter -Wmissing-prototypes -std=gnu99
-Werror-implicit-function-declaration -Wwrite-strings -pipe
-mno-tls-direct-seg-refs -g -I../../../../lib/drv/include -c pci.c -o pci.o
-Ofast
$ $CROSS_PREFIX/amd64-unknown-elf/bin/amd64-unknown-elf-gcc
-I../../../../lib/c/include -I../../../../lib/c/arch/amd64/include
-I../../../../../abi/include -imacros ../../../../../config.h -ffreestanding
-fno-builtin -nostdlib -nostdinc -fexec-charset=UTF-8 -finput-charset=UTF-8
-D__LE__ -Werror -fno-omit-frame-pointer -ffunction-sections -Wall -Wextra
-Wno-clobbered -Wno-unused-parameter -Wmissing-prototypes -std=gnu99
-Werror-implicit-function-declaration -Wwrite-strings -pipe
-mno-tls-direct-seg-refs -g -I../../../../lib/drv/include -c pci.c -o pci.o -Og
pci.c: In function 'pci_conf_write':
pci.c:322:7: error: 'val' may be used uninitialized in this function
[-Werror=maybe-uninitialized]
val &= ~(0xffU << ((reg & 3) * 8));
How does this behave on your end?
OH
On 20.10., Jiří Zárevúcky wrote:
> Weird!
>
> Whatever the reason for suspicious silence here, this needs to be fixed.
> It would be great if you could fix all the warnings you are getting.
> I'll merge your directive as soon as you have it.
>
> Thanks!
>
>
> On 20 October 2017 at 00:20, Ondřej Hlavatý <[email protected]> wrote:
> > Hi,
> >
> > On 19.10., Jiří Zárevúcky wrote:
> >> Could you elaborate on your setup?
> >> In particular, do you use the proper cross-compiler, as built using
> >> toolchain.sh?
> >
> > I just installed fresh toolchain, distclean, loaded amd64 defaults and
> > it happened. Strangely, no warnings are reported with -O2.
> >
> >> Also, did you add any additional compiler flags?
> >
> > No.
> >
> >> Any other changes? Differences from default settings?
> >
> > My CROSS_PREFIX is set to dir in my home, not the system default. It
> > still contains the old toolchain, if that could matter.
> >
> > I can't think of any other difference - I don't even use the mainline
> > checkout while working on xhci.
> >
> > OH
> >
> >> On 19 October 2017 at 23:40, Ondřej Hlavatý <[email protected]> wrote:
> >> > Well, it seems that the patch is sufficient only when compiling with
> >> > -O3. There are a lot of other warnings with -Og. It is probably worth
> >> > checking them all (possibly with -O0) and fixing/muting them at once.
> >> >
> >> > Shall I prepare that?
> >> >
> >> > OH
> >> >
> >> > On 19.10., Ondra Hlavatý wrote:
> >> >> Hi all,
> >> >>
> >> >> When building current mainline with freshly downloaded toolchain, GCC
> >> >> 7.1.0 complains about uninitialized variables. First of them is real
> >> >> (extent.c), the second is not, but it's probably too hard for GCC to
> >> >> infer.
> >> >>
> >> >> Hope you're enjoing the hangout.
> >> >> Ondra Hlavatý
> >> >
> >> >> # Bazaar merge directive format 2 (Bazaar 0.90)
> >> >> # revision_id: [email protected]
> >> >> # target_branch: bzr://bzr.helenos.org/mainline/
> >> >> # testament_sha1: 5343d00f1a73b4b8864f22d5e19dae0f155642cd
> >> >> # timestamp: 2017-10-19 22:32:34 +0200
> >> >> # base_revision_id: [email protected]\
> >> >> # ndrkufle1quqodg8
> >> >> #
> >> >> # Begin patch
> >> >> === modified file 'uspace/lib/ext4/src/extent.c'
> >> >> --- uspace/lib/ext4/src/extent.c 2017-05-11 22:07:09 +0000
> >> >> +++ uspace/lib/ext4/src/extent.c 2017-10-19 20:30:01 +0000
> >> >> @@ -374,7 +374,7 @@
> >> >> int ext4_extent_find_block(ext4_inode_ref_t *inode_ref, uint32_t
> >> >> iblock,
> >> >> uint32_t *fblock)
> >> >> {
> >> >> - int rc;
> >> >> + int rc = EOK;
> >> >> /* Compute bound defined by i-node size */
> >> >> uint64_t inode_size =
> >> >> ext4_inode_get_size(inode_ref->fs->superblock,
> >> >> inode_ref->inode);
> >> >>
> >> >> === modified file 'uspace/lib/trackmod/xm.c'
> >> >> --- uspace/lib/trackmod/xm.c 2014-10-13 17:31:01 +0000
> >> >> +++ uspace/lib/trackmod/xm.c 2017-10-19 20:30:01 +0000
> >> >> @@ -288,7 +288,7 @@
> >> >> size_t samples;
> >> >> size_t instr_size;
> >> >> size_t smp_size;
> >> >> - size_t smp_hdr_size;
> >> >> + size_t smp_hdr_size = 0; /* GCC false alarm on uninitialized */
> >> >> ssize_t nread;
> >> >> uint8_t ltype;
> >> >> trackmod_sample_t *sample;
> >> >>
> >> >> # Begin bundle
> >> >> IyBCYXphYXIgcmV2aXNpb24gYnVuZGxlIHY0CiMKQlpoOTFBWSZTWe8h8/IAAhpfrAAwUPf//17I
> >> >> lAC////wACAAAgoAUASu73TT2tb13oim3qnhJQgp4m1T0mnqemTVPyp+o9Sfoo9qn6oMh6jQbRBl
> >> >> GhGJpo0mkPU0A0AAAAABKEBRoyCbRMTT1GjQAAaNGgAaaoCbKNAAGjQaA0AGg0ABJJNGmpgTET0n
> >> >> oENNI8pkaDQGgNGE5ypN3TW0+0R5HZU5WV9U0/YwFtIdsdkMEzXS50UmZKCSSkkO9B2beBJRTDBB
> >> >> fETXzctT0PJvAt9bQk9U2VMYCzRs2vIqiyYKGc07734syjxSqw1mJBlQLfHZxNdkb7RszqhmPmzY
> >> >> L+AbSq+tfe9BqrcUtO2E5Qwx5KxA6RX9ae6s2j4UjvnbmBv+Os3l0ewCIY0HDDAwyEwkwiQgTGkd
> >> >> KppsRtJPGLIgqLCIPGf4Hd+wIEgyM41hteE6Rc3XdQUl7SltqQ4ZMpgvzIFuLoRaG/aXCyu7yFNq
> >> >> EKwVI2HxRJwt7cSbcSIBfIUyLiwFZAzLDzWjgByvVSmxSDIDpMtldhLoyjaTq6dDxziYCQpNxcUA
> >> >> UmyadFcQgM8Z7FprqSghIN+hLJSmhwAVsxF1ZCBRZcsz0BszFVp0V3idomXU0lZuwRhYSLg5lRbT
> >> >> W7moCZEk9rTjBzCsXpFIt0BT6MD1DVZbXkFyiBWWCnyI54CE77CwZkiS11pEdNQSZ9rUQi5ixt7i
> >> >> 64JiBZkBTqzC4Jg6TLDgFBZTAPaHSnVODxBYzGXDRyohYsvMQDPpKyV8nSMUH2OMlu5QxVezVOfk
> >> >> esUalyPYFiraTEDjpdSVy1tQiCiFjKLLJQmGMRRoBdQOLBBJOzsPY1PqDbF8jGdJengFEu5nHMKP
> >> >> qMpAM6leHOdcNhXTspYxNSYw+10EcO1dTVZMHrtxMY9/O9LSoU4INE9QQOOGNnFjaK3tget7SInN
> >> >> hFFtpv6sEqdEmXGoi1DjkG8fSdheYa7pWaRVLPn2SIKw5mfxklL99FMvbWEwM8SlnW9XAX9pBdBP
> >> >> CTGrcaJ5HvLTTl3vWgrAqphfE19OB3lZ2GM3Bh1haia+KDOdA/bncX4a37tDPd+kHOz3Qzsq5NMK
> >> >> gYRJgaCNcF2Fd9p/ZALzoRjx8yPWbpRh0YHXcS9vdldGpiZcTeSFqvaSEpYsRWHtWOIErYBVHnLk
> >> >> d50omtMjGwvR7xnjEm9wyrjQiRA7yh1mKrW0TzI8kPquqJX+f63Yw6UYIZBzRHMsvoPiQ8KfhJXo
> >> >> nm4zwkKW2on1O9iYueSgChEjQpNc3OMLUwz8dK4w8C3g57O0DZ4LcruCthUY2ghjK4cZFH9pIacG
> >> >> Q4CUEOVNfQ4ir74wNI0u3hBVDuZZf16C7erepZMURR2SnJFC63Kcz2gZfACtU6mGAWXai4Y9Tr0K
> >> >> F2AcqItgRvWZXPJlttKHEhUeCwpFWVS1yoITAzidBNU/qjVQYOVJFGlA4PZQELCWmQgClk6RXJCP
> >> >> zSKkCwKKItkBRz3m+QeRAzUxglsnxIgeF29VP4LNstLNyukyIpcZCySKtRjByqAgrj3nia6Dnjyb
> >> >> MkajQmgcewDuAbNsVYiePp6YwfxdyRThQkO8h8/I
> >> >
> >> >> _______________________________________________
> >> >> HelenOS-devel mailing list
> >> >> [email protected]
> >> >> http://lists.modry.cz/listinfo/helenos-devel
> >> >
> >> >
> >> > _______________________________________________
> >> > HelenOS-devel mailing list
> >> > [email protected]
> >> > http://lists.modry.cz/listinfo/helenos-devel
> >>
> >> _______________________________________________
> >> HelenOS-devel mailing list
> >> [email protected]
> >> http://lists.modry.cz/listinfo/helenos-devel
> >
> > _______________________________________________
> > HelenOS-devel mailing list
> > [email protected]
> > http://lists.modry.cz/listinfo/helenos-devel
>
> _______________________________________________
> HelenOS-devel mailing list
> [email protected]
> http://lists.modry.cz/listinfo/helenos-devel
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