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* [Bug ipa/94178] New: [10 Regression] wrong code with -fipa-sra + invalid -Wuninitialized warning
@ 2020-03-15 11:46 zsojka at seznam dot cz
2020-03-15 11:58 ` [Bug ipa/94178] " jakub at gcc dot gnu.org
0 siblings, 1 reply; 2+ messages in thread
From: zsojka at seznam dot cz @ 2020-03-15 11:46 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94178
Bug ID: 94178
Summary: [10 Regression] wrong code with -fipa-sra + invalid
-Wuninitialized warning
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Keywords: wrong-code
Severity: normal
Priority: P3
Component: ipa
Assignee: unassigned at gcc dot gnu.org
Reporter: zsojka at seznam dot cz
CC: marxin at gcc dot gnu.org
Target Milestone: ---
Host: x86_64-pc-linux-gnu
Created attachment 48034
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48034&action=edit
reduced testcase
Output:
$ x86_64-pc-linux-gnu-gcc -O -fno-dce -fipa-sra -fno-tree-dce testcase.c
-Wuninitialized
testcase.c: In function 'main':
testcase.c:10:5: warning: 'y' is used uninitialized in this function
[-Wuninitialized]
10 | y /= (u128) x;
| ^~
testcase.c:8:1: note: 'y' was declared here
8 | foo (u32 x, u8 y)
| ^~~
testcase.c:10:8: warning: 'x' is used uninitialized in this function
[-Wuninitialized]
10 | y /= (u128) x;
| ^~~~~~~~
testcase.c:8:1: note: 'x' was declared here
8 | foo (u32 x, u8 y)
| ^~~
$ ./a.out
Floating point exception
The generated assembly code:
mov edx, 0
mov ecx, 0
mov edi, 0
mov esi, 0
call __udivti3
shows it tries to do a 0/0 operation.
(I failed to search gcc bugs with keyword "wrong-code", I just can't find the
Keywords field at the Search page)
$ x86_64-pc-linux-gnu-gcc -v
Using built-in specs.
COLLECT_GCC=/repo/gcc-trunk/binary-latest-amd64/bin/x86_64-pc-linux-gnu-gcc
COLLECT_LTO_WRAPPER=/repo/gcc-trunk/binary-trunk-r10-7179-20200315012740-g9c3cdb43c2b-checking-yes-rtl-df-extra-nobootstrap-amd64/bin/../libexec/gcc/x86_64-pc-linux-gnu/10.0.1/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /repo/gcc-trunk//configure --enable-languages=c,c++
--enable-valgrind-annotations --disable-nls --enable-checking=yes,rtl,df,extra
--disable-bootstrap --with-cloog --with-ppl --with-isl
--build=x86_64-pc-linux-gnu --host=x86_64-pc-linux-gnu
--target=x86_64-pc-linux-gnu --with-ld=/usr/bin/x86_64-pc-linux-gnu-ld
--with-as=/usr/bin/x86_64-pc-linux-gnu-as --disable-libstdcxx-pch
--prefix=/repo/gcc-trunk//binary-trunk-r10-7179-20200315012740-g9c3cdb43c2b-checking-yes-rtl-df-extra-nobootstrap-amd64
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 10.0.1 20200315 (experimental) (GCC)
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2020-03-15 11:46 [Bug ipa/94178] New: [10 Regression] wrong code with -fipa-sra + invalid -Wuninitialized warning zsojka at seznam dot cz
2020-03-15 11:58 ` [Bug ipa/94178] " jakub at gcc dot gnu.org
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