[Bug middle-end/85989] New: Incorrect result for example involving unary minus in a loop
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85989
Bug ID: 85989
Summary: Incorrect result for example involving unary minus in
a loop
Product: gcc
Version: 6.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: ketan.surender at gmail dot com
Target Milestone: ---
Created attachment 44208
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=44208&action=edit
Preprocessed reproduction file
Please see the attached file 'standalone.i'. When I run this in -O0 I see the
result
gcc -Wall -Wstrict-aliasing=0 -O0 standalone.i -o standalone
./standalone
--> 0
--> 0
This is what I expect. If I compile with '-O1' I see
gcc -Wall -Wstrict-aliasing=0 -O1 standalone.i -o standalone
./standalone
--> 8
--> 8
Which is unexpected. I poked around in gdb and stared at the asm in godbolt and
it seems like the negation is being omitted in the following loop:
for (b_P5 = 0; b_P5 < 8; b_P5++) {
P26 = P29;
P29 = -(int)*P5;
}
Here is my gcc info
Using built-in specs.
COLLECT_GCC=[SNIP]/glnxa64/gcc-6.3.0/bin/gcc
COLLECT_LTO_WRAPPER=[SNIP]/glnxa64/gcc-6.3.0/bin/../libexec/gcc/x86_64-pc-linux-gnu/6.3.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: [SNIP]/sources/gcc-6.3/configure
--with-gmp=[SNIP]/glnxa64/gcc-6.3/gmp-4.3 --with-mpfr=[SNIP]/gcc-6.3/mpfr
--with-mpc=[SNIP]/gcc-6.3/mpc --enable-languages=c,c++,fortran
--with-bugurl=[SNIP],_Debugging --enable-shared --enable-linker-build-id
--enable-plugin --enable-checking=release --enable-multiarch --enable-gold
--enable-ld=default --enable-libstdcxx-time=no
--prefix=[SNIP]/glnxa64/gcc-6.3.0 --with-pkgversion='MW GCC 6.3.0-GLIBC2.12'
--with-tune=generic --with-system-zlib --enable-multilib
--with-multilib-list=m32,m64 --with-arch-directory=amd64 --with-arch-32=i586
--with-abi=m64
Thread model: posix
gcc version 6.3.0 (MW GCC 6.3.0-GLIBC2.12)
[Bug tree-optimization/86632] New: Incorrect value copied into output array with -O3 ftree-loop-vectorize
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86632
Bug ID: 86632
Summary: Incorrect value copied into output array with -O3
ftree-loop-vectorize
Product: gcc
Version: 6.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: ketan.surender at gmail dot com
Target Milestone: ---
I am observing incorrect results for the following function with -O3
static void mDiscBlocks2_repro_output(void)
{
/* local scratch DWork variables */
int32_T ForEach_itr_p;
real_T rtb_ImpAsg_InsertedFor_Out1_a_d[6];
real_T rtb_ImpAsg_InsertedFor_Out2_a_o[3];
int32_T i;
for (ForEach_itr_p = 0; ForEach_itr_p < 3; ForEach_itr_p++) {
rtb_ImpAsg_InsertedFor_Out2_a_o[ForEach_itr_p] =
mDiscBlocks2_repro_DW.CoreSubsys[ForEach_itr_p].Memory1_PreviousInput;
rtb_ImpAsg_InsertedFor_Out1_a_d[ForEach_itr_p << 1] =
mDiscBlocks2_repro_DW.CoreSubsys[ForEach_itr_p].Memory_PreviousInput[0];
rtb_ImpAsg_InsertedFor_Out1_a_d[1 + (ForEach_itr_p << 1)] =
mDiscBlocks2_repro_DW.CoreSubsys[ForEach_itr_p].Memory_PreviousInput[1];
}
/* KS REQUIRED */
for (i = 0; i < 6; i++) {
mDiscBlocks2_repro_Y.Out14[i] = rtb_ImpAsg_InsertedFor_Out1_a_d[i];
}
/* KS REQUIRED */
mDiscBlocks2_repro_Y.Out15[0] = rtb_ImpAsg_InsertedFor_Out2_a_o[0];
mDiscBlocks2_repro_Y.Out15[1] = rtb_ImpAsg_InsertedFor_Out2_a_o[1];
mDiscBlocks2_repro_Y.Out15[2] = rtb_ImpAsg_InsertedFor_Out2_a_o[2];
}
This code copies some global data to a local array, then copies the local array
to a global.
mDiscBlocks2_repro_DW.CoreSubsys[0-2].Memory1_PreviousInput -->
rtb_ImpAsg_InsertedFor_Out2_a_o[0-2] --> mDiscBlocks2_repro_Y.Out15[0-2]
mDiscBlocks2_repro_DW.CoreSubsys[0-2].Memory_PreviousInput[0] -->
rtb_ImpAsg_InsertedFor_Out1_a_d[0,2,4] --> mDiscBlocks2_repro_Y.Out14[0,2,4]
mDiscBlocks2_repro_DW.CoreSubsys[0-2].Memory_PreviousInput[1] -->
rtb_ImpAsg_InsertedFor_Out1_a_d[1,3,5] --> mDiscBlocks2_repro_Y.Out14[1,3,5]
For the global 'mDiscBlocks2_repro_Y.Out14' I am observing the incorrect value
at index 2. The issue goes away if I add the switch -fno-tree-loop-vectorize.
I looked at the generated asm a little and can see the incorrect assignment.
For some reason it writes to element 2 before writing the remaining elements.
Here is my gcc info
Using built-in specs.
COLLECT_GCC=[SNIP]/glnxa64/gcc-6.3.0/bin/gcc
COLLECT_LTO_WRAPPER=[SNIP]/glnxa64/gcc-6.3.0/bin/../libexec/gcc/x86_64-pc-linux-gnu/6.3.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: [SNIP]/sources/gcc-6.3/configure
--with-gmp=[SNIP]/glnxa64/gcc-6.3/gmp-4.3 --with-mpfr=[SNIP]/gcc-6.3/mpfr
--with-mpc=[SNIP]/gcc-6.3/mpc --enable-languages=c,c++,fortran
--with-bugurl=[SNIP],_Debugging --enable-shared --enable-linker-build-id
--enable-plugin --enable-checking=release --enable-multiarch --enable-gold
--enable-ld=default --enable-libstdcxx-time=no
--prefix=[SNIP]/glnxa64/gcc-6.3.0 --with-pkgversion='MW GCC 6.3.0-GLIBC2.12'
--with-tune=generic --with-system-zlib --enable-multilib
--with-multilib-list=m32,m64 --with-arch-directory=amd64 --with-arch-32=i586
--with-abi=m64
Thread model: posix
gcc version 6.3.0 (MW GCC 6.3.0-GLIBC2.12)
[Bug tree-optimization/86632] Incorrect value copied into output array with -O3 ftree-loop-vectorize
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86632 --- Comment #1 from Ketan --- Will add attachment in a moment.
[Bug tree-optimization/86632] Incorrect value copied into output array with -O3 ftree-loop-vectorize
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86632 --- Comment #2 from Ketan --- Created attachment 44419 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=44419&action=edit Reproduction Files Contents of archive - compile.sh : Compiles and runs code in -O0 (correct result), -O3 (incorrect result), -O3 -fno-tree-loop-vectorize (correct result) - main.c : Required source file - mDiscBlocks2_repro.c : Required source file - mDiscBlocks2_repro.h : Required header file. Defines various global structures used by the code.
[Bug tree-optimization/86632] Incorrect value copied into output array with -O3 ftree-loop-vectorize
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86632 --- Comment #3 from Ketan --- Example execution output: Compile and run with -O1 Out14[0] = 0.00 Out14[1] = 0.00 Out14[2] = 0.00 Out14[3] = 0.00 Out14[4] = 0.00 Out14[5] = 0.00 Out15[0] = 75.00 Out15[1] = 75.00 Out15[2] = 75.00 Compile and run with -O3 Out14[0] = 0.00 Out14[1] = 0.00 Out14[2] = 75.00 Out14[3] = 0.00 Out14[4] = 0.00 Out14[5] = 0.00 Out15[0] = 75.00 Out15[1] = 75.00 Out15[2] = 75.00 Compile and run with -O3 -fno-tree-loop-vectorize Out14[0] = 0.00 Out14[1] = 0.00 Out14[2] = 0.00 Out14[3] = 0.00 Out14[4] = 0.00 Out14[5] = 0.00 Out15[0] = 75.00 Out15[1] = 75.00 Out15[2] = 75.00
[Bug middle-end/83234] New: Aggressive loop optim warning for loop iteration that cannot happen
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83234
Bug ID: 83234
Summary: Aggressive loop optim warning for loop iteration that
cannot happen
Product: gcc
Version: 6.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: ketan.surender at gmail dot com
Target Milestone: ---
Created attachment 42759
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=42759&action=edit
Reproduction File
I have an example program with the code:
for (j = 0; j < 3; j++) {
for (i = 1; i <= 3 - j; i++) {
out8[i - 1][j] = (int8_T)(i + j);
}
for (i = 4 - j; i < 4; i++) {
out8[i - 1][j] = in15[(i + j) - 3];
}
}
that produces the warning
hankel_script.c: In function ‘hankel_script’:
hankel_script.c:235:32: warning: iteration 2147483644 invokes undefined
behavior [-Waggressive-loop-optimizations]
out8[i - 1][j] = in15[(i + j) - 3];
~~~^~~~
hankel_script.c:234:5: note: within this loop
for (i = 4 - j; i < 4; i++) {
The loop bounds have been defined with constants such that iteration 2147483644
cannot happen.
Repro:
gcc -c -O2 hankel_script.i
I do not see the warning with -O3 or -O1.
My gcc version is 6.3. See details below. I am able to reproduce this using
x86-64 gcc 7.2 on https://gcc.godbolt.org/.
COLLECT_GCC=gcc
Target: x86_64-pc-linux-gnu
Configured with: [SCRUB]/sources/gcc-6.3/configure
--with-gmp=[SCRUB]/gcc-6.3/gmp-4.3 --with-mpfr=[SCRUB]/gcc-6.3/mpfr
--with-mpc=[SCRUB]/gcc-6.3/mpc --enable-languages=c,c++,fortran
--with-bugurl=[SCRUB],_Debugging --enable-shared --enable-linker-build-id
--enable-plugin --enable-checking=release --enable-multiarch --enable-gold
--enable-ld=default --prefix=[SCRUB]/gcc-6.3.0 --with-pkgversion='MW GCC
6.3.0-GLIBC2.11' --with-tune=generic --with-system-zlib --enable-multilib
--with-multilib-list=m32,m64 --with-arch-directory=amd64 --with-arch-32=i586
--with-abi=m64
gcc version 6.3.0 (MW GCC 6.3.0-GLIBC2.11)
[Bug middle-end/83234] Aggressive loop optim warning for loop iteration that cannot happen
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83234 --- Comment #1 from Ketan --- I am on Debian 8
[Bug tree-optimization/66280] New: internal compiler error: in vect_get_vec_def_for_operand, at tree-vect-stmts.c:1322
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66280 Bug ID: 66280 Summary: internal compiler error: in vect_get_vec_def_for_operand, at tree-vect-stmts.c:1322 Product: gcc Version: 4.7.2 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: ketan.surender at gmail dot com Target Milestone: --- Created attachment 35622 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=35622&action=edit preprocessed reproduction file Hitting an internal compilation error for the attached repro.i file. g++ -c -std=c++98 -pedantic -Wno-long-long -fwrapv -fPIC -O3 -fno-loop-optimize repro.i dtodoublessingleststscript4.cpp: In function ‘void dtodoublessingleststscript4(short int, const cint16_T*, short int*, cint16_T*, int*, cint32_T*, cint32_T*, int*, cint32_T*, cint16_T*, cint32_T*, int*, int*, cint32_T*, cint32_T*, int*, cint32_T*, int*, int*, cint32_T*, cint32_T*, cint16_T*, short int*, short int*, short int*, short int*)’: dtodoublessingleststscript4.cpp:102:6: internal compiler error: in vect_get_vec_def_for_operand, at tree-vect-stmts.c:1322 Please submit a full bug report, with preprocessed source if appropriate. See <http://gcc.gnu.org/bugs.html> for instructions. I am seeing this on a Debian 7 machine. g++ -v Using built-in specs. COLLECT_GCC=g++ COLLECT_LTO_WRAPPER=/SNIP/glnxa64/gcc-4.7.2/libexec/gcc/x86_64-unknown-linux-gnu/4.7.2/lto-wrapper Target: x86_64-unknown-linux-gnu Configured with: /SNIP/gcc-4.7/configure --prefix=/SNIP/glnxa64/gcc-4.7.2 --with-gmp=/SNIP/glnxa64/gcc-4.7/gmp --with-mpfr=/SNIP/glnxa64/gcc-4.7/mpfr --with-mpc=/SNIP/glnxa64/gcc-4.7/mpc --enable-languages=c,c++,fortran --with-as=/SNIP/glnxa64/gcc-4.7.2/bin/as --with-ld=/SNIP/glnxa64/gcc-4.7.2/bin/ld Thread model: posix gcc version 4.7.2 (GCC)
[Bug tree-optimization/68389] New: internal compiler error: in tree_low_cst, at tree.h:4431
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68389 Bug ID: 68389 Summary: internal compiler error: in tree_low_cst, at tree.h:4431 Product: gcc Version: 4.7.2 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: ketan.surender at gmail dot com Target Milestone: --- Created attachment 36742 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36742&action=edit preprocessedReproFile For the attached file I am seeing an internal compiler error with -O3 COLLECT_GCC_OPTIONS='-v' '-save-temps' '-c' '-ansi' '-pedantic' '-Wno-long-long' '-fwrapv' '-fPIC' '-O3' '-D' 'MODEL=xOutOfOrderWrites_exec' '-D' 'HAVESTDIO' '-D' 'USE_RTMODEL' '-D' 'UNIX' '-I' 'anotherPath/gccBugs' '-I' 'anotherPath/gccBugs/codegen/dll/xOutOfOrderWrites' '-I' 'aPath/extern/include' '-I' 'aPath/simulink/include' '-I' 'aPath/rtw/c/src' '-I' 'aPath/rtw/c/src/ext_mode/common' '-I' 'aPath/rtw/c/ert' '-o' 'xOutOfOrderWrites.o' '-mtune=generic' '-march=x86-64' /anotherAnotherPath/glnxa64/gcc-4.7.2/libexec/gcc/x86_64-unknown-linux-gnu/4.7.2/cc1 -fpreprocessed xOutOfOrderWrites.i -quiet -dumpbase xOutOfOrderWrites.c -mtune=generic -march=x86-64 -auxbase-strip xOutOfOrderWrites.o -O3 -pedantic -Wno-long-long -ansi -version -fwrapv -fPIC -o xOutOfOrderWrites.s xOutOfOrderWrites.c: In function ‘xOutOfOrderWrites’: xOutOfOrderWrites.c:222:6: internal compiler error: in tree_low_cst, at tree.h:4431 This can be reproduced with the attached preprocessed file: gcc -c -O3 xOutOfOrderWrites.i GCC Version Info: GNU C (GCC) version 4.7.2 (x86_64-unknown-linux-gnu) compiled by GNU C version 4.7.2, GMP version 4.3.2, MPFR version 2.4.2, MPC version 0.8.2 GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 GNU C (GCC) version 4.7.2 (x86_64-unknown-linux-gnu) compiled by GNU C version 4.7.2, GMP version 4.3.2, MPFR version 2.4.2, MPC version 0.8.2 GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 Compiler executable checksum: aa64e71d3fbf9c408b8b9eecd9fda662
[Bug tree-optimization/68389] internal compiler error: in tree_low_cst, at tree.h:4431
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68389 --- Comment #2 from Ketan --- I tried 5.2 and did not see the issue.
