| Issue |
76477
|
| Summary |
[Flang] Compilation of a chain of indirect accesses of arrays needs a lot of time
|
| Labels |
flang:frontend
|
| Assignees |
|
| Reporter |
yus3710-fj
|
This is an issue from Fujitsu testsuite.
Flang-new needs a lot of time to compile the following code.
(The compilation command is executed with `ulimit -t 300` in Fujitsu testsuite.)
The following are the test program, the result of `time` command of flang-new and gfortran compilation.
```fortran
! test.f90
subroutine sub(a,c1,c2,c3,c4,c5,c6,c7,c8,c9,c10,c11,c12,c13,c14,c15,c16,c17,n)
real(8),dimension(1:n) :: a
integer,dimension(1:n) :: c1,c2,c3,c4,c5,c6,c7,c8,c9,c10,c11,c12,c13,c14,c15,c16,c17
do i=1,n
a(c1(c2(c3(c4(c5(c6(c7(c8(c9(c10(c11(c12(c13(c14(c15(c16(c17(i)))))))))))))))))) = 1.0
enddo
end subroutine
```
```console
$ time flang-new -v test.f90 -c
flang-new version 18.0.0git (https://github.com/llvm/llvm-project.git 0e07bf91f7e3d5a53f0a51309da12e91ea8accc9)
Target: aarch64-unknown-linux-gnu
Thread model: posix
InstalledDir: /path/to/install/bin
Found candidate GCC installation: /opt/rh/gcc-toolset-12/root/usr/lib/gcc/aarch64-redhat-linux/12
Selected GCC installation: /opt/rh/gcc-toolset-12/root/usr/lib/gcc/aarch64-redhat-linux/12
Candidate multilib: .;@m64
Selected multilib: .;@m64
"/path/to/install/bin/flang-new" -fc1 -triple aarch64-unknown-linux-gnu -emit-obj -fcolor-diagnostics -mrelocation-model pic -pic-level 2 -pic-is-pie -target-cpu generic -target-feature +neon -target-feature +v8a -mframe-pointer=non-leaf -o test.o -x f95-cpp-input test.f90
^C
real 6m0.521s
user 0m0.901s
sys 0m0.163s
```
```console
$ time gfortran -v test.f90 -c
Using built-in specs.
COLLECT_GCC=gfortran
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/aarch64-redhat-linux/8/lto-wrapper
Target: aarch64-redhat-linux
Configured with: ../configure --enable-bootstrap --enable-languages=c,c++,fortran,lto --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-shared --enable-threads=posix --enable-checking=release --enable-multilib --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-linker-build-id --with-gcc-major-version-only --with-linker-hash-style=gnu --enable-plugin --enable-initfini-array --with-isl --disable-libmpx --enable-gnu-indirect-function --build=aarch64-redhat-linux
Thread model: posix
gcc version 8.5.0 20210514 (Red Hat 8.5.0-18) (GCC)
:
real 0m0.126s
user 0m0.066s
sys 0m0.006s
```
It seems that parsing takes a long time.
```console
$ time flang-new -fc1 -E test.f90 -o /dev/null
real 0m1.142s
user 0m0.886s
sys 0m0.151s
$ time flang-new -fc1 -fdebug-dump-parse-tree-no-sema test.f90
^C
real 6m30.762s
user 6m30.564s
sys 0m0.132s
```
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