https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103710
Bug ID: 103710
Summary: Missed optimization: common bit prefix/suffixes of
multiple values
Product: gcc
Version: 11.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: jengelh at inai dot de
Target Milestone: ---
Environment:
ยป ./xgcc -v ...
Reading specs from /home/jengelh/repos/gcc/host-x86_64-pc-linux-gnu/gcc/specs
COLLECT_GCC=./xgcc
Target: x86_64-pc-linux-gnu
Configured with: ./configure --enable-languages=c,c++
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 12.0.0 20211214 (experimental) (GCC)
COLLECT_GCC_OPTIONS='-v' '-B'
'/home/jengelh/repos/gcc/host-x86_64-pc-linux-gnu/gcc' '-D' 'noexcept=' '-c'
'-O2' '-mtune=generic' '-march=x86-64'
GNU C17 (GCC) version 12.0.0 20211214 (experimental) (x86_64-pc-linux-gnu)
compiled by GNU C version 11.2.1 20211124 [revision
7510c23c1ec53aa4a62705f0384079661342ff7b], GMP version 6.2.1, MPFR version
4.1.0-p7, MPC version 1.2.1, isl version none
GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
Input: attachment #0
Observed output:
$ ./xgcc -B. -x c++ -c -O2 t.cpp && readelf -a t.o | grep fct
3: 0000000000000000 54 FUNC GLOBAL DEFAULT 1 _Z4fct0j
4: 0000000000000040 54 FUNC GLOBAL DEFAULT 1 _Z4fct4j
5: 0000000000000080 54 FUNC GLOBAL DEFAULT 1 _Z4fct8j
6: 00000000000000c0 54 FUNC GLOBAL DEFAULT 1 _Z5fct12j
7: 0000000000000100 54 FUNC GLOBAL DEFAULT 1 _Z5fct16j
8: 0000000000000140 54 FUNC GLOBAL DEFAULT 1 _Z5fct20j
9: 0000000000000180 38 FUNC GLOBAL DEFAULT 1 _Z5fct24j
10: 00000000000001b0 32 FUNC GLOBAL DEFAULT 1 _Z5fct25j
11: 00000000000001d0 35 FUNC GLOBAL DEFAULT 1 _Z6fctmaxj
Desired output:
Provided I made no mistake in the equivalency of all fct functions, the fct
functions should, preferably, all compile to the same machine code.
