http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53676
Bug #: 53676
Summary: [4.7/4.8 regression] constant folding regression,
shown as slowdown as measured by Adobe's C++Benchmark
Classification: Unclassified
Product: gcc
Version: 4.7.1
Status: UNCONFIRMED
Severity: major
Priority: P3
Component: middle-end
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: m...@use.net
The attached ZIP contains two binaries and preprocessor output files, based on
a subset of a test in Adobe's C++Benchmark suite. All GCC versions I tested
prior to 4.7 do the folding correctly. I tried using Ofast and other tricks to
workaround this new regression to no avail.
-rw-r--r-- 1 mhargett users 143573 Jun 14 15:31 int8_folding_test.gcc47.i
mhargett@chert:~/src/C++Benchmarks-gcc47-google-fast$ ./int8_folding_test-gcc46
./int8_folding_test-gcc46
test description absolute operations ratio with
number time per second test0
0 "int8_t constant" 0.00 sec inf M -nan
Total absolute time for int8_t simple constant folding: 0.00 sec
mhargett@chert:~/src/C++Benchmarks-gcc47-google-fast$ ./int8_folding_test-gcc47
./int8_folding_test-gcc47
test description absolute operations ratio with
number time per second test0
0 "int8_t constant" 0.69 sec 2318.84 M 1.00
Total absolute time for int8_t simple constant folding: 0.69 sec
