Summary:
GET_CALLER_PC doesn't work properly on 31-bit s390, as pointers are 31-bit, the MSB bit can be set when the return address is copied into integer.
This causes e.g. errors like:
    #0 0xfdadb129  (<unknown module>)
    #1 0x7da5e1d1 in __asan::GetStackTraceWithPcBpAndContext(__sanitizer::BufferedStackTrace*, unsigned long, unsigned long, unsigned long, void*, bool) ../../../../../libsanitizer/asan/asan_stack.h:50
    #2 0x7da5e1d1 in __asan::ErrorGeneric::Print() ../../../../../libsanitizer/asan/asan_errors.cc:482
    #3 0x7db178d5 in __asan::ErrorDescription::Print() ../../../../../libsanitizer/asan/asan_errors.h:360
    #4 0x7db178d5 in __asan::ScopedInErrorReport::~ScopedInErrorReport() ../../../../../libsanitizer/asan/asan_report.cc:167
    #5 0x7db178d5 in __asan::ReportGenericError(unsigned long, unsigned long, unsigned long, unsigned long, bool, unsigned long, unsigned int, bool) ../../../../../libsanitizer/asan/asan_report.cc:397
    #6 0x7dadb14f in __interceptor_memcmp ../../../../../libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:626
    #7 0x400cf5 in main /home/jakub/gcc/gcc/testsuite/c-c++-common/asan/memcmp-1.c:14
    #8 0x7d807215 in __libc_start_main (/lib/libc.so.6+0x1a215)
    #9 0x4007ed  (/home/jakub/gcc/obj/gcc/testsuite/memcmp-1.exe+0x4007ed)

The actual return PC inside __interceptor_memcmp was 0x7dadb129 rather than 0xfdadb129.

Reviewers: koriakin, kcc

Reviewed By: kcc

Subscribers: kubamracek

Differential Revision: https://reviews.llvm.org/D29824

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@294793 91177308-0d34-0410-b5e6-96231b3b80d8

Summary:
__builtin_clz used for Log calculation returns an undefined result
when argument is 0. I noticed that issue when was testing some fuzzers:

```
/src/libfuzzer/FuzzerTracePC.h:282:33: runtime error: shift exponent 450349 is too large for 32-bit type 'uint32_t' (aka 'unsigned int')
  #0 0x43d83f in operator() /src/libfuzzer/FuzzerTracePC.h:283:33
  #1 0x43d83f in void fuzzer::TracePC::CollectFeatures<fuzzer::Fuzzer::RunOne(unsigned char const*, unsigned long, bool, fuzzer::InputInfo*, bool*)::$_1>(fuzzer::Fuzzer::RunOne(unsigned char const*, unsigned long, bool, fuzzer::InputInfo*, bool*)::$_1) const /src/libfuzzer/FuzzerTracePC.h:290
  #2 0x43cbd4 in fuzzer::Fuzzer::RunOne(unsigned char const*, unsigned long, bool, fuzzer::InputInfo*, bool*) /src/libfuzzer/FuzzerLoop.cpp:445:7
  #3 0x43e5f1 in fuzzer::Fuzzer::ReadAndExecuteSeedCorpora(std::__1::vector<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, fuzzer::fuzzer_allocator<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > const&) /src/libfuzzer/FuzzerLoop.cpp:706:5
  #4 0x43e9e1 in fuzzer::Fuzzer::Loop(std::__1::vector<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, fuzzer::fuzzer_allocator<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > const&) /src/libfuzzer/FuzzerLoop.cpp:739:3
  #5 0x432f8c in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) /src/libfuzzer/FuzzerDriver.cpp:754:6
  #6 0x42ee18 in main /src/libfuzzer/FuzzerMain.cpp:20:10
  #7 0x7f17ffeb182f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)
  #8 0x407838 in _start (/out/rotate_fuzzer+0x407838)

Reviewers: kcc

Reviewed By: kcc

Subscribers: llvm-commits, #sanitizers

Differential Revision: https://reviews.llvm.org/D41457

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@321211 91177308-0d34-0410-b5e6-96231b3b80d8

Summary:
feature coverage is a useful signal that is available during the merge
process, but was not printed previously.

Output example:

```
$ ./fuzzer -use_value_profile=1 -merge=1 new_corpus/ seed_corpus/
INFO: Seed: 1676551929
INFO: Loaded 1 modules   (2380 inline 8-bit counters): 2380 [0x90d180, 0x90dacc), 
INFO: Loaded 1 PC tables (2380 PCs): 2380 [0x684018,0x68d4d8), 
MERGE-OUTER: 180 files, 78 in the initial corpus
MERGE-OUTER: attempt 1
INFO: Seed: 1676574577
INFO: Loaded 1 modules   (2380 inline 8-bit counters): 2380 [0x90d180, 0x90dacc), 
INFO: Loaded 1 PC tables (2380 PCs): 2380 [0x684018,0x68d4d8), 
INFO: -max_len is not provided; libFuzzer will not generate inputs larger than 1048576 bytes
MERGE-INNER: using the control file '/tmp/libFuzzerTemp.111754.txt'
MERGE-INNER: 180 total files; 0 processed earlier; will process 180 files now
#1	pulse  cov: 134 ft: 330 exec/s: 0 rss: 37Mb
#2	pulse  cov: 142 ft: 462 exec/s: 0 rss: 38Mb
#4	pulse  cov: 152 ft: 651 exec/s: 0 rss: 38Mb
#8	pulse  cov: 152 ft: 943 exec/s: 0 rss: 38Mb
#16	pulse  cov: 520 ft: 2783 exec/s: 0 rss: 39Mb
#32	pulse  cov: 552 ft: 3280 exec/s: 0 rss: 41Mb
#64	pulse  cov: 576 ft: 3641 exec/s: 0 rss: 50Mb
#78	LOADED cov: 602 ft: 3936 exec/s: 0 rss: 88Mb
#128	pulse  cov: 611 ft: 3996 exec/s: 0 rss: 93Mb
#180	DONE   cov: 611 ft: 4016 exec/s: 0 rss: 155Mb
MERGE-OUTER: succesfull in 1 attempt(s)
MERGE-OUTER: the control file has 39741 bytes
MERGE-OUTER: consumed 0Mb (37Mb rss) to parse the control file
MERGE-OUTER: 9 new files with 80 new features added; 9 new coverage edges
```

Reviewers: hctim, morehouse

Reviewed By: morehouse

Subscribers: delcypher, #sanitizers, llvm-commits, kcc

Tags: #llvm, #sanitizers

Differential Revision: https://reviews.llvm.org/D66030

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@368617 91177308-0d34-0410-b5e6-96231b3b80d8