forked from OSchip/llvm-project
6d31001cd6
This reverts r321138. It seems there are still underlying issues with
memdep. PR35519 seems to still be present if debug info is enabled. We
end up losing a memcpy. Somehow during store to memset merging, we
insert the memset after the memcpy or fail to update the memdep analysis
to account for the newly inserted memset of a pair.
Reduced test case:
#include <assert.h>
#include <stdio.h>
#include <string>
#include <utility>
#include <vector>
void do_push_back(
std::vector<std::pair<std::string, std::vector<std::string>>>* crls) {
crls->push_back(std::make_pair(std::string(), std::vector<std::string>()));
}
int __attribute__((optnone)) main() {
// Put some data in the vector and then remove it so we take the push_back
// fast path.
std::vector<std::pair<std::string, std::vector<std::string>>> crl_set;
crl_set.push_back({"asdf", {}});
crl_set.pop_back();
printf("first word in vector storage: %p\n", *(void**)crl_set.data());
// Do the push_back which may fail to initialize the data.
do_push_back(&crl_set);
auto* first = &crl_set.back().first;
printf("first word in vector storage (should be zero): %p\n",
*(void**)crl_set.data());
assert(first->empty());
puts("ok");
}
Compile with libc++, enable optimizations, and enable debug info:
$ clang++ -stdlib=libc++ -g -O2 t.cpp -o t.exe -Wl,-rpath=llvm/build/lib
This program will assert with this change.
llvm-svn: 321510
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