Revert "[memcpyopt] Teach memcpyopt to optimize across basic blocks"
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
diff --git a/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp b/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
index bb7bf96..bf83f52 100644
--- a/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
+++ b/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
@@ -920,14 +920,6 @@
Instruction *QueryInst, SmallVectorImpl<NonLocalDepResult> &Result) {
const MemoryLocation Loc = MemoryLocation::get(QueryInst);
bool isLoad = isa<LoadInst>(QueryInst);
- return getNonLocalPointerDependencyFrom(QueryInst, Loc, isLoad, Result);
-}
-
-void MemoryDependenceResults::getNonLocalPointerDependencyFrom(
- Instruction *QueryInst,
- const MemoryLocation &Loc,
- bool isLoad,
- SmallVectorImpl<NonLocalDepResult> &Result) {
BasicBlock *FromBB = QueryInst->getParent();
assert(FromBB);
@@ -1127,15 +1119,21 @@
// If we already have a cache entry for this CacheKey, we may need to do some
// work to reconcile the cache entry and the current query.
if (!Pair.second) {
- if (CacheInfo->Size != Loc.Size) {
- // The query's Size differs from the cached one. Throw out the
- // cached data and proceed with the query at the new size.
+ if (CacheInfo->Size < Loc.Size) {
+ // The query's Size is greater than the cached one. Throw out the
+ // cached data and proceed with the query at the greater size.
CacheInfo->Pair = BBSkipFirstBlockPair();
CacheInfo->Size = Loc.Size;
for (auto &Entry : CacheInfo->NonLocalDeps)
if (Instruction *Inst = Entry.getResult().getInst())
RemoveFromReverseMap(ReverseNonLocalPtrDeps, Inst, CacheKey);
CacheInfo->NonLocalDeps.clear();
+ } else if (CacheInfo->Size > Loc.Size) {
+ // This query's Size is less than the cached one. Conservatively restart
+ // the query using the greater size.
+ return getNonLocalPointerDepFromBB(
+ QueryInst, Pointer, Loc.getWithNewSize(CacheInfo->Size), isLoad,
+ StartBB, Result, Visited, SkipFirstBlock);
}
// If the query's AATags are inconsistent with the cached one,