6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-07-04 02:24:29 +00:00
Code Issues Projects Releases Wiki Activity

Revert r215343.

Browse Source 
This was contentious and needs invesigation.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218971 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
James Molloy
2014-10-03 09:29:24 +00:00
parent 4643143a65
commit c75d43e0c0
2 changed files with 1 additions and 58 deletions
Download Patch File Download Diff File Expand all files Collapse all files

26
lib/Analysis/LazyValueInfo.cpp
View File

@ -545,31 +545,7 @@ bool LazyValueInfoCache::solveBlockValue(Value *Val, BasicBlock *BB) {
// cache needs updating, i.e. if we have solve a new value or not.
OverDefinedCacheUpdater ODCacheUpdater(Val, BB, BBLV, this);
// Once this BB is encountered, Val's value for this BB will not be Undefined
// any longer. When we encounter this BB again, if Val's value is Overdefined,
// we need to compute its value again.
//
// For example, considering this control flow,
// BB1->BB2, BB1->BB3, BB2->BB3, BB2->BB4
//
// Suppose we have "icmp slt %v, 0" in BB1, and "icmp sgt %v, 0" in BB3. At
// the very beginning, when analyzing edge BB2->BB3, we don't know %v's value
// in BB2, and the data flow algorithm tries to compute BB2's predecessors, so
// then we know %v has negative value on edge BB1->BB2. And then we return to
// check BB2 again, and at this moment BB2 has Overdefined value for %v in
// BB2. So we should have to follow data flow propagation algorithm to get the
// value on edge BB1->BB2 propagated to BB2, and finally %v on BB2 has a
// constant range describing a negative value.
//
// In the mean time, limit the number of additional lowering lattice value to
// avoid unjustified memory grows.
if (LoweringOverdefinedTimes.count(BB) == 0)
LoweringOverdefinedTimes.insert(std::make_pair(BB, 0));
if ((!BBLV.isUndefined() && !BBLV.isOverdefined()) ||
(BBLV.isOverdefined() &&
(LoweringOverdefinedTimes[BB] > OverdefinedThreshold ||
LoweringOverdefinedTimes.size() > OverdefinedBBThreshold))) {
if (!BBLV.isUndefined()) {
DEBUG(dbgs() << " reuse BB '" << BB->getName() << "' val=" << BBLV <<'\n');
// Since we're reusing a cached value here, we don't need to update the