Add an early bailout to IsValueFullyAvailableInBlock from deeply nested blocks.
The limit is set to an arbitrary 1000 recursion depth to avoid stack overflow
issues. <rdar://problem/11286839>.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155722 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/GVN.cpp b/lib/Transforms/Scalar/GVN.cpp
index fb733ad..f282645 100644
--- a/lib/Transforms/Scalar/GVN.cpp
+++ b/lib/Transforms/Scalar/GVN.cpp
@@ -59,6 +59,11 @@
cl::init(true), cl::Hidden);
static cl::opt<bool> EnableLoadPRE("enable-load-pre", cl::init(true));
+// Maximum allowed recursion depth.
+static cl::opt<int>
+MaxRecurseDepth("max-recurse-depth", cl::Hidden, cl::init(1000), cl::ZeroOrMore,
+ cl::desc("Max recurse depth (default = 1000)"));
+
//===----------------------------------------------------------------------===//
// ValueTable Class
//===----------------------------------------------------------------------===//
@@ -647,7 +652,11 @@
/// 3) we are speculating for this block and have used that to speculate for
/// other blocks.
static bool IsValueFullyAvailableInBlock(BasicBlock *BB,
- DenseMap<BasicBlock*, char> &FullyAvailableBlocks) {
+ DenseMap<BasicBlock*, char> &FullyAvailableBlocks,
+ uint32_t RecurseDepth) {
+ if (RecurseDepth > MaxRecurseDepth)
+ return false;
+
// Optimistically assume that the block is fully available and check to see
// if we already know about this block in one lookup.
std::pair<DenseMap<BasicBlock*, char>::iterator, char> IV =
@@ -673,7 +682,7 @@
// If the value isn't fully available in one of our predecessors, then it
// isn't fully available in this block either. Undo our previous
// optimistic assumption and bail out.
- if (!IsValueFullyAvailableInBlock(*PI, FullyAvailableBlocks))
+ if (!IsValueFullyAvailableInBlock(*PI, FullyAvailableBlocks,RecurseDepth+1))
goto SpeculationFailure;
return true;
@@ -1570,7 +1579,7 @@
for (pred_iterator PI = pred_begin(LoadBB), E = pred_end(LoadBB);
PI != E; ++PI) {
BasicBlock *Pred = *PI;
- if (IsValueFullyAvailableInBlock(Pred, FullyAvailableBlocks)) {
+ if (IsValueFullyAvailableInBlock(Pred, FullyAvailableBlocks, 0)) {
continue;
}
PredLoads[Pred] = 0;