Don't crash on extra evil irreducible control flow.
When the CFG contains a loop with multiple entry blocks, the traces
computed by MachineTraceMetrics don't always have the same nice
properties. Loop back-edges are normally excluded from traces, but
MachineLoopInfo doesn't recognize loops with multiple entry blocks, so
those back-edges may be included.
Avoid asserting when that happens by adding an isEarlierInSameTrace()
function that accurately determines if a dominating block is part of the
same trace AND is above the currrent block in the trace.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165434 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/MachineTraceMetrics.cpp b/lib/CodeGen/MachineTraceMetrics.cpp
index 9b91af5..b3abec7 100644
--- a/lib/CodeGen/MachineTraceMetrics.cpp
+++ b/lib/CodeGen/MachineTraceMetrics.cpp
@@ -677,7 +677,7 @@
const MachineInstr *DefMI = MTM.MRI->getVRegDef(LIR.Reg);
// Ignore dependencies outside the current trace.
const TraceBlockInfo &DefTBI = BlockInfo[DefMI->getParent()->getNumber()];
- if (!DefTBI.hasValidDepth() || DefTBI.Head != TBI.Head)
+ if (!DefTBI.isEarlierInSameTrace(TBI))
continue;
unsigned Len = LIR.Height + Cycles[DefMI].Depth;
MaxLen = std::max(MaxLen, Len);
@@ -740,7 +740,7 @@
const TraceBlockInfo&DepTBI =
BlockInfo[Dep.DefMI->getParent()->getNumber()];
// Ignore dependencies from outside the current trace.
- if (!DepTBI.hasValidDepth() || DepTBI.Head != TBI.Head)
+ if (!DepTBI.isEarlierInSameTrace(TBI))
continue;
assert(DepTBI.HasValidInstrDepths && "Inconsistent dependency");
unsigned DepCycle = Cycles.lookup(Dep.DefMI).Depth;
diff --git a/lib/CodeGen/MachineTraceMetrics.h b/lib/CodeGen/MachineTraceMetrics.h
index d329c51..5f3b1d2 100644
--- a/lib/CodeGen/MachineTraceMetrics.h
+++ b/lib/CodeGen/MachineTraceMetrics.h
@@ -165,6 +165,14 @@
/// Invalidate height resources when a block below this one has changed.
void invalidateHeight() { InstrHeight = ~0u; HasValidInstrHeights = false; }
+ /// Determine if this block belongs to the same trace as TBI and comes
+ /// before it in the trace.
+ /// Also returns true when TBI == this.
+ bool isEarlierInSameTrace(const TraceBlockInfo &TBI) const {
+ return hasValidDepth() && TBI.hasValidDepth() &&
+ Head == TBI.Head && InstrDepth <= TBI.InstrDepth;
+ }
+
// Data-dependency-related information. Per-instruction depth and height
// are computed from data dependencies in the current trace, using
// itinerary data.