Add LiveIntervals::getLastSplitPoint().
A live range cannot be split everywhere in a basic block. A split must go before
the first terminator, and if the variable is live into a landing pad, the split
must happen before the call that can throw.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124894 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index 000fc40..32c553f 100644
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -746,6 +746,28 @@
// Register allocator hooks.
//
+MachineBasicBlock::iterator
+LiveIntervals::getLastSplitPoint(const LiveInterval &li,
+ MachineBasicBlock *mbb) {
+ const MachineBasicBlock *lpad = mbb->getLandingPadSuccessor();
+
+ // If li is not live into a landing pad, we can insert spill code before the
+ // first terminator.
+ if (!lpad || !isLiveInToMBB(li, lpad))
+ return mbb->getFirstTerminator();
+
+ // When there is a landing pad, spill code must go before the call instruction
+ // that can throw.
+ MachineBasicBlock::iterator I = mbb->end(), B = mbb->begin();
+ while (I != B) {
+ --I;
+ if (I->getDesc().isCall())
+ return I;
+ }
+ assert(0 && "Block with landing pad successor contains no call instruction");
+ return mbb->getFirstTerminator();
+}
+
/// getReMatImplicitUse - If the remat definition MI has one (for now, we only
/// allow one) virtual register operand, then its uses are implicitly using
/// the register. Returns the virtual register.
diff --git a/lib/CodeGen/MachineBasicBlock.cpp b/lib/CodeGen/MachineBasicBlock.cpp
index 95b8f86..ccbff0a 100644
--- a/lib/CodeGen/MachineBasicBlock.cpp
+++ b/lib/CodeGen/MachineBasicBlock.cpp
@@ -175,6 +175,16 @@
return end();
}
+const MachineBasicBlock *MachineBasicBlock::getLandingPadSuccessor() const {
+ // A block with a landing pad successor only has one other successor.
+ if (succ_size() > 2)
+ return 0;
+ for (const_succ_iterator I = succ_begin(), E = succ_end(); I != E; ++I)
+ if ((*I)->isLandingPad())
+ return *I;
+ return 0;
+}
+
void MachineBasicBlock::dump() const {
print(dbgs());
}
diff --git a/lib/CodeGen/SplitKit.cpp b/lib/CodeGen/SplitKit.cpp
index e4a82ad..68f782d 100644
--- a/lib/CodeGen/SplitKit.cpp
+++ b/lib/CodeGen/SplitKit.cpp
@@ -826,7 +826,7 @@
}
DEBUG(dbgs() << ": valno " << ParentVNI->id);
VNInfo *VNI = defFromParent(OpenIdx, ParentVNI, Last, MBB,
- MBB.getFirstTerminator());
+ LIS.getLastSplitPoint(Edit.getParent(), &MBB));
RegAssign.insert(VNI->def, End, OpenIdx);
DEBUG(dump());
return VNI->def;