[WinEH] Mark funclet entries and exits as clobbering all registers
Summary:
In this implementation, LiveIntervalAnalysis invents a few register
masks on basic block boundaries that preserve no registers. The nice
thing about this is that it prevents the prologue inserter from thinking
it needs to spill all XMM CSRs, because it doesn't see any explicit
physreg defs in the MI.
Reviewers: MatzeB, qcolombet, JosephTremoulet, majnemer
Subscribers: MatzeB, llvm-commits
Differential Revision: http://reviews.llvm.org/D14407
llvm-svn: 252318
diff --git a/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp b/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
index 8d9d984..afd8db8 100644
--- a/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -225,6 +225,13 @@
for (MachineBasicBlock &MBB : *MF) {
std::pair<unsigned, unsigned> &RMB = RegMaskBlocks[MBB.getNumber()];
RMB.first = RegMaskSlots.size();
+
+ // Some block starts, such as EH funclets, create masks.
+ if (const uint32_t *Mask = MBB.getBeginClobberMask(TRI)) {
+ RegMaskSlots.push_back(Indexes->getMBBStartIdx(&MBB));
+ RegMaskBits.push_back(Mask);
+ }
+
for (MachineInstr &MI : MBB) {
for (const MachineOperand &MO : MI.operands()) {
if (!MO.isRegMask())
@@ -233,6 +240,13 @@
RegMaskBits.push_back(MO.getRegMask());
}
}
+
+ // Some block ends, such as funclet returns, create masks.
+ if (const uint32_t *Mask = MBB.getEndClobberMask(TRI)) {
+ RegMaskSlots.push_back(Indexes->getMBBEndIdx(&MBB));
+ RegMaskBits.push_back(Mask);
+ }
+
// Compute the number of register mask instructions in this block.
RMB.second = RegMaskSlots.size() - RMB.first;
}