Fix nondeterministic output in local stack slot alloc pass
This finds all of the references to a frame index in a function, and
sorts by the offset. If multiple instructions use the same offset,
nothing was breaking the tie for sorting.
This avoids the test failures the reverted r282999 introduced.
llvm-svn: 285201
diff --git a/llvm/lib/CodeGen/LocalStackSlotAllocation.cpp b/llvm/lib/CodeGen/LocalStackSlotAllocation.cpp
index b86406e..e189fb0 100644
--- a/llvm/lib/CodeGen/LocalStackSlotAllocation.cpp
+++ b/llvm/lib/CodeGen/LocalStackSlotAllocation.cpp
@@ -51,13 +51,21 @@
MachineBasicBlock::iterator MI; // Instr referencing the frame
int64_t LocalOffset; // Local offset of the frame idx referenced
int FrameIdx; // The frame index
+
+ // Order reference instruction appears in program. Used to ensure
+ // deterministic order when multiple instructions may reference the same
+ // location.
+ unsigned Order;
+
public:
- FrameRef(MachineBasicBlock::iterator I, int64_t Offset, int Idx) :
- MI(I), LocalOffset(Offset), FrameIdx(Idx) {}
+ FrameRef(MachineInstr *I, int64_t Offset, int Idx, unsigned Ord) :
+ MI(I), LocalOffset(Offset), FrameIdx(Idx), Order(Ord) {}
+
bool operator<(const FrameRef &RHS) const {
- return std::tie(LocalOffset, FrameIdx) <
- std::tie(RHS.LocalOffset, RHS.FrameIdx);
+ return std::tie(LocalOffset, FrameIdx, Order) <
+ std::tie(RHS.LocalOffset, RHS.FrameIdx, RHS.Order);
}
+
MachineBasicBlock::iterator getMachineInstr() const { return MI; }
int64_t getLocalOffset() const { return LocalOffset; }
int getFrameIndex() const { return FrameIdx; }
@@ -78,7 +86,7 @@
bool insertFrameReferenceRegisters(MachineFunction &Fn);
public:
static char ID; // Pass identification, replacement for typeid
- explicit LocalStackSlotPass() : MachineFunctionPass(ID) {
+ explicit LocalStackSlotPass() : MachineFunctionPass(ID) {
initializeLocalStackSlotPassPass(*PassRegistry::getPassRegistry());
}
bool runOnMachineFunction(MachineFunction &MF) override;
@@ -286,6 +294,8 @@
// choose the first one).
SmallVector<FrameRef, 64> FrameReferenceInsns;
+ unsigned Order = 0;
+
for (MachineBasicBlock &BB : Fn) {
for (MachineInstr &MI : BB) {
// Debug value, stackmap and patchpoint instructions can't be out of
@@ -312,7 +322,7 @@
int64_t LocalOffset = LocalOffsets[Idx];
if (!TRI->needsFrameBaseReg(&MI, LocalOffset))
break;
- FrameReferenceInsns.push_back(FrameRef(&MI, LocalOffset, Idx));
+ FrameReferenceInsns.push_back(FrameRef(&MI, LocalOffset, Idx, Order++));
break;
}
}