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Fix nondeterministic output in local stack slot alloc pass

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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
This commit is contained in:
Matt Arsenault 2016-10-26 14:53:50 +00:00
parent bc2320e150
commit 9bbf2376bc
1 changed files with 16 additions and 6 deletions
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22
lib/CodeGen/LocalStackSlotAllocation.cpp
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@ -51,13 +51,21 @@ namespace {
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 @@ namespace {
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 @@ bool LocalStackSlotPass::insertFrameReferenceRegisters(MachineFunction &Fn) {
// 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 @@ bool LocalStackSlotPass::insertFrameReferenceRegisters(MachineFunction &Fn) {
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;
}
}