[Hexagon] Check for offset overflow when reserving scavenging slots
Scavenging slots were only reserved when pseudo-instruction expansion in
frame lowering created new virtual registers. It is possible to still
need a scavenging slot even if no virtual registers were created, in cases
where the stack is large enough to overflow instruction offsets.
llvm-svn: 277355
diff --git a/llvm/lib/Target/Hexagon/HexagonFrameLowering.cpp b/llvm/lib/Target/Hexagon/HexagonFrameLowering.cpp
index ed468fe..0577344 100644
--- a/llvm/lib/Target/Hexagon/HexagonFrameLowering.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonFrameLowering.cpp
@@ -1869,7 +1869,7 @@
// We need to reserve a a spill slot if scavenging could potentially require
// spilling a scavenged register.
- if (!NewRegs.empty()) {
+ if (!NewRegs.empty() || mayOverflowFrameOffset(MF)) {
MachineFrameInfo &MFI = MF.getFrameInfo();
MachineRegisterInfo &MRI = MF.getRegInfo();
SetVector<const TargetRegisterClass*> SpillRCs;
@@ -2407,3 +2407,16 @@
: SpillFuncThreshold;
return Threshold < NumCSI;
}
+
+
+bool HexagonFrameLowering::mayOverflowFrameOffset(MachineFunction &MF) const {
+ unsigned StackSize = MF.getFrameInfo().estimateStackSize(MF);
+ auto &HST = MF.getSubtarget<HexagonSubtarget>();
+ // A fairly simplistic guess as to whether a potential load/store to a
+ // stack location could require an extra register. It does not account
+ // for store-immediate instructions.
+ if (HST.useHVXOps())
+ return StackSize > 256;
+ return false;
+}
+
diff --git a/llvm/lib/Target/Hexagon/HexagonFrameLowering.h b/llvm/lib/Target/Hexagon/HexagonFrameLowering.h
index b4a3907..79e2cf1 100644
--- a/llvm/lib/Target/Hexagon/HexagonFrameLowering.h
+++ b/llvm/lib/Target/Hexagon/HexagonFrameLowering.h
@@ -141,9 +141,10 @@
void addCalleeSaveRegistersAsImpOperand(MachineInstr *MI, const CSIVect &CSI,
bool IsDef, bool IsKill) const;
- bool shouldInlineCSR(llvm::MachineFunction &MF, const CSIVect &CSI) const;
+ bool shouldInlineCSR(MachineFunction &MF, const CSIVect &CSI) const;
bool useSpillFunction(MachineFunction &MF, const CSIVect &CSI) const;
bool useRestoreFunction(MachineFunction &MF, const CSIVect &CSI) const;
+ bool mayOverflowFrameOffset(MachineFunction &MF) const;
};
} // End llvm namespace