================
@@ -580,25 +580,134 @@ static MCCFIInstruction createDefCFAOffset(const
TargetRegisterInfo &TRI,
Comment.str());
}
+// Allocate stack space and probe it if necessary.
void RISCVFrameLowering::allocateStack(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI,
- MachineFunction &MF, StackOffset Offset,
- uint64_t RealStackSize,
- bool EmitCFI) const {
+ MachineFunction &MF, uint64_t Offset,
+ uint64_t RealStackSize, bool EmitCFI,
+ bool NeedProbe,
+ uint64_t ProbeSize) const {
DebugLoc DL;
const RISCVRegisterInfo *RI = STI.getRegisterInfo();
const RISCVInstrInfo *TII = STI.getInstrInfo();
- RI->adjustReg(MBB, MBBI, DL, SPReg, SPReg, Offset, MachineInstr::FrameSetup,
+ // Simply allocate the stack if it's not big enough to require a probe.
+ if (!NeedProbe || Offset <= ProbeSize) {
+ RI->adjustReg(MBB, MBBI, DL, SPReg, SPReg, StackOffset::getFixed(-Offset),
+ MachineInstr::FrameSetup, getStackAlign());
+
+ if (EmitCFI) {
+ // Emit ".cfi_def_cfa_offset RealStackSize"
+ unsigned CFIIndex = MF.addFrameInst(
+ MCCFIInstruction::cfiDefCfaOffset(nullptr, RealStackSize));
+ BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))
+ .addCFIIndex(CFIIndex)
+ .setMIFlag(MachineInstr::FrameSetup);
+ }
+
+ return;
+ }
+
+ // Unroll the probe loop depending on the number of iterations.
+ if (Offset < ProbeSize * 5) {
+ uint64_t CurrentOffset = 0;
+ bool IsRV64 = STI.is64Bit();
+ while (CurrentOffset + ProbeSize <= Offset) {
+ RI->adjustReg(MBB, MBBI, DL, SPReg, SPReg,
+ StackOffset::getFixed(-ProbeSize),
MachineInstr::FrameSetup,
+ getStackAlign());
+ // s[d|w] zero, 0(sp)
+ BuildMI(MBB, MBBI, DL, TII->get(IsRV64 ? RISCV::SD : RISCV::SW))
+ .addReg(RISCV::X0)
+ .addReg(SPReg)
+ .addImm(0)
+ .setMIFlags(MachineInstr::FrameSetup);
+
+ CurrentOffset += ProbeSize;
+ if (EmitCFI) {
+ // Emit ".cfi_def_cfa_offset CurrentOffset"
+ unsigned CFIIndex = MF.addFrameInst(
+ MCCFIInstruction::cfiDefCfaOffset(nullptr, CurrentOffset));
+ BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))
+ .addCFIIndex(CFIIndex)
+ .setMIFlag(MachineInstr::FrameSetup);
+ }
+ }
+
+ uint64_t Residual = Offset - CurrentOffset;
+ if (Residual) {
+ RI->adjustReg(MBB, MBBI, DL, SPReg, SPReg,
+ StackOffset::getFixed(-Residual), MachineInstr::FrameSetup,
+ getStackAlign());
+ if (EmitCFI) {
+ // Emit ".cfi_def_cfa_offset Offset"
+ unsigned CFIIndex =
+ MF.addFrameInst(MCCFIInstruction::cfiDefCfaOffset(nullptr,
Offset));
+ BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))
+ .addCFIIndex(CFIIndex)
+ .setMIFlag(MachineInstr::FrameSetup);
+ }
+ }
+
+ return;
+ }
+
+ // Emit a variable-length allocation probing loop.
+ uint64_t RoundedSize = (Offset / ProbeSize) * ProbeSize;
----------------
rzinsly wrote:
Yes, just replaced it.
https://github.com/llvm/llvm-project/pull/117612
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