================
@@ -2277,6 +2351,70 @@ void AArch64FrameLowering::determineStackHazardSlot(
<< StackHazardSize << "\n");
AFI->setStackHazardSlotIndex(ID);
}
+
+ // Determine if we should use SplitSVEObjects. This should only be used if
+ // there's a possibility of a stack hazard between PPRs and ZPRs or FPRs.
+ if (SplitSVEObjects) {
+ if (!HasPPRCSRs && !HasPPRStackObjects) {
+ LLVM_DEBUG(
+ dbgs() << "Not using SplitSVEObjects as no PPRs are on the stack\n");
+ return;
+ }
+
+ if (!HasFPRCSRs && !HasFPRStackObjects) {
+ LLVM_DEBUG(
+ dbgs()
+ << "Not using SplitSVEObjects as no FPRs or ZPRs are on the
stack\n");
+ return;
+ }
+
+ const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
+ if (MFI.hasVarSizedObjects() || TRI->hasStackRealignment(MF)) {
+ LLVM_DEBUG(dbgs() << "SplitSVEObjects is not supported with variable "
+ "sized objects or realignment\n");
+ return;
+ }
+
+ if (arePPRsSpilledAsZPR(MF)) {
+ LLVM_DEBUG(dbgs() << "SplitSVEObjects is not supported with "
+ "-aarch64-enable-zpr-predicate-spills");
+ return;
+ }
+
+ [[maybe_unused]] const AArch64Subtarget &Subtarget =
+ MF.getSubtarget<AArch64Subtarget>();
+ assert(Subtarget.isSVEorStreamingSVEAvailable() &&
+ "Expected SVE to be available for PPRs");
+
+ // With SplitSVEObjects the CS hazard padding is placed between the
+ // PPRs and ZPRs. If there are any FPR CS there would be a hazard between
+ // them and the CS GRPs. Avoid this by promoting all FPR CS to ZPRs.
+ BitVector FPRZRegs(SavedRegs.size());
+ for (size_t Reg = 0, E = SavedRegs.size(); HasFPRCSRs && Reg < E; ++Reg) {
+ BitVector::reference RegBit = SavedRegs[Reg];
+ if (!RegBit)
+ continue;
+ unsigned SubRegIdx = 0;
+ if (AArch64::FPR64RegClass.contains(Reg))
+ SubRegIdx = AArch64::dsub;
+ else if (AArch64::FPR128RegClass.contains(Reg))
+ SubRegIdx = AArch64::zsub; // TODO: Is the the right sub-register?
+ else
+ continue;
+ // Clear the bit for the FPR save.
+ RegBit = false;
+ // Mark that we should save the corresponding ZPR.
+ Register ZReg =
+ TRI->getMatchingSuperReg(Reg, SubRegIdx, &AArch64::ZPRRegClass);
+ FPRZRegs.set(ZReg);
+ }
+ SavedRegs |= FPRZRegs;
+
+ // FIXME: Avoid setting setting the CC. Since we've replaced FPRs with ZPRs
+ // we need to set this or later in PEI the ZPR CS will be masked out.
+ AFI->setIsSVECC(true);
----------------
MacDue wrote:
Done, I've also added a check that splitSVEObjects is only applied to functions
with `C`, `Fast`, or `SVE` calling conventions, as otherwise promoting FPRs to
ZPRs won't work (as the `SaveList` will be overridden by some other calling
convention).
https://github.com/llvm/llvm-project/pull/142392
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