[PATCH] D124615: [AArch64][SVE] Restore SP from base pointer when it and SVE frame are present

[Bradley Smith via Phabricator via llvm-commits]

bsmith updated this revision to Diff 426012.
bsmith added a comment.

- Only restore from base pointer when SVE CSRs are present


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D124615/new/

https://reviews.llvm.org/D124615

Files:
  llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
  llvm/test/CodeGen/AArch64/sve-alloca.ll


Index: llvm/test/CodeGen/AArch64/sve-alloca.ll
===================================================================
--- llvm/test/CodeGen/AArch64/sve-alloca.ll
+++ llvm/test/CodeGen/AArch64/sve-alloca.ll
@@ -66,6 +66,7 @@
 ; CHECK-NEXT:    st1d { z1.d }, p0, [x0, #1, mul vl]
 ; CHECK-NEXT:    st1d { z0.d }, p0, [x0]
 ; CHECK-NEXT:    bl bar
+; CHECK-NEXT:    mov sp, x19
 ; CHECK-NEXT:    ldr p15, [sp, #4, mul vl] // 2-byte Folded Reload
 ; CHECK-NEXT:    ldr p14, [sp, #5, mul vl] // 2-byte Folded Reload
 ; CHECK-NEXT:    ldr p13, [sp, #6, mul vl] // 2-byte Folded Reload
Index: llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
===================================================================
--- llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
+++ llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
@@ -1757,6 +1757,7 @@
   MachineFrameInfo &MFI = MF.getFrameInfo();
   const AArch64Subtarget &Subtarget = MF.getSubtarget<AArch64Subtarget>();
   const TargetInstrInfo *TII = Subtarget.getInstrInfo();
+  const AArch64RegisterInfo &RegInfo = *Subtarget.getRegisterInfo();
   DebugLoc DL;
   bool NeedsWinCFI = needsWinCFI(MF);
   bool EmitCFI = MF.getInfo<AArch64FunctionInfo>()->needsAsyncDwarfUnwindInfo();
@@ -1909,7 +1910,6 @@
 
     // When we are about to restore the CSRs, the CFA register is SP again.
     if (EmitCFI && hasFP(MF)) {
-      const AArch64RegisterInfo &RegInfo = *Subtarget.getRegisterInfo();
       unsigned Reg = RegInfo.getDwarfRegNum(AArch64::SP, true);
       unsigned CFIIndex =
           MF.addFrameInst(MCCFIInstruction::cfiDefCfa(nullptr, Reg, NumBytes));
@@ -1953,6 +1953,15 @@
 
   // Deallocate the SVE area.
   if (SVEStackSize) {
+    // If we have a base pointer and SVE callee saves we must restore the stack
+    // pointer from the base pointer, we need to explicitly deallocate variable
+    // length stack allocations in order to correctly restore the SVE CSRs.
+    if (!IsFunclet && RegInfo.hasBasePointer(MF) &&
+        AFI->getSVECalleeSavedStackSize())
+      emitFrameOffset(MBB, RestoreBegin, DL, AArch64::SP,
+                      RegInfo.getBaseRegister(), StackOffset::getFixed(0), TII,
+                      MachineInstr::FrameDestroy);
+
     if (AFI->isStackRealigned()) {
       if (int64_t CalleeSavedSize = AFI->getSVECalleeSavedStackSize()) {
         // Set SP to start of SVE callee-save area from which they can


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