[llvm] [AArch64] Avoid hardcoding spill size/align in FrameLowering (NFC) (PR #123080)

[Benjamin Maxwell via llvm-commits]

https://github.com/MacDue created https://github.com/llvm/llvm-project/pull/123080

This is already defined for each register class in AArch64RegisterInfo, not hardcoding it here makes these values easier to change (perhaps based on hardware mode).

>From 41496d0a256705396094665218f2e5432ee1ac9c Mon Sep 17 00:00:00 2001
From: Benjamin Maxwell <benjamin.maxwell at arm.com>
Date: Wed, 15 Jan 2025 15:59:16 +0000
Subject: [PATCH] [AArch64] Avoid hardcoding spill size/align in FrameLowering
 (NFC)

This is already defined for each register class in AArch64RegisterInfo,
not hardcoding it here makes these values easier to change (perhaps
based on hardware mode).
---
 .../Target/AArch64/AArch64FrameLowering.cpp   | 69 ++++++-------------
 1 file changed, 20 insertions(+), 49 deletions(-)

diff --git a/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp b/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
index 206e410047db56..66a3266f989fe8 100644
--- a/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
@@ -2926,26 +2926,12 @@ struct RegPairInfo {
   int FrameIdx;
   int Offset;
   enum RegType { GPR, FPR64, FPR128, PPR, ZPR, VG } Type;
+  const TargetRegisterClass *RC;
 
   RegPairInfo() = default;
 
   bool isPaired() const { return Reg2 != AArch64::NoRegister; }
 
-  unsigned getScale() const {
-    switch (Type) {
-    case PPR:
-      return 2;
-    case GPR:
-    case FPR64:
-    case VG:
-      return 8;
-    case ZPR:
-    case FPR128:
-      return 16;
-    }
-    llvm_unreachable("Unsupported type");
-  }
-
   bool isScalable() const { return Type == PPR || Type == ZPR; }
 };
 
@@ -3023,20 +3009,27 @@ static void computeCalleeSaveRegisterPairs(
     RegPairInfo RPI;
     RPI.Reg1 = CSI[i].getReg();
 
-    if (AArch64::GPR64RegClass.contains(RPI.Reg1))
+    if (AArch64::GPR64RegClass.contains(RPI.Reg1)) {
       RPI.Type = RegPairInfo::GPR;
-    else if (AArch64::FPR64RegClass.contains(RPI.Reg1))
+      RPI.RC = &AArch64::GPR64RegClass;
+    } else if (AArch64::FPR64RegClass.contains(RPI.Reg1)) {
       RPI.Type = RegPairInfo::FPR64;
-    else if (AArch64::FPR128RegClass.contains(RPI.Reg1))
+      RPI.RC = &AArch64::FPR64RegClass;
+    } else if (AArch64::FPR128RegClass.contains(RPI.Reg1)) {
       RPI.Type = RegPairInfo::FPR128;
-    else if (AArch64::ZPRRegClass.contains(RPI.Reg1))
+      RPI.RC = &AArch64::FPR128RegClass;
+    } else if (AArch64::ZPRRegClass.contains(RPI.Reg1)) {
       RPI.Type = RegPairInfo::ZPR;
-    else if (AArch64::PPRRegClass.contains(RPI.Reg1))
+      RPI.RC = &AArch64::ZPRRegClass;
+    } else if (AArch64::PPRRegClass.contains(RPI.Reg1)) {
       RPI.Type = RegPairInfo::PPR;
-    else if (RPI.Reg1 == AArch64::VG)
+      RPI.RC = &AArch64::PPRRegClass;
+    } else if (RPI.Reg1 == AArch64::VG) {
       RPI.Type = RegPairInfo::VG;
-    else
+      RPI.RC = &AArch64::FIXED_REGSRegClass;
+    } else {
       llvm_unreachable("Unsupported register class.");
+    }
 
     // Add the stack hazard size as we transition from GPR->FPR CSRs.
     if (AFI->hasStackHazardSlotIndex() &&
@@ -3045,7 +3038,7 @@ static void computeCalleeSaveRegisterPairs(
       ByteOffset += StackFillDir * StackHazardSize;
     LastReg = RPI.Reg1;
 
-    int Scale = RPI.getScale();
+    int Scale = TRI->getSpillSize(*RPI.RC);
     // Add the next reg to the pair if it is in the same register class.
     if (unsigned(i + RegInc) < Count && !AFI->hasStackHazardSlotIndex()) {
       Register NextReg = CSI[i + RegInc].getReg();
@@ -3254,38 +3247,26 @@ bool AArch64FrameLowering::spillCalleeSavedRegisters(
     // Rationale: This sequence saves uop updates compared to a sequence of
     // pre-increment spills like stp xi,xj,[sp,#-16]!
     // Note: Similar rationale and sequence for restores in epilog.
-    unsigned Size;
-    Align Alignment;
+    unsigned Size = TRI->getSpillSize(*RPI.RC);
+    Align Alignment = TRI->getSpillAlign(*RPI.RC);
     switch (RPI.Type) {
     case RegPairInfo::GPR:
       StrOpc = RPI.isPaired() ? AArch64::STPXi : AArch64::STRXui;
-      Size = 8;
-      Alignment = Align(8);
       break;
     case RegPairInfo::FPR64:
       StrOpc = RPI.isPaired() ? AArch64::STPDi : AArch64::STRDui;
-      Size = 8;
-      Alignment = Align(8);
       break;
     case RegPairInfo::FPR128:
       StrOpc = RPI.isPaired() ? AArch64::STPQi : AArch64::STRQui;
-      Size = 16;
-      Alignment = Align(16);
       break;
     case RegPairInfo::ZPR:
       StrOpc = RPI.isPaired() ? AArch64::ST1B_2Z_IMM : AArch64::STR_ZXI;
-      Size = 16;
-      Alignment = Align(16);
       break;
     case RegPairInfo::PPR:
       StrOpc = AArch64::STR_PXI;
-      Size = 2;
-      Alignment = Align(2);
       break;
     case RegPairInfo::VG:
       StrOpc = AArch64::STRXui;
-      Size = 8;
-      Alignment = Align(8);
       break;
     }
 
@@ -3495,33 +3476,23 @@ bool AArch64FrameLowering::restoreCalleeSavedRegisters(
     //    ldp     x22, x21, [sp, #0]      // addImm(+0)
     // Note: see comment in spillCalleeSavedRegisters()
     unsigned LdrOpc;
-    unsigned Size;
-    Align Alignment;
+    unsigned Size = TRI->getSpillSize(*RPI.RC);
+    Align Alignment = TRI->getSpillAlign(*RPI.RC);
     switch (RPI.Type) {
     case RegPairInfo::GPR:
       LdrOpc = RPI.isPaired() ? AArch64::LDPXi : AArch64::LDRXui;
-      Size = 8;
-      Alignment = Align(8);
       break;
     case RegPairInfo::FPR64:
       LdrOpc = RPI.isPaired() ? AArch64::LDPDi : AArch64::LDRDui;
-      Size = 8;
-      Alignment = Align(8);
       break;
     case RegPairInfo::FPR128:
       LdrOpc = RPI.isPaired() ? AArch64::LDPQi : AArch64::LDRQui;
-      Size = 16;
-      Alignment = Align(16);
       break;
     case RegPairInfo::ZPR:
       LdrOpc = RPI.isPaired() ? AArch64::LD1B_2Z_IMM : AArch64::LDR_ZXI;
-      Size = 16;
-      Alignment = Align(16);
       break;
     case RegPairInfo::PPR:
       LdrOpc = AArch64::LDR_PXI;
-      Size = 2;
-      Alignment = Align(2);
       break;
     case RegPairInfo::VG:
       continue;