0059-Xtensa-Change-using-of-Frame-Pointer.patch

From 40f5b0087c52a6f771b36b409005a991ca4e86b3 Mon Sep 17 00:00:00 2001
From: Andrei Safronov <safronov@espressif.com>
Date: Wed, 5 Apr 2023 00:59:07 +0300
Subject: [PATCH 059/158] [Xtensa] Change using of Frame Pointer.

Do not use Frame Pointer by default.
Also improve storing function argument from a7 register to a8 register.
Corrected funnel shift test.
---
 clang/lib/Driver/ToolChains/Clang.cpp              | 1 +
 llvm/lib/Target/Xtensa/XtensaFrameLowering.cpp     | 9 ++++++---
 llvm/lib/Target/Xtensa/XtensaISelLowering.cpp      | 2 ++
 llvm/lib/Target/Xtensa/XtensaMachineFunctionInfo.h | 4 ++++
 4 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 238507e06335..43d262a7e4a7 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -455,6 +455,7 @@ static bool useFramePointerForTargetByDefault(const ArgList &Args,
   case llvm::Triple::csky:
   case llvm::Triple::loongarch32:
   case llvm::Triple::loongarch64:
+  case llvm::Triple::xtensa:
     return !areOptimizationsEnabled(Args);
   default:
     break;
diff --git a/llvm/lib/Target/Xtensa/XtensaFrameLowering.cpp b/llvm/lib/Target/Xtensa/XtensaFrameLowering.cpp
index 53b6b7e1b018..31ae43565974 100644
--- a/llvm/lib/Target/Xtensa/XtensaFrameLowering.cpp
+++ b/llvm/lib/Target/Xtensa/XtensaFrameLowering.cpp
@@ -100,6 +100,7 @@ void XtensaFrameLowering::emitPrologue(MachineFunction &MF,
   unsigned FP = RegInfo->getFrameRegister(MF);
   MachineModuleInfo &MMI = MF.getMMI();
   const MCRegisterInfo *MRI = MMI.getContext().getRegisterInfo();
+  XtensaFunctionInfo *XtensaFI = MF.getInfo<XtensaFunctionInfo>();
 
   // First, compute final stack size.
   uint64_t StackSize = MFI.getStackSize();
@@ -133,9 +134,11 @@ void XtensaFrameLowering::emitPrologue(MachineFunction &MF,
 
     // Store FP register in A8, because FP may be used to pass function
     // arguments
-    BuildMI(MBB, MBBI, dl, TII.get(Xtensa::OR), Xtensa::A8)
-        .addReg(FP)
-        .addReg(FP);
+    if (XtensaFI->isSaveFrameRegister()) {
+      BuildMI(MBB, MBBI, dl, TII.get(Xtensa::OR), Xtensa::A8)
+          .addReg(FP)
+          .addReg(FP);
+    }
 
     // if framepointer enabled, set it to point to the stack pointer.
     if (hasFP(MF)) {
diff --git a/llvm/lib/Target/Xtensa/XtensaISelLowering.cpp b/llvm/lib/Target/Xtensa/XtensaISelLowering.cpp
index 48f3fed4f909..e7642afebe78 100644
--- a/llvm/lib/Target/Xtensa/XtensaISelLowering.cpp
+++ b/llvm/lib/Target/Xtensa/XtensaISelLowering.cpp
@@ -793,6 +793,7 @@ SDValue XtensaTargetLowering::LowerFormalArguments(
       // so load argument from A8
       if (Subtarget.isWinABI() && (VA.getLocReg() == FrameReg)) {
         Reg = MF.addLiveIn(Xtensa::A8, RC);
+        XtensaFI->setSaveFrameRegister();
       } else {
         Reg = MF.addLiveIn(VA.getLocReg(), RC);
       }
@@ -887,6 +888,7 @@ SDValue XtensaTargetLowering::LowerFormalArguments(
       // so load argument from A8
       if (ArgRegs[I] == FrameReg) {
         RegInfo.addLiveIn(Xtensa::A8, Reg);
+        XtensaFI->setSaveFrameRegister();
       } else {
         RegInfo.addLiveIn(ArgRegs[I], Reg);
       }
diff --git a/llvm/lib/Target/Xtensa/XtensaMachineFunctionInfo.h b/llvm/lib/Target/Xtensa/XtensaMachineFunctionInfo.h
index ebc99f912ba0..10d11fcb21bf 100644
--- a/llvm/lib/Target/Xtensa/XtensaMachineFunctionInfo.h
+++ b/llvm/lib/Target/Xtensa/XtensaMachineFunctionInfo.h
@@ -25,6 +25,7 @@ class XtensaFunctionInfo : public MachineFunctionInfo {
   unsigned VarArgsFirstGPR;
   int VarArgsStackOffset;
   unsigned VarArgsFrameIndex;
+  bool SaveFrameRegister = false;
 
 public:
   explicit XtensaFunctionInfo(const Function &F, const TargetSubtargetInfo *STI)
@@ -39,6 +40,9 @@ public:
   // Get and set the frame index of the first stack vararg.
   unsigned getVarArgsFrameIndex() const { return VarArgsFrameIndex; }
   void setVarArgsFrameIndex(unsigned FI) { VarArgsFrameIndex = FI; }
+
+  bool isSaveFrameRegister() const { return SaveFrameRegister; }
+  void setSaveFrameRegister() { SaveFrameRegister = true; }
 };
 
 } // namespace llvm
-- 
2.40.1