From b3af3376ee7f50a6113b7216aea9c5648eaa1465 Mon Sep 17 00:00:00 2001
From: Amara Emerson <aemerson@apple.com>
Date: Wed, 15 Jan 2020 08:49:22 -0800
Subject: [PATCH] Revert "Revert rG6078f2fedcac5797ac39ee5ef3fd7a35ef1202d5 -
 "[AArch64][GlobalISel]: Support @llvm.{return,frame}address selection.""

The original change wasn't constraining the operand regclasses which broke EXPENSIVE_CHECKS.
---
 .../AArch64/AArch64InstructionSelector.cpp    | 42 ++++++++++++++++++-
 .../AArch64/GlobalISel/select-frameaddr.ll    | 20 +++++++++
 .../AArch64/GlobalISel/select-returnaddr.ll   | 22 ++++++++++
 3 files changed, 83 insertions(+), 1 deletion(-)
 create mode 100644 test/CodeGen/AArch64/GlobalISel/select-frameaddr.ll
 create mode 100644 test/CodeGen/AArch64/GlobalISel/select-returnaddr.ll

diff --git a/lib/Target/AArch64/AArch64InstructionSelector.cpp b/lib/Target/AArch64/AArch64InstructionSelector.cpp
index b9ac2657e1c..8629db4a8a7 100644
--- a/lib/Target/AArch64/AArch64InstructionSelector.cpp
+++ b/lib/Target/AArch64/AArch64InstructionSelector.cpp
@@ -4091,7 +4091,7 @@ bool AArch64InstructionSelector::selectIntrinsic(
   switch (IntrinID) {
   default:
     break;
-  case Intrinsic::aarch64_crypto_sha1h:
+  case Intrinsic::aarch64_crypto_sha1h: {
     Register DstReg = I.getOperand(0).getReg();
     Register SrcReg = I.getOperand(2).getReg();
 
@@ -4130,6 +4130,46 @@ bool AArch64InstructionSelector::selectIntrinsic(
     I.eraseFromParent();
     return true;
   }
+  case Intrinsic::frameaddress:
+  case Intrinsic::returnaddress: {
+    MachineFunction &MF = *I.getParent()->getParent();
+    MachineFrameInfo &MFI = MF.getFrameInfo();
+
+    unsigned Depth = I.getOperand(2).getImm();
+    Register DstReg = I.getOperand(0).getReg();
+    RBI.constrainGenericRegister(DstReg, AArch64::GPR64RegClass, MRI);
+
+    if (Depth == 0 && IntrinID == Intrinsic::returnaddress) {
+      MFI.setReturnAddressIsTaken(true);
+      MF.addLiveIn(AArch64::LR, &AArch64::GPR64spRegClass);
+      I.getParent()->addLiveIn(AArch64::LR);
+      MIRBuilder.buildCopy({DstReg}, {Register(AArch64::LR)});
+      I.eraseFromParent();
+      return true;
+    }
+
+    MFI.setFrameAddressIsTaken(true);
+    Register FrameAddr(AArch64::FP);
+    while (Depth--) {
+      Register NextFrame = MRI.createVirtualRegister(&AArch64::GPR64spRegClass);
+      auto Ldr =
+          MIRBuilder.buildInstr(AArch64::LDRXui, {NextFrame}, {FrameAddr})
+              .addImm(0);
+      constrainSelectedInstRegOperands(*Ldr, TII, TRI, RBI);
+      FrameAddr = NextFrame;
+    }
+
+    if (IntrinID == Intrinsic::frameaddress)
+      MIRBuilder.buildCopy({DstReg}, {FrameAddr});
+    else {
+      MFI.setReturnAddressIsTaken(true);
+      MIRBuilder.buildInstr(AArch64::LDRXui, {DstReg}, {FrameAddr}).addImm(1);
+    }
+
+    I.eraseFromParent();
+    return true;
+  }
+  }
   return false;
 }
 
diff --git a/test/CodeGen/AArch64/GlobalISel/select-frameaddr.ll b/test/CodeGen/AArch64/GlobalISel/select-frameaddr.ll
new file mode 100644
index 00000000000..83bea900bb6
--- /dev/null
+++ b/test/CodeGen/AArch64/GlobalISel/select-frameaddr.ll
@@ -0,0 +1,20 @@
+; RUN: llc -mtriple=arm64-apple-ios -global-isel -o - %s | FileCheck %s
+
+define i8* @rt0(i32 %x) nounwind readnone {
+entry:
+; CHECK-LABEL: rt0:
+; CHECK: mov x0, x29
+  %0 = tail call i8* @llvm.frameaddress(i32 0)
+  ret i8* %0
+}
+
+define i8* @rt2() nounwind readnone {
+entry:
+; CHECK-LABEL: rt2:
+; CHECK: ldr x[[reg:[0-9]+]], [x29]
+; CHECK: ldr x0, [x[[reg]]]
+  %0 = tail call i8* @llvm.frameaddress(i32 2)
+  ret i8* %0
+}
+
+declare i8* @llvm.frameaddress(i32) nounwind readnone
diff --git a/test/CodeGen/AArch64/GlobalISel/select-returnaddr.ll b/test/CodeGen/AArch64/GlobalISel/select-returnaddr.ll
new file mode 100644
index 00000000000..137f3266704
--- /dev/null
+++ b/test/CodeGen/AArch64/GlobalISel/select-returnaddr.ll
@@ -0,0 +1,22 @@
+; RUN: llc -mtriple=arm64-apple-ios -global-isel -o - %s | FileCheck %s
+
+define i8* @rt0(i32 %x) nounwind readnone {
+entry:
+; CHECK-LABEL: rt0:
+; CHECK-NOT: stp
+; CHECK: mov x0, x30
+  %0 = tail call i8* @llvm.returnaddress(i32 0)
+  ret i8* %0
+}
+
+define i8* @rt2() nounwind readnone {
+entry:
+; CHECK-LABEL: rt2:
+; CHECK: ldr x[[reg:[0-9]+]], [x29]
+; CHECK: ldr x[[reg]], [x[[reg]]]
+; CHECK: ldr x0, [x[[reg]], #8]
+  %0 = tail call i8* @llvm.returnaddress(i32 2)
+  ret i8* %0
+}
+
+declare i8* @llvm.returnaddress(i32) nounwind readnone