From 9ad0f02749f1a6566693a8d5dc33775b31cddbd5 Mon Sep 17 00:00:00 2001
From: Sid Manning <sidneym@codeaurora.org>
Date: Fri, 7 Sep 2018 13:36:21 +0000
Subject: [PATCH] Add support for getRegisterByName.

Support required to build the Hexagon Linux kernel.

Differential Revision: https://reviews.llvm.org/D51363

llvm-svn: 341658
---
 llvm/lib/Target/Hexagon/HexagonISelLowering.cpp | 13 +++++++++++++
 llvm/lib/Target/Hexagon/HexagonISelLowering.h   |  3 +++
 llvm/test/CodeGen/Hexagon/namedreg.ll           | 13 +++++++++++++
 3 files changed, 29 insertions(+)
 create mode 100644 llvm/test/CodeGen/Hexagon/namedreg.ll

diff --git a/llvm/lib/Target/Hexagon/HexagonISelLowering.cpp b/llvm/lib/Target/Hexagon/HexagonISelLowering.cpp
index 7cab0c5..b74be76 100644
--- a/llvm/lib/Target/Hexagon/HexagonISelLowering.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonISelLowering.cpp
@@ -22,6 +22,7 @@
 #include "llvm/ADT/APInt.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringSwitch.h"
 #include "llvm/CodeGen/CallingConvLower.h"
 #include "llvm/CodeGen/MachineFrameInfo.h"
 #include "llvm/CodeGen/MachineFunction.h"
@@ -240,6 +241,18 @@ bool HexagonTargetLowering::mayBeEmittedAsTailCall(const CallInst *CI) const {
   return true;
 }
 
+unsigned  HexagonTargetLowering::getRegisterByName(const char* RegName, EVT VT,
+                                              SelectionDAG &DAG) const {
+  // Just support r19, the linux kernel uses it.
+  unsigned Reg = StringSwitch<unsigned>(RegName)
+                     .Case("r19", Hexagon::R19)
+                     .Default(0);
+  if (Reg)
+    return Reg;
+
+  report_fatal_error("Invalid register name global variable");
+}
+
 /// LowerCallResult - Lower the result values of an ISD::CALL into the
 /// appropriate copies out of appropriate physical registers.  This assumes that
 /// Chain/Glue are the input chain/glue to use, and that TheCall is the call
diff --git a/llvm/lib/Target/Hexagon/HexagonISelLowering.h b/llvm/lib/Target/Hexagon/HexagonISelLowering.h
index 376d68c..d6d6ec6 100644
--- a/llvm/lib/Target/Hexagon/HexagonISelLowering.h
+++ b/llvm/lib/Target/Hexagon/HexagonISelLowering.h
@@ -223,6 +223,9 @@ namespace HexagonISD {
 
     bool mayBeEmittedAsTailCall(const CallInst *CI) const override;
 
+    unsigned getRegisterByName(const char* RegName, EVT VT,
+                               SelectionDAG &DAG) const override;
+
     /// If a physical register, this returns the register that receives the
     /// exception address on entry to an EH pad.
     unsigned
diff --git a/llvm/test/CodeGen/Hexagon/namedreg.ll b/llvm/test/CodeGen/Hexagon/namedreg.ll
new file mode 100644
index 0000000..72ca508
--- /dev/null
+++ b/llvm/test/CodeGen/Hexagon/namedreg.ll
@@ -0,0 +1,13 @@
+; RUN: llc -mattr=+reserved-r19 -march=hexagon < %s | FileCheck %s
+define dso_local i32 @r19f() #0 {
+entry:
+  %0 = call i32 @llvm.read_register.i32(metadata !0)
+  ret i32 %0
+}
+
+declare i32 @llvm.read_register.i32(metadata) #1
+
+!llvm.named.register.r19 = !{!0}
+
+!0 = !{!"r19"}
+; CHECK: r0 = r19
-- 
2.7.4