From e89d1ea35f7bacb4291129f95d0a42280ddac1ee Mon Sep 17 00:00:00 2001
From: Jonas Paulsson <paulsson@linux.vnet.ibm.com>
Date: Tue, 3 Sep 2019 11:21:12 +0000
Subject: [PATCH] [SystemZ]  Add support for fentry.

SystemZAsmPrinter now properly emits function calls to __fentry__.

Review: Ulrich Weigand
llvm-svn: 370743
---
 lib/Target/SystemZ/SystemZAsmPrinter.cpp | 14 ++++++++++++
 lib/Target/SystemZ/SystemZAsmPrinter.h   |  1 +
 test/CodeGen/SystemZ/fentry-insertion.ll | 29 ++++++++++++++++++++++++
 3 files changed, 44 insertions(+)
 create mode 100644 test/CodeGen/SystemZ/fentry-insertion.ll

diff --git a/lib/Target/SystemZ/SystemZAsmPrinter.cpp b/lib/Target/SystemZ/SystemZAsmPrinter.cpp
index ef378e4ade7..f03ed2014e4 100644
--- a/lib/Target/SystemZ/SystemZAsmPrinter.cpp
+++ b/lib/Target/SystemZ/SystemZAsmPrinter.cpp
@@ -501,6 +501,10 @@ void SystemZAsmPrinter::EmitInstruction(const MachineInstr *MI) {
     }
     break;
 
+  case TargetOpcode::FENTRY_CALL:
+    LowerFENTRY_CALL(*MI, Lower);
+    return;
+
   case TargetOpcode::STACKMAP:
     LowerSTACKMAP(*MI);
     return;
@@ -546,6 +550,16 @@ static unsigned EmitNop(MCContext &OutContext, MCStreamer &OutStreamer,
   }
 }
 
+void SystemZAsmPrinter::LowerFENTRY_CALL(const MachineInstr &MI,
+                                         SystemZMCInstLower &Lower) {
+  MCContext &Ctx = MF->getContext();
+  MCSymbol *fentry = Ctx.getOrCreateSymbol("__fentry__");
+  const MCSymbolRefExpr *Op =
+      MCSymbolRefExpr::create(fentry, MCSymbolRefExpr::VK_PLT, Ctx);
+  OutStreamer->EmitInstruction(MCInstBuilder(SystemZ::BRASL)
+                       .addReg(SystemZ::R0D).addExpr(Op), getSubtargetInfo());
+}
+
 void SystemZAsmPrinter::LowerSTACKMAP(const MachineInstr &MI) {
   const SystemZInstrInfo *TII =
     static_cast<const SystemZInstrInfo *>(MF->getSubtarget().getInstrInfo());
diff --git a/lib/Target/SystemZ/SystemZAsmPrinter.h b/lib/Target/SystemZ/SystemZAsmPrinter.h
index aa5d3ca78e6..d01a17c2ebe 100644
--- a/lib/Target/SystemZ/SystemZAsmPrinter.h
+++ b/lib/Target/SystemZ/SystemZAsmPrinter.h
@@ -46,6 +46,7 @@ public:
   }
 
 private:
+  void LowerFENTRY_CALL(const MachineInstr &MI, SystemZMCInstLower &MCIL);
   void LowerSTACKMAP(const MachineInstr &MI);
   void LowerPATCHPOINT(const MachineInstr &MI, SystemZMCInstLower &Lower);
 };
diff --git a/test/CodeGen/SystemZ/fentry-insertion.ll b/test/CodeGen/SystemZ/fentry-insertion.ll
new file mode 100644
index 00000000000..63632d58246
--- /dev/null
+++ b/test/CodeGen/SystemZ/fentry-insertion.ll
@@ -0,0 +1,29 @@
+; RUN: llc %s -mtriple=s390x-linux-gnu -mcpu=z10 -o - -verify-machineinstrs \
+; RUN:   | FileCheck %s
+
+define void @test1() #0 {
+entry:
+  ret void
+
+; CHECK-LABEL: @test1
+; CHECK: brasl %r0, __fentry__
+; CHECK-NOT: mcount
+; CHECK: br %r14
+}
+
+define void @test2() #1 {
+entry:
+  br label %bb1
+bb1:
+  call void @address_taken(i64 ptrtoint (i8* blockaddress(@test2, %bb1) to i64), i32 512)
+  ret void
+
+; CHECK-LABEL: @test2
+; CHECK: brasl %r0, __fentry__
+; CHECK-NOT: mcount
+; CHECK: br %r14
+}
+
+declare void @address_taken(i64, i32) local_unnamed_addr
+attributes #0 = { "fentry-call"="true" }
+attributes #1 = { inlinehint minsize noredzone nounwind optsize sspstrong "fentry-call"="true" }