From f81836bd18be6fb8bc6fe9942053f418dbb13d98 Mon Sep 17 00:00:00 2001
From: Paul Robinson <paul_robinson@playstation.sony.com>
Date: Thu, 24 Mar 2016 00:10:03 +0000
Subject: [PATCH] [PS4] Guarantee an instruction after a 'noreturn' call.

We need the "return address" of a noreturn call to be within the
bounds of the calling function; TrapUnreachable turns 'unreachable'
into a 'ud2' instruction, which has that desired effect.

Differential Revision: http://reviews.llvm.org/D18414

llvm-svn: 264224
---
 llvm/lib/Target/X86/X86TargetMachine.cpp |  4 +++-
 llvm/test/CodeGen/X86/br-fold.ll         |  4 ++++
 llvm/test/CodeGen/X86/ps4-noreturn.ll    | 38 ++++++++++++++++++++++++++++++++
 3 files changed, 45 insertions(+), 1 deletion(-)
 create mode 100644 llvm/test/CodeGen/X86/ps4-noreturn.ll

diff --git a/llvm/lib/Target/X86/X86TargetMachine.cpp b/llvm/lib/Target/X86/X86TargetMachine.cpp
index 806ba12..382de99 100644
--- a/llvm/lib/Target/X86/X86TargetMachine.cpp
+++ b/llvm/lib/Target/X86/X86TargetMachine.cpp
@@ -119,7 +119,9 @@ X86TargetMachine::X86TargetMachine(const Target &T, const Triple &TT,
   // after a call to 'noreturn' function.
   // To prevent that, we emit a trap for 'unreachable' IR instructions.
   // (which on X86, happens to be the 'ud2' instruction)
-  if (Subtarget.isTargetWin64())
+  // On PS4, the "return address" of a 'noreturn' call must still be within
+  // the calling function, and TrapUnreachable is an easy way to get that.
+  if (Subtarget.isTargetWin64() || Subtarget.isTargetPS4())
     this->Options.TrapUnreachable = true;
 
   // By default (and when -ffast-math is on), enable estimate codegen for
diff --git a/llvm/test/CodeGen/X86/br-fold.ll b/llvm/test/CodeGen/X86/br-fold.ll
index fd1e73b..5e5f860 100644
--- a/llvm/test/CodeGen/X86/br-fold.ll
+++ b/llvm/test/CodeGen/X86/br-fold.ll
@@ -2,6 +2,7 @@
 ; RUN: llc -mtriple=x86_64-pc-linux < %s | FileCheck  -check-prefix=X64_LINUX %s
 ; RUN: llc -mtriple=x86_64-pc-windows < %s | FileCheck  -check-prefix=X64_WINDOWS %s
 ; RUN: llc -mtriple=x86_64-pc-windows-gnu < %s | FileCheck  -check-prefix=X64_WINDOWS_GNU %s
+; RUN: llc -mtriple=x86_64-scei-ps4 < %s | FileCheck -check-prefix=PS4 %s
 
 ; X64_DARWIN: orq
 ; X64_DARWIN-NEXT: %bb8.i329
@@ -15,6 +16,9 @@
 ; X64_WINDOWS_GNU: orq %rax, %rcx
 ; X64_WINDOWS_GNU-NEXT: ud2
 
+; PS4: orq %rax, %rcx
+; PS4-NEXT: ud2
+
 @_ZN11xercesc_2_513SchemaSymbols21fgURI_SCHEMAFORSCHEMAE = external constant [33 x i16], align 32 ; <[33 x i16]*> [#uses=1]
 @_ZN11xercesc_2_56XMLUni16fgNotationStringE = external constant [9 x i16], align 16 ; <[9 x i16]*> [#uses=1]
 
diff --git a/llvm/test/CodeGen/X86/ps4-noreturn.ll b/llvm/test/CodeGen/X86/ps4-noreturn.ll
new file mode 100644
index 0000000..4c14f21
--- /dev/null
+++ b/llvm/test/CodeGen/X86/ps4-noreturn.ll
@@ -0,0 +1,38 @@
+; RUN: llc < %s -mtriple=x86_64-scei-ps4 | FileCheck %s
+
+declare i32 @personality(...)
+
+; Check that after the (implicitly noreturn) unwind call, there is
+; another instruction. It was easy to produce 'ud2' so we check for that.
+define void @foo1() personality i32 (...)* @personality {
+; CHECK-LABEL: foo1:
+; CHECK: .cfi_startproc
+; CHECK: callq bar
+; CHECK: retq
+; Check for 'ud2' between noreturn call and function end.
+; CHECK: callq _Unwind_Resume
+; CHECK-NEXT: ud2
+; CHECK-NEXT: .Lfunc_end0:
+    invoke void @bar()
+        to label %normal
+        unwind label %catch
+normal:
+    ret void
+catch:
+    %1 = landingpad { i8*, i32 } cleanup
+    resume { i8*, i32 } %1
+}
+
+declare void @bar() #0
+
+; Similar check after an explicit noreturn call.
+define void @foo2() {
+; CHECK-LABEL: foo2:
+; CHECK: callq bar
+; CHECK-NEXT: ud2
+; CHECK-NEXT: .Lfunc_end1:
+    tail call void @bar()
+    unreachable
+}
+
+attributes #0 = { noreturn }
-- 
2.7.4