[SystemZ] Support llvm.frameaddress/llvm.returnaddress intrinsics

Enable the SystemZ back-end to lower FRAMEADDR and RETURNADDR, which
previously would cause the back-end to crash.  Currently, only a
frame count of zero is supported.

Author: bryanpkc
Differential Revision: http://reviews.llvm.org/D18514

llvm-svn: 265291

2 files changed, 43 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/SystemZ/frameaddr-01.ll b/llvm/test/CodeGen/SystemZ/frameaddr-01.ll
new file mode 100644
index 00000000000..4dfdf308e8a
--- /dev/null
+++ b/llvm/test/CodeGen/SystemZ/frameaddr-01.ll
@@ -0,0 +1,28 @@
+; RUN: llc < %s -mtriple=s390x-linux-gnu | FileCheck %s
+
+; The current function's frame address is the address of
+; the optional back chain slot.
+define i8* @fp0() nounwind {
+entry:
+; CHECK-LABEL: fp0:
+; CHECK: la   %r2, 0(%r15)
+; CHECK: br   %r14
+  %0 = tail call i8* @llvm.frameaddress(i32 0)
+  ret i8* %0
+}
+
+; Check that the frame address is correct in a presence
+; of a stack frame.
+define i8* @fp0f() nounwind {
+entry:
+; CHECK-LABEL: fp0f:
+; CHECK: aghi %r15, -168
+; CHECK: la   %r2, 168(%r15)
+; CHECK: aghi %r15, 168
+; CHECK: br   %r14
+  %0 = alloca i64, align 8
+  %1 = tail call i8* @llvm.frameaddress(i32 0)
+  ret i8* %1
+}
+
+declare i8* @llvm.frameaddress(i32) nounwind readnone
diff --git a/llvm/test/CodeGen/SystemZ/ret-addr-01.ll b/llvm/test/CodeGen/SystemZ/ret-addr-01.ll
new file mode 100644
index 00000000000..9c3b246af57
--- /dev/null
+++ b/llvm/test/CodeGen/SystemZ/ret-addr-01.ll
@@ -0,0 +1,15 @@
+; Test support for the llvm.returnaddress intrinsic.
+; 
+; RUN: llc < %s -mtriple=s390x-linux-gnu | FileCheck %s
+
+; The current function's return address is in the link register.
+define i8* @rt0() norecurse nounwind readnone {
+entry:
+; CHECK-LABEL: rt0:
+; CHECK: lgr  %r2, %r14
+; CHECK: br   %r14
+  %0 = tail call i8* @llvm.returnaddress(i32 0)
+  ret i8* %0
+}
+
+declare i8* @llvm.returnaddress(i32) nounwind readnone