Revert "Revert "[FunctionAttrs] Identify norecurse functions""

This reapplies this patch, with test fixes.

llvm-svn: 252871

1 files changed, 57 insertions, 0 deletions

diff --git a/llvm/test/Transforms/FunctionAttrs/norecurse.ll b/llvm/test/Transforms/FunctionAttrs/norecurse.ll
new file mode 100644
index 00000000000..47481191d27
--- /dev/null
+++ b/llvm/test/Transforms/FunctionAttrs/norecurse.ll
@@ -0,0 +1,57 @@
+; RUN: opt < %s -basicaa -functionattrs -S | FileCheck %s
+
+; CHECK: define i32 @leaf() #0
+define i32 @leaf() {
+  ret i32 1
+}
+
+; CHECK: define i32 @self_rec() #1
+define i32 @self_rec() {
+  %a = call i32 @self_rec()
+  ret i32 4
+}
+
+; CHECK: define i32 @indirect_rec() #1
+define i32 @indirect_rec() {
+  %a = call i32 @indirect_rec2()
+  ret i32 %a
+}
+; CHECK: define i32 @indirect_rec2() #1
+define i32 @indirect_rec2() {
+  %a = call i32 @indirect_rec()
+  ret i32 %a
+}
+
+; CHECK: define i32 @extern() #1
+define i32 @extern() {
+  %a = call i32 @k()
+  ret i32 %a
+}
+declare i32 @k() readnone
+
+; CHECK: define internal i32 @called_by_norecurse() #0
+define internal i32 @called_by_norecurse() {
+  %a = call i32 @k()
+  ret i32 %a
+}
+define void @m() norecurse {
+  %a = call i32 @called_by_norecurse()
+  ret void
+}
+
+; CHECK: define internal i32 @called_by_norecurse_indirectly() #0
+define internal i32 @called_by_norecurse_indirectly() {
+  %a = call i32 @k()
+  ret i32 %a
+}
+define internal void @o() {
+  %a = call i32 @called_by_norecurse_indirectly()
+  ret void
+}
+define void @p() norecurse {
+  call void @o()
+  ret void
+}
+
+; CHECK: attributes #0 = { norecurse readnone }
+; CHECK: attributes #1 = { readnone }