[TRE] Add another test for OptRemark.

This shows we emit a remark for tail recursion -> loop.

llvm-svn: 308525

Author: dcci

llvm/test/Transforms/TailCallElim/opt-remarks-recursion.ll

@@ -0,0 +1,39 @@
+; RUN: opt %s -tailcallelim -pass-remarks=tailcallelim -o /dev/null 2>&1 | FileCheck %s
+; RUN: opt %s -o /dev/null -passes='require<opt-remark-emit>,tailcallelim' -pass-remarks=tailcallelim 2>&1 | FileCheck %s
+
+; CHECK: /home/davide/pat.c:2:20: marked as tail call candidate
+; CHECK: /home/davide/pat.c:2:20: transforming tail recursion into loop
+define i32 @fib(i32 %n) nounwind ssp {
+entry:
+  %cmp = icmp slt i32 %n, 2
+  br i1 %cmp, label %if.then, label %if.end
+
+if.then:                                          ; preds = %entry
+  br label %return
+
+if.end:                                           ; preds = %entry
+  %sub = add nsw i32 %n, -2
+  %call = call i32 @fib(i32 %sub)
+  %sub3 = add nsw i32 %n, -1
+  %call4 = call i32 @fib(i32 %sub3), !dbg !8
+  %add = add nsw i32 %call, %call4
+  br label %return
+
+return:                                           ; preds = %if.end, %if.then
+  %retval.0 = phi i32 [ 1, %if.then ], [ %add, %if.end ]
+  ret i32 %retval.0
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4}
+!llvm.ident = !{!5}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 3.9.0 ", isOptimized: true, runtimeVersion: 0, emissionKind: NoDebug, enums: !2)
+!1 = !DIFile(filename: "/home/davide/pat.c", directory: "/tmp")
+!2 = !{}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!4 = !{i32 1, !"PIC Level", i32 2}
+!5 = !{!"clang version 3.9.0 "}
+!6 = distinct !DISubprogram(name: "success", scope: !1, file: !1, line: 1, type: !7, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: true, unit: !0, variables: !2)
+!7 = !DISubroutineType(types: !2)
+!8 = !DILocation(line: 2, column: 20, scope: !6)