From d217cfcf468712780cb3b06a36e0ce53897592c1 Mon Sep 17 00:00:00 2001
From: Dan Gohman <gohman@apple.com>
Date: Wed, 21 Apr 2010 00:43:30 +0000
Subject: [PATCH] Revert r101471. For tight recursive functions which have
 multiple recursive callsites, inlining can reduce the number of calls by
 exponential factors, as it does in MultiSource/Benchmarks/Olden/treeadd. More
 involved heuristics will be needed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@101969 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Analysis/InlineCost.cpp              |  7 ------
 test/Transforms/Inline/tail-recursion.ll | 29 ------------------------
 2 files changed, 36 deletions(-)
 delete mode 100644 test/Transforms/Inline/tail-recursion.ll

diff --git a/lib/Analysis/InlineCost.cpp b/lib/Analysis/InlineCost.cpp
index 50400d3085d..cb9e5526fc4 100644
--- a/lib/Analysis/InlineCost.cpp
+++ b/lib/Analysis/InlineCost.cpp
@@ -263,13 +263,6 @@ InlineCost InlineCostAnalyzer::getInlineCost(CallSite CS,
       CS.isNoInline())
     return llvm::InlineCost::getNever();
 
-  // Don't inline directly recursive calls, for now. Inlining a directly
-  // recursive call is effectively unrolling a loop, so it calls for different
-  // heuristics, which aren't implemented yet. Until then, err on the
-  // conservative side.
-  if (Callee == Caller)
-    return llvm::InlineCost::getNever();
-
   // InlineCost - This value measures how good of an inline candidate this call
   // site is to inline.  A lower inline cost make is more likely for the call to
   // be inlined.  This value may go negative.
diff --git a/test/Transforms/Inline/tail-recursion.ll b/test/Transforms/Inline/tail-recursion.ll
deleted file mode 100644
index 146bed4cd07..00000000000
--- a/test/Transforms/Inline/tail-recursion.ll
+++ /dev/null
@@ -1,29 +0,0 @@
-; RUN: opt -inline -tailcallelim -indvars -loop-deletion -S < %s | FileCheck %s
-
-; Inline shouldn't inline foo into itself because it's a tailcallelim
-; candidate. Tailcallelim should convert the call into a loop. Indvars
-; should calculate the exit value, making the loop dead. Loop deletion
-; should delete the loop.
-; PR6842
-
-;      CHECK: define i32 @bar() nounwind {
-; CHECK-NEXT:     ret i32 10000
-; CHECK-NEXT: }
-
-define internal i32 @foo(i32 %x) nounwind {
-  %i = add i32 %x, 1                              ; <i32> [#uses=3]
-  %a = icmp slt i32 %i, 10000                     ; <i1> [#uses=1]
-  br i1 %a, label %more, label %done
-
-done:                                             ; preds = %0
-  ret i32 %i
-
-more:                                             ; preds = %0
-  %z = tail call i32 @foo(i32 %i)                  ; <i32> [#uses=1]
-  ret i32 %z
-}
-
-define i32 @bar() nounwind {
-  %z = call i32 @foo(i32 0)                        ; <i32> [#uses=1]
-  ret i32 %z
-}