From: Bill Wendling <isanbard@gmail.com>
Date: Mon, 4 Aug 2014 04:28:45 +0000 (+0000)
Subject: Merging r213726:
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=92a10767eba0b31e156265d3e149f464379f75aa;p=llvm

Merging r213726:
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r213726 | nicholas | 2014-07-22 23:24:49 -0700 (Tue, 22 Jul 2014) | 2 lines

We may visit a call that uses an alloca multiple times in callUsesLocalStack, sometimes with IsNocapture true and sometimes with IsNocapture false. We accidentally skipped work we needed to do in the IsNocapture=false case if we were called with IsNocapture=true the first time. Fixes PR20405!

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_35@214688 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/Scalar/TailRecursionElimination.cpp b/lib/Transforms/Scalar/TailRecursionElimination.cpp
index 05b9892470b..b7580255150 100644
--- a/lib/Transforms/Scalar/TailRecursionElimination.cpp
+++ b/lib/Transforms/Scalar/TailRecursionElimination.cpp
@@ -227,12 +227,10 @@ struct AllocaDerivedValueTracker {
   }
 
   void callUsesLocalStack(CallSite CS, bool IsNocapture) {
-    // Add it to the list of alloca users. If it's already there, skip further
-    // processing.
-    if (!AllocaUsers.insert(CS.getInstruction()))
-      return;
+    // Add it to the list of alloca users.
+    AllocaUsers.insert(CS.getInstruction());
 
-    // If it's nocapture then it can't capture the alloca.
+    // If it's nocapture then it can't capture this alloca.
     if (IsNocapture)
       return;
 
diff --git a/test/Transforms/TailCallElim/basic.ll b/test/Transforms/TailCallElim/basic.ll
index 341736d48ef..8e9814b52bb 100644
--- a/test/Transforms/TailCallElim/basic.ll
+++ b/test/Transforms/TailCallElim/basic.ll
@@ -174,3 +174,17 @@ if.end:
 return:
   ret void
 }
+
+declare void @test11_helper1(i8** nocapture, i8*)
+declare void @test11_helper2(i8*)
+define void @test11() {
+; CHECK-LABEL: @test11
+; CHECK-NOT: tail
+  %a = alloca i8*
+  %b = alloca i8
+  call void @test11_helper1(i8** %a, i8* %b)  ; a = &b
+  %c = load i8** %a
+  call void @test11_helper2(i8* %c)
+; CHECK: call void @test11_helper2
+  ret void
+}