From 7abdb22e52e2122cb04479a1129dc68916dece4c Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Tue, 14 Sep 2010 00:19:00 +0000
Subject: [PATCH] fix PR8102, a case where we'd copyValue from a value that we
 already deleted.  Fix this by doing the copyValue's before we delete stuff!

The testcase only repros the problem on my system with valgrind.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@113820 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/LICM.cpp | 22 +++++++++++-----------
 test/Transforms/LICM/crash.ll  | 20 ++++++++++++++++++++
 2 files changed, 31 insertions(+), 11 deletions(-)

diff --git a/lib/Transforms/Scalar/LICM.cpp b/lib/Transforms/Scalar/LICM.cpp
index 0db7ba771b4..af9a7eefb6a 100644
--- a/lib/Transforms/Scalar/LICM.cpp
+++ b/lib/Transforms/Scalar/LICM.cpp
@@ -837,6 +837,17 @@ void LICM::PromoteAliasSet(AliasSet &AS) {
     ReplacedLoads[ALoad] = NewVal;
   }
   
+  // If the preheader load is itself a pointer, we need to tell alias analysis
+  // about the new pointer we created in the preheader block and about any PHI
+  // nodes that just got inserted.
+  if (PreheaderLoad->getType()->isPointerTy()) {
+    // Copy any value stored to or loaded from a must-alias of the pointer.
+    CurAST->copyValue(SomeValue, PreheaderLoad);
+    
+    for (unsigned i = 0, e = NewPHIs.size(); i != e; ++i)
+      CurAST->copyValue(SomeValue, NewPHIs[i]);
+  }
+  
   // Now that everything is rewritten, delete the old instructions from the body
   // of the loop.  They should all be dead now.
   for (unsigned i = 0, e = LoopUses.size(); i != e; ++i) {
@@ -867,17 +878,6 @@ void LICM::PromoteAliasSet(AliasSet &AS) {
     User->eraseFromParent();
   }
   
-  // If the preheader load is itself a pointer, we need to tell alias analysis
-  // about the new pointer we created in the preheader block and about any PHI
-  // nodes that just got inserted.
-  if (PreheaderLoad->getType()->isPointerTy()) {
-    // Copy any value stored to or loaded from a must-alias of the pointer.
-    CurAST->copyValue(SomeValue, PreheaderLoad);
-
-    for (unsigned i = 0, e = NewPHIs.size(); i != e; ++i)
-      CurAST->copyValue(SomeValue, NewPHIs[i]);
-  }
-  
   // fwew, we're done!
 }
 
diff --git a/test/Transforms/LICM/crash.ll b/test/Transforms/LICM/crash.ll
index d0b6d78db1a..88be5c41ccc 100644
--- a/test/Transforms/LICM/crash.ll
+++ b/test/Transforms/LICM/crash.ll
@@ -39,3 +39,23 @@ for.body:                                         ; preds = %for.body, %entry
   store i32 undef, i32* @g_8, align 4
   br label %for.body
 }
+
+; PR8102
+define void @test3() {
+entry:
+  %__first = alloca { i32* }
+  br i1 undef, label %for.cond, label %for.end
+
+for.cond:                                         ; preds = %for.cond, %entry
+  %tmp1 = getelementptr { i32*}* %__first, i32 0, i32 0
+  %tmp2 = load i32** %tmp1, align 4
+  %call = tail call i32* @test3helper(i32* %tmp2)
+  %tmp3 = getelementptr { i32*}* %__first, i32 0, i32 0
+  store i32* %call, i32** %tmp3, align 4
+  br i1 false, label %for.cond, label %for.end
+
+for.end:                                          ; preds = %for.cond, %entry
+  ret void
+}
+
+declare i32* @test3helper(i32*)
-- 
2.34.1