From aabb04f52714ceb271dba7da18f757a4365bb4ac Mon Sep 17 00:00:00 2001
From: Dan Gohman <gohman@apple.com>
Date: Wed, 22 Apr 2009 16:11:16 +0000
Subject: [PATCH] SCEVExpander's InsertCastOfTo knows how to move existing cast
 instructions in order to avoid inserting new ones. However, if the cast
 instruction is the SCEVExpander's InsertPt, this causes subsequently emitted
 instructions to be inserted near the cast, and not at the location of the
 original insert point. Fix this by adjusting the insert point in such cases.
 This fixes PR4009.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@69808 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Analysis/ScalarEvolutionExpander.cpp      |  5 ++++
 .../IndVarSimplify/casted-argument.ll         | 24 +++++++++++++++++++
 2 files changed, 29 insertions(+)
 create mode 100644 test/Transforms/IndVarSimplify/casted-argument.ll

diff --git a/lib/Analysis/ScalarEvolutionExpander.cpp b/lib/Analysis/ScalarEvolutionExpander.cpp
index 394ad6c0109..74c11183e81 100644
--- a/lib/Analysis/ScalarEvolutionExpander.cpp
+++ b/lib/Analysis/ScalarEvolutionExpander.cpp
@@ -49,6 +49,9 @@ Value *SCEVExpander::InsertCastOfTo(Instruction::CastOps opcode, Value *V,
             // If the cast isn't the first instruction of the function, move it.
             if (BasicBlock::iterator(CI) != 
                 A->getParent()->getEntryBlock().begin()) {
+              // If the CastInst is the insert point, change the insert point.
+              if (CI == InsertPt) ++InsertPt;
+              // Splice the cast at the beginning of the entry block.
               CI->moveBefore(A->getParent()->getEntryBlock().begin());
             }
             return CI;
@@ -71,6 +74,8 @@ Value *SCEVExpander::InsertCastOfTo(Instruction::CastOps opcode, Value *V,
             It = cast<InvokeInst>(I)->getNormalDest()->begin();
           while (isa<PHINode>(It)) ++It;
           if (It != BasicBlock::iterator(CI)) {
+            // If the CastInst is the insert point, change the insert point.
+            if (CI == InsertPt) ++InsertPt;
             // Splice the cast immediately after the operand in question.
             CI->moveBefore(It);
           }
diff --git a/test/Transforms/IndVarSimplify/casted-argument.ll b/test/Transforms/IndVarSimplify/casted-argument.ll
new file mode 100644
index 00000000000..ae41e3a8b7c
--- /dev/null
+++ b/test/Transforms/IndVarSimplify/casted-argument.ll
@@ -0,0 +1,24 @@
+; RUN: llvm-as < %s | opt -indvars -disable-output
+; PR4009
+
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32"
+target triple = "i386-pc-linux-gnu"
+
+define void @safe_bcopy(i8* %to) nounwind {
+entry:
+	%cmp11 = icmp ult i8* %to, null		; <i1> [#uses=1]
+	br i1 %cmp11, label %loop, label %return
+
+return:		; preds = %entry
+	ret void
+
+loop:		; preds = %loop, %if.else
+	%pn = phi i8* [ %ge, %loop ], [ null, %entry ]		; <i8*> [#uses=1]
+	%cp = ptrtoint i8* %to to i32		; <i32> [#uses=1]
+	%su = sub i32 0, %cp		; <i32> [#uses=1]
+	%ge = getelementptr i8* %pn, i32 %su		; <i8*> [#uses=2]
+	tail call void @bcopy(i8* %ge) nounwind
+	br label %loop
+}
+
+declare void @bcopy(i8* nocapture) nounwind