From bdc76fc75ab915214a35649d99fcac0341585ef5 Mon Sep 17 00:00:00 2001
From: Richard Osborne <richard@xmos.com>
Date: Mon, 24 Sep 2012 17:10:03 +0000
Subject: [PATCH] Add missing check for presence of target data.

This avoids a crash in visitAllocaInst when target data isn't available.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@164539 91177308-0d34-0410-b5e6-96231b3b80d8
---
 .../InstCombineLoadStoreAlloca.cpp            | 42 ++++++++++---------
 .../2012-09-24-MemcpyFromGlobalCrash.ll       | 19 +++++++++
 2 files changed, 41 insertions(+), 20 deletions(-)
 create mode 100644 test/Transforms/InstCombine/2012-09-24-MemcpyFromGlobalCrash.ll

diff --git a/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
index 5b6cf4a4a83..a446e427e5b 100644
--- a/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+++ b/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
@@ -264,26 +264,28 @@ Instruction *InstCombiner::visitAllocaInst(AllocaInst &AI) {
     }
   }
 
-  // Check to see if this allocation is only modified by a memcpy/memmove from
-  // a constant global whose alignment is equal to or exceeds that of the
-  // allocation.  If this is the case, we can change all users to use
-  // the constant global instead.  This is commonly produced by the CFE by
-  // constructs like "void foo() { int A[] = {1,2,3,4,5,6,7,8,9...}; }" if 'A'
-  // is only subsequently read.
-  SmallVector<Instruction *, 4> ToDelete;
-  if (MemTransferInst *Copy = isOnlyCopiedFromConstantGlobal(&AI, ToDelete)) {
-    if (AI.getAlignment() <= getPointeeAlignment(Copy->getSource(), *TD)) {
-      DEBUG(dbgs() << "Found alloca equal to global: " << AI << '\n');
-      DEBUG(dbgs() << "  memcpy = " << *Copy << '\n');
-      for (unsigned i = 0, e = ToDelete.size(); i != e; ++i)
-        EraseInstFromFunction(*ToDelete[i]);
-      Constant *TheSrc = cast<Constant>(Copy->getSource());
-      Instruction *NewI
-        = ReplaceInstUsesWith(AI, ConstantExpr::getBitCast(TheSrc,
-                                                           AI.getType()));
-      EraseInstFromFunction(*Copy);
-      ++NumGlobalCopies;
-      return NewI;
+  if (TD) {
+    // Check to see if this allocation is only modified by a memcpy/memmove from
+    // a constant global whose alignment is equal to or exceeds that of the
+    // allocation.  If this is the case, we can change all users to use
+    // the constant global instead.  This is commonly produced by the CFE by
+    // constructs like "void foo() { int A[] = {1,2,3,4,5,6,7,8,9...}; }" if 'A'
+    // is only subsequently read.
+    SmallVector<Instruction *, 4> ToDelete;
+    if (MemTransferInst *Copy = isOnlyCopiedFromConstantGlobal(&AI, ToDelete)) {
+      if (AI.getAlignment() <= getPointeeAlignment(Copy->getSource(), *TD)) {
+        DEBUG(dbgs() << "Found alloca equal to global: " << AI << '\n');
+        DEBUG(dbgs() << "  memcpy = " << *Copy << '\n');
+        for (unsigned i = 0, e = ToDelete.size(); i != e; ++i)
+          EraseInstFromFunction(*ToDelete[i]);
+        Constant *TheSrc = cast<Constant>(Copy->getSource());
+        Instruction *NewI
+          = ReplaceInstUsesWith(AI, ConstantExpr::getBitCast(TheSrc,
+                                                             AI.getType()));
+        EraseInstFromFunction(*Copy);
+        ++NumGlobalCopies;
+        return NewI;
+      }
     }
   }
 
diff --git a/test/Transforms/InstCombine/2012-09-24-MemcpyFromGlobalCrash.ll b/test/Transforms/InstCombine/2012-09-24-MemcpyFromGlobalCrash.ll
new file mode 100644
index 00000000000..a31aa822e6a
--- /dev/null
+++ b/test/Transforms/InstCombine/2012-09-24-MemcpyFromGlobalCrash.ll
@@ -0,0 +1,19 @@
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+; Check we don't crash due to lack of target data.
+
+@G = constant [100 x i8] zeroinitializer
+
+declare void @bar(i8*)
+declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture, i64, i32, i1) nounwind
+
+define void @test() {
+; CHECK: @test
+; CHECK: llvm.memcpy
+; CHECK ret void
+  %A = alloca [100 x i8]
+  %a = getelementptr inbounds [100 x i8]* %A, i64 0, i64 0
+  call void @llvm.memcpy.p0i8.p0i8.i64(i8* %a, i8* getelementptr inbounds ([100 x i8]* @G, i64 0, i32 0), i64 100, i32 4, i1 false)
+  call void @bar(i8* %a) readonly
+  ret void
+}