[llvm-commits] [llvm] r153705 - /llvm/trunk/lib/CodeGen/SelectionDAG/FastISel.cpp

[Bill Wendling]

Author: void
Date: Thu Mar 29 19:02:55 2012
New Revision: 153705

URL: http://llvm.org/viewvc/llvm-project?rev=153705&view=rev
Log:
If we have a VLA that has a "use" in a metadata node that's then used
here but it has no other uses, then we have a problem. E.g.,

  int foo (const int *x) {
    char a[*x];
    return 0;
  }

If we assign 'a' a vreg and fast isel later on has to use the selection
DAG isel, it will want to copy the value to the vreg. However, there are
no uses, which goes counter to what selection DAG isel expects.
<rdar://problem/11134152>

Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/FastISel.cpp

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/FastISel.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/FastISel.cpp?rev=153705&r1=153704&r2=153705&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/FastISel.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/FastISel.cpp Thu Mar 29 19:02:55 2012
@@ -599,7 +599,18 @@
     if (!Reg)
       Reg = lookUpRegForValue(Address);
 
-    if (!Reg && isa<Instruction>(Address) &&
+    // If we have a VLA that has a "use" in a metadata node that's then used
+    // here but it has no other uses, then we have a problem. E.g.,
+    //
+    //   int foo (const int *x) {
+    //     char a[*x];
+    //     return 0;
+    //   }
+    //
+    // If we assign 'a' a vreg and fast isel later on has to use the selection
+    // DAG isel, it will want to copy the value to the vreg. However, there are
+    // no uses, which goes counter to what selection DAG isel expects.
+    if (!Reg && !Address->use_empty() && isa<Instruction>(Address) &&
         (!isa<AllocaInst>(Address) ||
          !FuncInfo.StaticAllocaMap.count(cast<AllocaInst>(Address))))
       Reg = FuncInfo.InitializeRegForValue(Address);