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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>

llvm-svn: 153705
This commit is contained in:
Bill Wendling 2012-03-30 00:02:55 +00:00
parent 323a5ced21
commit 9f829f1cc4
1 changed files with 12 additions and 1 deletions
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13
llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
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@ -599,7 +599,18 @@ bool FastISel::SelectCall(const User *I) {
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);