Commit c4476884 authored by Tom Stellard's avatar Tom Stellard
Browse files

Merging r332302: 

------------------------------------------------------------------------
r332302 | kfischer | 2018-05-14 15:05:01 -0700 (Mon, 14 May 2018) | 15 lines

[InstCombine] fix crash due to ignored addrspacecast

Summary:
Part of the InstCombine code for simplifying GEPs looks through
addrspacecasts. However, this was done by updating a variable
also used by the next transformation, for marking GEPs as
inbounds. This led to replacing a GEP with a similar instruction
in a different addrspace, which caused an assertion failure in RAUW.

This caused julia issue https://github.com/JuliaLang/julia/issues/27055

Patch by Jeff Bezanson <jeff@juliacomputing.com>

Reviewed By: arsenm
Differential Revision: https://reviews.llvm.org/D46722
------------------------------------------------------------------------

llvm-svn: 333477
parent 75f4129b

llvm/lib/Transforms/InstCombine/InstructionCombining.cpp

+3 −2
Original line number Diff line number Diff line
@@ -1947,13 +1947,14 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) { 
  // addrspacecast between types is canonicalized as a bitcast, then an

  // addrspacecast. To take advantage of the below bitcast + struct GEP, look

  // through the addrspacecast.

  Value *ASCStrippedPtrOp = PtrOp;

  if (AddrSpaceCastInst *ASC = dyn_cast<AddrSpaceCastInst>(PtrOp)) {

    //   X = bitcast A addrspace(1)* to B addrspace(1)*

    //   Y = addrspacecast A addrspace(1)* to B addrspace(2)*

    //   Z = gep Y, <...constant indices...>

    // Into an addrspacecasted GEP of the struct.

    if (BitCastInst *BC = dyn_cast<BitCastInst>(ASC->getOperand(0)))

      PtrOp = BC;

      ASCStrippedPtrOp = BC;

  }



  /// See if we can simplify:
@@ -1961,7 +1962,7 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) { 
  ///   Y = gep X, <...constant indices...>

  /// into a gep of the original struct.  This is important for SROA and alias

  /// analysis of unions.  If "A" is also a bitcast, wait for A/X to be merged.

  if (BitCastInst *BCI = dyn_cast<BitCastInst>(PtrOp)) {

  if (BitCastInst *BCI = dyn_cast<BitCastInst>(ASCStrippedPtrOp)) {

    Value *Operand = BCI->getOperand(0);

    PointerType *OpType = cast<PointerType>(Operand->getType());

    unsigned OffsetBits = DL.getPointerTypeSizeInBits(GEP.getType());

llvm/test/Transforms/InstCombine/gep-addrspace.ll

+19 −0
Original line number Diff line number Diff line
@@ -32,3 +32,22 @@ entry: 
  ret void

}



declare void @escape_alloca(i16*)



; check that addrspacecast is not ignored (leading to an assertion failure)

; when trying to mark a GEP as inbounds

define { i8, i8 } @inbounds_after_addrspacecast() {

top:

; CHECK-LABEL: @inbounds_after_addrspacecast

  %0 = alloca i16, align 2

  call void @escape_alloca(i16* %0)

  %tmpcast = bitcast i16* %0 to [2 x i8]*

; CHECK: addrspacecast [2 x i8]* %tmpcast to [2 x i8] addrspace(11)*

  %1 = addrspacecast [2 x i8]* %tmpcast to [2 x i8] addrspace(11)*

; CHECK: getelementptr [2 x i8], [2 x i8] addrspace(11)* %1, i64 0, i64 1

  %2 = getelementptr [2 x i8], [2 x i8] addrspace(11)* %1, i64 0, i64 1

; CHECK: addrspace(11)

  %3 = load i8, i8 addrspace(11)* %2, align 1

  %.fca.1.insert = insertvalue { i8, i8 } zeroinitializer, i8 %3, 1

  ret { i8, i8 } %.fca.1.insert

}