[GVN] Fix a crash on encountering non-integral pointers

[loladiro]

Summary

This fixes the immediate crash caused by introducing an incorrect inttoptr
before attempting the conversion. There may still be a legality
check missing somewhere earlier for non-integral pointers, but this change
seems necessary in any case.

[sanjoy]

The behavioral change looks fine to me, but I'll have to defer to @dberlin on whether this is the right place to do make the change.

[• dberlin]

This looks generally fine. I expect you are going to have some other issues (load widening, etc) to solve around these areas.

llvm/trunk/lib/Transforms/Utils/VNCoercion.cpp

 }
 
 template <class T, class HelperClass>
 static T *getStoreValueForLoadHelper(T *SrcVal, unsigned Offset, Type *LoadTy,
                                      HelperClass &Helper,
                                      const DataLayout &DL) {
   LLVMContext &Ctx = SrcVal->getType()->getContext();
 
+  // If two pointers are in the same address space, they have the same size,
+  // so we don't need to do any truncation, etc. This avoids introducing
+  // ptrtoint instructions for pointers that may be non-integral.
+  if (SrcVal->getType()->isPointerTy() && LoadTy->isPointerTy() &&
+      cast<PointerType>(SrcVal->getType())->getAddressSpace() ==
+          cast<PointerType>(LoadTy)->getAddressSpace()) {
+    return SrcVal;
+  }
+
   uint64_t StoreSize = (DL.getTypeSizeInBits(SrcVal->getType()) + 7) / 8;
   uint64_t LoadSize = (DL.getTypeSizeInBits(LoadTy) + 7) / 8;
   // Compute which bits of the stored value are being used by the load.  Convert
   // to an integer type to start with.
   if (SrcVal->getType()->getScalarType()->isPointerTy())
     SrcVal = Helper.CreatePtrToInt(SrcVal, DL.getIntPtrType(SrcVal->getType()));
   if (!SrcVal->getType()->isIntegerTy())
     SrcVal = Helper.CreateBitCast(SrcVal, IntegerType::get(Ctx, StoreSize * 8));

llvm/trunk/test/Transforms/GVN/PRE/nonintegral.ll

+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -gvn -S < %s | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128-ni:4"
+target triple = "x86_64-unknown-linux-gnu"
+
+define void @nipre(double addrspace(4)** noalias %p, i64 addrspace(4)** noalias %p2, i8 %jmp) {
+
+; CHECK-LABEL: @nipre(
+; CHECK:    [[PCAST:%.*]] = bitcast double addrspace(4)** [[P:%.*]] to i64 addrspace(4)**
+; CHECK:       a:
+; CHECK:    [[L1:%.*]] = load i64 addrspace(4)*, i64 addrspace(4)** [[PCAST]]
+; CHECK:    [[TMP0:%.*]] = bitcast i64 addrspace(4)* [[L1]] to double addrspace(4)*
+; CHECK:       b:
+; CHECK:    [[L2:%.*]] = load i64 addrspace(4)*, i64 addrspace(4)** [[PCAST]]
+; CHECK:    [[TMP1:%.*]] = bitcast i64 addrspace(4)* [[L2]] to double addrspace(4)*
+; CHECK:       c:
+; CHECK-NEXT:    [[L3_PRE:%.*]] = load double addrspace(4)*, double addrspace(4)** %p
+
+entry:
+  %pcast = bitcast double addrspace(4)** %p to i64 addrspace(4)**
+  switch i8 %jmp, label %c [ i8 0, label %a
+  i8 1, label %b]
+a:
+  %l1 = load i64 addrspace(4)*, i64 addrspace(4)** %pcast
+  store i64 addrspace(4)* %l1, i64 addrspace(4)** %p2
+  br label %tail
+b:
+  %l2 = load i64 addrspace(4)*, i64 addrspace(4)** %pcast
+  store i64 addrspace(4)* %l2, i64 addrspace(4)** %p2
+  br label %tail
+c:
+  br label %tail
+tail:
+  %l3 = load double addrspace(4)*, double addrspace(4)** %p
+  %l3cast = bitcast double addrspace(4)* %l3 to i64 addrspace(4)*
+  store i64 addrspace(4)* %l3cast, i64 addrspace(4)** %p2
+  ret void
+}