Revert "Don't look through addrspacecast in GetPointerBaseWithConstantOffset"

This reverts commit 4478320.

Reason: Breaks Analysis/ValueTracking/get-pointer-base-with-const-off.ll

Author: kzhuravl

lib/Analysis/ValueTracking.cpp

@@ -2854,14 +2854,9 @@ Value *llvm::GetPointerBaseWithConstantOffset(Value *Ptr, int64_t &Offset,
       ByteOffset += GEPOffset.getSExtValue();
 
       Ptr = GEP->getPointerOperand();
-    } else if (Operator::getOpcode(Ptr) == Instruction::BitCast) {
+    } else if (Operator::getOpcode(Ptr) == Instruction::BitCast ||
+               Operator::getOpcode(Ptr) == Instruction::AddrSpaceCast) {
       Ptr = cast<Operator>(Ptr)->getOperand(0);
-    } else if (AddrSpaceCastInst *ASCI = dyn_cast<AddrSpaceCastInst>(Ptr)) {
-      Value *SourcePtr = ASCI->getPointerOperand();
-      // Don't look through addrspace cast which changes pointer size
-      if (BitWidth != DL.getPointerTypeSizeInBits(SourcePtr->getType()))
-        break;
-      Ptr = SourcePtr;
     } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(Ptr)) {
       if (GA->isInterposable())
         break;

test/Transforms/GVN/PRE/rle-addrspace-cast.ll

@@ -318,6 +318,19 @@ define i8 @coerce_offset0(i32 %V, i32* %P) {
 ; CHECK: ret i8
 }
 
+define i8 @coerce_offset0_addrspacecast(i32 %V, i32* %P) {
+  store i32 %V, i32* %P
+
+  %P2 = addrspacecast i32* %P to i8 addrspace(1)*
+  %P3 = getelementptr i8, i8 addrspace(1)* %P2, i32 2
+
+  %A = load i8, i8 addrspace(1)* %P3
+  ret i8 %A
+; CHECK-LABEL: @coerce_offset0_addrspacecast(
+; CHECK-NOT: load
+; CHECK: ret i8
+}
+
 ;; non-local i32/float -> i8 load forwarding.
 define i8 @coerce_offset_nonlocal0(i32* %P, i1 %cond) {
   %P2 = bitcast i32* %P to float*