[ValueTracking][SVE] Fix isGEPKnownNonNull for scalable vector.

[huihuiz]

Summary

DataLayout::getTypeAllocSize() return TypeSize. For cases where the
scalable property doesn't matter, we should explicitly call getKnownMinSize()
to avoid implicit type conversion to uint64_t, which is not valid for scalable
vector type.

[huihuiz]

minor update test name

[efriedma]

LGTM

llvm/lib/Analysis/ValueTracking.cpp

if (StructType *STy = GTI.getStructTypeOrNull()) {
       const StructLayout *SL = Q.DL.getStructLayout(STy);
       uint64_t ElementOffset = SL->getElementOffset(ElementIdx);
       if (ElementOffset > 0)
         return true;
       continue;
     }
 
     // If we have a zero-sized type, the index doesn't matter. Keep looping.
-    if (Q.DL.getTypeAllocSize(GTI.getIndexedType()) == 0)
+    if (Q.DL.getTypeAllocSize(GTI.getIndexedType()).getKnownMinSize() == 0)
       continue;
 
     // Fast path the constant operand case both for efficiency and so we don't
     // increment Depth when just zipping down an all-constant GEP.
     if (ConstantInt *OpC = dyn_cast<ConstantInt>(GTI.getOperand())) {
       if (!OpC->isZero())
         return true;
       continue;

llvm/test/Transforms/InstSimplify/vscale.ll

 define <vscale x 4 x i32>* @getelementptr_not_constant_foldable(i64 %x) {
 ; CHECK-LABEL: @getelementptr_not_constant_foldable(
 ; CHECK-NEXT:    [[PTR:%.*]] = getelementptr <vscale x 4 x i32>, <vscale x 4 x i32>* null, i64 [[X:%.*]]
 ; CHECK-NEXT:    ret <vscale x 4 x i32>* [[PTR]]
 ;
   %ptr = getelementptr <vscale x 4 x i32>, <vscale x 4 x i32>* null, i64 %x
   ret <vscale x 4 x i32>* %ptr
 }
+
+; Check GEP's result is known to be non-null.
+define i1 @getelementptr_check_non_null(<vscale x 16 x i8>* %ptr) {
+; CHECK-LABEL: @getelementptr_check_non_null(
+; CHECK-NEXT:    ret i1 false
+;
+  %x = getelementptr inbounds <vscale x 16 x i8>, <vscale x 16 x i8>* %ptr, i32 1
+  %cmp = icmp eq <vscale x 16 x i8>* %x, null
+  ret i1 %cmp
+}