[Lint] Fix crash with scalable alloca

Author: nikic

llvm/lib/Analysis/Lint.cpp

@@ -436,8 +436,8 @@ void Lint::visitMemoryReference(Instruction &I, const MemoryLocation &Loc,
 
     if (AllocaInst *AI = dyn_cast<AllocaInst>(Base)) {
       Type *ATy = AI->getAllocatedType();
-      if (!AI->isArrayAllocation() && ATy->isSized())
-        BaseSize = DL->getTypeAllocSize(ATy);
+      if (!AI->isArrayAllocation() && ATy->isSized() && !ATy->isScalableTy())
+        BaseSize = DL->getTypeAllocSize(ATy).getFixedValue();
       BaseAlign = AI->getAlign();
     } else if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Base)) {
       // If the global may be defined differently in another compilation unit

llvm/test/Analysis/Lint/scalable.ll

@@ -0,0 +1,15 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -S -passes=lint < %s | FileCheck %s
+
+; Make sure we don't crash.
+
+define <vscale x 8 x i8> @test() {
+; CHECK-LABEL: define <vscale x 8 x i8> @test() {
+; CHECK-NEXT:    [[A:%.*]] = alloca <vscale x 8 x i8>, align 8
+; CHECK-NEXT:    [[V:%.*]] = load <vscale x 8 x i8>, ptr [[A]], align 8
+; CHECK-NEXT:    ret <vscale x 8 x i8> [[V]]
+;
+  %a = alloca <vscale x 8 x i8>
+  %v = load <vscale x 8 x i8>, ptr %a
+  ret <vscale x 8 x i8> %v
+}