[clang][bytecode] Fix a crash in codegen (llvm#151515)

getRecord() can return nullptr if any one of the fields does, in this
case because the array is too large for us to allocate.

Author: tbaederr

clang/lib/AST/ByteCode/Compiler.cpp

@@ -1758,6 +1758,9 @@ bool Compiler<Emitter>::visitInitList(ArrayRef<const Expr *> Inits,
     if (Inits.size() == 1 && E->getType() == Inits[0]->getType())
       return this->delegate(Inits[0]);
 
+    if (!R)
+      return false;
+
     auto initPrimitiveField = [=](const Record::Field *FieldToInit,
                                   const Expr *Init, PrimType T,
                                   bool Activate = false) -> bool {

clang/test/AST/ByteCode/codegen.cpp

@@ -23,6 +23,10 @@ S s;
 // CHECK: @sp = constant ptr getelementptr (i8, ptr @s, i64 16), align 8
 float &sp = s.c[3];
 
+namespace NearlyZeroInit {
+  // CHECK: @_ZN14NearlyZeroInit1bE ={{.*}} global{{.*}} { i32, <{ i32, [2147483647 x i32] }> } { i32 1, <{ i32, [2147483647 x i32] }> <{ i32 2, [2147483647 x i32] zeroinitializer }> }{{.*}}
+  struct B { int n; int arr[1024 * 1024 * 1024 * 2u]; } b = {1, {2}};
+}
 
 namespace BaseClassOffsets {
   struct A { int a; };

llvm/test/CodeGen/AArch64/cmp-to-cmn.ll

@@ -781,22 +781,36 @@ define i1 @almost_immediate_neg_ugt_64(i64 %x) {
 }
 
 define i1 @cmn_nsw(i32 %a, i32 %b) {
-; CHECK-LABEL: cmn_nsw:
-; CHECK:       // %bb.0:
-; CHECK-NEXT:    cmn w0, w1
-; CHECK-NEXT:    cset w0, gt
-; CHECK-NEXT:    ret
+; CHECK-SD-LABEL: cmn_nsw:
+; CHECK-SD:       // %bb.0:
+; CHECK-SD-NEXT:    cmn w0, w1
+; CHECK-SD-NEXT:    cset w0, gt
+; CHECK-SD-NEXT:    ret
+;
+; CHECK-GI-LABEL: cmn_nsw:
+; CHECK-GI:       // %bb.0:
+; CHECK-GI-NEXT:    neg w8, w1
+; CHECK-GI-NEXT:    cmp w0, w8
+; CHECK-GI-NEXT:    cset w0, gt
+; CHECK-GI-NEXT:    ret
   %sub = sub nsw i32 0, %b
   %cmp = icmp sgt i32 %a, %sub
   ret i1 %cmp
 }
 
 define i1 @cmn_nsw_64(i64 %a, i64 %b) {
-; CHECK-LABEL: cmn_nsw_64:
-; CHECK:       // %bb.0:
-; CHECK-NEXT:    cmn x0, x1
-; CHECK-NEXT:    cset w0, gt
-; CHECK-NEXT:    ret
+; CHECK-SD-LABEL: cmn_nsw_64:
+; CHECK-SD:       // %bb.0:
+; CHECK-SD-NEXT:    cmn x0, x1
+; CHECK-SD-NEXT:    cset w0, gt
+; CHECK-SD-NEXT:    ret
+;
+; CHECK-GI-LABEL: cmn_nsw_64:
+; CHECK-GI:       // %bb.0:
+; CHECK-GI-NEXT:    neg x8, x1
+; CHECK-GI-NEXT:    cmp x0, x8
+; CHECK-GI-NEXT:    cset w0, gt
+; CHECK-GI-NEXT:    ret
   %sub = sub nsw i64 0, %b
   %cmp = icmp sgt i64 %a, %sub
   ret i1 %cmp