text: // RUN: %clang_cc1 -emit-llvm -triple arm64-- -o - %s -O0 | FileCheck %s --check-prefix=CHECK-O0
  // RUN: %clang_cc1 -emit-llvm -disable-llvm-optzns -triple arm64-- -o - %s -O3 | FileCheck %s --check-prefix=CHECK-O3
  
  struct large {
      void* pointers[8];
  };
  
  void pass_large(struct large);
  
  // For arm64, we don't use byval to pass structs but instead we create
  // temporary allocas.
  //
  // Make sure we generate the appropriate lifetime markers for the temporary
  // allocas so that the optimizer can re-use stack slots if possible.
  void example() {
      struct large l = {0};
      pass_large(l);
      pass_large(l);
  }
  // CHECK-O0-LABEL: define{{.*}} void @example(
  // The alloca for the struct on the stack.
  // CHECK-O0: %[[l:[0-9A-Za-z-]+]] = alloca %struct.large, align 8
  // The alloca for the temporary stack space that we use to pass the argument.
  // CHECK-O0-NEXT: %[[byvaltemp:[0-9A-Za-z-]+]] = alloca %struct.large, align 8
  // Another one to pass the argument to the second function call.
  // CHECK-O0-NEXT: %[[byvaltemp1:[0-9A-Za-z-]+]] = alloca %struct.large, align 8
  // First, memset `l` to 0.
  // CHECK-O0-NEXT: %[[bitcastl:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[l]] to i8*
  // CHECK-O0-NEXT: call void @llvm.memset.p0i8.i64(i8* align 8 %[[bitcastl]], i8 0, i64 64, i1 false)
  // Then, memcpy `l` to the temporary stack space.
  // CHECK-O0-NEXT: %[[src:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[byvaltemp]] to i8*
  // CHECK-O0-NEXT: %[[dst:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[l]] to i8*
  // CHECK-O0-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 8 %[[src]], i8* align 8 %[[dst]], i64 64, i1 false)
  // Finally, call using a pointer to the temporary stack space.
  // CHECK-O0-NEXT: call void @pass_large(%struct.large* %[[byvaltemp]])
  // Now, do the same for the second call, using the second temporary alloca.
  // CHECK-O0-NEXT: %[[src:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[byvaltemp1]] to i8*
  // CHECK-O0-NEXT: %[[dst:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[l]] to i8*
  // CHECK-O0-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 8 %[[src]], i8* align 8 %[[dst]], i64 64, i1 false)
  // CHECK-O0-NEXT: call void @pass_large(%struct.large* %[[byvaltemp1]])
  // CHECK-O0-NEXT: ret void
  //
  // At O3, we should have lifetime markers to help the optimizer re-use the temporary allocas.
  //
  // CHECK-O3-LABEL: define{{.*}} void @example(
  // The alloca for the struct on the stack.
  // CHECK-O3: %[[l:[0-9A-Za-z-]+]] = alloca %struct.large, align 8
  // The alloca for the temporary stack space that we use to pass the argument.
  // CHECK-O3-NEXT: %[[byvaltemp:[0-9A-Za-z-]+]] = alloca %struct.large, align 8
  // Another one to pass the argument to the second function call.
  // CHECK-O3-NEXT: %[[byvaltemp1:[0-9A-Za-z-]+]] = alloca %struct.large, align 8
  //
  // Mark the start of the lifetime for `l`
  // CHECK-O3-NEXT: %[[bitcastl:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[l]] to i8*
  // CHECK-O3-NEXT: call void @llvm.lifetime.start.p0i8(i64 64, i8* %[[bitcastl]])
  //
  // First, memset `l` to 0.
  // CHECK-O3-NEXT: %[[bitcastl:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[l]] to i8*
  // CHECK-O3-NEXT: call void @llvm.memset.p0i8.i64(i8* align 8 %[[bitcastl]], i8 0, i64 64, i1 false)
  //
  // Lifetime of the first temporary starts here and ends right after the call.
  // CHECK-O3-NEXT: %[[bitcastbyvaltemp:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[byvaltemp]] to i8*
  // CHECK-O3-NEXT: call void @llvm.lifetime.start.p0i8(i64 64, i8* %[[bitcastbyvaltemp]])
  //
  // Then, memcpy `l` to the temporary stack space.
  // CHECK-O3-NEXT: %[[src:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[byvaltemp]] to i8*
  // CHECK-O3-NEXT: %[[dst:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[l]] to i8*
  // CHECK-O3-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 8 %[[src]], i8* align 8 %[[dst]], i64 64, i1 false)
  // Finally, call using a pointer to the temporary stack space.
  // CHECK-O3-NEXT: call void @pass_large(%struct.large* %[[byvaltemp]])
  //
  // The lifetime of the temporary used to pass a pointer to the struct ends here.
  // CHECK-O3-NEXT: %[[bitcastbyvaltemp:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[byvaltemp]] to i8*
  // CHECK-O3-NEXT: call void @llvm.lifetime.end.p0i8(i64 64, i8* %[[bitcastbyvaltemp]])
  //
  // Now, do the same for the second call, using the second temporary alloca.
  // CHECK-O3-NEXT: %[[bitcastbyvaltemp:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[byvaltemp1]] to i8*
  // CHECK-O3-NEXT: call void @llvm.lifetime.start.p0i8(i64 64, i8* %[[bitcastbyvaltemp]])
  // CHECK-O3-NEXT: %[[src:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[byvaltemp1]] to i8*
  // CHECK-O3-NEXT: %[[dst:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[l]] to i8*
  // CHECK-O3-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 8 %[[src]], i8* align 8 %[[dst]], i64 64, i1 false)
  // CHECK-O3-NEXT: call void @pass_large(%struct.large* %[[byvaltemp1]])
  // CHECK-O3-NEXT: %[[bitcastbyvaltemp:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[byvaltemp1]] to i8*
  // CHECK-O3-NEXT: call void @llvm.lifetime.end.p0i8(i64 64, i8* %[[bitcastbyvaltemp]])
  //
  // Mark the end of the lifetime of `l`.
  // CHECK-O3-NEXT: %[[bitcastl:[0-9A-Za-z-]+]] = bitcast %struct.large* %l to i8*
  // CHECK-O3-NEXT: call void @llvm.lifetime.end.p0i8(i64 64, i8* %[[bitcastl]])
  // CHECK-O3-NEXT: ret void
  