1; RUN: llc < %s -march=avr | FileCheck %s 2target triple = "avr-unknown-unknown" 3 4; The case illustrate DAG schedular may pre-schedule the node has 5; ADJCALLSTACKDOWN parent, so ADJCALLSTACKUP may hold CallResource too long 6; and make other calls can't be scheduled. If there's no other available node 7; to schedule, the scheduler will try to rename the register by creating the 8; copy to avoid the conflict which will fail because CallResource is not a real 9; physical register. 10; 11; The issue is found by Tim on https://github.com/avr-rust/rust/issues/111 and 12; discuss in http://lists.llvm.org/pipermail/llvm-dev/2018-October/127083.html. 13 14define void @"main"() addrspace(1) { 15start: 16 %0 = or i64 undef, undef 17 br i1 undef, label %mul_and_call, label %fail 18 19 mul_and_call: 20 %1 = mul i64 %0, %0 21 call addrspace(1) void @"three_ints"(i64 undef, i64 %1, i64 %0) 22; The CHECK line only want to make sure the following assertion message 23; won't trigger due to create copy of artificial CallResource register. 24; llc: llvm/lib/CodeGen/TargetRegisterInfo.cpp:203: const llvm::TargetRegisterClass* llvm::TargetRegisterInfo::getMinimalPhysRegClass(unsigned int, llvm::MVT) const: Assertion `BestRC && "Couldn't find the register class"' failed. 25; CHECK: call __muldi3 26 ret void 27 28 fail: 29 ret void 30} 31 32declare void @"three_ints"(i64, i64, i64) addrspace(1) 33