r1025 = s/zext r1024, 4
r1026 = extract_subreg r1025, 4
to a copy:
r1026 = copy r1024
This is correct. However it uses TII->isCoalescableExtInstr() which can return
true for instructions which essentially does a sext_in_reg so this can end up
with an illegal copy where the source and destination register classes do not
match. Add a check to avoid it. Sorry, no test case possible at this time.
rdar://
11849816
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160059
91177308-0d34-0410-b5e6-
96231b3b80d8
unsigned SrcReg, DstReg, DefSubIdx;
if (DefMI &&
TII->isCoalescableExtInstr(*DefMI, SrcReg, DstReg, DefSubIdx) &&
- SubIdx == DefSubIdx) {
+ SubIdx == DefSubIdx &&
+ TRC == MRI->getRegClass(SrcReg)) {
// Optimize these:
// r1025 = s/zext r1024, 4
// r1026 = extract_subreg r1025, 4