tree 9ce25ebbd8ed7454ddcf041c713c536b4cf1048f
parent 4241727b0578f8b63e505d26e0e7e30bf28ec763
author Sanjay Patel <spatel@rotateright.com> 1544366437 +0000
committer Sanjay Patel <spatel@rotateright.com> 1544366437 +0000

[x86] don't try to convert add with undef operands to LEA

The existing code tries to handle an undef operand while transforming an add to an LEA, 
but it's incomplete because we will crash on the i16 test with the debug output shown below. 
It's better to just give up instead. Really, GlobalIsel should have folded these before we 
could get into trouble.

# Machine code for function add_undef_i16: NoPHIs, TracksLiveness, Legalized, RegBankSelected, Selected

bb.0 (%ir-block.0):
  liveins: $edi
  %1:gr32 = COPY killed $edi
  %0:gr16 = COPY %1.sub_16bit:gr32
  %5:gr64_nosp = IMPLICIT_DEF
  %5.sub_16bit:gr64_nosp = COPY %0:gr16
  %6:gr64_nosp = IMPLICIT_DEF
  %6.sub_16bit:gr64_nosp = COPY %2:gr16
  %4:gr32 = LEA64_32r killed %5:gr64_nosp, 1, killed %6:gr64_nosp, 0, $noreg
  %3:gr16 = COPY killed %4.sub_16bit:gr32
  $ax = COPY killed %3:gr16
  RET 0, implicit killed $ax

# End machine code for function add_undef_i16.

*** Bad machine code: Reading virtual register without a def ***
- function:    add_undef_i16
- basic block: %bb.0  (0x7fe6cd83d940)
- instruction: %6.sub_16bit:gr64_nosp = COPY %2:gr16
- operand 1:   %2:gr16
LLVM ERROR: Found 1 machine code errors.

Differential Revision: https://reviews.llvm.org/D54710


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@348722 91177308-0d34-0410-b5e6-96231b3b80d8