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Author SHA1 Message Date
Quentin Colombet d652aeb144 [MIRPrinter] Print empty successor lists when they cannot be guessed
This re-applies commit r313685, this time with the proper updates to
the test cases.

Original commit message:
Unreachable blocks in the machine instr representation are these
weird empty blocks with no successors.
The MIR printer used to not print empty lists of successors. However,
the MIR parser now treats non-printed list of successors as "please
guess it for me". As a result, the parser tries to guess the list of
successors and given the block is empty, just assumes it falls through
the next block (if any).

For instance, the following test case used to fail the verifier.
The MIR printer would print

         entry
        /      \
   true (def)   false (no list of successors)
       |
 split.true (use)

The MIR parser would understand this:

         entry
        /      \
   true (def)   false
       |        /  <-- invalid edge
 split.true (use)

Because of the invalid edge, we get the "def does not
dominate all uses" error.

The fix consists in printing empty successor lists, so that the parser
knows what to do for unreachable blocks.

rdar://problem/34022159

llvm-svn: 313696
2017-09-19 23:34:12 +00:00
Quentin Colombet 6888dbcda7 Revert "[MIRPrinter] Print empty successor lists when they cannot be guessed"
This reverts commit r313685.

I thought I had ran ninja check, but apparently I didn't...
Need to update a bunch of mir tests.

llvm-svn: 313686
2017-09-19 22:03:50 +00:00
Quentin Colombet 7fdaa5e641 [MIRPrinter] Print empty successor lists when they cannot be guessed
Unreachable blocks in the machine instr representation are these
weird empty blocks with no successors.
The MIR printer used to not print empty lists of successors. However,
the MIR parser now treats non-printed list of successors as "please
guess it for me". As a result, the parser tries to guess the list of
successors and given the block is empty, just assumes it falls through
the next block (if any).

For instance, the following test case used to fail the verifier.
The MIR printer would print
          entry
         /      \
    true (def)   false (no list of successors)
        |
  split.true (use)

The MIR parser would understand this:
          entry
         /      \
    true (def)   false
        |        /  <-- invalid edge
  split.true (use)

Because of the invalid edge, we get the "def does not
dominate all uses" error.

The fix consists in printing empty successor lists, so that the parser
knows what to do for unreachable blocks.

rdar://problem/34022159

llvm-svn: 313685
2017-09-19 21:55:51 +00:00