[00/13] remove phi-sources from removed branches

Message

Luc Van Oostenryck March 21, 2021, 12:34 p.m. UTC

This series, after some related and preparatory patches, contains
fixes for the problem of phi-sources being left in place after their
corresponding branches have been removed. This results in situations,
for example, where a phi-node has 3 arguments/inputs/sources but only
2 parent BBs and create all sort of problems, like:
* some dead code is not removed
* some optimizations involving phi-nodes are blocked (if-conversions)
* more importantly, these phi-nodes are invalid/meaningless and so
  it's impossible to reason correctly about them.

Note: This series only fixes *some* of these problems. Other probably
      still exists, especially when rewrite_branch() is used.


Luc Van Oostenryck (13):
  Revert "simplify CBR-CBR on the same condition"
  add testcases to check if phi-sources from removed targets are removed
    too
  remove insert_branch() redundant arg
  simplify remove_parent()
  fold remove_parent() into insert_branch()
  let insert_branch() reuse the terminating instruction
  move insert_branch() to flow.c
  let insert_branch() return a status
  rename insert_branch() to convert_to_jump()
  add remove_phisources()
  fix phisources during CBR-BR conversion
  use convert_to_jump() when converting a CBR with same targets
  fix phisources during SWITCH-BR conversion

 flow.c                          | 205 +++++++++++++++-----------------
 flow.h                          |   3 +
 linearize.c                     |  36 ------
 linearize.h                     |   1 -
 simplify.c                      |  34 ++----
 validation/optim/bad-phisrc1.c  |  15 +++
 validation/optim/bad-phisrc1a.c |  23 ++++
 validation/optim/bad-phisrc2.c  |  16 +++
 validation/optim/bad-phisrc3.c  |  20 ++++
 9 files changed, 184 insertions(+), 169 deletions(-)
 create mode 100644 validation/optim/bad-phisrc1.c
 create mode 100644 validation/optim/bad-phisrc1a.c
 create mode 100644 validation/optim/bad-phisrc2.c
 create mode 100644 validation/optim/bad-phisrc3.c