Commit Graph

4 Commits

Author SHA1 Message Date
Derek Schuff ad154c837e Introduce MachineFunctionProperties and the AllVRegsAllocated property
MachineFunctionProperties represents a set of properties that a MachineFunction
can have at particular points in time. Existing examples of this idea are
MachineRegisterInfo::isSSA() and MachineRegisterInfo::tracksLiveness() which
will eventually be switched to use this mechanism.
This change introduces the AllVRegsAllocated property; i.e. the property that
all virtual registers have been allocated and there are no VReg operands
left.

With this mechanism, passes can declare that they require a particular property
to be set, or that they set or clear properties by implementing e.g.
MachineFunctionPass::getRequiredProperties(). The MachineFunctionPass base class
verifies that the requirements are met, and handles the setting and clearing
based on the delcarations. Passes can also directly query and update the current
properties of the MF if they want to have conditional behavior.

This change annotates the target-independent post-regalloc passes; future
changes will also annotate target-specific ones.

Reviewers: qcolombet, hfinkel

Differential Revision: http://reviews.llvm.org/D18421

llvm-svn: 264593
2016-03-28 17:05:30 +00:00
Matthias Braun 9dcd65f478 MachineCopyPropagation: Catch copies of the form A<-B;A<-B
Differential Revision: http://reviews.llvm.org/D17475

llvm-svn: 261966
2016-02-26 03:18:55 +00:00
Matthias Braun e39ff70685 MachineCopyPropagation: Keep scanning through instructions with regmasks
This also simplifies the code by removing the overly conservative
NoInterveningSideEffect() function. This function checked:
- That the two copies belong to the same block: We only process one
  block at a time and clear our maps in between it is impossible to find a
  copy from a different block.
- There is no terminator between the two copy instructions: This is not
  allowed anyway (the MachineVerifier would complain)
- Does not have instructions with hasUnmodeledSideEffects() or isCall()
  set: Even for those instructuction we must have all clobbers/defs of
  registers explicit as an operand. If the register is explicitely
  clobbered we would never come to the point of checking for
  NoInterveningSideEffect() anyway.

(I also checked this with a temporary build of the test-suite with all
 potentially failing conditions in NoInterveningSideEffect() turned into
 asserts)

Differential Revision: http://reviews.llvm.org/D17474

llvm-svn: 261965
2016-02-26 03:18:50 +00:00
Matthias Braun aca625a4fe MachineInstr: Respect register aliases in clearRegiserKills()
This fixes bugs in copy elimination code in llvm. It slightly changes the
semantics of clearRegisterKills(). This is appropriate because:
- Users in lib/CodeGen/MachineCopyPropagation.cpp and
  lib/Target/AArch64RedundantCopyElimination.cpp and
  lib/Target/SystemZ/SystemZElimCompare.cpp are incorrect without it
  (see included testcase).
- All other users in llvm are unaffected (they pass TRI==nullptr)
- (Kill flags are optional anyway so removing too many shouldn't hurt.)

Differential Revision: http://reviews.llvm.org/D17554

llvm-svn: 261763
2016-02-24 19:21:48 +00:00