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  1. Jun 09, 2012
    • Benjamin Kramer's avatar
    • Andrew Trick's avatar
      Register pressure: added getPressureAfterInstr. · fc8ce08b
      Andrew Trick authored
      llvm-svn: 158256
      fc8ce08b
    • Jakob Stoklund Olesen's avatar
      Sketch a LiveRegMatrix analysis pass. · c26fbbfb
      Jakob Stoklund Olesen authored
      The LiveRegMatrix represents the live range of assigned virtual
      registers in a Live interval union per register unit. This is not
      fundamentally different from the interference tracking in RegAllocBase
      that both RABasic and RAGreedy use.
      
      The important differences are:
      
      - LiveRegMatrix tracks interference per register unit instead of per
        physical register. This makes interference checks cheaper and
        assignments slightly more expensive. For example, the ARM D7 reigster
        has 24 aliases, so we would check 24 physregs before assigning to one.
        With unit-based interference, we check 2 units before assigning to 2
        units.
      
      - LiveRegMatrix caches regmask interference checks. That is currently
        duplicated functionality in RABasic and RAGreedy.
      
      - LiveRegMatrix is a pass which makes it possible to insert
        target-dependent passes between register allocation and rewriting.
        Such passes could tweak the register assignments with interference
        checking support from LiveRegMatrix.
      
      Eventually, RABasic and RAGreedy will be switched to LiveRegMatrix.
      
      llvm-svn: 158255
      c26fbbfb
    • Jakob Stoklund Olesen's avatar
      Also compute MBB live-in lists in the new rewriter pass. · be336295
      Jakob Stoklund Olesen authored
      This deduplicates some code from the optimizing register allocators, and
      it means that it is now possible to change the register allocators'
      solutions simply by editing the VirtRegMap between the register
      allocator pass and the rewriter.
      
      llvm-svn: 158249
      be336295
    • Jakob Stoklund Olesen's avatar
      Reintroduce VirtRegRewriter. · 1224312f
      Jakob Stoklund Olesen authored
      OK, not really. We don't want to reintroduce the old rewriter hacks.
      
      This patch extracts virtual register rewriting as a separate pass that
      runs after the register allocator. This is possible now that
      CodeGen/Passes.cpp can configure the full optimizing register allocator
      pipeline.
      
      The rewriter pass uses register assignments in VirtRegMap to rewrite
      virtual registers to physical registers, and it inserts kill flags based
      on live intervals.
      
      These finalization steps are the same for the optimizing register
      allocators: RABasic, RAGreedy, and PBQP.
      
      llvm-svn: 158244
      1224312f
  2. Jun 08, 2012
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