Extend pre-emit peephole for S_CBRANCH_VCC[N]Z to eliminate
redundant S_AND operations against EXEC for V_CMP results in VCC.
These occur after after register allocation when VCC has been
selected as the comparison destination.
Reviewed By: rampitec
Differential Revision: https://reviews.llvm.org/D120202
When SCC is dead, but VCC is required then replace s_and / s_andn2
with s_mov into VCC when mask value is 0 or -1.
Reviewed By: rampitec
Differential Revision: https://reviews.llvm.org/D83850
Add handling of s_andn2 and mask of 0.
This eliminates redundant instructions from uniform control flow.
Reviewed By: rampitec
Differential Revision: https://reviews.llvm.org/D83641
This pass can handle all the optimization
opportunities found just before code emission.
Presently it includes the handling of vcc branch
optimization that was handled earlier in SIInsertSkips.
Reviewed By: arsenm
Differential Revision: https://reviews.llvm.org/D76712
Sometimes after basic block placement we end up with a code like:
sreg = s_mov_b64 -1
vcc = s_and_b64 exec, sreg
s_cbranch_vccz
This happens as a join of a block assigning -1 to a saved mask and
another block which consumes that saved mask with s_and_b64 and a
branch.
This is essentially a single s_cbranch_execz instruction when moved
into a single new basic block.
Differential Revision: https://reviews.llvm.org/D54164
llvm-svn: 346690
