[all-commits] [llvm/llvm-project] a361de: [RDF] Create phi nodes for clobbering defs (#123694)

[Yashas Andaluri via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: a361de6d13183111e942d9f5c6345ed3e8964b2b
      https://github.com/llvm/llvm-project/commit/a361de6d13183111e942d9f5c6345ed3e8964b2b
  Author: Yashas Andaluri <quic_yandalur at quicinc.com>
  Date:   2025-02-07 (Fri, 07 Feb 2025)

  Changed paths:
    M llvm/include/llvm/CodeGen/RDFGraph.h
    M llvm/lib/CodeGen/RDFGraph.cpp
    A llvm/test/CodeGen/Hexagon/rdf-copy-clobber.mir
    A llvm/test/CodeGen/Hexagon/rdf-phi-clobber.mir

  Log Message:
  -----------
  [RDF] Create phi nodes for clobbering defs (#123694)

When a def in a block A reaches another block B that is in A's iterated
dominance frontier, a phi node is added to B for the def register.

A clobbering def can be created at a call instruction, for a register
clobbered by a call.
However, phi nodes are not created for a register, when one of the
reaching defs of the register is a clobbering def.

This patch adds phi nodes for registers that have a clobbering reaching
def. These additional phis help in checking reaching defs for an
instruction in RDF based copy propagation and addressing mode
optimizations.



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