[PATCH] D140931: Improve and enable folding of conditional branches with tail calls.

[Noah Goldstein via Phabricator via llvm-commits]

goldstein.w.n created this revision.
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1. Make it so that conditional tail calls can be emitted even when there are multiple predecessors.

2. Don't guard the transformation behind -Os. Instead add a flag `MayChangeDirection` that guards against changing direction which is only enabled with optsize. Note on X86 (the only Target that implements this), branches are only replaced if the conditions match (so no direction change).


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D140931

Files:
  llvm/include/llvm/CodeGen/TargetInstrInfo.h
  llvm/lib/CodeGen/BranchFolding.cpp
  llvm/lib/Target/X86/X86InstrInfo.cpp
  llvm/lib/Target/X86/X86InstrInfo.h
  llvm/test/CodeGen/X86/add.ll
  llvm/test/CodeGen/X86/atom-pad-short-functions.ll
  llvm/test/CodeGen/X86/avx512-i1test.ll
  llvm/test/CodeGen/X86/bmi.ll
  llvm/test/CodeGen/X86/brcond.ll
  llvm/test/CodeGen/X86/btq.ll
  llvm/test/CodeGen/X86/cmp-merge.ll
  llvm/test/CodeGen/X86/cmp.ll
  llvm/test/CodeGen/X86/comi-flags.ll
  llvm/test/CodeGen/X86/extern_weak.ll
  llvm/test/CodeGen/X86/fold-rmw-ops.ll
  llvm/test/CodeGen/X86/fp-strict-scalar-cmp-fp16.ll
  llvm/test/CodeGen/X86/fp-strict-scalar-cmp.ll
  llvm/test/CodeGen/X86/funnel-shift.ll
  llvm/test/CodeGen/X86/jump_sign.ll
  llvm/test/CodeGen/X86/neg_cmp.ll
  llvm/test/CodeGen/X86/or-branch.ll
  llvm/test/CodeGen/X86/peep-test-4.ll
  llvm/test/CodeGen/X86/pr37025.ll
  llvm/test/CodeGen/X86/pr37063.ll
  llvm/test/CodeGen/X86/rd-mod-wr-eflags.ll
  llvm/test/CodeGen/X86/segmented-stacks.ll
  llvm/test/CodeGen/X86/sibcall.ll
  llvm/test/CodeGen/X86/slow-incdec.ll
  llvm/test/CodeGen/X86/sqrt-partial.ll
  llvm/test/CodeGen/X86/switch-bt.ll
  llvm/test/CodeGen/X86/tail-opts.ll
  llvm/test/CodeGen/X86/tailcall-cgp-dup.ll
  llvm/test/CodeGen/X86/tailcall-extract.ll
  llvm/test/CodeGen/X86/xor-icmp.ll

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