[PATCH] D36512: [ValueTracking] Honour recursion limit

[Davide Italiano via Phabricator via llvm-commits]

davide created this revision.

The recently improved support for `icmp` in ValueTracking,

  commit c6b02fa9154c7b897afe5fb746cec527fb3f8bb0
  Author: Chad Rosier <mcrosier at codeaurora.org>
  Date:   Thu Jul 6 20:00:25 2017 +0000
  
      [ValueTracking] Support icmps fed by 'and' and 'or'.
  
      This patch adds support for handling some forms of ands and ors in
      ValueTracking's isImpliedCondition API.
  
      PR33611
      https://reviews.llvm.org/D34901

exposes the fact that `isImplied` condition doesn't really bail out if we hit the recursion limit (and this function calls `computeKnownBits` which increases the depth and asserts).

This is the top of the stack, for archeologists (the frame is #13 because this is running inside `rr`).

  #13 0x000000000215d12f in llvm::computeKnownBits (V=0x7a05fc0, Known=..., DL=...,
      Depth=7, AC=0x0, CxtI=0x0, DT=0x0, ORE=0x0) at ../lib/Analysis/ValueTracking.cpp:142
  #14 0x0000000002171143 in isTruePredicate(llvm::CmpInst::Predicate, llvm::Value const*, llvm::Value const*, llvm::DataLayout const&, unsigned int)::$_9::operator()(llvm::Value const
  *, llvm::Value const*, llvm::Value const*&, llvm::APInt const*&, llvm::APInt const*&) const (this=0x7ffd945de098, A=0x7a078d0, B=0x7a05c00, X=@0x7ffd945de090: 0x7a05fc0,
      CA=@0x7ffd945de088: 0x7a07888, CB=@0x7ffd945de080: 0x7a05af8)
      at ../lib/Analysis/ValueTracking.cpp:4376
  #15 0x0000000002170ec0 in isTruePredicate (Pred=llvm::CmpInst::ICMP_ULE, LHS=0x7a078d0,
      RHS=0x7a05c00, DL=..., Depth=6) at ../lib/Analysis/ValueTracking.cpp:4387
  #16 0x0000000002170c71 in isImpliedCondOperands (Pred=llvm::CmpInst::ICMP_ULT,
      ALHS=0x7a05c00, ARHS=0x7a05b10, BLHS=0x7a078d0, BRHS=0x7a05b10, DL=..., Depth=6)
      at ../lib/Analysis/ValueTracking.cpp:4414
  #17 0x00000000021675c1 in isImpliedCondICmps (LHS=0x7a27d60, RHS=0x7a07960, DL=...,
      LHSIsTrue=true, Depth=6) at ../lib/Analysis/ValueTracking.cpp:4518
  #18 0x000000000216720a in llvm::isImpliedCondition (LHS=0x7a27d60, RHS=0x7a07960,
      DL=..., LHSIsTrue=true, Depth=6) at ../lib/Analysis/ValueTracking.cpp:4581
  #19 0x000000000216785a in isImpliedCondAndOr (LHS=0x7a27dd0, RHS=0x7a07960, DL=...,
      LHSIsTrue=true, Depth=5) at ../lib/Analysis/ValueTracking.cpp:4549
  #20 0x0000000002167278 in llvm::isImpliedCondition (LHS=0x7a27dd0, RHS=0x7a07960,
      DL=..., LHSIsTrue=true, Depth=5) at ../lib/Analysis/ValueTracking.cpp:4589
  #21 0x0000000002167798 in isImpliedCondAndOr (LHS=0x7a066b0, RHS=0x7a07960, DL=...,
      LHSIsTrue=true, Depth=4) at ../lib/Analysis/ValueTracking.cpp:4546
  #22 0x0000000002167278 in llvm::isImpliedCondition (LHS=0x7a066b0, RHS=0x7a07960,


https://reviews.llvm.org/D36512

Files:
  lib/Analysis/ValueTracking.cpp
  test/Transforms/SimplifyCFG/pr34131.ll

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