[all-commits] [llvm/llvm-project] 3c44c4: [DAGCombine] Remove the getNegatibleCost to avoid ...

[QingShan Zhang via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 3c44c441db0f8d7e210806b5b221cd9ed66f2d7b
      https://github.com/llvm/llvm-project/commit/3c44c441db0f8d7e210806b5b221cd9ed66f2d7b
  Author: QingShan Zhang <qshanz at cn.ibm.com>
  Date:   2020-05-11 (Mon, 11 May 2020)

  Changed paths:
    M llvm/include/llvm/CodeGen/TargetLowering.h
    M llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
    M llvm/lib/Target/AMDGPU/AMDGPUISelLowering.cpp
    M llvm/lib/Target/AMDGPU/AMDGPUISelLowering.h
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    M llvm/lib/Target/X86/X86ISelLowering.h
    M llvm/test/CodeGen/X86/neg_fp.ll

  Log Message:
  -----------
  [DAGCombine] Remove the getNegatibleCost to avoid the out of sync with getNegatedExpression

We have the getNegatibleCost/getNegatedExpression to evaluate the cost and negate the expression.
However, during negating the expression, the cost might change as we are changing the DAG,
and then, hit the assertion if we negated the wrong expression as the cost is not trustful anymore.

This patch is target to remove the getNegatibleCost to avoid the out of sync with getNegatedExpression,
and check the cost during negating the expression. It also reduce the duplicated code between
getNegatibleCost and getNegatedExpression. And fix the crash for the test in D76638

Reviewed By: RKSimon, spatel

Differential Revision: https://reviews.llvm.org/D77319