[Lldb-commits] [PATCH] D26295: Change UnwindAssemblyInstEmulation to remove a register location instead of marking it as IsSame()

[Jason Molenda via lldb-commits]

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This is a minor change and maybe more of a personal preference, but UnwindAssemblyInstEmulation marks registers that have been restored to their original values as "IsSame" - which is equivalent to the UnwindPlan not mentioning a location for the register at all.  When I look at an unwind plan while a function is executing it's epilogue, the output looks like

row[14]:  520: CFA=sp+320 => x8=[CFA-240] x19= <same> x20= <same> x21= <same> x22= <same> x23=[CFA-56] x24=[CFA-64] x25=[CFA-72] x26=[CFA-80] x27=[CFA-88] x28=[CFA-96] fp= <same> lr= <same> 
row[15]:  524: CFA=sp+320 => x8=[CFA-240] x19= <same> x20= <same> x21= <same> x22= <same> x23= <same> x24= <same> x25=[CFA-72] x26=[CFA-80] x27=[CFA-88] x28=[CFA-96] fp= <same> lr= <same> 
row[16]:  528: CFA=sp+320 => x8=[CFA-240] x19= <same> x20= <same> x21= <same> x22= <same> x23= <same> x24= <same> x25= <same> x26= <same> x27=[CFA-88] x28=[CFA-96] fp= <same> lr= <same> 
row[17]:  532: CFA=sp +0 => x8=[CFA-240] x19= <same> x20= <same> x21= <same> x22= <same> x23= <same> x24= <same> x25= <same> x26= <same> x27= <same> x28= <same> fp= <same> lr= <same>

etc.  If we remove the registers from the row, the unwind dump will read like

row[14]:  516: CFA=sp+96 => x8=[CFA-240] x21=[CFA-40] x22=[CFA-48] x23=[CFA-56] x24=[CFA-64] x25=[CFA-72] x26=[CFA-80] x27=[CFA-88] x28=[CFA-96] 
row[15]:  520: CFA=sp+96 => x8=[CFA-240] x23=[CFA-56] x24=[CFA-64] x25=[CFA-72] x26=[CFA-80] x27=[CFA-88] x28=[CFA-96] 
row[16]:  524: CFA=sp+96 => x8=[CFA-240] x25=[CFA-72] x26=[CFA-80] x27=[CFA-88] x28=[CFA-96] 
row[17]:  528: CFA=sp+96 => x8=[CFA-240] x27=[CFA-88] x28=[CFA-96]

There's no functional difference between the two (there SHOULD be no functional difference) - but I think it's a bit easier to read without the IsSame's.  Does anyone care one way or the other?


Repository:
  rL LLVM

https://reviews.llvm.org/D26295

Files:
  source/Plugins/UnwindAssembly/InstEmulation/UnwindAssemblyInstEmulation.cpp
  unittests/UnwindAssembly/InstEmulation/TestArm64InstEmulation.cpp

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