[llvm-dev] How to get the case value from Machine Instruction

[yao via llvm-dev]

Hi, guys
I am interesting about how to get the switch case value form the Machine Instruction.


I know the switch will be converted to jump-table in the Machine Instruction.
And in the phase CodeGen ,  the case-value of SwitchInst can get esasly.
but it seems no case -value in Machine Instruction.

The MI as follows:
Frame Objects:
  fi#0: size=1, align=0, at location [SP]
  fi#1: size=4, align=4, at location [SP+8]
  fi#2: size=4, align=4, at location [SP+4]
  fi#3: size=4, align=4, at location [SP]
Jump Tables:
%jump-table.0:  %bb.2 %bb.3 %bb.4 %bb.5


%bb.0: derived from LLVM BB %0
%r0 = MOVi 0, 14, %noreg, %noreg
STRi12 %r0, %stack.1, 14, %noreg
%r0 = MOVi 4, 14, %noreg, %noreg
STRi12 %r0, %stack.2, 14, %noreg
%r0 = LDRi12 %stack.2, 14, %noreg
%r0 = SUBri %r0, 1, 14, %noreg, %noreg
CMPri %r0, 3, 14, %noreg, implicit-def %cpsr
STRi12 %r0, %stack.3, 14, %noreg
Bcc %bb.6, 8, %cpsr
    Successors according to CFG: %bb.6 %bb.1


%bb.1: derived from LLVM BB %1
    Predecessors according to CFG: %bb.0
%1:gprnopc = LEApcrelJT %jump-table.0, 14, %noreg
%2:gprnopc = LDRrs killed %0:gprnopc, %1, 0, 14, %noreg; mem:LD4[JumpTable]
BR_JTr killed %2, %jump-table.0
    Successors according to CFG: %bb.2(?%) %bb.3(?%) %bb.4(?%) %bb.5(?%)


%bb.2: derived from LLVM BB %2
    Predecessors according to CFG: %bb.1
%r0 = LDRi12 %stack.2, 14, %noreg
%r0 = ADDri %r0, 11, 14, %noreg, %noreg
STRi12 %r0, %stack.2, 14, %noreg
B %bb.6
    Successors according to CFG: %bb.6


%bb.3: derived from LLVM BB %3
    Predecessors according to CFG: %bb.1
%r0 = LDRi12 %stack.2, 14, %noreg
%r0 = ADDri %r0, 12, 14, %noreg, %noreg
STRi12 %r0, %stack.2, 14, %noreg
B %bb.6
    Successors according to CFG: %bb.6


%bb.4: derived from LLVM BB %4
    Predecessors according to CFG: %bb.1
%r0 = LDRi12 %stack.2, 14, %noreg
%r0 = ADDri %r0, 13, 14, %noreg, %noreg
STRi12 %r0, %stack.2, 14, %noreg
B %bb.6
    Successors according to CFG: %bb.6


%bb.5: derived from LLVM BB %5
    Predecessors according to CFG: %bb.1
%r0 = LDRi12 %stack.2, 14, %noreg
%r0 = ADDri %r0, 14, 14, %noreg, %noreg
STRi12 %r0, %stack.2, 14, %noreg
    Successors according to CFG: %bb.6


%bb.6: derived from LLVM BB %6
    Predecessors according to CFG: %bb.0 %bb.2 %bb.3 %bb.4 %bb.5
%r0 = LDRi12 %stack.2, 14, %noreg
BX_RET 14, %noreg


I  hope to get the Case value from the MI, 
Thanks,
yaoxiao
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