[PATCH] D66467: [Codegen] skip debug instr to avoid code change

[Bjorn Pettersson via Phabricator via llvm-commits]

bjope added a comment.

Here is an test case that currently fail. The test1, test2 and test3 functions only differ by DBG_VALUE and CFI_INSTRUCTION instructions. So I guess we want to see the same real instructions being generated for all three functions.

  # RUN: llc -mtriple=x86_64-- -run-pass branch-folder -O3 -o - %s | FileCheck %s
  
  ---
  name:            test1
  body:             |
    bb.0:
      TEST8rr killed renamable $al, renamable $al, implicit-def $eflags
      JCC_1 %bb.2, 5, implicit killed $eflags
  
    bb.1:
      MOV8mi $r12, 1, $noreg, 0, $noreg, 0
      MOV8mi $r13, 1, $noreg, 0, $noreg, 0
      RET 0
  
    bb.2:
      MOV8mi $r13, 1, $noreg, 0, $noreg, 0
      RET 0
  ...
  
  # CHECK-LABEL: name:            test1
  # CHECK: bb.0:
  # CHECK:   TEST8rr
  # CHECK:   JCC_1
  # CHECK: bb.1:
  # CHECK:   successors: %bb.2
  # CHECK:   MOV8mi $r12
  # CHECK: bb.2:
  # CHECK:   MOV8mi $r13
  # CHECK:   RET 0
  
  ---
  name:            test2
  body:             |
    bb.0:
      TEST8rr killed renamable $al, renamable $al, implicit-def $eflags
      JCC_1 %bb.2, 5, implicit killed $eflags
  
    bb.1:
      MOV8mi $r12, 1, $noreg, 0, $noreg, 0
      MOV8mi $r13, 1, $noreg, 0, $noreg, 0
      CFI_INSTRUCTION def_cfa_offset 8
      RET 0
  
    bb.2:
      DBG_VALUE
      DBG_VALUE
      CFI_INSTRUCTION def_cfa_offset 8
      MOV8mi $r13, 1, $noreg, 0, $noreg, 0
      RET 0
  ...
  
  # CHECK-LABEL: name:            test2
  # CHECK: bb.0:
  # CHECK:   TEST8rr
  # CHECK:   JCC_1
  # CHECK: bb.1:
  # CHECK:   successors: %bb.2
  # CHECK:   MOV8mi $r12
  # CHECK: bb.2:
  # CHECK:   MOV8mi $r13
  # CHECK:   RET 0
  
  ---
  name:            test3
  body:             |
    bb.0:
      TEST8rr killed renamable $al, renamable $al, implicit-def $eflags
      JCC_1 %bb.1, 5, implicit killed $eflags
  
    bb.1:
      MOV8mi $r12, 1, $noreg, 0, $noreg, 0
      DBG_VALUE
      CFI_INSTRUCTION def_cfa_offset 8
      MOV8mi $r13, 1, $noreg, 0, $noreg, 0
      CFI_INSTRUCTION offset $r13, -123
      RET 0
  
    bb.2:
      DBG_VALUE
      CFI_INSTRUCTION def_cfa_offset 8
      DBG_VALUE
      MOV8mi $r13, 1, $noreg, 0, $noreg, 0
      DBG_VALUE
      CFI_INSTRUCTION offset $r13, -123
      DBG_VALUE
      RET 0
  ...
  
  # CHECK-LABEL: name:            test3
  # CHECK: bb.0:
  # CHECK:   TEST8rr
  # CHECK:   JCC_1
  # CHECK: bb.1:
  # CHECK:   successors: %bb.2
  # CHECK:   MOV8mi $r12
  # CHECK: bb.2:
  # CHECK:   MOV8mi $r13
  # CHECK:   RET 0

But we now get these three different functions:

  name:            test1
    bb.0:
      successors: %bb.2(0x40000000), %bb.1(0x40000000)
      TEST8rr killed renamable $al, renamable $al, implicit-def $eflags
      JCC_1 %bb.2, 5, implicit $eflags
    bb.1:
      successors: %bb.2(0x80000000)
      MOV8mi $r12, 1, $noreg, 0, $noreg, 0
    bb.2:
      MOV8mi $r13, 1, $noreg, 0, $noreg, 0
      RET 0
  
  
  name:            test2
    bb.0:
      successors: %bb.2(0x40000000), %bb.1(0x40000000)
      TEST8rr killed renamable $al, renamable $al, implicit-def $eflags
      JCC_1 %bb.2, 5, implicit killed $eflags
    bb.1:
      MOV8mi $r12, 1, $noreg, 0, $noreg, 0
      MOV8mi $r13, 1, $noreg, 0, $noreg, 0
      CFI_INSTRUCTION def_cfa_offset 8
      RET 0
    bb.2:
      DBG_VALUE
      DBG_VALUE
      CFI_INSTRUCTION def_cfa_offset 8
      MOV8mi $r13, 1, $noreg, 0, $noreg, 0
      RET 0
  
  
  name:            test3
    bb.0:
      TEST8rr killed renamable $al, renamable $al, implicit-def $eflags
      MOV8mi $r12, 1, $noreg, 0, $noreg, 0
      DBG_VALUE
      CFI_INSTRUCTION def_cfa_offset 8
      MOV8mi $r13, 1, $noreg, 0, $noreg, 0
      CFI_INSTRUCTION offset $r13, -123
      RET 0


Repository:
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