[PATCH] D51968: [deadargelim] Update dbg.value of 'unused' parameters

[Djordje Todorovic via Phabricator via llvm-commits]

djtodoro added a comment.

Please see the following lldb session:

  ...
  (lldb) b f2
  Breakpoint 1: where = test`f2 at test.c:4, address = 0x0000000000400460
  (lldb) r
  Process 12105 launched: './test' (x86_64)
  Process 12105 stopped
  * thread #1, name = 'test', stop reason = breakpoint 1.1
      frame #0: 0x0000000000400460 test`f2(k=1) at test.c:4
  (lldb) p k
  (int) $0 = 1
  (lldb) register read
  General Purpose Registers:
         rax = 0x0000000000400480  test`main at test.c:12
         rbx = 0x0000000000000000
         rcx = 0x0000000000000000
         rdx = 0x00007fffffffdcd8
         rdi = 0x0000000000000001
         rsi = 0x00007fffffffdcc8
         rbp = 0x00000000004004a0  test`__libc_csu_init
         rsp = 0x00007fffffffdbd8
          r8 = 0x0000000000400490  test`__libc_csu_fini
          r9 = 0x00007ffff7de7ab0  ld-linux-x86-64.so.2`___lldb_unnamed_symbol57$$ld-linux-x86-64.so.2
         r10 = 0x0000000000000846
         r11 = 0x00007ffff7a2d740  libc.so.6`__libc_start_main at libc-start.c:134
         r12 = 0x0000000000400370  test`_start
         r13 = 0x00007fffffffdcc0
         r14 = 0x0000000000000000
         r15 = 0x0000000000000000
         rip = 0x0000000000400460  test`f2 at test.c:4
      rflags = 0x0000000000000246
          cs = 0x0000000000000033
          fs = 0x0000000000000000
          gs = 0x0000000000000000
          ss = 0x000000000000002b
          ds = 0x0000000000000000
          es = 0x0000000000000000
  ...

So, parameter 'k' does not have value 1, it is wrong. After applying the patch the value will be optimized out.
C code of the test case can be found as a comment in the attached llvm test.


Repository:
  rL LLVM

https://reviews.llvm.org/D51968