[PATCH] D135488: [codegen][WIP] Display stack layouts in console

Wed Oct 12 19:35:46 PDT 2022

nickdesaulniers added a comment.

Playing around with `llvm-dwarfdump` today, I think I found an interesting example:

Consider the following DWARF DIE:

  0x00017e5e:           DW_TAG_variable
                          DW_AT_location  (0x00002144:
                             [0x00000000000007c4, 0x00000000000007c8): DW_OP_reg8 W8
                             [0x00000000000007c8, 0x00000000000007d8): DW_OP_breg31 WSP+48
                             [0x00000000000007d8, 0x00000000000007e8): DW_OP_lit0, DW_OP_stack_value)
                          DW_AT_abstract_origin   (0x00016776 "sp_el0")

How I read this: `sp_el0` is in `w8` while the program counter is from 0x7c4 until 0x7c8, at which point it's spilled to `wsp+48` until the program counter reaches 0x7e8 at which point (this gets hazy, but https://dwarfstd.org/ShowIssue.php?issue=100831.1 is worth a read) the value is "rematerializable?"

Though I also see DW_AT_location attributes getting pretty crazy.

Repository:
  rG LLVM Github Monorepo

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https://reviews.llvm.org/D135488