[PATCH] D73526: [SafeStack][DebugInfo] Insert DW_OP_deref in correct location

[Bjorn Pettersson via Phabricator via llvm-commits]

bjope added a comment.

In D73526#1857628 <https://reviews.llvm.org/D73526#1857628>, @leonardchan wrote:

> In D73526#1857223 <https://reviews.llvm.org/D73526#1857223>, @bjope wrote:
>
> > This broke some of our downstream tests using vla:s. Those are compiled from C and executed in gdb. What happens is that DW_OP_deref disappears and then the debugger prints the wrong value.
>
>
> Separate from my previous comment, would it be possible to share your downstream test for debugging, or at least a "sanitized" version safe for upstream?


As I wrote earlier, this is seen when running `llc -O1 -mtriple=x86_64-unknown-linux-gnu -o - test/DebugInfo/X86/safestack-deref.ll`.

If also adding `-print-after-all` you'll find

  DBG_VALUE %2:gr64, 0, !"value", !DIExpression(DW_OP_constu, 8, DW_OP_minus), debug-location !7; /tmp/test3.cpp:8:5 line no:8 indirect

before regalloc, and after you get

  DBG_VALUE $rbx, $noreg, !"value", !DIExpression(DW_OP_constu, 8, DW_OP_minus), debug-location !7; /tmp/test3.cpp:8:5 line no:8

so LiveDebugVariables simply drops the "indirect" information.

Is that good enough as a test case?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D73526/new/

https://reviews.llvm.org/D73526