[PATCH] D27296: Don't assume mingw is providing SSP functions

[Martin Storsjö via Phabricator via llvm-commits]

mstorsjo added a comment.

In https://reviews.llvm.org/D27296#1041079, @vchuravy wrote:

> @mstorsjo Thanks for your feedback. Might I ask how you tested this? Did you simply compiled clang as well and run the testsuite?


I tested compiling a minimal trivial C file with clang:

  $ cat ssp.c
  void other(void* ptr);
  void func(void) {
  	char c;
  	other(&c);
  }
  $ clang -target x86_64-w64-mingw32 -S -o - ssp.c -O2 -fstack-protector-strong

It can also easily be reproduced with plain IR and llc:

  $ cat ssp.ll
  define dso_local void @func() sspstrong {
  entry:
    %c = alloca i8, align 1
    call void @llvm.lifetime.start.p0i8(i64 1, i8* nonnull %c) 
    call void @other(i8* nonnull %c) 
    call void @llvm.lifetime.end.p0i8(i64 1, i8* nonnull %c) 
    ret void
  }
  declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture) 
  declare dso_local void @other(i8*) 
  declare void @llvm.lifetime.end.p0i8(i64, i8* nocapture) 
  $ llc -mtriple x86_64-w64-mingw32 ssp.ll



> Yes this should only be an issue when `StackProtectStrong` is set on functions, which Julia does in certain build configurations (we could also not do that on Windows, but I would rather fix the issue upstream)

Ok, well if you are setting this you will need to have GCC's `libssp` available for linking as well (I presume you have that and that's what you intend?), since the example above should produce references to `__stack_chk_guard` and `__stack_chk_fail` if it didn't error out during compilation.


Repository:
  rL LLVM

https://reviews.llvm.org/D27296