[all-commits] [llvm/llvm-project] dad55c: [ARM] [ELF] Fix ARMMaterializeGV for Indirect calls

[Adhemerval Zanella via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: dad55c22182e267c5baaeec9754039081b052dba
      https://github.com/llvm/llvm-project/commit/dad55c22182e267c5baaeec9754039081b052dba
  Author: Adhemerval Zanella <adhemerval.zanella at linaro.org>
  Date:   2021-01-26 (Tue, 26 Jan 2021)

  Changed paths:
    M llvm/lib/Target/ARM/ARMFastISel.cpp
    M llvm/test/CodeGen/ARM/fast-isel-intrinsic.ll

  Log Message:
  -----------
  [ARM] [ELF] Fix ARMMaterializeGV for Indirect calls

Recent shouldAssumeDSOLocal changes (introduced by 961f31d8ad14c66)
do not take in consideration the relocation model anymore.  The ARM
fast-isel pass uses the function return to set whether a global symbol
is loaded indirectly or not, and without the expected information
llvm now generates an extra load for following code:

```
$ cat test.ll
@__asan_option_detect_stack_use_after_return = external global i32
define dso_local i32 @main(i32 %argc, i8** %argv) #0 {
entry:
  %0 = load i32, i32* @__asan_option_detect_stack_use_after_return,
align 4
  %1 = icmp ne i32 %0, 0
  br i1 %1, label %2, label %3

2:
  ret i32 0

3:
  ret i32 1
}

attributes #0 = { noinline optnone }

$ lcc test.ll -o -
[...]
main:
        .fnstart
[...]
        movw    r0, :lower16:__asan_option_detect_stack_use_after_return
        movt    r0, :upper16:__asan_option_detect_stack_use_after_return
        ldr     r0, [r0]
        ldr     r0, [r0]
        cmp     r0, #0
[...]
```

And without 'optnone' it produces:
```
[...]
main:
        .fnstart
[...]
        movw    r0, :lower16:__asan_option_detect_stack_use_after_return
        movt    r0, :upper16:__asan_option_detect_stack_use_after_return
        ldr     r0, [r0]
        clz     r0, r0
        lsr     r0, r0, #5
        bx      lr

[...]
```

This triggered a lot of invalid memory access in sanitizers for
arm-linux-gnueabihf.  I checked this patch both a stage1 built with
gcc and a stage2 bootstrap and it fixes all the Linux sanitizers
issues.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D95379