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[ARM] [ELF] Fix ARMMaterializeGV for Indirect calls 

Recent shouldAssumeDSOLocal changes (introduced by 961f31d8ad)
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
This commit is contained in:
Adhemerval Zanella 2021-01-26 15:20:26 -03:00
parent f9d7f77267
commit dad55c2218
2 changed files with 6 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
llvm/lib/Target/ARM/ARMFastISel.cpp
View File

@ -606,7 +606,9 @@ unsigned ARMFastISel::ARMMaterializeGV(const GlobalValue *GV, MVT VT) {
}
}
if (IsIndirect) {
if ((Subtarget->isTargetELF() && Subtarget->isGVInGOT(GV)) ||
(Subtarget->isTargetMachO() && IsIndirect) ||
Subtarget->genLongCalls()) {
MachineInstrBuilder MIB;
unsigned NewDestReg = createResultReg(TLI.getRegClassFor(VT));
if (isThumb2)

6
llvm/test/CodeGen/ARM/fast-isel-intrinsic.ll
View File

@ -61,8 +61,8 @@ define void @t2() nounwind ssp {
; ARM-ELF: movw [[REG1:r[0-9]+]], :lower16:temp
; ARM-ELF: movt [[REG1]], :upper16:temp
; ARM-ELF: add [[REG1]], r1, #4
; ARM-ELF-NEXT: add r1, r1, #16
; ARM-ELF: add r0, [[REG1]], #4
; ARM-ELF-NEXT: add r1, [[REG1]], #16
; ARM: movw r2, #17
; ARM: bl {{_?}}memcpy
@ -106,7 +106,7 @@ define void @t3() nounwind ssp {
; ARM-ELF: movw [[REG0:r[0-9]+]], :lower16:temp
; ARM-ELF: movt [[REG0]], :upper16:temp
; ARM-ELF: add [[REG0]], r1, #4
; ARM-ELF: add r0, [[REG0]], #4
; ARM-ELF-NEXT: add r1, r1, #16
; ARM: movw r2, #10