| Issue |
86717
|
| Summary |
AAarch64 backend turning OOB insertelement into OOB store
|
| Labels |
backend:AArch64,
llvm:codegen,
miscompilation
|
| Assignees |
|
| Reporter |
regehr
|
this function:
```llvm
define <16 x i8> @f(i32 %0) {
%2 = sub nuw i32 1, %0
%3 = insertelement <16 x i8> zeroinitializer, i8 3, i32 %2
ret <16 x i8> %3
}
```
is getting lowered to this AArch64:
```
_f: ; @f
sub sp, sp, #16
movi.2d v0, #0000000000000000
mov w8, #1 ; =0x1
mov x9, sp
sub w8, w8, w0
mov w10, #3 ; =0x3
orr x8, x9, x8
str q0, [sp]
strb w10, [x8]
ldr q0, [sp], #16
ret
```
I believe this is incorrect. if we pass an argument such as 5 into this function, then we get -4 put into w8, resulting in a nonsense address after we orr -4 with sp.
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