| Issue |
180396
|
| Summary |
[ARM][Backend] Stack Overflow in AArch64 Backend on QNX
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
yizhew-kk
|
Hi, I hit a `llc` crashes with SIGSEGV on QNX/aarch64 backend. Root cause: PR #172942 changed `AArch64Subtarget` from heap to stack allocation, causing stack overflow on platforms with smaller default stack sizes. (Reverting PR #172942's changes to `AArch64AsmPrinter.cpp` resolves the crash.)
## Reproducer
**test.ll**:
```llvm
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128-Fn32"
@g1 = internal global { i64, i64, i64, ptr, i64, ptr, i64, i64, ptr } undef
@g2 = internal constant [4 x i8] c"foo\00"
@g3 = internal constant [1 x { ptr, i64, i64, ptr, ptr, ptr, ptr, ptr }] [{ ptr, i64, i64, ptr, ptr, ptr, ptr, ptr } { ptr @g2, i64 0, i64 0, ptr null, ptr null, ptr @func1, ptr null, ptr null }]
@g4 = constant { i64, i64, i64, ptr, i64, ptr, i64, i64, ptr } { i64 2, i64 0, i64 0, ptr null, i64 64, ptr @g3, i64 1, i64 1, ptr @func2 }
define internal i32 @func1(ptr %0, ptr %1, ptr %2, ptr %3, ptr %4) {
br i1 false, label %6, label %7
6:
br label %7
7:
%8 = phi i64 [ 8, %6 ], [ 0, %5 ]
%9 = add i64 %8, 8
%10 = urem i64 %9, 8
%11 = icmp ugt i64 %10, 0
br i1 %11, label %12, label %15
12:
%13 = add i64 %9, 8
%14 = sub i64 %13, %10
br label %15
15:
%16 = phi i64 [ %14, %12 ], [ %9, %7 ]
%17 = add i64 %16, 8
%18 = urem i64 %17, 4
%19 = icmp ugt i64 %18, 0
br i1 %19, label %20, label %21
20:
br label %21
21:
ret i32 0
}
define i32 @func2(ptr %0, ptr %1, i32 %2, ptr %3) {
%5 = alloca i32, align 4
%6 = icmp eq i32 %2, 0
br i1 %6, label %7, label %8
7:
ret i32 1
8:
%9 = getelementptr { i64, ptr, ptr, ptr, ptr, ptr, ptr }, ptr %0, i32 0, i32 6
%10 = load ptr, ptr %9, align 8
%11 = call i32 %10(ptr %1, i32 16, ptr %5)
%12 = load { i64, i64, i64, ptr, i64, ptr, i64, i64, ptr }, ptr @g4, align 8
store { i64, i64, i64, ptr, i64, ptr, i64, i64, ptr } %12, ptr @g1, align 8
store i64 0, ptr getelementptr inbounds nuw (i8, ptr @g1, i64 16), align 8
store ptr @g1, ptr %3, align 8
ret i32 0
}
!llvm.module.flags = !{!0}
!0 = !{i32 2, !"Debug Info Version", i32 3}
```
```bash
# On QNX/aarch64:
./llc test.ll -filetype=obj -o test.o
# SIGSEGV
```
## Crash Analysis
```
(gdb) bt
#0 AArch64AsmPrinter::emitHwasanMemaccessSymbols(llvm::Module&)
#1 AArch64AsmPrinter::emitEndOfAsmFile(llvm::Module&)
#2 llvm::AsmPrinter::doFinalization(llvm::Module&)
(gdb) x/i $pc
=> stp x29, x30, [sp, #64] ; crash at function prologue
(gdb) x/gx $sp
Cannot access memory at address 0x... ; stack overflow
```
My internal fork tracks upstream main (around mid-Dec 2025). If this issue has been already fixed please point me the fix commit. Thanks!
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