[llvm] c180e24 - Fix crash lowering stack guard on OpenBSD/aarch64. (#125416)

[via llvm-commits]

Author: 3405691582
Date: 2025-03-31T09:17:55-07:00
New Revision: c180e249d0013474d502cd779ec65b33cf7e9468

URL: https://github.com/llvm/llvm-project/commit/c180e249d0013474d502cd779ec65b33cf7e9468
DIFF: https://github.com/llvm/llvm-project/commit/c180e249d0013474d502cd779ec65b33cf7e9468.diff

LOG: Fix crash lowering stack guard on OpenBSD/aarch64. (#125416)

TargetLoweringBase::getIRStackGuard refers to a platform-specific guard
variable. Before this change, TargetLoweringBase::getSDagStackGuard only
referred to a different variable.

This means that SelectionDAGBuilder's getLoadStackGuard does not get
memory operands. However, AArch64InstrInfo::expandPostRAPseudo assumes
that the passed MachineInstr has nonzero memoperands, causing a
segfault.

We have two possible options here: either disabling the LOAD_STACK_GUARD
node entirely in AArch64TargetLowering::useLoadStackGuardNode or just
making the platform-specific values match across TargetLoweringBase.
Here, we try the latter.

Added: 
    

Modified: 
    llvm/lib/CodeGen/TargetLoweringBase.cpp

Removed: 
    


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diff  --git a/llvm/lib/CodeGen/TargetLoweringBase.cpp b/llvm/lib/CodeGen/TargetLoweringBase.cpp
index 3da66a4113334..91ae9040581ee 100644
--- a/llvm/lib/CodeGen/TargetLoweringBase.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringBase.cpp
@@ -2005,6 +2005,9 @@ void TargetLoweringBase::insertSSPDeclarations(Module &M) const {
 // Currently only support "standard" __stack_chk_guard.
 // TODO: add LOAD_STACK_GUARD support.
 Value *TargetLoweringBase::getSDagStackGuard(const Module &M) const {
+  if (getTargetMachine().getTargetTriple().isOSOpenBSD()) {
+    return M.getNamedValue("__guard_local");
+  }
   return M.getNamedValue("__stack_chk_guard");
 }