From 42f7364fcb239a4d57b54a20244a1564314455a8 Mon Sep 17 00:00:00 2001
From: Kai Nacke <kai.peter.nacke@ibm.com>
Date: Mon, 11 Jul 2022 14:32:42 -0400
Subject: [PATCH] [GISel] Check useLoadStackGuardNode() before generating
 LOAD_STACK_GUARD

When lowering llvm::stackprotect intrinsic, the SDAG implementation
checks useLoadStackGuardNode() to either create a LOAD_STACK_GUARD or use
the first argument of the intrinsic. This check is not present in the
IRTranslator, which results in always generating a LOAD_STACK_GUARD even
if the target does not support it.

Reviewed By: arsenm

Differential Revision: https://reviews.llvm.org/D129505
---
 llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp       |  9 +++-
 .../GlobalISel/ppc-irtranslator-stackprotect.ll    | 49 ++++++++++++++++++++++
 2 files changed, 56 insertions(+), 2 deletions(-)
 create mode 100644 llvm/test/CodeGen/PowerPC/GlobalISel/ppc-irtranslator-stackprotect.ll

diff --git a/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp b/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
index dcd17fe..947facc 100644
--- a/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
@@ -2076,9 +2076,14 @@ bool IRTranslator::translateKnownIntrinsic(const CallInst &CI, Intrinsic::ID ID,
     getStackGuard(getOrCreateVReg(CI), MIRBuilder);
     return true;
   case Intrinsic::stackprotector: {
+    const TargetLowering &TLI = *MF->getSubtarget().getTargetLowering();
     LLT PtrTy = getLLTForType(*CI.getArgOperand(0)->getType(), *DL);
-    Register GuardVal = MRI->createGenericVirtualRegister(PtrTy);
-    getStackGuard(GuardVal, MIRBuilder);
+    Register GuardVal;
+    if (TLI.useLoadStackGuardNode()) {
+      GuardVal = MRI->createGenericVirtualRegister(PtrTy);
+      getStackGuard(GuardVal, MIRBuilder);
+    } else
+      GuardVal = getOrCreateVReg(*CI.getArgOperand(0)); // The guard's value.
 
     AllocaInst *Slot = cast<AllocaInst>(CI.getArgOperand(1));
     int FI = getOrCreateFrameIndex(*Slot);
diff --git a/llvm/test/CodeGen/PowerPC/GlobalISel/ppc-irtranslator-stackprotect.ll b/llvm/test/CodeGen/PowerPC/GlobalISel/ppc-irtranslator-stackprotect.ll
new file mode 100644
index 0000000..ce19688
--- /dev/null
+++ b/llvm/test/CodeGen/PowerPC/GlobalISel/ppc-irtranslator-stackprotect.ll
@@ -0,0 +1,49 @@
+; RUN: llc -verify-machineinstrs -mtriple=ppc64le-unknown-linux %s -global-isel -stop-after=irtranslator -o - | FileCheck %s --check-prefix=LINUX
+; RUN: llc -verify-machineinstrs -mtriple=ppc64le-unknown-openbsd %s -global-isel -stop-after=irtranslator -o - | FileCheck %s --check-prefix=OPENBSD
+
+
+; The stack guard on Linux
+@__stack_chk_guard = external global ptr
+
+; The stack guard on OpenBSD
+@__guard_local = external hidden global ptr
+
+declare void @llvm.stackprotector(ptr, ptr)
+
+; LINUX-LABEL: name: test_stack_guard_linux
+
+; LINUX: frameInfo:
+; LINUX: stackProtector:  '%stack.0.StackGuardSlot'
+
+; LINUX: stack:
+; LINUX:  - { id: 0, name: StackGuardSlot,  type: default, offset: 0, size: 8, alignment: 8,
+; LINUX-NOT: id: 1
+
+; LINUX: [[GUARD_SLOT:%[0-9]+]]:_(p0) = G_FRAME_INDEX %stack.0.StackGuardSlot
+; LINUX: [[GUARD:%[0-9]+]]:g8rc(p0) = LOAD_STACK_GUARD :: (dereferenceable invariant load (p0) from @__stack_chk_guard)
+; LINUX: G_STORE [[GUARD]](p0), [[GUARD_SLOT]](p0) :: (volatile store (p0) into %stack.0.StackGuardSlot)
+define void @test_stack_guard_linux() {
+  %StackGuardSlot = alloca ptr
+  call void @llvm.stackprotector(ptr undef, ptr %StackGuardSlot)
+  ret void
+}
+
+; OPENBSD-LABEL: name: test_stack_guard_openbsd
+
+; OPENBSD: frameInfo:
+; OPENBSD: stackProtector:  '%stack.0.StackGuardSlot'
+
+; OPENBSD: stack:
+; OPENBSD:  - { id: 0, name: StackGuardSlot,  type: default, offset: 0, size: 8, alignment: 8,
+; OPENBSD-NOT: id: 1
+
+; OPENBSD: [[GUARD_LOCAL:%[0-9]+]]:_(p0) = G_GLOBAL_VALUE @__guard_local
+; OPENBSD: [[GUARD_SLOT:%[0-9]+]]:_(p0) = G_FRAME_INDEX %stack.0.StackGuardSlot
+; OPENBSD: [[GUARD:%[0-9]+]]:_(p0) = G_LOAD [[GUARD_LOCAL]](p0) :: (dereferenceable load (p0) from @__guard_local)
+; OPENBSD: G_STORE [[GUARD]](p0), [[GUARD_SLOT]](p0) :: (volatile store (p0) into %stack.0.StackGuardSlot)
+define void @test_stack_guard_openbsd() {
+  %StackGuardSlot = alloca i8*
+  %StackGuard = load ptr, ptr @__guard_local
+  call void @llvm.stackprotector(ptr %StackGuard, ptr %StackGuardSlot)
+  ret void
+}
-- 
2.7.4