[PATCH] D129505: [GISel] Check useLoadStackGuardNode() before generating LOAD_STACK_GUARD

[Kai Nacke via Phabricator via llvm-commits]

Kai created this revision.
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When lowering `llvm::stackprotect` intrinsic, the SDAG implementation
checks function `useLoadStackGuardNode()` to either create a
`LOAD_STACK_GUARD` node 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.


https://reviews.llvm.org/D129505

Files:
  llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
  llvm/test/CodeGen/PowerPC/GlobalISel/ppc-irtranslator-stackprotect.ll


Index: llvm/test/CodeGen/PowerPC/GlobalISel/ppc-irtranslator-stackprotect.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/PowerPC/GlobalISel/ppc-irtranslator-stackprotect.ll
@@ -0,0 +1,49 @@
+; RUN: llc -verify-machineinstrs -mtriple=ppc64le-linux %s -global-isel -stop-after=irtranslator -o - | FileCheck %s --check-prefix=LINUX
+; RUN: llc -verify-machineinstrs -mtriple=ppc64le-openbsd %s -global-isel -stop-after=irtranslator -o - | FileCheck %s --check-prefix=OPENBSD
+
+
+; The stack guard on Linux
+ at __stack_chk_guard = external global ptr
+
+; The stack guard on OpenBSD
+ at __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
+}
Index: llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
===================================================================
--- llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
+++ llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
@@ -2076,9 +2076,14 @@
     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);


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