[llvm] arm64_32: extend @llvm.stackguard call to in-DAG 64-bits before handing off (PR #77318)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-selectiondag

@llvm/pr-subscribers-backend-aarch64

Author: Tim Northover (TNorthover)

<details>
<summary>Changes</summary>

arm64_32 pointers are 64-bits in the DAG, so we need to extend the result of loading the cookie when building the DAG.

Most callers of `getLoadStackGuard` feed immediately into a comparison or other use where where the size it already returns is fine, but this one gets put into the canonical value mapping table so it needs fixing to what other nodes are expecting for `ptr` type.

Should also fix some issues in Swift CI.

---
Full diff: https://github.com/llvm/llvm-project/pull/77318.diff


2 Files Affected:

- (modified) llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp (+3-1) 
- (modified) llvm/test/CodeGen/AArch64/arm64_32.ll (+14) 


``````````diff
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 1ae682eaf2511c..e772697828f1d7 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -6928,11 +6928,13 @@ void SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I,
   case Intrinsic::stackguard: {
     MachineFunction &MF = DAG.getMachineFunction();
     const Module &M = *MF.getFunction().getParent();
+    EVT PtrTy = TLI.getValueType(DAG.getDataLayout(), I.getType());
     SDValue Chain = getRoot();
     if (TLI.useLoadStackGuardNode()) {
       Res = getLoadStackGuard(DAG, sdl, Chain);
+      if (Res.getValueType() != PtrTy)
+        Res = DAG.getPtrExtOrTrunc(Res, sdl, PtrTy);
     } else {
-      EVT PtrTy = TLI.getValueType(DAG.getDataLayout(), I.getType());
       const Value *Global = TLI.getSDagStackGuard(M);
       Align Align = DAG.getDataLayout().getPrefTypeAlign(Global->getType());
       Res = DAG.getLoad(PtrTy, sdl, Chain, getValue(Global),
diff --git a/llvm/test/CodeGen/AArch64/arm64_32.ll b/llvm/test/CodeGen/AArch64/arm64_32.ll
index 16e2e84a14329d..716fdd6eac15c6 100644
--- a/llvm/test/CodeGen/AArch64/arm64_32.ll
+++ b/llvm/test/CodeGen/AArch64/arm64_32.ll
@@ -759,5 +759,19 @@ define void @test_bzero(i64 %in)  {
 
 declare void @llvm.memset.p0.i32(ptr nocapture writeonly, i8, i32, i1)
 
+define i1 @test_stackguard(ptr %p1) {
+; CHECK-LABEL: test_stackguard:
+; CHECK: adrp x[[TMP:[0-9]+]], ___stack_chk_guard at GOTPAGE
+; CHECK: ldr [[GUARD:w[0-9]+]], [x[[TMP]], ___stack_chk_guard at GOTPAGEOFF]
+; CHECK: cmp [[GUARD]], w
+
+  %p2 = call ptr @llvm.stackguard()
+  %res = icmp ne ptr %p2, %p1
+  ret i1 %res
+}
+declare ptr @llvm.stackguard()
+ at __stack_chk_guard = external global i32
+
+
 !llvm.module.flags = !{!0}
 !0 = !{i32 7, !"PIC Level", i32 2}

``````````

</details>


https://github.com/llvm/llvm-project/pull/77318