[llvm-branch-commits] [llvm] release/22.x: [SafeStack] Fix crashing with scalable TypeSizes (#180547) (PR #203306)

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llvmorg-github-actions[bot] wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-aarch64

Author: llvmbot

<details>
<summary>Changes</summary>

Backport 537f3d3a7588d226b86590f97c4401107585e1ce

Requested by: @<!-- -->brad0

---
Full diff: https://github.com/llvm/llvm-project/pull/203306.diff


2 Files Affected:

- (modified) llvm/lib/CodeGen/SafeStack.cpp (+12) 
- (added) llvm/test/CodeGen/AArch64/safestack_scalar.ll (+17) 


``````````diff
diff --git a/llvm/lib/CodeGen/SafeStack.cpp b/llvm/lib/CodeGen/SafeStack.cpp
index 1c109a1f9fed1..33ffd94e4f8f0 100644
--- a/llvm/lib/CodeGen/SafeStack.cpp
+++ b/llvm/lib/CodeGen/SafeStack.cpp
@@ -176,6 +176,8 @@ class SafeStack {
 
   bool IsMemIntrinsicSafe(const MemIntrinsic *MI, const Use &U,
                           const Value *AllocaPtr, uint64_t AllocaSize);
+  bool IsAccessSafe(Value *Addr, TypeSize Size, const Value *AllocaPtr,
+                    uint64_t AllocaSize);
   bool IsAccessSafe(Value *Addr, uint64_t Size, const Value *AllocaPtr,
                     uint64_t AllocaSize);
 
@@ -206,6 +208,16 @@ uint64_t SafeStack::getStaticAllocaAllocationSize(const AllocaInst* AI) {
   return Size;
 }
 
+bool SafeStack::IsAccessSafe(Value *Addr, TypeSize AccessSize,
+                             const Value *AllocaPtr, uint64_t AllocaSize) {
+  if (AccessSize.isScalable()) {
+    // In case we don't know the size at compile time we cannot verify if the
+    // access is safe.
+    return false;
+  }
+  return IsAccessSafe(Addr, AccessSize.getFixedValue(), AllocaPtr, AllocaSize);
+}
+
 bool SafeStack::IsAccessSafe(Value *Addr, uint64_t AccessSize,
                              const Value *AllocaPtr, uint64_t AllocaSize) {
   const SCEV *AddrExpr = SE.getSCEV(Addr);
diff --git a/llvm/test/CodeGen/AArch64/safestack_scalar.ll b/llvm/test/CodeGen/AArch64/safestack_scalar.ll
new file mode 100644
index 0000000000000..f8675e7a709d3
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/safestack_scalar.ll
@@ -0,0 +1,17 @@
+; RUN: llc -mtriple=aarch64-linux-gnu -stop-after=safe-stack < %s | FileCheck %s
+
+define void @test_sve() safestack {
+entry:
+  %v = alloca <vscale x 16 x i8>, align 16
+  %val = load <vscale x 16 x i8>, ptr %v
+  ret void
+}
+
+; CHECK-LABEL: define void @test_sve(
+; CHECK: [[USP:%.*]] = load ptr, ptr @__safestack_unsafe_stack_ptr
+; CHECK: [[USST:%.*]] = getelementptr i8, ptr [[USP]], i32 -16
+; CHECK: store ptr [[USST]], ptr @__safestack_unsafe_stack_ptr
+; CHECK: [[PTR:%.*]] = getelementptr i8, ptr [[USP]], i32 -16
+; CHECK: load <vscale x 16 x i8>, ptr [[PTR]]
+; CHECK: store ptr [[USP]], ptr @__safestack_unsafe_stack_ptr
+; CHECK: ret void

``````````

</details>


https://github.com/llvm/llvm-project/pull/203306