[llvm] [ASan] Prevent assert from scalable vectors in FunctionStackPoisoner. (PR #155357)

[David Green via llvm-commits]

https://github.com/davemgreen updated https://github.com/llvm/llvm-project/pull/155357

>From e0e74ae1e2bb55976ec7ef7537d43177ef077253 Mon Sep 17 00:00:00 2001
From: David Green <david.green at arm.com>
Date: Wed, 27 Aug 2025 08:57:46 +0100
Subject: [PATCH] [ASan] Protect against scalable vectors in
 FunctionStackPoisoner.

This has recently started causing 'Invalid size request on a scalable vector.'
---
 .../Instrumentation/AddressSanitizer.cpp      |  4 ++-
 .../AddressSanitizer/asan-scalable-vector.ll  | 27 +++++++++++++++++++
 2 files changed, 30 insertions(+), 1 deletion(-)
 create mode 100644 llvm/test/Instrumentation/AddressSanitizer/asan-scalable-vector.ll

diff --git a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index 50258af5e26c3..42c3d4a4f4c46 100644
--- a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -1219,7 +1219,9 @@ struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
 
     std::optional<TypeSize> Size = AI->getAllocationSize(AI->getDataLayout());
     // Check that size is known and can be stored in IntptrTy.
-    if (!Size || !ConstantInt::isValueValidForType(IntptrTy, *Size))
+    // TODO: Add support for scalable vectors if possible.
+    if (!Size || Size->isScalable() ||
+        !ConstantInt::isValueValidForType(IntptrTy, *Size))
       return;
 
     bool DoPoison = (ID == Intrinsic::lifetime_end);
diff --git a/llvm/test/Instrumentation/AddressSanitizer/asan-scalable-vector.ll b/llvm/test/Instrumentation/AddressSanitizer/asan-scalable-vector.ll
new file mode 100644
index 0000000000000..6a841f2d399c0
--- /dev/null
+++ b/llvm/test/Instrumentation/AddressSanitizer/asan-scalable-vector.ll
@@ -0,0 +1,27 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt < %s -passes='asan<use-after-scope>' -S | FileCheck %s
+
+define void @test() #1 {
+; CHECK-LABEL: define void @test(
+; CHECK-SAME: ) #[[ATTR0:[0-9]+]] {
+; CHECK-NEXT:  [[ENTRY:.*:]]
+; CHECK-NEXT:    [[CTX_PG:%.*]] = alloca <vscale x 16 x i1>, align 2
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(ptr [[CTX_PG]])
+; CHECK-NEXT:    [[TMP0:%.*]] = load i8, ptr inttoptr (i64 17592186044416 to ptr), align 1
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp ne i8 [[TMP0]], 0
+; CHECK-NEXT:    br i1 [[TMP1]], label %[[BB2:.*]], label %[[BB3:.*]]
+; CHECK:       [[BB2]]:
+; CHECK-NEXT:    call void @__asan_report_store8(i64 0) #[[ATTR4:[0-9]+]]
+; CHECK-NEXT:    unreachable
+; CHECK:       [[BB3]]:
+; CHECK-NEXT:    store ptr [[CTX_PG]], ptr null, align 8
+; CHECK-NEXT:    ret void
+;
+entry:
+  %ctx_pg = alloca <vscale x 16 x i1>, align 2
+  call void @llvm.lifetime.start.p0(ptr %ctx_pg)
+  store ptr %ctx_pg, ptr null, align 8
+  ret void
+}
+
+attributes #1 = { sanitize_address }