[llvm] Fix getShadowAddress computation (PR #162864)

[via llvm-commits]

https://github.com/anoopkg6 updated https://github.com/llvm/llvm-project/pull/162864

>From 0f3144206fbd5b6c7a27f8818448901618c3a7a1 Mon Sep 17 00:00:00 2001
From: anoopkg6 <anoopkg6 at github.com>
Date: Fri, 10 Oct 2025 16:46:49 +0200
Subject: [PATCH] Fix getShadowAddress computation by adding ShadowBase if it
 is not zero.

---
 llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
index 5ba2167859490..cc53ec2c0f2f3 100644
--- a/llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
@@ -1957,8 +1957,12 @@ Value *DataFlowSanitizer::getShadowAddress(Value *Addr,
 Value *DataFlowSanitizer::getShadowAddress(Value *Addr,
                                            BasicBlock::iterator Pos) {
   IRBuilder<> IRB(Pos->getParent(), Pos);
-  Value *ShadowOffset = getShadowOffset(Addr, IRB);
-  return getShadowAddress(Addr, Pos, ShadowOffset);
+  Value *ShadowAddr = getShadowOffset(Addr, IRB);
+  uint64_t ShadowBase = MapParams->ShadowBase;
+  if (ShadowBase != 0)
+    ShadowAddr =
+        IRB.CreateAdd(ShadowAddr, ConstantInt::get(IntptrTy, ShadowBase));
+  return getShadowAddress(Addr, Pos, ShadowAddr);
 }
 
 Value *DFSanFunction::combineShadowsThenConvert(Type *T, Value *V1, Value *V2,