[WebAssembly] Implement __builtin_wasm_tls_base intrinsic

Summary:
Add `__builtin_wasm_tls_base` so that LeakSanitizer can find the thread-local
block and scan through it for memory leaks.

Reviewers: tlively, aheejin, sbc100

Subscribers: dschuff, jgravelle-google, hiraditya, sunfish, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D64900

llvm-svn: 366475

3 files changed, 32 insertions, 0 deletions

diff --git a/llvm/include/llvm/IR/IntrinsicsWebAssembly.td b/llvm/include/llvm/IR/IntrinsicsWebAssembly.td
index 1b892727547..0dc68a5e0c0 100644
--- a/llvm/include/llvm/IR/IntrinsicsWebAssembly.td
+++ b/llvm/include/llvm/IR/IntrinsicsWebAssembly.td
@@ -133,4 +133,9 @@ def int_wasm_tls_size :
             [],
             [IntrNoMem, IntrSpeculatable]>;
 
+def int_wasm_tls_base :
+  Intrinsic<[llvm_ptr_ty],
+            [],
+            [IntrReadMem]>;
+
 } // TargetPrefix = "wasm"
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyISelDAGToDAG.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyISelDAGToDAG.cpp
index 26339eaef37..e57e194fdde 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyISelDAGToDAG.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyISelDAGToDAG.cpp
@@ -227,6 +227,23 @@ void WebAssemblyDAGToDAGISel::Select(SDNode *Node) {
     }
     break;
   }
+  case ISD::INTRINSIC_W_CHAIN: {
+    unsigned IntNo = cast<ConstantSDNode>(Node->getOperand(1))->getZExtValue();
+    switch (IntNo) {
+    case Intrinsic::wasm_tls_base: {
+      MVT PtrVT = TLI->getPointerTy(CurDAG->getDataLayout());
+      assert(PtrVT == MVT::i32 && "only wasm32 is supported for now");
+
+      MachineSDNode *TLSBase = CurDAG->getMachineNode(
+          WebAssembly::GLOBAL_GET_I32, DL, MVT::i32,
+          CurDAG->getTargetExternalSymbol("__tls_base", PtrVT),
+          Node->getOperand(0));
+      ReplaceNode(Node, TLSBase);
+      return;
+    }
+    }
+    break;
+  }
 
   default:
     break;
diff --git a/llvm/test/CodeGen/WebAssembly/tls-general-dynamic.ll b/llvm/test/CodeGen/WebAssembly/tls-general-dynamic.ll
index 3f6d9d325c6..975e2ce5569 100644
--- a/llvm/test/CodeGen/WebAssembly/tls-general-dynamic.ll
+++ b/llvm/test/CodeGen/WebAssembly/tls-general-dynamic.ll
@@ -75,6 +75,15 @@ define i32 @tls_size() {
   ret i32 %1
 }
 
+; CHECK-LABEL: tls_base:
+; CHECK-NEXT: .functype tls_base () -> (i32)
+define i8* @tls_base() {
+; CHECK-NEXT: global.get __tls_base
+; CHECK-NEXT: return
+  %1 = call i8* @llvm.wasm.tls.base()
+  ret i8* %1
+}
+
 ; CHECK: .type tls,@object
 ; TLS-NEXT: .section .tbss.tls,"",@
 ; NO-TLS-NEXT: .section .bss.tls,"",@
@@ -84,3 +93,4 @@ define i32 @tls_size() {
 @tls = internal thread_local global i32 0
 
 declare i32 @llvm.wasm.tls.size.i32()
+declare i8* @llvm.wasm.tls.base()