[llvm] ce1b24c - [IRBuilder] Handle constexpr-bitcast for IRBuilder::CreateThreadLocalAddress

[Chuanqi Xu via llvm-commits]

Author: Chuanqi Xu
Date: 2022-08-03T11:13:49+08:00
New Revision: ce1b24cca886eb9f05e252f399059167473d0ba3

URL: https://github.com/llvm/llvm-project/commit/ce1b24cca886eb9f05e252f399059167473d0ba3
DIFF: https://github.com/llvm/llvm-project/commit/ce1b24cca886eb9f05e252f399059167473d0ba3.diff

LOG: [IRBuilder] Handle constexpr-bitcast for IRBuilder::CreateThreadLocalAddress

In case that opaque pointers not enabled, there may be some constexpr
bitcast uses for thread local variables and the design of llvm allow
people to sink constant arbitrarily. This breaks the assumption of
IRBuilder::CreateThreadLocalAddress. This patch tries to handle the
case.

Added: 
    

Modified: 
    llvm/lib/IR/IRBuilder.cpp
    llvm/unittests/IR/IRBuilderTest.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/IR/IRBuilder.cpp b/llvm/lib/IR/IRBuilder.cpp
index 469bd4db57c29..1dcf5fb0800dd 100644
--- a/llvm/lib/IR/IRBuilder.cpp
+++ b/llvm/lib/IR/IRBuilder.cpp
@@ -527,8 +527,19 @@ CallInst *IRBuilderBase::CreateInvariantStart(Value *Ptr, ConstantInt *Size) {
 }
 
 CallInst *IRBuilderBase::CreateThreadLocalAddress(Value *Ptr) {
-  assert(isa<GlobalValue>(Ptr) && cast<GlobalValue>(Ptr)->isThreadLocal() &&
+#ifndef NDEBUG
+  // Handle specially for constexpr cast. This is possible when
+  // opaque pointers not enabled since constant could be sinked
+  // directly by the design of llvm. This could be eliminated
+  // after we eliminate the abuse of constexpr.
+  auto *V = Ptr;
+  if (auto *CE = dyn_cast<ConstantExpr>(V))
+    if (CE->isCast())
+      V = CE->getOperand(0);
+
+  assert(isa<GlobalValue>(V) && cast<GlobalValue>(V)->isThreadLocal() &&
          "threadlocal_address only applies to thread local variables.");
+#endif
   return CreateIntrinsic(llvm::Intrinsic::threadlocal_address, {Ptr->getType()},
                          {Ptr});
 }

diff  --git a/llvm/unittests/IR/IRBuilderTest.cpp b/llvm/unittests/IR/IRBuilderTest.cpp
index 4a6c46eae8f8b..ca08329e500b6 100644
--- a/llvm/unittests/IR/IRBuilderTest.cpp
+++ b/llvm/unittests/IR/IRBuilderTest.cpp
@@ -1009,6 +1009,21 @@ TEST_F(IRBuilderTest, CreateGlobalStringPtr) {
   EXPECT_TRUE(String3->getType()->getPointerAddressSpace() == 2);
 }
 
+TEST_F(IRBuilderTest, CreateThreadLocalAddress) {
+  IRBuilder<> Builder(BB);
+
+  GlobalVariable *G = new GlobalVariable(*M, Builder.getInt64Ty(), /*isConstant*/true,
+                                         GlobalValue::ExternalLinkage, nullptr, "", nullptr,
+                                         GlobalValue::GeneralDynamicTLSModel);
+
+  Constant *CEBC = ConstantExpr::getBitCast(G, Builder.getInt8PtrTy());
+  // Tests that IRBuilder::CreateThreadLocalAddress wouldn't crash if its operand
+  // is BitCast ConstExpr. The case should be eliminated after we eliminate the
+  // abuse of constexpr.
+  CallInst *CI = Builder.CreateThreadLocalAddress(CEBC);
+  EXPECT_NE(CI, nullptr);
+}
+
 TEST_F(IRBuilderTest, DebugLoc) {
   auto CalleeTy = FunctionType::get(Type::getVoidTy(Ctx),
                                     /*isVarArg=*/false);