[X86] Don't try to generate direct calls to TLS globals

[mkuper]

Summary

The Call lowering assumes that if it's a global, we want to emit a direct call.
This is correct for regular globals, but not for TLS ones.

[• rafael]

LGTM with a nit.

test/CodeGen/X86/pr22103.ll

12 ↗

(On Diff #17850)

Please check what we actually generate.

[majnemer]

LGTM to me as well with Rafael's nit addressed, thanks for fixing this!

llvm/trunk/lib/Target/X86/X86ISelLowering.cpp

X86TargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
   }
 
   if (DAG.getTarget().getCodeModel() == CodeModel::Large) {
     assert(Is64Bit && "Large code model is only legal in 64-bit mode.");
     // In the 64-bit large code model, we have to make all calls
     // through a register, since the call instruction's 32-bit
     // pc-relative offset may not be large enough to hold the whole
     // address.
-  } else if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee)) {
+  } else if (Callee->getOpcode() == ISD::GlobalAddress) {
     // If the callee is a GlobalAddress node (quite common, every direct call
     // is) turn it into a TargetGlobalAddress node so that legalize doesn't hack
     // it.
+    GlobalAddressSDNode* G = cast<GlobalAddressSDNode>(Callee);
 
     // We should use extra load for direct calls to dllimported functions in
     // non-JIT mode.
     const GlobalValue *GV = G->getGlobal();
     if (!GV->hasDLLImportStorageClass()) {
       unsigned char OpFlags = 0;
       bool ExtraLoad = false;
       unsigned WrapperKind = ISD::DELETED_NODE;

llvm/trunk/test/CodeGen/X86/pr22103.ll

+; RUN: llc < %s | FileCheck %s
+; Don't try to emit a direct call through a TLS global.
+; This fixes PR22103
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@a = external thread_local global i64
+
+; Function Attrs: nounwind
+define void @_Z1fv() {
+; CHECK-NOT: callq *$a
+; CHECK: movq %fs:0, [[RAX:%r..]]
+; CHECK-NEXT: addq    a@GOTTPOFF(%rip), [[RAX]]
+; CHECK-NEXT: callq *%rax
+entry:
+  call void bitcast (i64* @a to void ()*)()
+  ret void
+}