[PATCH] D110681: [X86][ISel] Lowering llvm.thread.pointer

[Freddy, Ye via Phabricator via llvm-commits]

FreddyYe created this revision.
Herald added subscribers: pengfei, hiraditya.
FreddyYe requested review of this revision.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D110681

Files:
  llvm/lib/Target/X86/X86ISelLowering.cpp
  llvm/test/CodeGen/X86/thread_pointer.ll


Index: llvm/test/CodeGen/X86/thread_pointer.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/X86/thread_pointer.ll
@@ -0,0 +1,56 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-linux-gnu | FileCheck %s --check-prefix=X64
+; RUN: llc < %s -mtriple=x86_64-linux-gnux32 | FileCheck %s --check-prefix=X32
+; RUN: llc < %s -mtriple=i386-linux-gnu | FileCheck %s --check-prefix=X86
+
+declare i8* @llvm.thread.pointer()
+
+define i8* @thread_pointer() nounwind {
+; X64-LABEL: thread_pointer:
+; X64:       # %bb.0:
+; X64-NEXT:    movq %fs:0, %rax
+; X64-NEXT:    retq
+;
+; X32-LABEL: thread_pointer:
+; X32:       # %bb.0:
+; X32-NEXT:    movl %fs:0, %eax
+; X32-NEXT:    retq
+;
+; X86-LABEL: thread_pointer:
+; X86:       # %bb.0:
+; X86-NEXT:    movl %gs:0, %eax
+; X86-NEXT:    retl
+; X64_WIN-LABEL: thread_pointer:
+; X64_WIN:       # %bb.0:
+; X64_WIN-NEXT:    movq %fs:0, %rax
+; X64_WIN-NEXT:    retq
+  %1 = tail call i8* @llvm.thread.pointer()
+  ret i8* %1
+}
+
+define i32 @thread_pointer2(i32 %i) nounwind {
+; X64-LABEL: thread_pointer2:
+; X64:       # %bb.0: # %entry
+; X64-NEXT:    movslq %edi, %rax
+; X64-NEXT:    movl %fs:(,%rax,4), %eax
+; X64-NEXT:    retq
+;
+; X32-LABEL: thread_pointer2:
+; X32:       # %bb.0: # %entry
+; X32-NEXT:    movl %fs:0, %eax
+; X32-NEXT:    movl (%eax,%edi,4), %eax
+; X32-NEXT:    retq
+;
+; X86-LABEL: thread_pointer2:
+; X86:       # %bb.0: # %entry
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    movl %gs:(,%eax,4), %eax
+; X86-NEXT:    retl
+entry:
+  %0 = tail call i8* @llvm.thread.pointer()
+  %1 = bitcast i8* %0 to i32*
+  %idxprom = sext i32 %i to i64
+  %arrayidx = getelementptr inbounds i32, i32* %1, i64 %idxprom
+  %2 = load i32, i32* %arrayidx, align 4
+  ret i32 %2
+}
Index: llvm/lib/Target/X86/X86ISelLowering.cpp
===================================================================
--- llvm/lib/Target/X86/X86ISelLowering.cpp
+++ llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -26715,6 +26715,19 @@
                                              getPointerTy(DAG.getDataLayout())),
                        Op.getOperand(1), ShAmt);
   }
+  case Intrinsic::thread_pointer: {
+    if (Subtarget.getTargetTriple().isOSLinux()) {
+      SDLoc dl(Op);
+      EVT PtrVT = getPointerTy(DAG.getDataLayout());
+      // Get the Thread Pointer, which is %gs:0 (32-bit) or %fs:0 (64-bit).
+      Value *Ptr = Constant::getNullValue(Type::getInt8PtrTy(
+          *DAG.getContext(), Subtarget.is64Bit() ? 257 : 256));
+      return DAG.getLoad(PtrVT, dl, DAG.getEntryNode(),
+                         DAG.getIntPtrConstant(0, dl), MachinePointerInfo(Ptr));
+    } else {
+      report_fatal_error("OS doesn't support __builtin_thread_pointer() yet.");
+    }
+  }
   }
 }
 


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