[PATCH] D39065: Support nonlazybind attribute for X86 64-bit ELF (invoked via -fno-plt)

[Sriraman Tallam via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rL317292: Avoid PLT for external calls when attribute nonlazybind is used. (authored by tmsriram).

Changed prior to commit:
  https://reviews.llvm.org/D39065?vs=119509&id=121413#toc

Repository:
  rL LLVM

https://reviews.llvm.org/D39065

Files:
  llvm/trunk/lib/Target/X86/X86Subtarget.cpp
  llvm/trunk/test/CodeGen/X86/no-plt.ll


Index: llvm/trunk/test/CodeGen/X86/no-plt.ll
===================================================================
--- llvm/trunk/test/CodeGen/X86/no-plt.ll
+++ llvm/trunk/test/CodeGen/X86/no-plt.ll
@@ -0,0 +1,23 @@
+; RUN: llc < %s -mcpu=generic -mtriple=x86_64-linux-gnu -relocation-model=pic \
+; RUN:   | FileCheck -check-prefix=X64 %s
+; RUN: llc < %s -mcpu=generic -mtriple=x86_64-linux-gnu \
+; RUN:   | FileCheck -check-prefix=X64 %s
+
+define i32 @main() #0 {
+; X64: callq *_Z3foov at GOTPCREL(%rip)
+; X64: callq _Z3barv
+
+entry:
+  %retval = alloca i32, align 4
+  store i32 0, i32* %retval, align 4
+  %call1 = call i32 @_Z3foov()
+  %call2 = call i32 @_Z3barv()
+  ret i32 0
+}
+
+; Function Attrs: nonlazybind
+declare i32 @_Z3foov() #1
+
+declare i32 @_Z3barv() #2
+
+attributes #1 = { nonlazybind }
Index: llvm/trunk/lib/Target/X86/X86Subtarget.cpp
===================================================================
--- llvm/trunk/lib/Target/X86/X86Subtarget.cpp
+++ llvm/trunk/lib/Target/X86/X86Subtarget.cpp
@@ -144,6 +144,15 @@
 unsigned char
 X86Subtarget::classifyGlobalFunctionReference(const GlobalValue *GV,
                                               const Module &M) const {
+  const Function *F = dyn_cast_or_null<Function>(GV);
+
+  // Do not use the PLT when explicitly told to do so for ELF 64-bit
+  // target.
+  if (isTargetELF() && is64Bit() && F &&
+      F->hasFnAttribute(Attribute::NonLazyBind) &&
+      GV->isDeclarationForLinker())
+    return X86II::MO_GOTPCREL;
+
   if (TM.shouldAssumeDSOLocal(M, GV))
     return X86II::MO_NO_FLAG;
 
@@ -153,8 +162,6 @@
     return X86II::MO_DLLIMPORT;
   }
 
-  const Function *F = dyn_cast_or_null<Function>(GV);
-
   if (isTargetELF()) {
     if (is64Bit() && F && (CallingConv::X86_RegCall == F->getCallingConv()))
       // According to psABI, PLT stub clobbers XMM8-XMM15.


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