Pass CPU string to LTO pipeline.

Previously an empty CPU string was passed to the LTO engine which
resulted in a generic CPU for which certain features like NOPL were
disabled. This fixes that.

Patch by Pratik Bhatu!

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@323801 91177308-0d34-0410-b5e6-96231b3b80d8

Common/TargetOptionsCommandFlags.cpp

@@ -30,3 +30,5 @@ llvm::TargetOptions lld::InitTargetOptionsFromCodeGenFlags() {
 llvm::Optional<llvm::CodeModel::Model> lld::GetCodeModelFromCMModel() {
   return getCodeModel();
 }
+
+std::string lld::GetCPUStr() { return ::getCPUStr(); }

ELF/LTO.cpp

@@ -87,6 +87,7 @@ static std::unique_ptr<lto::LTO> createLTO() {
   Conf.DisableVerify = Config->DisableVerify;
   Conf.DiagHandler = diagnosticHandler;
   Conf.OptLevel = Config->LTOO;
+  Conf.CPU = GetCPUStr();
 
   // Set up a custom pipeline if we've been asked to.
   Conf.OptPipeline = Config->LTONewPmPasses;

include/lld/Common/TargetOptionsCommandFlags.h

@@ -18,4 +18,5 @@
 namespace lld {
 llvm::TargetOptions InitTargetOptionsFromCodeGenFlags();
 llvm::Optional<llvm::CodeModel::Model> GetCodeModelFromCMModel();
+std::string GetCPUStr();
 }

test/ELF/lto/cpu-string.ll

@@ -0,0 +1,23 @@
+; REQUIRES: x86
+; RUN: llvm-as %s -o %t.o
+
+; RUN: ld.lld %t.o -o %t.so -shared
+; RUN: llvm-objdump -d -section=".text" -no-leading-addr -no-show-raw-insn %t.so | FileCheck %s
+
+; RUN: ld.lld -mllvm -mcpu=znver1 %t.o -o %m.so -shared
+; RUN: llvm-objdump -d -section=".text" -no-leading-addr -no-show-raw-insn %m.so | FileCheck -check-prefix=ZNVER1 %s
+
+; CHECK: nop{{$}}
+
+; ZNVER1: nopw
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define void @foo() #0 {
+entry:
+  call void asm sideeffect ".p2align        4, 0x90", "~{dirflag},~{fpsr},~{flags}"()
+  ret void
+}
+
+attributes #0 = { "no-frame-pointer-elim"="true" }