From: Hans Wennborg <hans@hanshq.net>
Date: Mon, 26 Jan 2015 23:17:18 +0000 (+0000)
Subject: Merging r227062:
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=c47313c631cc4117c76a1e1c34203370392655ea;p=clang

Merging r227062:
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r227062 | rengolin | 2015-01-25 15:17:48 -0800 (Sun, 25 Jan 2015) | 10 lines

Allows Clang to use LLVM's fixes-x18 option

This patch allows clang to have llvm reserve the x18
platform register on AArch64. FreeBSD will use this in the kernel for
per-cpu data but has no need to reserve this register in userland so
will need this flag to reserve it.

This uses llvm r226664 to allow this register to be reserved.

Patch by Andrew Turner.
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git-svn-id: https://llvm.org/svn/llvm-project/cfe/branches/release_36@227151 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/include/clang/Driver/Options.td b/include/clang/Driver/Options.td
index 4daddba332..b68a46bad8 100644
--- a/include/clang/Driver/Options.td
+++ b/include/clang/Driver/Options.td
@@ -1209,6 +1209,8 @@ def mfix_cortex_a53_835769 : Flag<["-"], "mfix-cortex-a53-835769">,
 def mno_fix_cortex_a53_835769 : Flag<["-"], "mno-fix-cortex-a53-835769">,
   Group<m_aarch64_Features_Group>,
   HelpText<"Don't workaround Cortex-A53 erratum 835769 (AArch64 only)">;
+def ffixed_x18 : Flag<["-"], "ffixed-x18">, Group<m_aarch64_Features_Group>,
+  HelpText<"Reserve the x18 register (AArch64 only)">;
 
 def mvsx : Flag<["-"], "mvsx">, Group<m_ppc_Features_Group>;
 def mno_vsx : Flag<["-"], "mno-vsx">, Group<m_ppc_Features_Group>;
diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index d625c0e3e2..810a4d7caa 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -958,6 +958,11 @@ void Clang::AddAArch64TargetArgs(const ArgList &Args,
     if (A->getOption().matches(options::OPT_mno_global_merge))
       CmdArgs.push_back("-mno-global-merge");
   }
+
+  if (Args.hasArg(options::OPT_ffixed_x18)) {
+    CmdArgs.push_back("-backend-option");
+    CmdArgs.push_back("-aarch64-reserve-x18");
+  }
 }
 
 // Get CPU and ABI names. They are not independent
diff --git a/test/Driver/aarch64-fixed-x18.c b/test/Driver/aarch64-fixed-x18.c
new file mode 100644
index 0000000000..35d0caf032
--- /dev/null
+++ b/test/Driver/aarch64-fixed-x18.c
@@ -0,0 +1,4 @@
+// RUN: %clang -target aarch64-none-gnu -ffixed-x18 -### %s 2> %t
+// RUN: FileCheck --check-prefix=CHECK-FIXED-X18 < %t %s
+
+// CHECK-FIXED-X18: "-backend-option" "-aarch64-reserve-x18"