[AArch64] Support adding X[8-15,18] registers as CSRs.

[trong]

Summary

Making X[8-15,18] registers call-saved is used to support
CONFIG_ARM64_LSE_ATOMICS in Linux kernel.

Signed-off-by: Tri Vo <[e-mail]>

[nickdesaulniers]

Test mixing -fcall-saved-x18 and -ffixed-x18?

[nickdesaulniers]

Test mixing -fcall-saved-x18 and -ffixed-x18?

[nickdesaulniers]

Test mixing -fcall-saved-x18 and -ffixed-x18?

[nickdesaulniers]

Test mixing -fcall-saved-x18 and -ffixed-x18?

[nickdesaulniers]

Test mixing -fcall-saved-x18 and -ffixed-x18?

[trong]

• Added test case for using -fcall-saved-x18 and -ffixed-x18 together.

[nickdesaulniers]

Thanks for this patch, Tri!

docs/ClangCommandLineReference.rst

 .. option:: -ffixed-x18
 
 Reserve the x18 register (AArch64 only)
 
 .. option:: -ffixed-x20
 
 Reserve the x20 register (AArch64 only)
 
+.. option:: -fcall-saved-x8
+
+Make the x8 register call-saved (AArch64 only)
+
+.. option:: -fcall-saved-x9
+
+Make the x9 register call-saved (AArch64 only)
+
+.. option:: -fcall-saved-x10
+
+Make the x10 register call-saved (AArch64 only)
+
+.. option:: -fcall-saved-x11
+
+Make the x11 register call-saved (AArch64 only)
+
+.. option:: -fcall-saved-x12
+
+Make the x12 register call-saved (AArch64 only)
+
+.. option:: -fcall-saved-x13
+
+Make the x13 register call-saved (AArch64 only)
+
+.. option:: -fcall-saved-x14
+
+Make the x14 register call-saved (AArch64 only)
+
+.. option:: -fcall-saved-x15
+
+Make the x15 register call-saved (AArch64 only)
+
+.. option:: -fcall-saved-x18
+
+Make the x18 register call-saved (AArch64 only)
+
 .. option:: -mfix-cortex-a53-835769, -mno-fix-cortex-a53-835769
 
 Workaround Cortex-A53 erratum 835769 (AArch64 only)
 
 .. option:: -mgeneral-regs-only
 
 Generate code which only uses the general purpose registers (AArch64 only)
 

include/clang/Driver/Options.td

def mfix_cortex_a53_835769 : Flag<["-"], "mfix-cortex-a53-835769">,
   HelpText<"Workaround Cortex-A53 erratum 835769 (AArch64 only)">;
 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)">;
 foreach i = {1-7,18,20} in
   def ffixed_x#i : Flag<["-"], "ffixed-x"#i>, Group<m_aarch64_Features_Group>,
     HelpText<"Reserve the "#i#" register (AArch64 only)">;
 
+foreach i = {8-15,18} in
+  def fcall_saved_x#i : Flag<["-"], "fcall-saved-x"#i>, Group<m_aarch64_Features_Group>,
+    HelpText<"Make the x"#i#" register call-saved (AArch64 only)">;
+
 def msign_return_address : Joined<["-"], "msign-return-address=">,
   Flags<[CC1Option]>, Group<m_Group>,
   HelpText<"Select return address signing scope">, Values<"none,all,non-leaf">;
 
 def msimd128 : Flag<["-"], "msimd128">, Group<m_wasm_Features_Group>;
 def mno_simd128 : Flag<["-"], "mno-simd128">, Group<m_wasm_Features_Group>;
 def mnontrapping_fptoint : Flag<["-"], "mnontrapping-fptoint">, Group<m_wasm_Features_Group>;
 def mno_nontrapping_fptoint : Flag<["-"], "mno-nontrapping-fptoint">, Group<m_wasm_Features_Group>;

lib/Driver/ToolChains/Arch/AArch64.cpp

if (Args.hasArg(options::OPT_ffixed_x7))
     Features.push_back("+reserve-x7");
 
   if (Args.hasArg(options::OPT_ffixed_x18))
     Features.push_back("+reserve-x18");
 
   if (Args.hasArg(options::OPT_ffixed_x20))
     Features.push_back("+reserve-x20");
 
+  if (Args.hasArg(options::OPT_fcall_saved_x8))
+    Features.push_back("+call-saved-x8");
+
+  if (Args.hasArg(options::OPT_fcall_saved_x9))
+    Features.push_back("+call-saved-x9");
+
+  if (Args.hasArg(options::OPT_fcall_saved_x10))
+    Features.push_back("+call-saved-x10");
+
+  if (Args.hasArg(options::OPT_fcall_saved_x11))
+    Features.push_back("+call-saved-x11");
+
+  if (Args.hasArg(options::OPT_fcall_saved_x12))
+    Features.push_back("+call-saved-x12");
+
+  if (Args.hasArg(options::OPT_fcall_saved_x13))
+    Features.push_back("+call-saved-x13");
+
+  if (Args.hasArg(options::OPT_fcall_saved_x14))
+    Features.push_back("+call-saved-x14");
+
+  if (Args.hasArg(options::OPT_fcall_saved_x15))
+    Features.push_back("+call-saved-x15");
+
+  if (Args.hasArg(options::OPT_fcall_saved_x18))
+    Features.push_back("+call-saved-x18");
+
   if (Args.hasArg(options::OPT_mno_neg_immediates))
     Features.push_back("+no-neg-immediates");
 }

test/Driver/aarch64-call-saved-x-register.c

+// RUN: %clang -target aarch64-none-gnu -fcall-saved-x8 -### %s  2>&1  \
+// RUN: | FileCheck --check-prefix=CHECK-CALL-SAVED-X8 %s
+
+// RUN: %clang -target aarch64-none-gnu -fcall-saved-x9 -### %s  2>&1  \
+// RUN: | FileCheck --check-prefix=CHECK-CALL-SAVED-X9 %s
+
+// RUN: %clang -target aarch64-none-gnu -fcall-saved-x10 -### %s  2>&1  \
+// RUN: | FileCheck --check-prefix=CHECK-CALL-SAVED-X10 %s
+
+// RUN: %clang -target aarch64-none-gnu -fcall-saved-x11 -### %s  2>&1  \
+// RUN: | FileCheck --check-prefix=CHECK-CALL-SAVED-X11 %s
+
+// RUN: %clang -target aarch64-none-gnu -fcall-saved-x12 -### %s  2>&1  \
+// RUN: | FileCheck --check-prefix=CHECK-CALL-SAVED-X12 %s
+
+// RUN: %clang -target aarch64-none-gnu -fcall-saved-x13 -### %s  2>&1  \
+// RUN: | FileCheck --check-prefix=CHECK-CALL-SAVED-X13 %s
+
+// RUN: %clang -target aarch64-none-gnu -fcall-saved-x14 -### %s  2>&1  \
+// RUN: | FileCheck --check-prefix=CHECK-CALL-SAVED-X14 %s
+
+// RUN: %clang -target aarch64-none-gnu -fcall-saved-x15 -### %s  2>&1  \
+// RUN: | FileCheck --check-prefix=CHECK-CALL-SAVED-X15 %s
+
+// RUN: %clang -target aarch64-none-gnu -fcall-saved-x18 -### %s  2>&1  \
+// RUN: | FileCheck --check-prefix=CHECK-CALL-SAVED-X18 %s
+
+// Test all call-saved-x# options together.
+// RUN: %clang -target aarch64-none-gnu \
+// RUN: -fcall-saved-x8 \
+// RUN: -fcall-saved-x9 \
+// RUN: -fcall-saved-x10 \
+// RUN: -fcall-saved-x11 \
+// RUN: -fcall-saved-x12 \
+// RUN: -fcall-saved-x13 \
+// RUN: -fcall-saved-x14 \
+// RUN: -fcall-saved-x15 \
+// RUN: -fcall-saved-x18 \
+// RUN: -### %s  2>&1 | FileCheck %s \
+// RUN: --check-prefix=CHECK-CALL-SAVED-X8 \
+// RUN: --check-prefix=CHECK-CALL-SAVED-X9 \
+// RUN: --check-prefix=CHECK-CALL-SAVED-X10 \
+// RUN: --check-prefix=CHECK-CALL-SAVED-X11 \
+// RUN: --check-prefix=CHECK-CALL-SAVED-X12 \
+// RUN: --check-prefix=CHECK-CALL-SAVED-X13 \
+// RUN: --check-prefix=CHECK-CALL-SAVED-X14 \
+// RUN: --check-prefix=CHECK-CALL-SAVED-X15 \
+// RUN: --check-prefix=CHECK-CALL-SAVED-X18
+
+// CHECK-CALL-SAVED-X8: "-target-feature" "+call-saved-x8"
+// CHECK-CALL-SAVED-X9: "-target-feature" "+call-saved-x9"
+// CHECK-CALL-SAVED-X10: "-target-feature" "+call-saved-x10"
+// CHECK-CALL-SAVED-X11: "-target-feature" "+call-saved-x11"
+// CHECK-CALL-SAVED-X12: "-target-feature" "+call-saved-x12"
+// CHECK-CALL-SAVED-X13: "-target-feature" "+call-saved-x13"
+// CHECK-CALL-SAVED-X14: "-target-feature" "+call-saved-x14"
+// CHECK-CALL-SAVED-X15: "-target-feature" "+call-saved-x15"
+// CHECK-CALL-SAVED-X18: "-target-feature" "+call-saved-x18"

test/Driver/aarch64-fixed-call-saved-x-register.c

+// Check that -ffixed and -fcall-saved flags work correctly together.
+// RUN: %clang -target aarch64-none-gnu \
+// RUN: -ffixed-x18 \
+// RUN: -fcall-saved-x18 \
+// RUN: -### %s  2>&1 | FileCheck %s
+
+// CHECK: "-target-feature" "+reserve-x18"
+// CHECK: "-target-feature" "+call-saved-x18"