[compiler-rt] Use mangled function names on ARM64EC

[cjacek]

On ARM64EC, function names and calls (but not address-taking or data symbol references) use symbols prefixed with "#". Since it's an unique behavior, introduce a new FUNC_SYMBOL macro instead of reusing something like SYMBOL_NAME, which is also used for data symbols.

Based on patch by Billy Laws.

[cjacek]

CC @bylaws

[github-actions]

⚠️ C/C++ code formatter, clang-format found issues in your code. ⚠️

You can test this locally with the following command:

git-clang-format --diff HEAD~1 HEAD --extensions h -- compiler-rt/lib/builtins/assembly.h

View the diff from clang-format here.

diff --git a/compiler-rt/lib/builtins/assembly.h b/compiler-rt/lib/builtins/assembly.h
index 385dc1903..37ad00258 100644
--- a/compiler-rt/lib/builtins/assembly.h
+++ b/compiler-rt/lib/builtins/assembly.h
@@ -61,10 +61,7 @@
 #define LOCAL_LABEL(name) .L ## name
 #define FILE_LEVEL_DIRECTIVE
 #define SYMBOL_IS_FUNC(name)                                                   \
-  .def FUNC_SYMBOL(name) SEPARATOR                                             \
-    .scl 2 SEPARATOR                                                           \
-    .type 32 SEPARATOR                                                         \
-  .endef
+  .def FUNC_SYMBOL(name) SEPARATOR.scl 2 SEPARATOR.type 32 SEPARATOR.endef
 #define CONST_SECTION .section .rdata,"rd"
 
 #define NO_EXEC_STACK_DIRECTIVE
@@ -231,55 +228,52 @@
 
 #define DEFINE_COMPILERRT_FUNCTION(name)                                       \
   DEFINE_CODE_STATE                                                            \
-  FILE_LEVEL_DIRECTIVE SEPARATOR                                               \
-  .globl FUNC_SYMBOL(SYMBOL_NAME(name)) SEPARATOR                              \
-  SYMBOL_IS_FUNC(SYMBOL_NAME(name)) SEPARATOR                                  \
-  DECLARE_SYMBOL_VISIBILITY(name)                                              \
+  FILE_LEVEL_DIRECTIVE SEPARATOR.globl FUNC_SYMBOL(SYMBOL_NAME(name))          \
+      SEPARATOR SYMBOL_IS_FUNC(SYMBOL_NAME(name))                              \
+          SEPARATOR DECLARE_SYMBOL_VISIBILITY(name)                            \
   DECLARE_FUNC_ENCODING                                                        \
-  FUNC_SYMBOL(SYMBOL_NAME(name)):
+  FUNC_SYMBOL(SYMBOL_NAME(name)) :
 
 #define DEFINE_COMPILERRT_THUMB_FUNCTION(name)                                 \
   DEFINE_CODE_STATE                                                            \
   FILE_LEVEL_DIRECTIVE SEPARATOR                                               \
-  .globl FUNC_SYMBOL(SYMBOL_NAME(name)) SEPARATOR                              \
-  SYMBOL_IS_FUNC(SYMBOL_NAME(name)) SEPARATOR                                  \
-  DECLARE_SYMBOL_VISIBILITY(name) SEPARATOR                                    \
-  .thumb_func SEPARATOR                                                        \
-  FUNC_SYMBOL(SYMBOL_NAME(name)):
+      .globl                                                                   \
+      FUNC_SYMBOL(SYMBOL_NAME(name)) SEPARATOR SYMBOL_IS_FUNC(                 \
+          SYMBOL_NAME(name)) SEPARATOR DECLARE_SYMBOL_VISIBILITY(name)         \
+          SEPARATOR.thumb_func SEPARATOR FUNC_SYMBOL(SYMBOL_NAME(name))        \
+      :
 
 #define DEFINE_COMPILERRT_PRIVATE_FUNCTION(name)                               \
   DEFINE_CODE_STATE                                                            \
-  FILE_LEVEL_DIRECTIVE SEPARATOR                                               \
-  .globl FUNC_SYMBOL(SYMBOL_NAME(name)) SEPARATOR                              \
-  SYMBOL_IS_FUNC(SYMBOL_NAME(name)) SEPARATOR                                  \
-  HIDDEN(SYMBOL_NAME(name)) SEPARATOR                                          \
-  DECLARE_FUNC_ENCODING                                                        \
-  FUNC_SYMBOL(SYMBOL_NAME(name)):
+  FILE_LEVEL_DIRECTIVE SEPARATOR.globl FUNC_SYMBOL(SYMBOL_NAME(name))          \
+      SEPARATOR SYMBOL_IS_FUNC(SYMBOL_NAME(name))                              \
+          SEPARATOR HIDDEN(SYMBOL_NAME(name))                                  \
+              SEPARATOR DECLARE_FUNC_ENCODING FUNC_SYMBOL(SYMBOL_NAME(name))   \
+      :
 
 #define DEFINE_COMPILERRT_PRIVATE_FUNCTION_UNMANGLED(name)                     \
-  DEFINE_CODE_STATE                                                            \
-  .globl FUNC_SYMBOL(name) SEPARATOR                                           \
-  SYMBOL_IS_FUNC(name) SEPARATOR                                               \
-  HIDDEN(name) SEPARATOR                                                       \
+  DEFINE_CODE_STATE.globl FUNC_SYMBOL(name)                                    \
+  SEPARATOR                                                                    \
+  SYMBOL_IS_FUNC(name) SEPARATOR HIDDEN(name)                                  \
+  SEPARATOR                                                                    \
   DECLARE_FUNC_ENCODING                                                        \
-  FUNC_SYMBOL(name):
+  FUNC_SYMBOL(name) :
 
 #define DEFINE_COMPILERRT_OUTLINE_FUNCTION_UNMANGLED(name)                     \
   DEFINE_CODE_STATE                                                            \
-  FUNC_ALIGN                                                                   \
-  .globl FUNC_SYMBOL(name) SEPARATOR                                           \
-  SYMBOL_IS_FUNC(name) SEPARATOR                                               \
-  DECLARE_SYMBOL_VISIBILITY_UNMANGLED(FUNC_SYMBOL(name)) SEPARATOR             \
-  DECLARE_FUNC_ENCODING                                                        \
-  FUNC_SYMBOL(name):                                                           \
-  SEPARATOR CFI_START                                                          \
-  SEPARATOR BTI_C
+  FUNC_ALIGN.globl FUNC_SYMBOL(name)                                           \
+  SEPARATOR                                                                    \
+  SYMBOL_IS_FUNC(name)                                                         \
+  SEPARATOR DECLARE_SYMBOL_VISIBILITY_UNMANGLED(FUNC_SYMBOL(name))             \
+      SEPARATOR DECLARE_FUNC_ENCODING FUNC_SYMBOL(name)                        \
+      : SEPARATOR CFI_START SEPARATOR BTI_C
 
 #define DEFINE_COMPILERRT_FUNCTION_ALIAS(name, target)                         \
-  .globl FUNC_SYMBOL(SYMBOL_NAME(name)) SEPARATOR                              \
-  SYMBOL_IS_FUNC(SYMBOL_NAME(name)) SEPARATOR                                  \
-  DECLARE_SYMBOL_VISIBILITY(name) SEPARATOR                                    \
-  .set FUNC_SYMBOL(SYMBOL_NAME(name)), FUNC_SYMBOL(target) SEPARATOR
+  .globl FUNC_SYMBOL(SYMBOL_NAME(name))                                        \
+      SEPARATOR SYMBOL_IS_FUNC(SYMBOL_NAME(name))                              \
+          SEPARATOR DECLARE_SYMBOL_VISIBILITY(name)                            \
+              SEPARATOR.set FUNC_SYMBOL(SYMBOL_NAME(name)),                    \
+      FUNC_SYMBOL(target) SEPARATOR
 
 #if defined(__ARM_EABI__)
 #define DEFINE_AEABI_FUNCTION_ALIAS(aeabi_name, name)                          \

[cjacek]

FWIW, the formatting warnings are from clang-format trying to adjust indentation in modified macros. I believe the current formatting is intentional and is meant to remain unchanged.

[mstorsjo]

Looks good to me overall.

[mstorsjo]

I added a couple other reviewers as well, in case they have comments on it, but this does look good to me - and in case the others have comments within a couple of days, we can probably merge this.

[compnerd]

I wonder if there is a way to unify SYMBOL_IS_FUNC and FUNC_SYMBOL. We have a number of different places where we indicate that a label is a function, and it seems it would be very confusing for most to know which one belongs where.

[cjacek]

I wonder if there is a way to unify SYMBOL_IS_FUNC and FUNC_SYMBOL. We have a number of different places where we indicate that a label is a function, and it seems it would be very confusing for most to know which one belongs where.

Thanks for the reviews. The best I could come up with is renaming SYMBOL_IS_FUNC to DEFINE_FUNC_SYMBOL. That name seems more accurate, especially if we move the .globl directive into the macro as well. What do you think? Should I go ahead with that?