[Builtins] ARM: Fix assembling files in thumb mode.

[manojgupta]

Summary

clang does not assemble files in thumb mode unless .thumb declaration
is present. Add .thumb/.arm decl to _FUNCTION macros to ensure that
files are assembled correctly.

Fixes PR 34715.

[manojgupta]

lib/builtins/arm/aeabi_cdcmp.S

54–56 ↗

(On Diff #116496)

Please review this change and the one below since I am not much of an ARM assembly expert.

lib/builtins/arm/aeabi_memset.S

27 ↗

(On Diff #116496)

This was the only function I found without a .p2align. Please let me know if this change is not required.

[peter.smith]

Apologies for being a pain, could you split the changes into their own review, even if they depend on each other? It will be easier to review, and to commit each one separately.

lib/builtins/arm/aeabi_cdcmp.S

54–56 ↗

(On Diff #116496)

I think that this would be better split out into a separate patch, potentially dependent on this one.

I think that you don't need an extra case for Thumb2. ARM_ARCH_7M and ARM_ARCH_7EM only support Thumb 2 so I think all you need to do is replace that condition with USE_THUMB2.

Apologies I've not got an assembler at hand to check.

lib/builtins/arm/aeabi_memset.S

27 ↗

(On Diff #116496)

Arm functions need to be 4-byte aligned, Thumb functions 2-byte aligned. We might be able to move this to be part of DEFINE_COMPILERRT_FUNCTION so that it can be set to 2 or 4. Having it set to 4 as you suggest is probably good enough for now.

[manojgupta]

Thanks Peter,
I'll split out msr & .p2align into separate patches.

lib/builtins/arm/aeabi_cdcmp.S

54–56 ↗

(On Diff #116496)

I can't build in thumb without this change since clang complains about the illegal operand to msr instruction. But agree that this should be a separate patch.

[manojgupta]

Removed assembly file changes. They are moved to their own separate reviews.

[weimingz]

LGTM.

lib/builtins/assembly.h

 #if defined(__arm__)
 
 /*
  * Determine actual [ARM][THUMB[1][2]] ISA using compiler predefined macros:
  * - for '-mthumb -march=armv6' compiler defines '__thumb__'
  * - for '-mthumb -march=armv7' compiler defines '__thumb__' and '__thumb2__'
  */
 #if defined(__thumb2__) || defined(__thumb__)
-#define DEFINE_CODE_STATE .thumb
+#define DEFINE_CODE_STATE .thumb SEPARATOR
 #define DECLARE_FUNC_ENCODING    .thumb_func SEPARATOR
 #if defined(__thumb2__)
 #define USE_THUMB_2
 #define IT(cond)  it cond
 #define ITT(cond) itt cond
 #define ITE(cond) ite cond
 #else
 #define USE_THUMB_1
 #define IT(cond)
 #define ITT(cond)
 #define ITE(cond)
 #endif // defined(__thumb__2)
 #else // !defined(__thumb2__) && !defined(__thumb__)
-#define DEFINE_CODE_STATE .arm
+#define DEFINE_CODE_STATE .arm SEPARATOR
 #define DECLARE_FUNC_ENCODING
 #define IT(cond)
 #define ITT(cond)
 #define ITE(cond)
 #endif
 
 #if defined(USE_THUMB_1) && defined(USE_THUMB_2)
 #error "USE_THUMB_1 and USE_THUMB_2 can't be defined together."

 #ifdef VISIBILITY_HIDDEN
 #define DECLARE_SYMBOL_VISIBILITY(name)                                        \
   HIDDEN(SYMBOL_NAME(name)) SEPARATOR
 #else
 #define DECLARE_SYMBOL_VISIBILITY(name)
 #endif
 
 #define DEFINE_COMPILERRT_FUNCTION(name)                                       \
+  DEFINE_CODE_STATE                                                            \
   FILE_LEVEL_DIRECTIVE SEPARATOR                                               \
   .globl SYMBOL_NAME(name) SEPARATOR                                           \
   SYMBOL_IS_FUNC(SYMBOL_NAME(name)) SEPARATOR                                  \
   DECLARE_SYMBOL_VISIBILITY(name)                                              \
   DECLARE_FUNC_ENCODING                                                        \
   SYMBOL_NAME(name):
 
 #define DEFINE_COMPILERRT_THUMB_FUNCTION(name)                                 \
+  DEFINE_CODE_STATE                                                            \
   FILE_LEVEL_DIRECTIVE SEPARATOR                                               \
   .globl SYMBOL_NAME(name) SEPARATOR                                           \
   SYMBOL_IS_FUNC(SYMBOL_NAME(name)) SEPARATOR                                  \
   DECLARE_SYMBOL_VISIBILITY(name) SEPARATOR                                    \
   .thumb_func SEPARATOR                                                        \
   SYMBOL_NAME(name):
 
 #define DEFINE_COMPILERRT_PRIVATE_FUNCTION(name)                               \
+  DEFINE_CODE_STATE                                                            \
   FILE_LEVEL_DIRECTIVE SEPARATOR                                               \
   .globl SYMBOL_NAME(name) SEPARATOR                                           \
   SYMBOL_IS_FUNC(SYMBOL_NAME(name)) SEPARATOR                                  \
   HIDDEN(SYMBOL_NAME(name)) SEPARATOR                                          \
   DECLARE_FUNC_ENCODING                                                        \
   SYMBOL_NAME(name):
 
 #define DEFINE_COMPILERRT_PRIVATE_FUNCTION_UNMANGLED(name)                     \
+  DEFINE_CODE_STATE                                                            \
   .globl name SEPARATOR                                                        \
   SYMBOL_IS_FUNC(name) SEPARATOR                                               \
   HIDDEN(name) SEPARATOR                                                       \
   DECLARE_FUNC_ENCODING                                                        \
   name:
 
 #define DEFINE_COMPILERRT_FUNCTION_ALIAS(name, target)                         \
   .globl SYMBOL_NAME(name) SEPARATOR                                           \