libatomic: atomic_16.S: Improve ENTRY, END and ALIAS macro interface

The introduction of further architectural-feature dependent ifuncs
for AArch64 makes hard-coding ifunc `_i<n>' suffixes to functions
cumbersome to work with.  It is awkward to remember which ifunc maps
onto which arch feature and makes the code harder to maintain when new
ifuncs are added and their suffixes possibly altered.

This patch uses pre-processor `#define' statements to map each suffix to
a descriptive feature name macro, for example:

  #define LSE(NAME) NAME##_i1

Where we wish to generate ifunc names with the pre-processor's token
concatenation feature, we add a level of indirection to previous macro
calls.  If before we would have had`MACRO(<name>_i<n>)', we now have
`MACRO_FEAT(name, feature)'.  Where we wish to refer to base
functionality (i.e., functions where ifunc suffixes are absent), the
original `MACRO(<name>)' may be used to bypass suffixing.

Consequently, for base functionality, where the ifunc suffix is
absent, the macro interface remains the same.  For example, the entry
and endpoints of `libat_store_16' remain defined by:

  ENTRY (libat_store_16)

and

  END (libat_store_16)

For the LSE2 implementation of the same 16-byte atomic store, we now
have:

  ENTRY_FEAT (libat_store_16, LSE2)

and

  END_FEAT (libat_store_16, LSE2)

For the aliasing of function names, we define the following new
implementation of the ALIAS macro:

  ALIAS (FN_BASE_NAME, FROM_SUFFIX, TO_SUFFIX)

Defining the `CORE(NAME)' macro to be the identity operator, it
returns the base function name unaltered and allows us to alias
target-specific ifuncs to the corresponding base implementation.
For example, we'd alias the LSE2 `libat_exchange_16' to it base
implementation with:

  ALIAS (libat_exchange_16, LSE2, CORE)

libatomic/ChangeLog:
	* config/linux/aarch64/atomic_16.S (CORE): New macro.
	(LSE2): Likewise.
	(ENTRY_FEAT): Likewise.
	(ENTRY_FEAT1): Likewise.
	(END_FEAT): Likewise.
	(END_FEAT1): Likewise.
	(ALIAS): Modify macro to take in `arch' arguments.
	(ALIAS1): New.

diff --git a/libatomic/config/linux/aarch64/atomic_16.S b/libatomic/config/linux/aarch64/atomic_16.S
index ad14f8f2e6e796311202c28c46d1b9a06c5abfea..33f2f569d06744c9e0dbe113d3a9c0c55cf661a3 100644 (file)
--- a/libatomic/config/linux/aarch64/atomic_16.S
+++ b/libatomic/config/linux/aarch64/atomic_16.S
@@ -40,22 +40,34 @@
 
        .arch   armv8-a+lse
 
-#define ENTRY(name)            \
-       .global name;           \
-       .hidden name;           \
-       .type name,%function;   \
+#define LSE2(NAME)     NAME##_i1
+#define CORE(NAME)     NAME
+
+#define ENTRY_FEAT(NAME, FEAT)  \
+       ENTRY (FEAT (NAME))
+
+#define ENTRY(NAME)            \
+       .global NAME;           \
+       .hidden NAME;           \
+       .type NAME,%function;   \
        .p2align 4;             \
-name:                          \
-       .cfi_startproc;         \
+NAME:                          \
+       .cfi_startproc; \
        hint    34      // bti c
 
-#define END(name)              \
+#define END_FEAT(NAME, FEAT)   \
+       END (FEAT (NAME))
+
+#define END(NAME)              \
        .cfi_endproc;           \
-       .size name, .-name;
+       .size NAME, .-NAME;
 
-#define ALIAS(alias,name)      \
-       .global alias;          \
-       .set alias, name;
+#define ALIAS(NAME, FROM, TO)  \
+       ALIAS1 (FROM (NAME),TO (NAME))
+
+#define ALIAS1(ALIAS, NAME)    \
+       .global ALIAS;          \
+       .set ALIAS, NAME;
 
 #define res0 x0
 #define res1 x1
@@ -108,7 +120,7 @@ ENTRY (libat_load_16)
 END (libat_load_16)
 
 
-ENTRY (libat_load_16_i1)
+ENTRY_FEAT (libat_load_16, LSE2)
        cbnz    w1, 1f
 
        /* RELAXED.  */
@@ -128,7 +140,7 @@ ENTRY (libat_load_16_i1)
        ldp     res0, res1, [x0]
        dmb     ishld
        ret
-END (libat_load_16_i1)
+END_FEAT (libat_load_16, LSE2)
 
 
 ENTRY (libat_store_16)
@@ -148,7 +160,7 @@ ENTRY (libat_store_16)
 END (libat_store_16)
 
 
-ENTRY (libat_store_16_i1)
+ENTRY_FEAT (libat_store_16, LSE2)
        cbnz    w4, 1f
 
        /* RELAXED.  */
@@ -160,7 +172,7 @@ ENTRY (libat_store_16_i1)
        stlxp   w4, in0, in1, [x0]
        cbnz    w4, 1b
        ret
-END (libat_store_16_i1)
+END_FEAT (libat_store_16, LSE2)
 
 
 ENTRY (libat_exchange_16)
@@ -237,7 +249,7 @@ ENTRY (libat_compare_exchange_16)
 END (libat_compare_exchange_16)
 
 
-ENTRY (libat_compare_exchange_16_i1)
+ENTRY_FEAT (libat_compare_exchange_16, LSE2)
        ldp     exp0, exp1, [x1]
        mov     tmp0, exp0
        mov     tmp1, exp1
@@ -270,7 +282,7 @@ ENTRY (libat_compare_exchange_16_i1)
        /* ACQ_REL/SEQ_CST.  */
 4:     caspal  exp0, exp1, in0, in1, [x0]
        b       0b
-END (libat_compare_exchange_16_i1)
+END_FEAT (libat_compare_exchange_16, LSE2)
 
 
 ENTRY (libat_fetch_add_16)
@@ -556,21 +568,20 @@ END (libat_test_and_set_16)
 
 /* Alias entry points which are the same in baseline and LSE2.  */
 
-ALIAS (libat_exchange_16_i1, libat_exchange_16)
-ALIAS (libat_fetch_add_16_i1, libat_fetch_add_16)
-ALIAS (libat_add_fetch_16_i1, libat_add_fetch_16)
-ALIAS (libat_fetch_sub_16_i1, libat_fetch_sub_16)
-ALIAS (libat_sub_fetch_16_i1, libat_sub_fetch_16)
-ALIAS (libat_fetch_or_16_i1, libat_fetch_or_16)
-ALIAS (libat_or_fetch_16_i1, libat_or_fetch_16)
-ALIAS (libat_fetch_and_16_i1, libat_fetch_and_16)
-ALIAS (libat_and_fetch_16_i1, libat_and_fetch_16)
-ALIAS (libat_fetch_xor_16_i1, libat_fetch_xor_16)
-ALIAS (libat_xor_fetch_16_i1, libat_xor_fetch_16)
-ALIAS (libat_fetch_nand_16_i1, libat_fetch_nand_16)
-ALIAS (libat_nand_fetch_16_i1, libat_nand_fetch_16)
-ALIAS (libat_test_and_set_16_i1, libat_test_and_set_16)
-
+ALIAS (libat_exchange_16, LSE2, CORE)
+ALIAS (libat_fetch_add_16, LSE2, CORE)
+ALIAS (libat_add_fetch_16, LSE2, CORE)
+ALIAS (libat_fetch_sub_16, LSE2, CORE)
+ALIAS (libat_sub_fetch_16, LSE2, CORE)
+ALIAS (libat_fetch_or_16, LSE2, CORE)
+ALIAS (libat_or_fetch_16, LSE2, CORE)
+ALIAS (libat_fetch_and_16, LSE2, CORE)
+ALIAS (libat_and_fetch_16, LSE2, CORE)
+ALIAS (libat_fetch_xor_16, LSE2, CORE)
+ALIAS (libat_xor_fetch_16, LSE2, CORE)
+ALIAS (libat_fetch_nand_16, LSE2, CORE)
+ALIAS (libat_nand_fetch_16, LSE2, CORE)
+ALIAS (libat_test_and_set_16, LSE2, CORE)
 
 /* GNU_PROPERTY_AARCH64_* macros from elf.h for use in asm code.  */
 #define FEATURE_1_AND 0xc0000000