This effectively merges support for all architecture variants into a
common function path with appropriate build conditions.
ARM performance is 1-2 instructions faster; Thumb-2 is about 50% faster.
gcc/libgcc/ChangeLog:
2021-01-13 Daniel Engel <g...@danielengel.com>
* config/arm/bpabi.S (__aeabi_lcmp, __aeabi_ulcmp): Removed.
* config/arm/eabi/lcmp.S (__aeabi_lcmp, __aeabi_ulcmp): Added
conditional execution on supported architectures (__ARM_FEATURE_IT).
* config/arm/lib1funcs.S: Moved #include scope of eabi/lcmp.S.
---
libgcc/config/arm/bpabi.S | 42 -------------------------------
libgcc/config/arm/eabi/lcmp.S | 47 ++++++++++++++++++++++++++++++++++-
libgcc/config/arm/lib1funcs.S | 2 +-
3 files changed, 47 insertions(+), 44 deletions(-)
diff --git a/libgcc/config/arm/bpabi.S b/libgcc/config/arm/bpabi.S
index 2cbb67d54ad..4281a2be594 100644
--- a/libgcc/config/arm/bpabi.S
+++ b/libgcc/config/arm/bpabi.S
@@ -34,48 +34,6 @@
.eabi_attribute 25, 1
#endif /* __ARM_EABI__ */
-#ifdef L_aeabi_lcmp
-
-ARM_FUNC_START aeabi_lcmp
- cmp xxh, yyh
- do_it lt
- movlt r0, #-1
- do_it gt
- movgt r0, #1
- do_it ne
- RETc(ne)
- subs r0, xxl, yyl
- do_it lo
- movlo r0, #-1
- do_it hi
- movhi r0, #1
- RET
- FUNC_END aeabi_lcmp
-
-#endif /* L_aeabi_lcmp */
-
-#ifdef L_aeabi_ulcmp
-
-ARM_FUNC_START aeabi_ulcmp
- cmp xxh, yyh
- do_it lo
- movlo r0, #-1
- do_it hi
- movhi r0, #1
- do_it ne
- RETc(ne)
- cmp xxl, yyl
- do_it lo
- movlo r0, #-1
- do_it hi
- movhi r0, #1
- do_it eq
- moveq r0, #0
- RET
- FUNC_END aeabi_ulcmp
-
-#endif /* L_aeabi_ulcmp */
-
.macro test_div_by_zero signed
/* Tail-call to divide-by-zero handlers which may be overridden by the user,
so unwinding works properly. */
diff --git a/libgcc/config/arm/eabi/lcmp.S b/libgcc/config/arm/eabi/lcmp.S
index 2ac9d178b34..f1a9c3b8fe0 100644
--- a/libgcc/config/arm/eabi/lcmp.S
+++ b/libgcc/config/arm/eabi/lcmp.S
@@ -46,6 +46,19 @@ FUNC_START_SECTION LCMP_NAME LCMP_SECTION
subs xxl, yyl
sbcs xxh, yyh
+ #ifdef __HAVE_FEATURE_IT
+ do_it lt,t
+
+ #ifdef L_aeabi_lcmp
+ movlt r0, #-1
+ #else
+ movlt r0, #0
+ #endif
+
+ // Early return on '<'.
+ RETc(lt)
+
+ #else /* !__HAVE_FEATURE_IT */
// With $r2 free, create a known offset value without affecting
// the N or Z flags.
// BUG? The originally unified instruction for v6m was 'mov r2, r3'.
@@ -62,17 +75,27 @@ FUNC_START_SECTION LCMP_NAME LCMP_SECTION
// argument is larger, otherwise the offset value remains 0.
adds r2, #2
+ #endif
+
// Check for zero (equality in 64 bits).
// It doesn't matter which register was originally "hi".
orrs r0, r1
+ #ifdef __HAVE_FEATURE_IT
+ // The result is already 0 on equality.
+ // -1 already returned, so just force +1.
+ do_it ne
+ movne r0, #1
+
+ #else /* !__HAVE_FEATURE_IT */
// The result is already 0 on equality.
beq LLSYM(__lcmp_return)
- LLSYM(__lcmp_lt):
+ LLSYM(__lcmp_lt):
// Create +1 or -1 from the offset value defined earlier.
adds r3, #1
subs r0, r2, r3
+ #endif
LLSYM(__lcmp_return):
#ifdef L_cmpdi2
@@ -111,21 +134,43 @@ FUNC_START_SECTION ULCMP_NAME ULCMP_SECTION
subs xxl, yyl
sbcs xxh, yyh
+ #ifdef __HAVE_FEATURE_IT
+ do_it lo,t
+
+ #ifdef L_aeabi_ulcmp
+ movlo r0, -1
+ #else
+ movlo r0, #0
+ #endif
+
+ // Early return on '<'.
+ RETc(lo)
+
+ #else
// Capture the carry flg.
// $r2 will contain -1 if the first value is smaller,
// 0 if the first value is larger or equal.
sbcs r2, r2
+ #endif
// Check for zero (equality in 64 bits).
// It doesn't matter which register was originally "hi".
orrs r0, r1
+ #ifdef __HAVE_FEATURE_IT
+ // The result is already 0 on equality.
+ // -1 already returned, so just force +1.
+ do_it ne
+ movne r0, #1
+
+ #else /* !__HAVE_FEATURE_IT */
// The result is already 0 on equality.
beq LLSYM(__ulcmp_return)
// Assume +1. If -1 is correct, $r2 will override.
movs r0, #1
orrs r0, r2
+ #endif
LLSYM(__ulcmp_return):
#ifdef L_ucmpdi2
diff --git a/libgcc/config/arm/lib1funcs.S b/libgcc/config/arm/lib1funcs.S
index 5e24d0a6749..f41354f811e 100644
--- a/libgcc/config/arm/lib1funcs.S
+++ b/libgcc/config/arm/lib1funcs.S
@@ -1991,6 +1991,6 @@ LSYM(Lchange_\register):
#include "bpabi.S"
#else /* NOT_ISA_TARGET_32BIT */
#include "bpabi-v6m.S"
-#include "eabi/lcmp.S"
#endif /* NOT_ISA_TARGET_32BIT */
+#include "eabi/lcmp.S"
#endif /* !__symbian__ */
--
2.25.1
