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First draft at fixing the choice of asm

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Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
This commit is contained in:
Dave Rodgman 2023-05-24 17:19:10 +01:00
parent a1f51c213c
commit 0ffc6f48fa
1 changed files with 31 additions and 27 deletions
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58
library/bn_mul.h
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@ -659,39 +659,46 @@
#endif /* TriCore */
/*
* There is a fairly complex matrix of supported options for Thumb / Thumb2 / Arm
* assembly. Choosing the correct code path depends on the target, the compiler,
* and the optimisation level.
*
* Note, gcc -O0 by default uses r7 for the frame pointer, so it complains about
* our use of r7 below, unless -fomit-frame-pointer is passed.
*
* On the other hand, -fomit-frame-pointer is implied by any -Ox options with
* x !=0, which we can detect using __OPTIMIZE__ (which is also defined by
* clang and armcc5 under the same conditions).
*
* So, only use the optimized assembly below for optimized build, which avoids
* the build error and is pretty reasonable anyway.
*/
#if defined(__GNUC__) && !defined(__OPTIMIZE__)
#define MULADDC_CANNOT_USE_R7
#if defined(__thumb__) && !defined(__thumb2__) // Thumb1 (not Thumb 2) ISA
// Only supported by gcc, when optimisation is enabled; only option A works
#if defined(__OPTIMIZE__) && !defined(__ARMCC_VERSION)
#define ARM_OPTION_A
#endif
/*
* Similarly, we need to disable the assembly below if:
* - compiler is armclang
* - optimisation is not -O0
* - target is Thumb
* - target cpu is one of cortex-m0, cortex-m0plus, cortex-m1, cortex-m23, sc000
*
* Checking for __ARM_ARCH_6M__ or __ARM_ARCH_8M_BASE__ seems to identify exactly these
* cpus and no others (tested against all values for -mcpu known to armclang 6.20).
*/
#if defined(__ARMCC_VERSION) && defined(__OPTIMIZE__) && defined(__thumb__)
#if defined(__ARM_ARCH_8M_BASE__) || defined(__ARM_ARCH_6M__)
#define MULADDC_CANNOT_USE_R7
#endif
#elif defined(__thumb2__) // Thumb 2 ISA
#if !defined(__ARMCC_VERSION) && !defined(__OPTIMIZE__)
// gcc -O0
// only option B builds
#define ARM_OPTION_B
#elif !defined(__ARMCC_VERSION)
// gcc with optimisation - any option builds
#define ARM_OPTION_A
#else
// armclang
// options A or C build
#define ARM_OPTION_A
#endif
#if defined(__arm__) && !defined(MULADDC_CANNOT_USE_R7)
#elif defined(__arm__) // Arm ISA
// any option builds. A does not seem to work; B is about 2x faster than C (under emulation).
#define ARM_OPTION_B
#endif
#if defined(__thumb__) && !defined(__thumb2__)
#if defined(ARM_OPTION_A)
#define MULADDC_X1_INIT \
asm( \
@ -746,8 +753,7 @@
"r6", "r7", "r8", "r9", "cc" \
);
#elif (__ARM_ARCH >= 6) && \
defined (__ARM_FEATURE_DSP) && (__ARM_FEATURE_DSP == 1)
#elif defined(ARM_OPTION_B)
#define MULADDC_X1_INIT \
{ \
@ -812,7 +818,7 @@
); \
}
#else
#elif defined(ARM_OPTION_C)
#define MULADDC_X1_INIT \
asm( \
@ -840,9 +846,7 @@
"r6", "r7", "cc" \
);
#endif /* Thumb */
#endif /* ARMv3 */
#endif /* Arm */
#if defined(__alpha__)