From: Stam Markianos-Wright <stam.markianos-wri...@arm.com> Hi all,
We noticed that calls to the vadcq and vsbcq intrinsics, both of which use __builtin_arm_set_fpscr_nzcvqc to set the Carry flag in the FPSCR, would produce the following code: ``` < r2 is the *carry input > vmrs r3, FPSCR_nzcvqc bic r3, r3, #536870912 orr r3, r3, r2, lsl #29 vmsr FPSCR_nzcvqc, r3 ``` when the MVE ACLE instead gives a different instruction sequence of: ``` < Rt is the *carry input > VMRS Rs,FPSCR_nzcvqc BFI Rs,Rt,#29,#1 VMSR FPSCR_nzcvqc,Rs ``` the bic + orr pair is slower and it's also wrong, because, if the *carry input is greater than 1, then we risk overwriting the top two bits of the FPSCR register (the N and Z flags). This turned out to be a problem in the header file and the solution was to simply add a `& 1x0u` to the `*carry` input: then the compiler knows that we only care about the lowest bit and can optimise to a BFI. Ok for trunk? Thanks, Stam Markianos-Wright gcc/ChangeLog: * config/arm/arm_mve.h (__arm_vadcq_s32): Fix arithmetic. (__arm_vadcq_u32): Likewise. (__arm_vadcq_m_s32): Likewise. (__arm_vadcq_m_u32): Likewise. (__arm_vsbcq_s32): Likewise. (__arm_vsbcq_u32): Likewise. (__arm_vsbcq_m_s32): Likewise. (__arm_vsbcq_m_u32): Likewise. --- gcc/config/arm/arm_mve.h | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/gcc/config/arm/arm_mve.h b/gcc/config/arm/arm_mve.h index 1262d668121..8778216304b 100644 --- a/gcc/config/arm/arm_mve.h +++ b/gcc/config/arm/arm_mve.h @@ -16055,7 +16055,7 @@ __extension__ extern __inline int32x4_t __attribute__ ((__always_inline__, __gnu_inline__, __artificial__)) __arm_vadcq_s32 (int32x4_t __a, int32x4_t __b, unsigned * __carry) { - __builtin_arm_set_fpscr_nzcvqc((__builtin_arm_get_fpscr_nzcvqc () & ~0x20000000u) | (*__carry << 29)); + __builtin_arm_set_fpscr_nzcvqc((__builtin_arm_get_fpscr_nzcvqc () & ~0x20000000u) | ((*__carry & 0x1u) << 29)); int32x4_t __res = __builtin_mve_vadcq_sv4si (__a, __b); *__carry = (__builtin_arm_get_fpscr_nzcvqc () >> 29) & 0x1u; return __res; @@ -16065,7 +16065,7 @@ __extension__ extern __inline uint32x4_t __attribute__ ((__always_inline__, __gnu_inline__, __artificial__)) __arm_vadcq_u32 (uint32x4_t __a, uint32x4_t __b, unsigned * __carry) { - __builtin_arm_set_fpscr_nzcvqc((__builtin_arm_get_fpscr_nzcvqc () & ~0x20000000u) | (*__carry << 29)); + __builtin_arm_set_fpscr_nzcvqc((__builtin_arm_get_fpscr_nzcvqc () & ~0x20000000u) | ((*__carry & 0x1u) << 29)); uint32x4_t __res = __builtin_mve_vadcq_uv4si (__a, __b); *__carry = (__builtin_arm_get_fpscr_nzcvqc () >> 29) & 0x1u; return __res; @@ -16075,7 +16075,7 @@ __extension__ extern __inline int32x4_t __attribute__ ((__always_inline__, __gnu_inline__, __artificial__)) __arm_vadcq_m_s32 (int32x4_t __inactive, int32x4_t __a, int32x4_t __b, unsigned * __carry, mve_pred16_t __p) { - __builtin_arm_set_fpscr_nzcvqc((__builtin_arm_get_fpscr_nzcvqc () & ~0x20000000u) | (*__carry << 29)); + __builtin_arm_set_fpscr_nzcvqc((__builtin_arm_get_fpscr_nzcvqc () & ~0x20000000u) | ((*__carry & 0x1u) << 29)); int32x4_t __res = __builtin_mve_vadcq_m_sv4si (__inactive, __a, __b, __p); *__carry = (__builtin_arm_get_fpscr_nzcvqc () >> 29) & 0x1u; return __res; @@ -16085,7 +16085,7 @@ __extension__ extern __inline uint32x4_t __attribute__ ((__always_inline__, __gnu_inline__, __artificial__)) __arm_vadcq_m_u32 (uint32x4_t __inactive, uint32x4_t __a, uint32x4_t __b, unsigned * __carry, mve_pred16_t __p) { - __builtin_arm_set_fpscr_nzcvqc((__builtin_arm_get_fpscr_nzcvqc () & ~0x20000000u) | (*__carry << 29)); + __builtin_arm_set_fpscr_nzcvqc((__builtin_arm_get_fpscr_nzcvqc () & ~0x20000000u) | ((*__carry & 0x1u) << 29)); uint32x4_t __res = __builtin_mve_vadcq_m_uv4si (__inactive, __a, __b, __p); *__carry = (__builtin_arm_get_fpscr_nzcvqc () >> 29) & 0x1u; return __res; @@ -16131,7 +16131,7 @@ __extension__ extern __inline int32x4_t __attribute__ ((__always_inline__, __gnu_inline__, __artificial__)) __arm_vsbcq_s32 (int32x4_t __a, int32x4_t __b, unsigned * __carry) { - __builtin_arm_set_fpscr_nzcvqc((__builtin_arm_get_fpscr_nzcvqc () & ~0x20000000u) | (*__carry << 29)); + __builtin_arm_set_fpscr_nzcvqc((__builtin_arm_get_fpscr_nzcvqc () & ~0x20000000u) | ((*__carry & 0x1u) << 29)); int32x4_t __res = __builtin_mve_vsbcq_sv4si (__a, __b); *__carry = (__builtin_arm_get_fpscr_nzcvqc () >> 29) & 0x1u; return __res; @@ -16141,7 +16141,7 @@ __extension__ extern __inline uint32x4_t __attribute__ ((__always_inline__, __gnu_inline__, __artificial__)) __arm_vsbcq_u32 (uint32x4_t __a, uint32x4_t __b, unsigned * __carry) { - __builtin_arm_set_fpscr_nzcvqc((__builtin_arm_get_fpscr_nzcvqc () & ~0x20000000u) | (*__carry << 29)); + __builtin_arm_set_fpscr_nzcvqc((__builtin_arm_get_fpscr_nzcvqc () & ~0x20000000u) | ((*__carry & 0x1u) << 29)); uint32x4_t __res = __builtin_mve_vsbcq_uv4si (__a, __b); *__carry = (__builtin_arm_get_fpscr_nzcvqc () >> 29) & 0x1u; return __res; @@ -16151,7 +16151,7 @@ __extension__ extern __inline int32x4_t __attribute__ ((__always_inline__, __gnu_inline__, __artificial__)) __arm_vsbcq_m_s32 (int32x4_t __inactive, int32x4_t __a, int32x4_t __b, unsigned * __carry, mve_pred16_t __p) { - __builtin_arm_set_fpscr_nzcvqc((__builtin_arm_get_fpscr_nzcvqc () & ~0x20000000u) | (*__carry << 29)); + __builtin_arm_set_fpscr_nzcvqc((__builtin_arm_get_fpscr_nzcvqc () & ~0x20000000u) | ((*__carry & 0x1u) << 29)); int32x4_t __res = __builtin_mve_vsbcq_m_sv4si (__inactive, __a, __b, __p); *__carry = (__builtin_arm_get_fpscr_nzcvqc () >> 29) & 0x1u; return __res; @@ -16161,7 +16161,7 @@ __extension__ extern __inline uint32x4_t __attribute__ ((__always_inline__, __gnu_inline__, __artificial__)) __arm_vsbcq_m_u32 (uint32x4_t __inactive, uint32x4_t __a, uint32x4_t __b, unsigned * __carry, mve_pred16_t __p) { - __builtin_arm_set_fpscr_nzcvqc((__builtin_arm_get_fpscr_nzcvqc () & ~0x20000000u) | (*__carry << 29)); + __builtin_arm_set_fpscr_nzcvqc((__builtin_arm_get_fpscr_nzcvqc () & ~0x20000000u) | ((*__carry & 0x1u) << 29)); uint32x4_t __res = __builtin_mve_vsbcq_m_uv4si (__inactive, __a, __b, __p); *__carry = (__builtin_arm_get_fpscr_nzcvqc () >> 29) & 0x1u; return __res; -- 2.25.1