commit 0b3c9e57a41d9f7c26fb6aa45b99f671bef9c7e0 Author: Paul A. Clarke Date: Tue Aug 20 15:57:35 2019 -0500 [powerpc] fegetenv_status: simplify instruction generation fegetenv_status() wants to use the lighter weight instruction 'mffsl' for reading the Floating-Point Status and Control Register (FPSCR). It currently will use it directly if compiled '-mcpu=power9', and will perform a runtime check (cpu_supports("arch_3_00")) otherwise. Nicely, it turns out that the 'mffsl' instruction will decode to 'mffs' on architectures older than "arch_3_00" because the additional bits set for 'mffsl' are "don't care" for 'mffs'. 'mffs' is a superset of 'mffsl'. So, just generate 'mffsl'. diff --git a/sysdeps/powerpc/fpu/fenv_libc.h b/sysdeps/powerpc/fpu/fenv_libc.h index b244770d115ea7bb..e8d40ea256b6c5bc 100644 --- a/sysdeps/powerpc/fpu/fenv_libc.h +++ b/sysdeps/powerpc/fpu/fenv_libc.h @@ -36,9 +36,12 @@ extern const fenv_t *__fe_mask_env (void) attribute_hidden; ({ fenv_t env; asm volatile ("mffs %0" : "=f" (env)); env; }) /* Equivalent to fegetenv_register, but only returns bits for - status, exception enables, and mode. */ - -#define fegetenv_status_ISA300() \ + status, exception enables, and mode. + Nicely, it turns out that the 'mffsl' instruction will decode to + 'mffs' on architectures older than "power9" because the additional + bits set for 'mffsl' are "don't care" for 'mffs'. 'mffs' is a superset + of 'mffsl'. */ +#define fegetenv_status() \ ({register double __fr; \ __asm__ __volatile__ ( \ ".machine push; .machine \"power9\"; mffsl %0; .machine pop" \ @@ -46,18 +49,6 @@ extern const fenv_t *__fe_mask_env (void) attribute_hidden; __fr; \ }) -#ifdef _ARCH_PWR9 -# define fegetenv_status() fegetenv_status_ISA300() -#elif defined __BUILTIN_CPU_SUPPORTS__ -# define fegetenv_status() \ - (__glibc_likely (__builtin_cpu_supports ("arch_3_00")) \ - ? fegetenv_status_ISA300() \ - : fegetenv_register() \ - ) -#else -# define fegetenv_status() fegetenv_register () -#endif - /* Equivalent to fesetenv, but takes a fenv_t instead of a pointer. */ #define fesetenv_register(env) \ do { \