From fe9a0667b879ef28327782e54047c029576c9fcd Mon Sep 17 00:00:00 2001 From: Erin Date: Sun, 4 Feb 2024 22:36:52 +0100 Subject: [PATCH] Maybe fixed questionable code --- hbvm/src/float/aarch64.rs | 51 +++++++++++++-------------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/hbvm/src/float/aarch64.rs b/hbvm/src/float/aarch64.rs index 1d14d7f..b47ccf1 100644 --- a/hbvm/src/float/aarch64.rs +++ b/hbvm/src/float/aarch64.rs @@ -9,13 +9,28 @@ macro_rules! fnsdef { $vis fn $name(val: $from, mode: RoundingMode) -> $to { let result: $to; unsafe { - set_rounding_mode(mode); + if mode == RoundingMode::NearestEven { + return; + } + + let fpcr: u64; + unsafe { asm!("mrs {}, fpcr", out(reg) fpcr) }; + + let fpcr_new = fpcr & !(0b11 << 22) + | (match mode { + RoundingMode::NearestEven => 0b00, + RoundingMode::Truncate => 0b11, + RoundingMode::Up => 0b01, + RoundingMode::Down => 0b10, + }) << 22; + + unsafe { asm!("msr fpcr, {}", in(reg) fpcr_new) }; asm!( $ins, out($outreg) result, in($inreg) val, ); - default_rounding_mode(); + unsafe { asm!("msr fpcr, {}", in(reg) fpcr) }; } result } @@ -32,35 +47,3 @@ fnsdef! { /// Convert [`f64`] to [`i64`] with chosen rounding mode pub fn f64toint[vreg -> reg](f64 -> i64): "fcvtzs {}, {:d}"; } - -/// Set rounding mode -/// -/// # Safety -/// - Do not call if rounding mode isn't [`RoundingMode::NearestEven`] -/// - Do not perform any Rust FP operations until reset using -/// [`default_rounding_mode`], you have to rely on inline assembly -#[inline(always)] -unsafe fn set_rounding_mode(mode: RoundingMode) { - if mode == RoundingMode::NearestEven { - return; - } - - let fpcr: u64; - unsafe { asm!("mrs {}, fpcr", out(reg) fpcr) }; - - let fpcr = fpcr & !(0b11 << 22) - | (match mode { - RoundingMode::NearestEven => 0b00, - RoundingMode::Truncate => 0b11, - RoundingMode::Up => 0b01, - RoundingMode::Down => 0b10, - }) << 22; - - unsafe { asm!("msr fpcr, {}", in(reg) fpcr) }; -} - -#[inline(always)] -unsafe fn default_rounding_mode() { - // I hope so much it gets optimised - set_rounding_mode(RoundingMode::NearestEven); -}