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YJIT: Branch directly when nil? is known from types

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This commit is contained in:
John Hawthorn 2022-09-08 21:51:39 -07:00
parent d319184390
commit 5e39b3b844
Notes: git 2022-09-10 12:30:03 +09:00 
Merged: https://github.com/ruby/ruby/pull/6350
2 changed files with 34 additions and 18 deletions
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16
yjit/src/codegen.rs
View File

@ -3340,11 +3340,6 @@ fn gen_branchnil(
gen_check_ints(asm, side_exit); gen_check_ints(asm, side_exit);
} }
// Test if the value is Qnil
// RUBY_Qnil /* ...0000 1000 */
let val_opnd = ctx.stack_pop(1);
asm.cmp(val_opnd, Opnd::UImm(Qnil.into()));
// Get the branch target instruction offsets // Get the branch target instruction offsets
let next_idx = jit_next_insn_idx(jit) as i32; let next_idx = jit_next_insn_idx(jit) as i32;
let jump_idx = next_idx + jump_offset; let jump_idx = next_idx + jump_offset;
@ -3357,6 +3352,16 @@ fn gen_branchnil(
idx: jump_idx.try_into().unwrap(), idx: jump_idx.try_into().unwrap(),
}; };
let val_type = ctx.get_opnd_type(StackOpnd(0));
let val_opnd = ctx.stack_pop(1);
if let Some(result) = val_type.known_nil() {
let target = if result { jump_block } else { next_block };
gen_direct_jump(jit, ctx, target, asm);
} else {
// Test if the value is Qnil
// RUBY_Qnil /* ...0000 1000 */
asm.cmp(val_opnd, Opnd::UImm(Qnil.into()));
// Generate the branch instructions // Generate the branch instructions
gen_branch( gen_branch(
jit, jit,
@ -3369,6 +3374,7 @@ fn gen_branchnil(
Some(ctx), Some(ctx),
gen_branchnil_branch, gen_branchnil_branch,
); );
}
EndBlock EndBlock
} }

12
yjit/src/core.rs
View File

@ -172,7 +172,7 @@ impl Type {
} }
} }
/// Returns an Option with the exact value if it is known, otherwise None /// Returns an Option boolean representing whether the value is truthy if known, otherwise None
pub fn known_truthy(&self) -> Option<bool> { pub fn known_truthy(&self) -> Option<bool> {
match self { match self {
Type::Nil => Some(false), Type::Nil => Some(false),
@ -183,6 +183,16 @@ impl Type {
} }
} }
/// Returns an Option boolean representing whether the value is equal to nil if known, otherwise None
pub fn known_nil(&self) -> Option<bool> {
match (self, self.known_truthy()) {
(Type::Nil, _) => Some(true),
(Type::False, _) => Some(false), // Qfalse is not nil
(_, Some(true)) => Some(false), // if truthy, can't be nil
(_, _) => None // otherwise unknown
}
}
/// Compute a difference between two value types /// Compute a difference between two value types
/// Returns 0 if the two are the same /// Returns 0 if the two are the same
/// Returns > 0 if different but compatible /// Returns > 0 if different but compatible