T0b1/wasmtime
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

cranelift: Remove redundant branch and select instructions (#5097)

Browse Source 
As discussed in the 2022/10/19 meeting, this PR removes many of the branch and select instructions that used iflags, in favor if using brz/brnz and select in their place. Additionally, it reworks selectif_spectre_guard to take an i8 input instead of an iflags input.

For reference, the removed instructions are: br_icmp, brif, brff, trueif, trueff, and selectif.
This commit is contained in:
Trevor Elliott
2022-10-24 16:14:35 -07:00
committed by GitHub
parent 30589170b4
commit ec12415b1f
40 changed files with 579 additions and 2527 deletions
Download Patch File Download Diff File Expand all files Collapse all files

32
crates/cranelift/src/func_environ.rs
View File

@@ -542,10 +542,10 @@ impl<'module_environment> FuncEnvironment<'module_environment> {
// Otherwise we can continue on like usual.
let zero = builder.ins().iconst(ir::types::I64, 0);
let fuel = builder.use_var(self.fuel_var);
let cmp = builder.ins().ifcmp(fuel, zero);
builder
let cmp = builder
.ins()
.brif(IntCC::SignedGreaterThanOrEqual, cmp, out_of_gas_block, &[]);
.icmp(IntCC::SignedGreaterThanOrEqual, fuel, zero);
builder.ins().brnz(cmp, out_of_gas_block, &[]);
builder.ins().jump(continuation_block, &[]);
builder.seal_block(out_of_gas_block);
@@ -649,10 +649,12 @@ impl<'module_environment> FuncEnvironment<'module_environment> {
// fine, as we'll reload it and check again before yielding in
// the cold path.
let cur_epoch_value = self.epoch_load_current(builder);
let cmp = builder.ins().ifcmp(cur_epoch_value, epoch_deadline);
builder
.ins()
.brif(IntCC::UnsignedGreaterThanOrEqual, cmp, new_epoch_block, &[]);
let cmp = builder.ins().icmp(
IntCC::UnsignedGreaterThanOrEqual,
cur_epoch_value,
epoch_deadline,
);
builder.ins().brnz(cmp, new_epoch_block, &[]);
builder.ins().jump(continuation_block, &[]);
builder.seal_block(new_epoch_block);
@@ -666,13 +668,14 @@ impl<'module_environment> FuncEnvironment<'module_environment> {
builder.switch_to_block(new_epoch_block);
self.epoch_load_deadline_into_var(builder);
let fresh_epoch_deadline = builder.use_var(self.epoch_deadline_var);
let fresh_cmp = builder.ins().ifcmp(cur_epoch_value, fresh_epoch_deadline);
builder.ins().brif(
let fresh_cmp = builder.ins().icmp(
IntCC::UnsignedGreaterThanOrEqual,
fresh_cmp,
new_epoch_doublecheck_block,
&[],
cur_epoch_value,
fresh_epoch_deadline,
);
builder
.ins()
.brnz(fresh_cmp, new_epoch_doublecheck_block, &[]);
builder.ins().jump(continuation_block, &[]);
builder.seal_block(new_epoch_doublecheck_block);
@@ -1183,9 +1186,8 @@ impl<'module_environment> cranelift_wasm::FuncEnvironment for FuncEnvironment<'m
builder.switch_to_block(dec_ref_count_block);
let prev_ref_count = self.mutate_externref_ref_count(builder, current_elem, -1);
let one = builder.ins().iconst(pointer_type, 1);
builder
.ins()
.br_icmp(IntCC::Equal, one, prev_ref_count, drop_block, &[]);
let cond = builder.ins().icmp(IntCC::Equal, one, prev_ref_count);
builder.ins().brnz(cond, drop_block, &[]);
builder.ins().jump(continue_block, &[]);
// Call the `drop_externref` builtin to (you guessed it) drop