48cf2c2f50
- Undo temporary changes to default features (`all-arch`) and a
signal-handler test.
- Remove `SIGTRAP` handler: no longer needed now that we've found an
"undefined opcode" option on ARM64.
- Rename pp.rs to pretty_print.rs in machinst/.
- Only use empty stack-probe on non-x86. As per a comment in
rust-lang/compiler-builtins [1], LLVM only supports stack probes on
x86 and x86-64. Thus, on any other CPU architecture, we cannot refer
to `__rust_probestack`, because it does not exist.
- Rename arm64 to aarch64.
- Use `target` directive in vcode filetests.
- Run the flags verifier, but without encinfo, when using new backends.
- Clean up warning overrides.
- Fix up use of casts: use u32::from(x) and siblings when possible,
u32::try_from(x).unwrap() when not, to avoid silent truncation.
- Take immutable `Function` borrows as input; we don't actually
mutate the input IR.
- Lots of other miscellaneous cleanups.
[1] cae3e6ea23/src/probestack.rs (L39)
37 lines
1.2 KiB
Rust
37 lines
1.2 KiB
Rust
//! A Dead-Code Elimination (DCE) pass.
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//!
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//! Dead code here means instructions that have no side effects and have no
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//! result values used by other instructions.
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use crate::cursor::{Cursor, FuncCursor};
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use crate::dominator_tree::DominatorTree;
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use crate::entity::EntityRef;
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use crate::inst_predicates::{any_inst_results_used, has_side_effect};
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use crate::ir::Function;
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use crate::timing;
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/// Perform DCE on `func`.
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pub fn do_dce(func: &mut Function, domtree: &mut DominatorTree) {
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let _tt = timing::dce();
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debug_assert!(domtree.is_valid());
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let mut live = vec![false; func.dfg.num_values()];
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for &block in domtree.cfg_postorder() {
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let mut pos = FuncCursor::new(func).at_bottom(block);
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while let Some(inst) = pos.prev_inst() {
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{
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if has_side_effect(pos.func, inst)
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|| any_inst_results_used(inst, &live, &pos.func.dfg)
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{
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for arg in pos.func.dfg.inst_args(inst) {
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let v = pos.func.dfg.resolve_aliases(*arg);
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live[v.index()] = true;
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}
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continue;
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}
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}
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pos.remove_inst();
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}
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}
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}
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