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AstGen: fix elision of unnecessary dbg_stmt instructions

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AstGen has logic to elide leading `dbg_stmt` instructions when multiple
are emitted consecutively; however, it only applied in some cases. A
simple reshuffle here makes this logic apply universally, saving some
bytes in ZIR.
This commit is contained in:
mlugg 2024-02-11 21:26:35 +00:00
parent 2e27967a81
commit aba29f9789
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GPG Key ID: E60D96B91E86EF9F
1 changed files with 43 additions and 30 deletions
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73
src/AstGen.zig
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@ -3332,31 +3332,11 @@ fn emitDbgNode(gz: *GenZir, node: Ast.Node.Index) !void {
// If the current block will be evaluated only during semantic analysis
// then no dbg_stmt ZIR instruction is needed.
if (gz.is_comptime) return;
const astgen = gz.astgen;
astgen.advanceSourceCursorToNode(node);
const line = astgen.source_line - gz.decl_line;
const column = astgen.source_column;
if (gz.instructions.items.len > 0) {
const last = gz.instructions.items[gz.instructions.items.len - 1];
const zir_tags = astgen.instructions.items(.tag);
if (zir_tags[@intFromEnum(last)] == .dbg_stmt) {
const zir_datas = astgen.instructions.items(.data);
zir_datas[@intFromEnum(last)].dbg_stmt = .{
.line = line,
.column = column,
};
return;
}
}
_ = try gz.add(.{ .tag = .dbg_stmt, .data = .{
.dbg_stmt = .{
.line = line,
.column = column,
},
} });
try emitDbgStmt(gz, .{ line, column });
}
fn assign(gz: *GenZir, scope: *Scope, infix_node: Ast.Node.Index) InnerError!void {
@ -7143,7 +7123,7 @@ fn switchExprErrUnion(
block_scope.setBreakResultInfo(block_ri);
// Sema expects a dbg_stmt immediately before switch_block_err_union
try emitDbgStmt(parent_gz, operand_lc);
try emitDbgStmtForceCurrentIndex(parent_gz, operand_lc);
// This gets added to the parent block later, after the item expressions.
const switch_block = try parent_gz.makeBlockInst(.switch_block_err_union, switch_node);
@ -7723,7 +7703,7 @@ fn switchExpr(
block_scope.setBreakResultInfo(block_ri);
// Sema expects a dbg_stmt immediately before switch_block(_ref)
try emitDbgStmt(parent_gz, operand_lc);
try emitDbgStmtForceCurrentIndex(parent_gz, operand_lc);
// This gets added to the parent block later, after the item expressions.
const switch_tag: Zir.Inst.Tag = if (any_payload_is_ref) .switch_block_ref else .switch_block;
const switch_block = try parent_gz.makeBlockInst(switch_tag, switch_node);
@ -9847,13 +9827,8 @@ fn callExpr(
astgen.advanceSourceCursor(astgen.tree.tokens.items(.start)[call.ast.lparen]);
const line = astgen.source_line - gz.decl_line;
const column = astgen.source_column;
_ = try gz.add(.{ .tag = .dbg_stmt, .data = .{
.dbg_stmt = .{
.line = line,
.column = column,
},
} });
// Sema expects a dbg_stmt immediately before call,
try emitDbgStmtForceCurrentIndex(gz, .{ line, column });
}
switch (callee) {
@ -13536,6 +13511,44 @@ fn countBodyLenAfterFixups(astgen: *AstGen, body: []const Zir.Inst.Index) u32 {
fn emitDbgStmt(gz: *GenZir, lc: LineColumn) !void {
if (gz.is_comptime) return;
if (gz.instructions.items.len > 0) {
const astgen = gz.astgen;
const last = gz.instructions.items[gz.instructions.items.len - 1];
if (astgen.instructions.items(.tag)[@intFromEnum(last)] == .dbg_stmt) {
astgen.instructions.items(.data)[@intFromEnum(last)].dbg_stmt = .{
.line = lc[0],
.column = lc[1],
};
return;
}
}
_ = try gz.add(.{ .tag = .dbg_stmt, .data = .{
.dbg_stmt = .{
.line = lc[0],
.column = lc[1],
},
} });
}
/// In some cases, Sema expects us to generate a `dbg_stmt` at the instruction
/// *index* directly preceding the next instruction (e.g. if a call is %10, it
/// expects a dbg_stmt at %9). TODO: this logic may allow redundant dbg_stmt
/// instructions; fix up Sema so we don't need it!
fn emitDbgStmtForceCurrentIndex(gz: *GenZir, lc: LineColumn) !void {
const astgen = gz.astgen;
if (gz.instructions.items.len > 0 and
@intFromEnum(gz.instructions.items[gz.instructions.items.len - 1]) == astgen.instructions.len - 1)
{
const last = astgen.instructions.len - 1;
if (astgen.instructions.items(.tag)[last] == .dbg_stmt) {
astgen.instructions.items(.data)[last].dbg_stmt = .{
.line = lc[0],
.column = lc[1],
};
return;
}
}
_ = try gz.add(.{ .tag = .dbg_stmt, .data = .{
.dbg_stmt = .{