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Translate lazy && and || operators in rustc.

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This commit is contained in:
Graydon Hoare 2010-10-19 17:24:15 -07:00
parent 71b1f1d117
commit 368943998d
1 changed files with 58 additions and 7 deletions
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65
src/comp/middle/trans.rs
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@ -137,6 +137,10 @@ fn T_f64() -> TypeRef {
ret llvm.LLVMDoubleType();
}
fn T_bool() -> TypeRef {
ret T_i1();
}
fn T_int() -> TypeRef {
// FIXME: switch on target type.
ret T_i32();
@ -228,7 +232,7 @@ fn T_taskptr() -> TypeRef {
fn type_of(@trans_ctxt cx, @ast.ty t) -> TypeRef {
alt (t.node) {
case (ast.ty_nil) { ret T_nil(); }
case (ast.ty_bool) { ret T_i1(); }
case (ast.ty_bool) { ret T_bool(); }
case (ast.ty_int) { ret T_int(); }
case (ast.ty_uint) { ret T_int(); }
case (ast.ty_machine(?tm)) {
@ -291,9 +295,9 @@ fn C_nil() -> ValueRef {
fn C_bool(bool b) -> ValueRef {
if (b) {
ret C_integral(1, T_i1());
ret C_integral(1, T_bool());
} else {
ret C_integral(0, T_i1());
ret C_integral(0, T_bool());
}
}
@ -465,6 +469,54 @@ fn trans_unary(@block_ctxt cx, ast.unop op, &ast.expr e) -> result {
fn trans_binary(@block_ctxt cx, ast.binop op,
&ast.expr a, &ast.expr b) -> result {
// First couple cases are lazy:
alt (op) {
case (ast.and) {
// Lazy-eval and
auto lhs_res = trans_expr(cx, a);
auto rhs_cx = new_empty_block_ctxt(cx.fcx);
auto rhs_res = trans_expr(rhs_cx, b);
auto next_cx = new_extension_block_ctxt(cx);
rhs_res.bcx.build.Br(next_cx.llbb);
lhs_res.bcx.build.CondBr(lhs_res.val,
rhs_cx.llbb,
next_cx.llbb);
auto phi = next_cx.build.Phi(T_bool(),
vec(lhs_res.val,
rhs_res.val),
vec(lhs_res.bcx.llbb,
rhs_res.bcx.llbb));
ret res(next_cx, phi);
}
case (ast.or) {
// Lazy-eval or
auto lhs_res = trans_expr(cx, a);
auto rhs_cx = new_empty_block_ctxt(cx.fcx);
auto rhs_res = trans_expr(rhs_cx, b);
auto next_cx = new_extension_block_ctxt(cx);
rhs_res.bcx.build.Br(next_cx.llbb);
lhs_res.bcx.build.CondBr(lhs_res.val,
next_cx.llbb,
rhs_cx.llbb);
auto phi = next_cx.build.Phi(T_bool(),
vec(lhs_res.val,
rhs_res.val),
vec(lhs_res.bcx.llbb,
rhs_res.bcx.llbb));
ret res(next_cx, phi);
}
}
// Remaining cases are eager:
auto lhs = trans_expr(cx, a);
auto sub = trans_expr(lhs.bcx, b);
@ -774,10 +826,9 @@ fn new_top_block_ctxt(@fn_ctxt fcx) -> @block_ctxt {
}
// Use this when you are making a block_ctxt to replace the
// current one, i.e. when chaining together sequences of stmts
// or making sub-blocks you will branch back out of and wish to
// "carry on" in the parent block's context.
// Use this when you are making a block_ctxt that starts with a fresh
// terminator and empty cleanups (no locals, no implicit return when
// falling off the end).
fn new_empty_block_ctxt(@fn_ctxt fcx) -> @block_ctxt {
fn terminate_no_op(@fn_ctxt cx, builder build) {
}