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Finish translating const indexing. Close #1417, close #570, close #571, close #1272, close #2317.

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This commit is contained in:
Graydon Hoare 2012-08-09 16:05:34 -07:00
parent 22a14dd700
commit f0775d7bfe
4 changed files with 64 additions and 23 deletions
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1
src/rustc/middle/trans/base.rs
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@ -5717,6 +5717,7 @@ fn trans_crate(sess: session::session, crate: @ast::crate, tcx: ty::ctxt,
type_use_cache: ast_util::new_def_hash(),
vtables: map::hashmap(hash_mono_id, sys::shape_eq),
const_cstr_cache: map::str_hash(),
const_globals: int_hash::<ValueRef>(),
module_data: str_hash::<ValueRef>(),
lltypes: ty::new_ty_hash(),
names: new_namegen(),

4
src/rustc/middle/trans/common.rs
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@ -107,6 +107,10 @@ type crate_ctxt = {
vtables: hashmap<mono_id, ValueRef>,
// Cache of constant strings,
const_cstr_cache: hashmap<~str, ValueRef>,
// Reverse-direction for const ptrs cast from globals,
// since the ptr -> init association is lost any
// time a GlobalValue is cast.
const_globals: hashmap<int, ValueRef>,
module_data: hashmap<~str, ValueRef>,
lltypes: hashmap<ty::t, TypeRef>,
names: namegen,

68
src/rustc/middle/trans/consts.rs
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@ -32,6 +32,12 @@ fn const_lit(cx: @crate_ctxt, e: @ast::expr, lit: ast::lit)
// duplicate constants. I think. Maybe LLVM has a magical mode that does so
// later on?
fn const_ptrcast(cx: @crate_ctxt, a: ValueRef, t: TypeRef) -> ValueRef {
let b = llvm::LLVMConstPointerCast(a, T_ptr(t));
assert cx.const_globals.insert(b as int, a);
b
}
fn const_vec(cx: @crate_ctxt, e: @ast::expr, es: &[@ast::expr])
-> (ValueRef, ValueRef, TypeRef) {
let vec_ty = ty::expr_ty(cx.tcx, e);
@ -43,9 +49,14 @@ fn const_vec(cx: @crate_ctxt, e: @ast::expr, es: &[@ast::expr])
return (v, sz, llunitty);
}
fn const_deref(v: ValueRef) -> ValueRef {
fn const_deref(cx: @crate_ctxt, v: ValueRef) -> ValueRef {
let v = match cx.const_globals.find(v as int) {
some(v) => v,
none => v
};
assert llvm::LLVMIsGlobalConstant(v) == True;
llvm::LLVMGetInitializer(v)
let v = llvm::LLVMGetInitializer(v);
v
}
fn const_get_elt(v: ValueRef, u: uint) -> ValueRef {
@ -53,7 +64,7 @@ fn const_get_elt(v: ValueRef, u: uint) -> ValueRef {
llvm::LLVMConstExtractValue(v, ptr::addr_of(u), 1 as c_uint)
}
fn const_autoderef(ty: ty::t, v: ValueRef)
fn const_autoderef(cx: @crate_ctxt, ty: ty::t, v: ValueRef)
-> (ty::t, ValueRef) {
let mut t1 = ty;
let mut v1 = v;
@ -62,7 +73,7 @@ fn const_autoderef(ty: ty::t, v: ValueRef)
match ty::get(ty).struct {
ty::ty_rptr(_, mt) => {
t1 = mt.ty;
v1 = const_deref(v1);
v1 = const_deref(cx, v1);
}
_ => return (t1,v1)
}
@ -133,7 +144,7 @@ fn const_expr(cx: @crate_ctxt, e: @ast::expr) -> ValueRef {
return match u {
ast::box(_) |
ast::uniq(_) |
ast::deref => const_deref(te),
ast::deref => const_deref(cx, te),
ast::not => llvm::LLVMConstNot(te),
ast::neg => {
if is_float { llvm::LLVMConstFNeg(te) }
@ -144,7 +155,7 @@ fn const_expr(cx: @crate_ctxt, e: @ast::expr) -> ValueRef {
ast::expr_field(base, field, _) => {
let bt = ty::expr_ty(cx.tcx, base);
let bv = const_expr(cx, base);
let (bt, bv) = const_autoderef(bt, bv);
let (bt, bv) = const_autoderef(cx, bt, bv);
let fields = match ty::get(bt).struct {
ty::ty_rec(fs) => fs,
ty::ty_class(did, substs) =>
@ -159,7 +170,7 @@ fn const_expr(cx: @crate_ctxt, e: @ast::expr) -> ValueRef {
ast::expr_index(base, index) => {
let bt = ty::expr_ty(cx.tcx, base);
let bv = const_expr(cx, base);
let (bt, bv) = const_autoderef(bt, bv);
let (bt, bv) = const_autoderef(cx, bt, bv);
let iv = match const_eval::eval_const_expr(cx.tcx, index) {
const_eval::const_int(i) => i as u64,
const_eval::const_uint(u) => u,
@ -167,7 +178,7 @@ fn const_expr(cx: @crate_ctxt, e: @ast::expr) -> ValueRef {
~"index is not an integer-constant \
expression")
};
let (arr,len) = match ty::get(bt).struct {
let (arr, _len) = match ty::get(bt).struct {
ty::ty_evec(_, vstore) | ty::ty_estr(vstore) =>
match vstore {
ty::vstore_fixed(u) =>
@ -177,9 +188,10 @@ fn const_expr(cx: @crate_ctxt, e: @ast::expr) -> ValueRef {
let unit_ty = ty::sequence_element_type(cx.tcx, bt);
let llunitty = type_of::type_of(cx, unit_ty);
let unit_sz = shape::llsize_of(cx, llunitty);
(const_deref(const_get_elt(bv, 0)),
(const_deref(cx, const_get_elt(bv, 0)),
llvm::LLVMConstUDiv(const_get_elt(bv, 1),
unit_sz))
unit_sz))
},
_ => cx.sess.span_bug(base.span,
~"index-expr base must be \
@ -189,13 +201,42 @@ fn const_expr(cx: @crate_ctxt, e: @ast::expr) -> ValueRef {
~"index-expr base must be \
a vector or string type")
};
let len = llvm::LLVMConstIntGetZExtValue(len) as u64;
// FIXME #3169: This is a little odd but it arises due to a weird
// wrinkle in LLVM: it doesn't appear willing to let us call
// LLVMConstIntGetZExtValue on the size element of the slice, or
// seemingly any integer-const involving a sizeof() call. Despite
// that being "a const", it's not the kind of const you can ask
// for the integer-value of, evidently. This might be an LLVM
// bug, not sure. In any case, to work around this we drop down
// to the array-type level here and just ask how long the
// array-type itself is, ignoring the length we pulled out of the
// slice. This in turn only works because we picked out the
// original globalvar via const_deref and so can recover the
// array-size of the underlying array, and all this will hold
// together exactly as long as we _don't_ support const
// sub-slices (that is, slices that represent something other
// than a whole array). At that point we'll have more and uglier
// work to do here, but for now this should work.
//
// In the future, what we should be doing here is the
// moral equivalent of:
//
// let len = llvm::LLVMConstIntGetZExtValue(len) as u64;
//
// but we might have to do substantially more magic to
// make it work. Or figure out what is causing LLVM to
// not want to consider sizeof() a constant expression
// we can get the value (as a number) out of.
let len = llvm::LLVMGetArrayLength(val_ty(arr)) as u64;
let len = match ty::get(bt).struct {
ty::ty_estr(*) => {assert len > 0; len - 1},
_ => len
};
if iv >= len {
// Better late than never for reporting this?
// FIXME #3170: report this earlier on in the const-eval
// pass. Reporting here is a bit late.
cx.sess.span_err(e.span,
~"const index-expr is out of bounds");
}
@ -292,8 +333,7 @@ fn const_expr(cx: @crate_ctxt, e: @ast::expr) -> ValueRef {
};
llvm::LLVMSetInitializer(gv, cv);
llvm::LLVMSetGlobalConstant(gv, True);
let p = llvm::LLVMConstPointerCast(gv, T_ptr(llunitty));
let p = const_ptrcast(cx, gv, llunitty);
C_struct(~[p, sz])
}
_ => cx.sess.span_bug(e.span,

14
src/test/run-pass/const-fields-and-indexing.rs
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@ -1,20 +1,16 @@
// Not quite working on the indexing part yet.
/*
const x : [int]/4 = [1,2,3,4];
const y : &[int] = &[1,2,3,4];
const p : int = x[2];
const y : &[int] = &[1,2,3,4];
const q : int = y[2];
*/
const s : {a: int, b: int} = {a: 10, b: 20};
const t : int = s.b;
fn main() {
// io::println(fmt!("%?", p));
// io::println(fmt!("%?", q));
io::println(fmt!("%?", p));
io::println(fmt!("%?", q));
io::println(fmt!("%?", t));
// assert p == 3;
// assert q == 3;
assert p == 3;
assert q == 3;
assert t == 20;
}