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auto merge of #9332 : eugals/rust/master, r=alexcrichton
It is intended to optimize/beautify the code generated in a few trivial trait operations.
Let's take the following code as an example:
```
trait Stuff {
fn bar(&self);
}
fn callBar(s: &Stuff) {
s.bar();
}
struct Foo;
impl Stuff for Foo {
fn bar(&self) {
}
}
pub fn main() {
let o = Foo;
callBar(&o as &Stuff);
}
```
At present it is translated into something like:
```
define void @_ZN7callBar_UUID.0E({ i32, %tydesc*, i8*, i8*, i8 }*, { %tydesc*, i8* }*) #4 {
"function top level":
%__trait_callee = alloca { %tydesc*, i8* }
%__auto_borrow_obj = alloca { %tydesc*, i8* }
%2 = getelementptr inbounds { %tydesc*, i8* }* %1, i32 0, i32 0
%3 = load %tydesc** %2
%4 = getelementptr inbounds { %tydesc*, i8* }* %__auto_borrow_obj, i32 0, i32 0
store %tydesc* %3, %tydesc** %4
%5 = getelementptr inbounds { %tydesc*, i8* }* %1, i32 0, i32 1
%6 = load i8** %5
%7 = getelementptr inbounds { %tydesc*, i8* }* %__auto_borrow_obj, i32 0, i32 1
store i8* %6, i8** %7
%8 = bitcast { %tydesc*, i8* }* %__auto_borrow_obj to i8*
%9 = bitcast { %tydesc*, i8* }* %__trait_callee to i8*
call void @llvm.memcpy.p0i8.p0i8.i32(i8* %9, i8* %8, i32 8, i32 4, i1 false)
%10 = getelementptr inbounds { %tydesc*, i8* }* %__trait_callee, i32 0, i32 1
%11 = load i8** %10
%12 = bitcast i8* %11 to { i32, %tydesc*, i8*, i8*, i8 }*
%13 = getelementptr inbounds { %tydesc*, i8* }* %__trait_callee, i32 0, i32 0
%14 = bitcast %tydesc** %13 to [1 x i8*]**
%15 = load [1 x i8*]** %14
%16 = getelementptr inbounds [1 x i8*]* %15, i32 0, i32 1
%17 = load i8** %16
%18 = bitcast i8* %17 to void ({ i32, %tydesc*, i8*, i8*, i8 }*)*
call void %18({ i32, %tydesc*, i8*, i8*, i8 }* %12)
ret void
}
...
define void @_ZN4main_UUID.0E({ i32, %tydesc*, i8*, i8*, i8 }*) #4 {
"function top level":
%o = alloca %struct.Foo
%1 = alloca { %tydesc*, i8* }
%__auto_borrow_obj = alloca { %tydesc*, i8* }
%2 = getelementptr inbounds { %tydesc*, i8* }* %1, i32 0, i32 1
%3 = bitcast i8** %2 to %struct.Foo**
store %struct.Foo* %o, %struct.Foo** %3
%4 = getelementptr inbounds { %tydesc*, i8* }* %1, i32 0, i32 0
%5 = bitcast %tydesc** %4 to { %tydesc*, void ({ i32, %tydesc*, i8*, i8*, i8 }*)* }**
store { %tydesc*, void ({ i32, %tydesc*, i8*, i8*, i8 }*)* }* @vtable1081, { %tydesc*, void ({ i32, %tydesc*, i8*, i8*, i8 }*)* }** %5
%6 = getelementptr inbounds { %tydesc*, i8* }* %1, i32 0, i32 0
%7 = load %tydesc** %6
%8 = getelementptr inbounds { %tydesc*, i8* }* %__auto_borrow_obj, i32 0, i32 0
store %tydesc* %7, %tydesc** %8
%9 = getelementptr inbounds { %tydesc*, i8* }* %1, i32 0, i32 1
%10 = load i8** %9
%11 = getelementptr inbounds { %tydesc*, i8* }* %__auto_borrow_obj, i32 0, i32 1
store i8* %10, i8** %11
call void @_ZN7callBar_UUID.0E({ i32, %tydesc*, i8*, i8*, i8 }* undef, { %tydesc*, i8* }* %__auto_borrow_obj)
ret void
}
```
If you apply my patch, it would become way shorter and cleaner:
```
define void @_ZN7callBar_UUID.0E({ i32, %tydesc*, i8*, i8*, i8 }*, { %tydesc*, i8* }*) #4 {
"function top level":
%2 = getelementptr inbounds { %tydesc*, i8* }* %1, i32 0, i32 1
%3 = load i8** %2
%4 = bitcast i8* %3 to { i32, %tydesc*, i8*, i8*, i8 }*
%5 = getelementptr inbounds { %tydesc*, i8* }* %1, i32 0, i32 0
%6 = bitcast %tydesc** %5 to [1 x i8*]**
%7 = load [1 x i8*]** %6
%8 = getelementptr inbounds [1 x i8*]* %7, i32 0, i32 1
%9 = load i8** %8
%10 = bitcast i8* %9 to void ({ i32, %tydesc*, i8*, i8*, i8 }*)*
call void %10({ i32, %tydesc*, i8*, i8*, i8 }* %4)
ret void
}
...
define void @_ZN4main_UUID.0E({ i32, %tydesc*, i8*, i8*, i8 }*) #4 {
"function top level":
%o = alloca %struct.Foo
%1 = alloca { %tydesc*, i8* }
%2 = getelementptr inbounds { %tydesc*, i8* }* %1, i32 0, i32 1
%3 = bitcast i8** %2 to %struct.Foo**
store %struct.Foo* %o, %struct.Foo** %3
%4 = getelementptr inbounds { %tydesc*, i8* }* %1, i32 0, i32 0
%5 = bitcast %tydesc** %4 to { %tydesc*, void ({ i32, %tydesc*, i8*, i8*, i8 }*)* }**
store { %tydesc*, void ({ i32, %tydesc*, i8*, i8*, i8 }*)* }* @vtable1081, { %tydesc*, void ({ i32, %tydesc*, i8*, i8*, i8 }*)* }** %5
call void @_ZN7callBar_UUID.0E({ i32, %tydesc*, i8*, i8*, i8 }* undef, { %tydesc*, i8* }* %1)
ret void
}
```
Although this change doesn't increase the compilation speed much (I mentioned only about 1-2% boost on "rustc -O -Z time-passes syntax.rs"), but I still think it's a good thing to do as it greatly simplifies/clarifies LL generated in some cases which would definitely help in the future code generation investigations.
I don't provide any new test cases in this patch as it is merely an optimization.
Sorry guys, I somehow messed my previous PR and I don't see any better way to fix as to recreate it here.
This commit is contained in:
bors
commit
89cc8529cc
@ -313,6 +313,36 @@ pub fn trans_to_datum(bcx: @mut Block, expr: @ast::Expr) -> DatumBlock {
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let target_obj_ty = expr_ty_adjusted(bcx, expr);
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debug!("auto_borrow_obj(target=%s)",
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target_obj_ty.repr(tcx));
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// Extract source store information
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let (source_store, source_mutbl) = match ty::get(source_datum.ty).sty {
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ty::ty_trait(_, _, s, m, _) => (s, m),
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_ => {
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bcx.sess().span_bug(
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expr.span,
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fmt!("auto_borrow_trait_obj expected a trait, found %s",
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source_datum.ty.repr(bcx.tcx())));
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}
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};
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// check if any borrowing is really needed or we could reuse the source_datum instead
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match ty::get(target_obj_ty).sty {
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ty::ty_trait(_, _, ty::RegionTraitStore(target_scope), target_mutbl, _) => {
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if target_mutbl == ast::MutImmutable && target_mutbl == source_mutbl {
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match source_store {
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ty::RegionTraitStore(source_scope) => {
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if tcx.region_maps.is_subregion_of(target_scope, source_scope) {
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return DatumBlock { bcx: bcx, datum: source_datum };
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}
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},
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_ => {}
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};
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}
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},
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_ => {}
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}
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let scratch = scratch_datum(bcx, target_obj_ty,
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"__auto_borrow_obj", false);
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@ -331,15 +361,6 @@ pub fn trans_to_datum(bcx: @mut Block, expr: @ast::Expr) -> DatumBlock {
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// ~T, or &T, depending on source_obj_ty.
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let source_data_ptr = GEPi(bcx, source_llval, [0u, abi::trt_field_box]);
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let source_data = Load(bcx, source_data_ptr); // always a ptr
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let (source_store, source_mutbl) = match ty::get(source_datum.ty).sty {
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ty::ty_trait(_, _, s, m, _) => (s, m),
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_ => {
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bcx.sess().span_bug(
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expr.span,
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fmt!("auto_borrow_trait_obj expected a trait, found %s",
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source_datum.ty.repr(bcx.tcx())));
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}
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};
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let target_data = match source_store {
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ty::BoxTraitStore(*) => {
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// For deref of @T or @mut T, create a dummy datum and
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@ -434,13 +434,22 @@ pub fn trans_trait_callee(bcx: @mut Block,
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let _icx = push_ctxt("impl::trans_trait_callee");
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let mut bcx = bcx;
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// make a local copy for trait if needed
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let self_ty = expr_ty_adjusted(bcx, self_expr);
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let self_scratch = scratch_datum(bcx, self_ty, "__trait_callee", false);
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bcx = expr::trans_into(bcx, self_expr, expr::SaveIn(self_scratch.val));
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let self_scratch = match ty::get(self_ty).sty {
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ty::ty_trait(_, _, ty::RegionTraitStore(*), _, _) => {
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unpack_datum!(bcx, expr::trans_to_datum(bcx, self_expr))
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}
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_ => {
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let d = scratch_datum(bcx, self_ty, "__trait_callee", false);
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bcx = expr::trans_into(bcx, self_expr, expr::SaveIn(d.val));
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// Arrange a temporary cleanup for the object in case something
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// should go wrong before the method is actually *invoked*.
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d.add_clean(bcx);
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d
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}
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};
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// Arrange a temporary cleanup for the object in case something
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// should go wrong before the method is actually *invoked*.
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self_scratch.add_clean(bcx);
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let callee_ty = node_id_type(bcx, callee_id);
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trans_trait_callee_from_llval(bcx,
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@ -278,23 +278,12 @@ impl Type {
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pub fn opaque_trait(ctx: &CrateContext, store: ty::TraitStore) -> Type {
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let tydesc_ptr = ctx.tydesc_type.ptr_to();
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match store {
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ty::BoxTraitStore => {
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Type::struct_(
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[ tydesc_ptr, Type::opaque_box(ctx).ptr_to() ],
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false)
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}
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ty::UniqTraitStore => {
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Type::struct_(
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[ tydesc_ptr, Type::unique(ctx, &Type::i8()).ptr_to()],
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false)
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}
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ty::RegionTraitStore(*) => {
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Type::struct_(
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[ tydesc_ptr, Type::i8().ptr_to() ],
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false)
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}
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}
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let box_ty = match store {
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ty::BoxTraitStore => Type::opaque_box(ctx),
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ty::UniqTraitStore => Type::unique(ctx, &Type::i8()),
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ty::RegionTraitStore(*) => Type::i8()
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};
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Type::struct_([tydesc_ptr, box_ty.ptr_to()], false)
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}
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pub fn kind(&self) -> TypeKind {
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@ -55,6 +55,7 @@ fn test_destroy_actually_kills(force: bool) {
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#[cfg(windows)]
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fn process_exists(pid: libc::pid_t) -> bool {
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#[fixed_stack_segment];
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use std::libc::types::os::arch::extra::DWORD;
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use std::libc::funcs::extra::kernel32::{CloseHandle, GetExitCodeProcess, OpenProcess};
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