rustc: Use memmove instructions more aggressively in DPS mode. LLVM converts these to optimized block transfer instructions, significantly reducing code size.
This commit is contained in:
Patrick Walton
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4b7884e1fa
commit
22db8b1d53
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@ -20,6 +20,7 @@ import std::ivec;
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import std::option::none;
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import std::option::some;
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import std::str;
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import std::uint;
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import LLFalse = lib::llvm::False;
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import LLTrue = lib::llvm::True;
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@ -36,6 +37,30 @@ fn llelement_type(TypeRef llty) -> TypeRef {
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lib::llvm::llvm::LLVMGetElementType(llty)
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}
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fn llalign_of(&@crate_ctxt ccx, TypeRef llty) -> uint {
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ret llvm::LLVMPreferredAlignmentOfType(ccx.td.lltd, llty);
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}
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fn llsize_of(&@crate_ctxt ccx, TypeRef llty) -> uint {
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ret llvm::LLVMStoreSizeOfType(ccx.td.lltd, llty);
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}
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fn mk_const(&@crate_ctxt ccx, &str name, bool exported, ValueRef llval)
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-> ValueRef {
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auto llglobal = llvm::LLVMAddGlobal(ccx.llmod, trans::val_ty(llval),
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str::buf(name));
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llvm::LLVMSetInitializer(llglobal, llval);
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llvm::LLVMSetGlobalConstant(llglobal, LLTrue);
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if !exported {
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llvm::LLVMSetLinkage(llglobal,
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lib::llvm::LLVMInternalLinkage as llvm::Linkage);
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}
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ret llglobal;
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}
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// Destination utilities
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@ -138,10 +163,38 @@ fn store(&@block_ctxt bcx, &dest dest, ValueRef llsrc, bool cast)
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ret bcx;
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}
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tag heap { hp_task; hp_shared; }
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fn memmove(&@block_ctxt bcx, &dest dest, ValueRef llsrcptr) -> @block_ctxt {
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alt (dest.slot) {
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// TODO: We might want to support these; I can't think of any case in
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// which we would want them off the top of my head, but feel free to add
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// them if they aid orthogonality.
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dst_nil { fail "dst_nil in memmove"; }
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dst_imm(_) { fail "dst_imm in memmove"; }
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dst_ptr(?lldestptr) {
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auto lldestty = llelement_type(trans::val_ty(llsrcptr));
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auto llsrcty = llelement_type(trans::val_ty(llsrcptr));
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auto dest_align = llalign_of(bcx_ccx(bcx), lldestty);
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auto src_align = llalign_of(bcx_ccx(bcx), llsrcty);
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auto align = uint::min(dest_align, src_align);
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auto llfn = bcx_ccx(bcx).intrinsics.get("llvm.memmove.p0i8.p0i8.i32");
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auto lldestptr_i8 = bcx.build.PointerCast(lldestptr,
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tc::T_ptr(tc::T_i8()));
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auto llsrcptr_i8 = bcx.build.PointerCast(llsrcptr,
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tc::T_ptr(tc::T_i8()));
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bcx.build.Call(llfn,
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~[lldestptr_i8,
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llsrcptr_i8,
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tc::C_uint(llsize_of(bcx_ccx(bcx), llsrcty)),
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tc::C_uint(align),
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tc::C_bool(false)]);
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ret bcx;
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}
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}
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}
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// Allocates a value of the given LLVM size on either the task heap or the
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// shared heap.
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tag heap { hp_task; hp_shared; }
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fn malloc(&@block_ctxt bcx, ValueRef lldest, heap heap,
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option[ValueRef] llcustom_size_opt) -> @block_ctxt {
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auto llptrty = llelement_type(lltype_of(lldest));
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@ -177,7 +230,7 @@ fn trans_lit(&@block_ctxt cx, &dest dest, &ast::lit lit) -> @block_ctxt {
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ast::lit_str(?s, ast::sk_unique) {
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auto r = trans_lit_str_common(bcx_ccx(bcx), s);
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auto llstackpart = r._0; auto llheappartopt = r._1;
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bcx = store(bcx, dest, llstackpart, true);
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bcx = memmove(bcx, dest, llstackpart);
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alt (llheappartopt) {
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none { /* no-op */ }
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some(?llheappart) {
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@ -191,7 +244,8 @@ fn trans_lit(&@block_ctxt cx, &dest dest, &ast::lit lit) -> @block_ctxt {
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tc::T_ptr(tc::T_ptr(llheappartty)));
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malloc(bcx, lldestptrptr, hp_shared, none);
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auto lldestptr = bcx.build.Load(lldestptrptr);
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bcx.build.Store(llheappart, lldestptr);
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memmove(bcx, rec(slot=dst_ptr(lldestptr), mode=dm_copy),
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llheappart);
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}
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}
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}
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@ -341,6 +395,8 @@ fn trans_block(&@block_ctxt cx, &dest dest, &ast::block block)
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// since that doesn't work for crate constants.
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fn trans_lit_str_common(&@crate_ctxt ccx, &str s)
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-> tup(ValueRef, option[ValueRef]) {
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auto llstackpart; auto llheappartopt;
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auto len = str::byte_len(s);
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auto array = ~[];
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@ -352,18 +408,23 @@ fn trans_lit_str_common(&@crate_ctxt ccx, &str s)
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array += ~[tc::C_u8(0u)];
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}
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ret tup(tc::C_struct(~[tc::C_uint(len + 1u),
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tc::C_uint(abi::ivec_default_length),
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tc::C_array(tc::T_i8(), array)]),
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none);
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llstackpart = tc::C_struct(~[tc::C_uint(len + 1u),
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tc::C_uint(abi::ivec_default_length),
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tc::C_array(tc::T_i8(), array)]);
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llheappartopt = none;
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} else {
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auto llheappart = tc::C_struct(~[tc::C_uint(len),
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tc::C_array(tc::T_i8(), array)]);
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llstackpart =
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tc::C_struct(~[tc::C_uint(0u),
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tc::C_uint(abi::ivec_default_length),
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tc::C_null(tc::T_ptr(lltype_of(llheappart)))]);
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llheappartopt = some(mk_const(ccx, "const_istr_heap", false,
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llheappart));
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}
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auto llheappart = tc::C_struct(~[tc::C_uint(len),
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tc::C_array(tc::T_i8(), array)]);
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ret tup(tc::C_struct(~[tc::C_uint(0u),
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tc::C_uint(abi::ivec_default_length),
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tc::C_null(tc::T_ptr(lltype_of(llheappart)))]),
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some(llheappart));
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ret tup(mk_const(ccx, "const_istr_stack", false, llstackpart),
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llheappartopt);
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}
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// As above, we don't use destination-passing style here.
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