diff options
| author | Ömer Sinan Ağacan <omeragacan@gmail.com> | 2020-04-01 13:31:35 +0300 |
|---|---|---|
| committer | Ben Gamari <ben@smart-cactus.org> | 2022-10-21 09:59:27 -0400 |
| commit | eb43bf22f1439aa74cf8f9fa53710ba42a002597 (patch) | |
| tree | 275c37ca0ee2aa7f6f824ac8bdcafb724cdb4128 /compiler/GHC/Cmm.hs | |
| parent | b8304648731f1430dba9037f31107d75b3da78b0 (diff) | |
| download | haskell-wip/osa1/std_string_thunks.tar.gz | |
Introduce a standard thunk for allocating stringswip/osa1/std_string_thunks
Currently for a top-level closure in the form
hey = unpackCString# x
we generate code like this:
Main.hey_entry() // [R1]
{ info_tbls: [(c2T4,
label: Main.hey_info
rep: HeapRep static { Thunk }
srt: Nothing)]
stack_info: arg_space: 8 updfr_space: Just 8
}
{offset
c2T4: // global
_rqm::P64 = R1;
if ((Sp + 8) - 24 < SpLim) (likely: False) goto c2T5; else goto c2T6;
c2T5: // global
R1 = _rqm::P64;
call (stg_gc_enter_1)(R1) args: 8, res: 0, upd: 8;
c2T6: // global
(_c2T1::I64) = call "ccall" arg hints: [PtrHint,
PtrHint] result hints: [PtrHint] newCAF(BaseReg, _rqm::P64);
if (_c2T1::I64 == 0) goto c2T3; else goto c2T2;
c2T3: // global
call (I64[_rqm::P64])() args: 8, res: 0, upd: 8;
c2T2: // global
I64[Sp - 16] = stg_bh_upd_frame_info;
I64[Sp - 8] = _c2T1::I64;
R2 = hey1_r2Gg_bytes;
Sp = Sp - 16;
call GHC.CString.unpackCString#_info(R2) args: 24, res: 0, upd: 24;
}
}
This code is generated for every string literal. Only difference between
top-level closures like this is the argument for the bytes of the string
(hey1_r2Gg_bytes in the code above).
With this patch we introduce a standard thunk in the RTS, called
stg_MK_STRING_info, that does what `unpackCString# x` does, except it
gets the bytes address from the payload. Using this, for the closure
above, we generate this:
Main.hey_closure" {
Main.hey_closure:
const stg_MK_STRING_info;
const 0; // padding for indirectee
const 0; // static link
const 0; // saved info
const hey1_r1Gg_bytes; // the payload
}
This is much smaller in code.
Metric Decrease:
T10421
T11195
T12150
T12425
T16577
T18282
T18698a
T18698b
Co-Authored By: Ben Gamari <ben@well-typed.com>
Diffstat (limited to 'compiler/GHC/Cmm.hs')
| -rw-r--r-- | compiler/GHC/Cmm.hs | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/compiler/GHC/Cmm.hs b/compiler/GHC/Cmm.hs index 3533dc2389..b764e80281 100644 --- a/compiler/GHC/Cmm.hs +++ b/compiler/GHC/Cmm.hs @@ -301,6 +301,9 @@ data GenCmmStatics (rawOnly :: Bool) where -> CmmInfoTable -> CostCentreStack -> [CmmLit] -- Payload + -> [CmmLit] -- Non-pointers that go to the end of the closure + -- This is used by stg_unpack_cstring closures. + -- See Note [unpack_cstring closures] in StgStdThunks.cmm. -> GenCmmStatics 'False -- | Static data, after SRTs are generated @@ -432,8 +435,8 @@ pprInfoTable platform (CmmInfoTable { cit_lbl = lbl, cit_rep = rep -- pprStatics :: Platform -> GenCmmStatics a -> SDoc -pprStatics platform (CmmStatics lbl itbl ccs payload) = - pdoc platform lbl <> colon <+> pdoc platform itbl <+> ppr ccs <+> pdoc platform payload +pprStatics platform (CmmStatics lbl itbl ccs payload extras) = + pdoc platform lbl <> colon <+> pdoc platform itbl <+> ppr ccs <+> pdoc platform payload <+> ppr extras pprStatics platform (CmmStaticsRaw lbl ds) = vcat ((pdoc platform lbl <> colon) : map (pprStatic platform) ds) pprStatic :: Platform -> CmmStatic -> SDoc |