[WIP] Generate single-entry (instead of updatable) thunks for string literals
Fixes #15113
Previously for a string like
hey :: String
hey = "hey"We would generate this thunk:
hey_rgf :: GHC.Base.String
[LclId] = \u [] GHC.CString.unpackCString# "hey"#;With this patch we now generate single-entry thunks for string literals:
hey_rgf :: GHC.Base.String
[GblId] = {} \s [] GHC.CString.unpackCString# "hey"#;Cmm before:
[hey_r2_entry() { // [R1]
{ info_tbls: [(c1rH,
label: hey_r2_info
rep: HeapRep static { Thunk }
srt: Nothing)]
stack_info: arg_space: 8 updfr_space: Just 8
}
{offset
c1rH: // global
_r2::P64 = R1;
if ((Sp + 8) - 24 < SpLim) (likely: False) goto c1rI; else goto c1rJ;
c1rI: // global
R1 = _r2::P64;
call (stg_gc_enter_1)(R1) args: 8, res: 0, upd: 8;
c1rJ: // global
(_c1rE::I64) = call "ccall" arg hints: [PtrHint,
PtrHint] result hints: [PtrHint] newCAF(BaseReg, _r2::P64);
if (_c1rE::I64 == 0) goto c1rG; else goto c1rF;
c1rG: // global
call (I64[_r2::P64])() args: 8, res: 0, upd: 8;
c1rF: // global
I64[Sp - 16] = stg_bh_upd_frame_info;
I64[Sp - 8] = _c1rE::I64;
R2 = hey1_r1lh_bytes;
Sp = Sp - 16;
call GHC.CString.unpackCString#_info(R2) args: 24, res: 0, upd: 24;
}
},
section ""data" . hey_r2_closure" {
hey_r2_closure:
const hey_r2_info;
const 0;
const 0;
const 0;
}]After:
[hey_r2_entry() { // []
{ info_tbls: [(c1rE,
label: hey_r2_info
rep: HeapRep static { Thunk }
srt: Nothing)]
stack_info: arg_space: 8 updfr_space: Just 8
}
{offset
c1rE: // global
goto c1rG;
c1rG: // global
R2 = hey1_r1lh_bytes;
call GHC.CString.unpackCString#_info(R2) args: 8, res: 0, upd: 8;
}
},
section ""data" . hey_r2_closure" {
hey_r2_closure:
const hey_r2_info;
const 0;
const 0;
const 0;
}]However we currently don't omit single-entry THUNKs in SRTs so references to this closure will still end up in SRTs. This is fixed in !2968.
NoFib:
--------------------------------------------------------------------------------
Program Size Allocs Instrs Reads Writes
--------------------------------------------------------------------------------
CS -1.3% -0.0% -0.0% -0.0% -0.0%
CSD -1.3% -0.0% -0.0% -0.0% -0.0%
FS -1.3% -0.0% -0.0% -0.0% -0.0%
S -1.3% -0.0% -0.0% -0.0% -0.0%
VS -1.3% -0.0% -0.0% -0.0% -0.0%
VSD -1.3% -0.3% -0.0% -0.0% -1.0%
VSM -1.3% -0.0% -0.0% -0.0% -0.0%
anna -1.4% +20.8% +4.9% +2.9% +7.4%
ansi -1.4% +0.0% -0.4% -0.5% -0.2%
atom -1.4% +0.0% +0.1% +0.1% +0.1%
awards -1.6% +1.7% +0.7% +0.6% +0.8%
banner -2.1% +31.6% +15.3% +12.9% +19.9%
bernouilli -1.4% +0.3% +0.1% +0.1% +0.1%
binary-trees -1.6% +0.1% +0.0% +0.0% +0.0%
boyer -1.4% +0.0% +0.1% +0.1% +0.1%
boyer2 -2.3% +1.4% +0.2% +0.2% +0.2%
bspt -1.4% +0.3% +0.1% +0.1% +0.1%
cacheprof -2.8% +11.5% +5.8% +5.6% +6.9%
calendar -1.5% +7.4% +5.0% +4.4% +5.7%
cichelli -1.7% +0.0% -0.4% -0.5% -0.4%
circsim -1.4% +0.1% -0.0% -0.0% +0.0%
clausify -1.4% +0.1% -0.6% -0.9% -0.5%
comp_lab_zift -1.5% +1.7% +1.3% +1.1% +1.2%
compress -1.3% +0.0% +0.0% +0.0% +0.0%
compress2 -1.2% +0.0% +0.0% +0.0% +0.0%
constraints -1.4% +0.0% +0.1% +0.1% +0.1%
cryptarithm1 -1.4% +0.0% +0.0% +0.0% +0.0%
cryptarithm2 -1.7% +0.1% +0.0% +0.0% +0.0%
cse -1.5% +40.5% +11.7% +5.5% +17.4%
digits-of-e1 -1.4% +0.1% +0.0% +0.0% +0.0%
digits-of-e2 -1.6% +0.1% +0.0% +0.0% +0.0%
dom-lt -1.4% +2.3% +1.4% +1.6% +1.5%
eliza -2.4% +4.6% +1.5% +1.5% +2.4%
event -1.5% +0.1% -0.5% -0.8% -0.5%
exact-reals -1.2% +0.0% -0.0% -0.0% -0.0%
exp3_8 -1.4% +0.0% -0.0% -0.0% -0.0%
expert -1.5% +20.6% +4.6% +3.0% +6.8%
fannkuch-redux -1.4% +3.4% -0.0% -0.0% -0.0%
fasta -1.5% +0.0% -0.0% -0.0% -0.0%
fem -1.3% +0.0% +0.1% +0.1% +0.1%
fft -1.4% +1.0% +0.8% +0.7% +0.8%
fft2 -1.5% +0.1% +0.3% +0.4% +0.2%
fibheaps -1.5% +0.0% +0.0% +0.0% +0.0%
fish -1.4% +0.0% -0.0% -0.0% -0.0%
fluid -1.1% +16.4% +5.9% +5.3% +7.7%
fulsom -1.3% +0.2% +0.1% +0.1% +0.1%
gamteb -1.4% +0.8% +0.4% +0.4% +0.5%
gcd -1.4% +0.0% -0.0% -0.0% -0.0%
gen_regexps -1.3% +0.0% +0.1% +0.1% +0.1%
genfft -1.6% +14.0% +10.1% +8.5% +10.7%
gg -1.8% +4.9% +3.5% +3.5% +3.6%
grep -1.5% +0.0% +0.1% +0.2% +0.1%
hidden -1.3% +3.5% +1.6% +1.4% +2.0%
hpg -1.6% +7.2% +4.0% +3.5% +4.8%
ida -1.4% +1.1% +0.6% +0.5% +0.7%
infer -1.4% +4.6% +1.1% +0.6% +1.6%
integer -1.4% +0.0% -0.0% -0.0% -0.0%
integrate -1.4% +0.0% -0.0% -0.0% -0.0%
k-nucleotide -1.6% +1.3% -0.0% -0.0% -0.0%
kahan -1.5% +4.5% -0.0% -0.0% -0.0%
knights -1.3% +0.0% -0.0% -0.0% -0.0%
lambda -1.7% +82.7% +24.9% +18.6% +33.8%
last-piece -1.3% +0.0% -0.0% +0.0% -0.0%
lcss -1.4% +0.5% +0.1% +0.0% +0.2%
life -1.4% +2.7% +1.5% +1.0% +1.6%
lift -1.4% +14.8% +5.8% +3.9% +7.7%
linear -1.4% +0.1% +0.1% +0.1% +0.1%
listcompr -1.7% +4.5% +3.5% +2.7% +3.6%
listcopy -1.7% +4.1% +3.2% +2.4% +3.3%
maillist -1.7% +0.5% +1.1% +1.0% +1.4%
mandel -1.4% +0.6% +0.1% +0.1% +0.2%
mandel2 -1.5% +0.0% -0.0% -0.0% -0.0%
mate -1.4% +0.0% +0.0% +0.0% +0.0%
minimax -1.5% +4.5% +0.5% +0.2% +1.0%
mkhprog -1.6% +6.6% +4.0% +3.5% +4.7%
multiplier -1.4% +0.3% +0.2% +0.2% +0.2%
n-body -1.6% +3.5% -0.0% -0.0% -0.0%
nucleic2 -1.3% +0.0% -0.1% -0.0% -0.0%
para -1.4% +0.0% -0.2% -0.3% -0.2%
paraffins -1.4% +0.3% -0.3% -0.4% -0.1%
parser -1.8% +12.7% +4.1% +3.0% +5.8%
parstof -1.6% +39.5% +12.5% +12.0% +13.9%
pic -1.4% +0.1% -1.2% -1.3% -0.9%
pidigits -1.4% +0.0% +0.0% +0.0% -0.0%
power -1.3% +0.1% +0.0% +0.0% +0.0%
pretty -1.2% +12.4% +0.4% -0.2% +2.0%
primes -1.5% +0.0% -0.0% -0.0% -0.0%
primetest -1.4% +0.0% +0.0% +0.0% +0.0%
prolog -1.3% +22.7% +8.7% +7.5% +10.7%
puzzle -1.5% +0.1% +0.1% +0.1% +0.1%
queens -1.4% +0.0% -0.0% -0.0% -0.0%
reptile -1.5% +0.5% +0.4% +0.3% +0.3%
reverse-complem -1.4% -0.0% -0.0% -0.0% -0.0%
rewrite -1.4% +80.2% +15.7% +14.6% +22.5%
rfib -1.4% +2.1% -0.0% -0.0% -0.0%
rsa -1.4% +0.0% -0.0% -0.0% -0.0%
scc -1.3% -0.2% -0.8% -0.8% -1.0%
sched -1.4% +0.1% +0.0% +0.0% +0.0%
scs -1.4% +0.0% +0.0% +0.1% +0.0%
simple -1.3% +0.0% -0.0% -0.0% -0.0%
solid -1.4% +0.1% -0.0% -0.0% +0.0%
sorting -1.4% +0.0% -0.0% -0.0% -0.0%
spectral-norm -1.6% +2.0% -0.0% -0.0% -0.0%
sphere -1.3% +0.1% +0.0% +0.0% +0.0%
symalg -1.5% +2.8% +0.1% -0.0% +0.4%
tak -1.4% +4.7% -0.0% -0.0% -0.0%
transform -1.5% +4.3% +1.6% +0.8% +2.0%
treejoin -1.4% +0.0% +0.1% +0.0% -0.0%
typecheck -1.6% +28.5% +8.2% +5.6% +11.1%
veritas -2.2% +11.2% +13.2% +12.1% +10.2%
wang -1.4% +4.6% +3.2% +2.0% +3.1%
wave4main -1.4% +0.6% +0.2% +0.1% +0.2%
wheel-sieve1 -1.5% +0.4% +0.2% +0.4% -0.0%
wheel-sieve2 -1.4% +0.0% +0.1% +0.1% +0.1%
x2n1 -1.4% +0.0% -0.0% -0.0% -0.0%
--------------------------------------------------------------------------------
Min -2.8% -0.3% -1.2% -1.3% -1.0%
Max -1.1% +82.7% +24.9% +18.6% +33.8%
Geometric Mean -1.5% +4.3% +1.6% +1.3% +2.0%