bitint: Some bitint store fixes [PR114405]

Hi!

The following patch fixes some bugs in the handling of stores to large/huge
_BitInt bitfields.

In the first 2 hunks we are processing the most significant limb of the
actual type (not necessarily limb in the storage), and so we know it is
either partial or full limb, so [1, limb_prec] bits rather than
[0, limb_prec - 1] bits as the code actually assumed.  So, those 2
spots are fixed by making sure if tprec is a multiple of limb_prec we
actually use limb_prec bits rather than 0.  Otherwise, it e.g. happily
could create and use 0 precision INTEGER_TYPE even when it actually
should have processed 64 bits, or for non-zero bo_bit could handle just
say 1 bit rather than 64 bits plus 1 bit in the last hunk spot.

In the last hunk we are dealing with the extra bits in the last storage
limb, and the code was e.g. happily creating 65 bit precision INTEGER_TYPE,
even when we really should use 1 bit precision in that case.  Also, it
used a wrong offset in that case.

The large testcase covers all these cases.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2024-03-22  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/114405
	* gimple-lower-bitint.cc (bitint_large_huge::lower_mergeable_stmt):
	Set rprec to limb_prec rather than 0 if tprec is divisible by
	limb_prec.  In the last bf_cur handling, set rprec to (tprec + bo_bit)
	% limb_prec rather than tprec % limb_prec and use just rprec instead
	of rprec + bo_bit.  For build_bit_field_ref offset, divide
	(tprec + bo_bit) by limb_prec rather than just tprec.

        * gcc.dg/bitint-103.c: New test.


	Jakub

On Fri, 22 Mar 2024, Jakub Jelinek wrote:

> Hi!
> 
> The following patch fixes some bugs in the handling of stores to large/huge
> _BitInt bitfields.
> 
> In the first 2 hunks we are processing the most significant limb of the
> actual type (not necessarily limb in the storage), and so we know it is
> either partial or full limb, so [1, limb_prec] bits rather than
> [0, limb_prec - 1] bits as the code actually assumed.  So, those 2
> spots are fixed by making sure if tprec is a multiple of limb_prec we
> actually use limb_prec bits rather than 0.  Otherwise, it e.g. happily
> could create and use 0 precision INTEGER_TYPE even when it actually
> should have processed 64 bits, or for non-zero bo_bit could handle just
> say 1 bit rather than 64 bits plus 1 bit in the last hunk spot.
> 
> In the last hunk we are dealing with the extra bits in the last storage
> limb, and the code was e.g. happily creating 65 bit precision INTEGER_TYPE,
> even when we really should use 1 bit precision in that case.  Also, it
> used a wrong offset in that case.
> 
> The large testcase covers all these cases.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

OK.

Richard.

> 2024-03-22  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR tree-optimization/114405
> 	* gimple-lower-bitint.cc (bitint_large_huge::lower_mergeable_stmt):
> 	Set rprec to limb_prec rather than 0 if tprec is divisible by
> 	limb_prec.  In the last bf_cur handling, set rprec to (tprec + bo_bit)
> 	% limb_prec rather than tprec % limb_prec and use just rprec instead
> 	of rprec + bo_bit.  For build_bit_field_ref offset, divide
> 	(tprec + bo_bit) by limb_prec rather than just tprec.
> 
>         * gcc.dg/bitint-103.c: New test.
> 
> --- gcc/gimple-lower-bitint.cc.jj	2024-03-20 15:03:30.868068343 +0100
> +++ gcc/gimple-lower-bitint.cc	2024-03-21 12:51:26.728296098 +0100
> @@ -2737,7 +2737,7 @@ bitint_large_huge::lower_mergeable_stmt
>  		  && tree_fits_uhwi_p (idx))
>  		{
>  		  unsigned int tprec = TYPE_PRECISION (type);
> -		  unsigned int rprec = tprec % limb_prec;
> +		  unsigned int rprec = (tprec - 1) % limb_prec + 1;
>  		  if (rprec + bo_bit < (unsigned) limb_prec)
>  		    {
>  		      tree ftype
> @@ -2882,7 +2882,7 @@ bitint_large_huge::lower_mergeable_stmt
>  	  if (nlhs && i == cnt - 1)
>  	    {
>  	      unsigned int tprec = TYPE_PRECISION (type);
> -	      unsigned int rprec = tprec % limb_prec;
> +	      unsigned int rprec = (tprec - 1) % limb_prec + 1;
>  	      if (rprec + bo_bit < (unsigned) limb_prec)
>  		{
>  		  tree ftype
> @@ -2934,11 +2934,11 @@ bitint_large_huge::lower_mergeable_stmt
>    if (bf_cur != NULL_TREE)
>      {
>        unsigned int tprec = TYPE_PRECISION (type);
> -      unsigned int rprec = tprec % limb_prec;
> -      tree ftype = build_nonstandard_integer_type (rprec + bo_bit, 1);
> +      unsigned int rprec = (tprec + bo_bit) % limb_prec;
> +      tree ftype = build_nonstandard_integer_type (rprec, 1);
>        tree bfr = build_bit_field_ref (ftype, unshare_expr (nlhs),
> -				      rprec + bo_bit,
> -				      (bo_idx + tprec / limb_prec)
> +				      rprec,
> +				      (bo_idx + (tprec + bo_bit) / limb_prec)
>  				      * limb_prec);
>        rhs1 = bf_cur;
>        if (bf_cur != ext)
> --- gcc/testsuite/gcc.dg/torture/bitint-66.c.jj	2024-03-21 11:53:00.790647163 +0100
> +++ gcc/testsuite/gcc.dg/torture/bitint-66.c	2024-03-21 11:52:29.296082298 +0100
> @@ -0,0 +1,187 @@
> +/* PR tree-optimization/114405 */
> +/* { dg-do run { target bitint } } */
> +/* { dg-options "-std=c23" } */
> +/* { dg-skip-if "" { ! run_expensive_tests }  { "*" } { "-O0" "-O2" } } */
> +/* { dg-skip-if "" { ! run_expensive_tests } { "-flto" } { "" } } */
> +
> +#if __BITINT_MAXWIDTH__ >= 22658
> +struct S1 { unsigned _BitInt(22592) b : 22592; } s1;
> +struct S2 { unsigned _BitInt(22656) b : 22656; } s2;
> +struct S3 { unsigned _BitInt(22656) a : 1; unsigned _BitInt(22656) b : 22592; } s3;
> +struct S4 { unsigned _BitInt(22720) a : 1; unsigned _BitInt(22720) b : 22656; } s4;
> +struct S5 { unsigned _BitInt(22656) a : 63; unsigned _BitInt(22656) b : 22592; } s5;
> +struct S6 { unsigned _BitInt(22720) a : 63; unsigned _BitInt(22720) b : 22656; } s6;
> +struct S7 { unsigned _BitInt(22656) a : 63; unsigned _BitInt(22656) b : 22593; } s7;
> +struct S8 { unsigned _BitInt(22720) a : 63; unsigned _BitInt(22720) b : 22657; } s8;
> +struct S9 { unsigned _BitInt(22720) a : 63; unsigned _BitInt(22720) b : 22594; } s9;
> +struct S10 { unsigned _BitInt(22784) a : 63; unsigned _BitInt(22784) b : 22658; } s10;
> +
> +void
> +f1 ()
> +{
> +  s1.b -= 1;
> +}
> +
> +void
> +f2 ()
> +{
> +  s2.b -= 2;
> +}
> +
> +void
> +f3 ()
> +{
> +  s3.b -= 3;
> +}
> +
> +void
> +f4 ()
> +{
> +  s4.b -= 4;
> +}
> +
> +void
> +f5 ()
> +{
> +  s5.b -= 5;
> +}
> +
> +void
> +f6 ()
> +{
> +  s6.b -= 6;
> +}
> +
> +void
> +f7 ()
> +{
> +  s7.b -= 7;
> +}
> +
> +void
> +f8 ()
> +{
> +  s8.b -= 8;
> +}
> +
> +void
> +f9 ()
> +{
> +  s9.b -= 9;
> +}
> +
> +void
> +f10 ()
> +{
> +  s10.b -= 10;
> +}
> +#endif
> +
> +int
> +main ()
> +{
> +#if __BITINT_MAXWIDTH__ >= 22658
> +  unsigned _BitInt (22658) x = 3501580033805053749865300897557477748847108711329567819459950478637111871058594476448431982181406867749052786465568547119127081237631518700636291761657692711130286544798301573970754389430181232761313430384112082690679079970794557194035367971799245661822847552854751058689774923352618076279671533857647416220848224757950147275156424428066646775909830613059147055969908435491029488219272365184159239392675718030519595002477456422002503056329294735478175929919496649872687647968807723892148311099405402751084714404228175329038682692189134908965253321284763753920366394429186473575417235289083442686263212696116398504697202530139901868456674078599632672207665940094189378896012274962391648560141536000227467537703024522843127564358988666808529295039927617882180358290797693401871123229357470298820489718939095566339078181096952355501349273568695715290536537030927540926367088533791408779004958420139510975491969746508442551722498053308778185098046700981285673069607429
 7910828639377203631339464675255240105642870755676377580847320171721410474552064279926175805508159289600278139657791849436955572980238115099785715087280249620991823931002767709388014969775014532212905291917079945444559149155885537869443203998149528921864913273054936504913012987390968722761436324692074211426577825330615158003561217398156744067970380132500886173138375004010286681801118436837157169356000174611385663795085963585748604221595275406157579119331428498714316454502878707144485541046851763795055069716380454650877888082099155307604956585565750095456844726339707735735457306818630192757960862820008907032696106990880643682877297054778560972681289475676822120960274032924190097299892650196374738015462740789768656492119706888461868600641030840748136350368218121335079547275823933746794720376649284092875982043181284314358557128707984260557357154662378677928178190735268683492714017854629967153014231157377885091064447831201063510650297385915804287319939506628451435721208364052433627434988
 7298662378072029694678352540100381344582406385372089002610714745433017263971246287780098138858445161168758147579517122047257558660730026818550665432969475798588251031980609543594536607704004284643671832629456597414421298864967827502032914361307828728358332109316327886922442493843907268417663046683437294533161252426630358454578409533376882850312377085740706727584706071883065032915501382320314266799396174517395898171126691776116839064587641297361142733285421882576014636790421571043264527432282199047065156175545274040484862594439887719775125510778610165240710649669702450178422560226062520615338480524359449770750116836269249278642802657582046653770615940590170998509794658765324193134862407174869068241593536055633086226251014577885194625411661775602814877995037981085884408254266073030002874099684207120496049916957909216398108674801381283064454189869127438005216713546145328338722658631127997155356877394789876797870183369709196956603906822646361505775669667647218025399986089915965965465569
 6041764175806997830988661505506570268705364569312499547833245414680035989401508937878332603696114785031760589634831372662555378106192337871868765042004938316399029922046201490115097572397634399079073980935654723916987312320325707848563520372220518761329467258570671247604267759011063903006911383788841543800548434412776878092108527493561987417394898971584019389684922039236810451851403140917905252458507059606627700181991099055359750878654027452004298102254317942669228411576884730076031979860278271950271147997784187427993025681631445236633102464546578517080096798491577027430205637328858984848358627110281605835382860215484869451298488587179094216208242723800558137655675403579009115551342574105547116614383452531998695222631800922621940166465384286025568044807066440751367245844978207473901136547335822965098874847249062937074402239146662536111305441261257467813421603285655686364226541439841193527380410804499378326924926231091634327891769813861171406111239337389718538888214657118679476930091
 4631780033370026907455350009100991398234230544005707225639911199001521060556494353269734418926976543883020167814965921931535096716826458262250189637748592376073865192810054352613051207327474619337934761146663426134935118503413825504082424332977262179190227449970171913254842194017309504632878985906186166214692140433429536009075713610528721894447986767468896884878765453610651622692341168938373665683970274583865449382798823150851403509730677053140708625595483245639618740574210653530198624859276131133783495033522802696413029101559426339050058584932631815922210413946199510350852865446812403106276713939581929546785460511137593419056060306250217029285811803013980616801841304694722011435758766177962049701664613512583182049260761144544863256467186213830060851829683883752577265078689385674617164146035435092588247318322733523567283845432256120837686647944780078580265417701923133121360511602219094764926277534354807040327859447719471002245844782328492039359603459083181436222097669007774554756731
 2680160514879333129726161376588536503174614941960704887174049756335486859344618154678796730437380285016623857657263394473190242609307399515056939928261783433741498575457191002814344076045074699451115450324376560994244125733363690791688620030948556896005459334486992630811287741350843254329359700251606341653571454433780062206621604456479431281953525614251270994176471966683843351093490311346964638559068748656754197807419811396455872748394198642308213954694186836369359308346092913532277753127161762666534419658346979275791601776801867089703083157496506876624595993870551718087267196646736592546937426297422108750191983363747055083719030935424109952530135016014260163282148647070095343886999715396169729189257487291117924761471320991514080674156717712687585623364723331735613774248566070160762173458132002098376222932612692960491023571292592918473033107884023354730551047939250181082663655663341449579770110220809542744835130761810955721396736227972790768312192727111082560814259913758135181354426
 65798185129409104195642582574005698068543758814799878628816260575002894250723437469293380754329373751478069967151946701724550270952583590048204731437620446357611597703063140065615278014456977266371201795995646459704425842307781189527028486070466105764495249910844961272734411722090576328496690678921549811732110098855139371357058264972132635004768261508328436120677484741464226299067993312922923316398805257936717699519222213192533192746600829048907097046462066206043987729487350920474035219484795840791105847762753227958460953129122508970162044661061074090561192446511631511339514682638233698374095743691902757648070625949939841339410289027899541368321851192767145693326883564251857041615916159616490433637711319076039315762942426225728417924096927156791836747462094823404471357021596544260573448601630171546391583358297381573516226814145190492133449221202013592319137021uwb;
> +  unsigned _BitInt (22658) y = ~x, a;
> +  a = x >> (22658 - 22592);
> +  s1.b = a;
> +  f1 ();
> +  if (s1.b != a - 1)
> +    __builtin_abort ();
> +  a = y >> (22658 - 22592);
> +  s1.b = a;
> +  f1 ();
> +  if (s1.b != a - 1)
> +    __builtin_abort ();
> +  a = x >> (22658 - 22656);
> +  s2.b = a;
> +  f2 ();
> +  if (s2.b != a - 2)
> +    __builtin_abort ();
> +  a = y >> (22658 - 22656);
> +  s2.b = a;
> +  f2 ();
> +  if (s2.b != a - 2)
> +    __builtin_abort ();
> +  a = x >> (22658 - 22592);
> +  s3.b = a;
> +  f3 ();
> +  if (s3.b != a - 3)
> +    __builtin_abort ();
> +  a = y >> (22658 - 22592);
> +  s3.b = a;
> +  f3 ();
> +  if (s3.b != a - 3)
> +    __builtin_abort ();
> +  a = x >> (22658 - 22656);
> +  s4.b = a;
> +  f4 ();
> +  if (s4.b != a - 4)
> +    __builtin_abort ();
> +  a = y >> (22658 - 22656);
> +  s4.b = a;
> +  f4 ();
> +  if (s4.b != a - 4)
> +    __builtin_abort ();
> +  a = x >> (22658 - 22592);
> +  s5.b = a;
> +  f5 ();
> +  if (s5.b != a - 5)
> +    __builtin_abort ();
> +  a = y >> (22658 - 22592);
> +  s5.b = a;
> +  f5 ();
> +  if (s5.b != a - 5)
> +    __builtin_abort ();
> +  a = x >> (22658 - 22656);
> +  s6.b = a;
> +  f6 ();
> +  if (s6.b != a - 6)
> +    __builtin_abort ();
> +  a = y >> (22658 - 22656);
> +  s6.b = a;
> +  f6 ();
> +  if (s6.b != a - 6)
> +    __builtin_abort ();
> +  a = x >> (22658 - 22593);
> +  s7.b = a;
> +  f7 ();
> +  if (s7.b != a - 7)
> +    __builtin_abort ();
> +  a = y >> (22658 - 22593);
> +  s7.b = a;
> +  f7 ();
> +  if (s7.b != a - 7)
> +    __builtin_abort ();
> +  a = x >> (22658 - 22657);
> +  s8.b = a;
> +  f8 ();
> +  if (s8.b != a - 8)
> +    __builtin_abort ();
> +  a = y >> (22658 - 22657);
> +  s8.b = a;
> +  f8 ();
> +  if (s8.b != a - 8)
> +    __builtin_abort ();
> +  a = x >> (22658 - 22594);
> +  s9.b = a;
> +  f9 ();
> +  if (s9.b != a - 9)
> +    __builtin_abort ();
> +  a = y >> (22658 - 22594);
> +  s9.b = a;
> +  f9 ();
> +  if (s9.b != a - 9)
> +    __builtin_abort ();
> +  a = x >> (22658 - 22658);
> +  s10.b = a;
> +  f10 ();
> +  if (s10.b != a - 10)
> +    __builtin_abort ();
> +  a = y >> (22658 - 22658);
> +  s10.b = a;
> +  f10 ();
> +  if (s10.b != a - 10)
> +    __builtin_abort ();
> +#endif
> +}
> 
> 	Jakub
> 
>