* Setting insn mnemonic partly automagically @ 2024-06-17 19:13 Stefan Schulze Frielinghaus 2024-06-21 19:50 ` Georg-Johann Lay 0 siblings, 1 reply; 5+ messages in thread From: Stefan Schulze Frielinghaus @ 2024-06-17 19:13 UTC (permalink / raw) To: gcc Hi all, I'm trying to add an alternative to an existing insn foobar: (define_insn "foobar" [(set (match_operand ...) (match_operand ...))] "" "@ foo bar #") Since the asm output depends on the operands in a non-trivial way which isn't easily solved via iterators, I went for a general C function and came up with: (define_insn "foobar" [(set (match_operand ...) (match_operand ...))] "" "@ foo * return foobar_helper (operands[0], operands[1]); bar #" [(set_attr_alternative "mnemonic" [(const_string "foo") (const_string "specialcase") (const_string "bar") (const_string "unknown")])]) If there exist a lot of alternatives, then setting the mnemonic attribute like this feels repetitive and is error prone. Furthermore, if there exists no other insn with an output template containing foo/bar, then I would have to declare foo/bar via (define_attr "mnemonic" "...,foo,bar,..." (const_string "unknown")) which again is repetitive. Thus, I'm wondering if there exists a more elegant way to achieve this? Ultimately, I would like to set the mnemonic attribute only manually for the alternative which is implemented via C code and let the mnemonic attribute for the remaining alternatives be set automagically. Not sure whether this is supported? If all fails, I have another idea how to solve this by utilizing PRINT_OPERAND. However, now I'm curious whether my current attempt is feasible or not. Cheers, Stefan ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Setting insn mnemonic partly automagically 2024-06-17 19:13 Setting insn mnemonic partly automagically Stefan Schulze Frielinghaus @ 2024-06-21 19:50 ` Georg-Johann Lay 2024-06-22 8:46 ` Stefan Schulze Frielinghaus 0 siblings, 1 reply; 5+ messages in thread From: Georg-Johann Lay @ 2024-06-21 19:50 UTC (permalink / raw) To: Stefan Schulze Frielinghaus, gcc Am 17.06.24 um 21:13 schrieb Stefan Schulze Frielinghaus via Gcc: > Hi all, > > I'm trying to add an alternative to an existing insn foobar: > > (define_insn "foobar" > [(set (match_operand ...) > (match_operand ...))] > "" > "@ > foo > bar > #") > > Since the asm output depends on the operands in a non-trivial way which isn't > easily solved via iterators, I went for a general C function and came up with: > > (define_insn "foobar" > [(set (match_operand ...) > (match_operand ...))] > "" > "@ > foo > * return foobar_helper (operands[0], operands[1]); > bar > #" > [(set_attr_alternative "mnemonic" [(const_string "foo") > (const_string "specialcase") > (const_string "bar") > (const_string "unknown")])]) > > If there exist a lot of alternatives, then setting the mnemonic attribute like > this feels repetitive and is error prone. Furthermore, if there exists no > other insn with an output template containing foo/bar, then I would have to > declare foo/bar via > > (define_attr "mnemonic" "...,foo,bar,..." (const_string "unknown")) > > which again is repetitive. Thus, I'm wondering if there exists a more elegant > way to achieve this? Ultimately, I would like to set the mnemonic > attribute only manually for the alternative which is implemented via C > code and let the mnemonic attribute for the remaining alternatives be > set automagically. Not sure whether this is supported? > > If all fails, I have another idea how to solve this by utilizing PRINT_OPERAND. > However, now I'm curious whether my current attempt is feasible or not. > > Cheers, > Stefan It's a bit unclear to me what you are trying to do, as you are not only adding an insn alternative, but also are adding insn attribute "mnemonic", which the original insn did not have. Also, it's unclear how PRINT_OPERAND would help with setting the attribute. Johann ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Setting insn mnemonic partly automagically 2024-06-21 19:50 ` Georg-Johann Lay @ 2024-06-22 8:46 ` Stefan Schulze Frielinghaus 2024-06-22 11:00 ` Georg-Johann Lay 0 siblings, 1 reply; 5+ messages in thread From: Stefan Schulze Frielinghaus @ 2024-06-22 8:46 UTC (permalink / raw) To: Georg-Johann Lay; +Cc: gcc On Fri, Jun 21, 2024 at 09:50:43PM +0200, Georg-Johann Lay wrote: > > > Am 17.06.24 um 21:13 schrieb Stefan Schulze Frielinghaus via Gcc: > > Hi all, > > > > I'm trying to add an alternative to an existing insn foobar: > > > > (define_insn "foobar" > > [(set (match_operand ...) > > (match_operand ...))] > > "" > > "@ > > foo > > bar > > #") > > > > Since the asm output depends on the operands in a non-trivial way which isn't > > easily solved via iterators, I went for a general C function and came up with: > > > > (define_insn "foobar" > > [(set (match_operand ...) > > (match_operand ...))] > > "" > > "@ > > foo > > * return foobar_helper (operands[0], operands[1]); > > bar > > #" > > [(set_attr_alternative "mnemonic" [(const_string "foo") > > (const_string "specialcase") > > (const_string "bar") > > (const_string "unknown")])]) > > > > If there exist a lot of alternatives, then setting the mnemonic attribute like > > this feels repetitive and is error prone. Furthermore, if there exists no > > other insn with an output template containing foo/bar, then I would have to > > declare foo/bar via > > > > (define_attr "mnemonic" "...,foo,bar,..." (const_string "unknown")) > > > > which again is repetitive. Thus, I'm wondering if there exists a more elegant > > way to achieve this? Ultimately, I would like to set the mnemonic > > attribute only manually for the alternative which is implemented via C > > code and let the mnemonic attribute for the remaining alternatives be > > set automagically. Not sure whether this is supported? > > > > If all fails, I have another idea how to solve this by utilizing PRINT_OPERAND. > > However, now I'm curious whether my current attempt is feasible or not. > > > > Cheers, > > Stefan > > It's a bit unclear to me what you are trying to do, as you are not only > adding an insn alternative, but also are adding insn attribute > "mnemonic", which the original insn did not have. My take so far is that every insn has a mnemonic attribute which is set either explicitly or implicitly (assuming that the target requested this via define_attr "mnemonic" "..."). This is done in function gen_mnemonic_attr() from gensupport.cc. Thus, something like (define_insn "foobar" [(set (match_operand ...) (match_operand ...))] "" "@ foo bar #") and (define_insn "foobar" [(set (match_operand ...) (match_operand ...))] "" "@ foo bar #" [(set_attr_alternative "mnemonic" [(const_string "foo") (const_string "bar") (const_string "unknown")])]) should be equivalent. Of course, the implicit method fails if the pattern is generated via C statements which is way I set it manually in the initial example. The initial example contained 3 alternatives plus 1 for the generated one. Setting it manually there might be feasible, however, for my actual problem I have an insn with 27 alternatives where I do not want to set and maintain it manually. A side effect of setting the attribute implicitly is that each mnemonic is added automatically to the mnemonic hash table which I would have to do manually for my 27 alternatives which I would like to avoid, too. > > Also, it's unclear how PRINT_OPERAND would help with setting the attribute. For my particular problem I think one can also utilize PRINT_OPERAND which I should have elaborated a bit more but feared to make the example unnecessarily complicated. The C code foobar_helper (operands[0], operands[1]) emits actually an extended mnemonic "specialcase$VAR\t%0,%1" where $VAR can be either A, B, or C. The extended mnemonic is just syntactic sugar for the base mnemonic "specialcase\t%0,%1,$IMM" which is why we can lie and hard code the mnemonic attribute to specialcase since this won't effect scheduling. Since the choice which extended mnemonic should be used depends only on operands[1] I thought about rewriting all this into (define_insn "foobar" [(set (match_operand ...) (match_operand ...))] "" "@ foo specialcase\t%0,%1,%X1 bar #") Obviously we have to sacrifice the usage of an extended mnemonic but more problematic is that we have to allocate one of those very few codes X just for this insn. So this doesn't scale either if one has to come up with many different codes. Furthermore, this only works in my very particular case since I can split the extended mnemonic into a base mnemonic and an immediate which only depends on one operand, i.e., it would fail if it depended on operands[0] and operands[1]. I hope this makes it a bit more clear, if not just let me know. Cheers, Stefan > > Johann ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Setting insn mnemonic partly automagically 2024-06-22 8:46 ` Stefan Schulze Frielinghaus @ 2024-06-22 11:00 ` Georg-Johann Lay 2024-06-22 15:24 ` Stefan Schulze Frielinghaus 0 siblings, 1 reply; 5+ messages in thread From: Georg-Johann Lay @ 2024-06-22 11:00 UTC (permalink / raw) To: Stefan Schulze Frielinghaus; +Cc: gcc Am 22.06.24 um 10:46 schrieb Stefan Schulze Frielinghaus: > On Fri, Jun 21, 2024 at 09:50:43PM +0200, Georg-Johann Lay wrote: >> >> >> Am 17.06.24 um 21:13 schrieb Stefan Schulze Frielinghaus via Gcc: >>> Hi all, >>> >>> I'm trying to add an alternative to an existing insn foobar: >>> >>> (define_insn "foobar" >>> [(set (match_operand ...) >>> (match_operand ...))] >>> "" >>> "@ >>> foo >>> bar >>> #") >>> >>> Since the asm output depends on the operands in a non-trivial way which isn't >>> easily solved via iterators, I went for a general C function and came up with: >>> >>> (define_insn "foobar" >>> [(set (match_operand ...) >>> (match_operand ...))] >>> "" >>> "@ >>> foo >>> * return foobar_helper (operands[0], operands[1]); >>> bar >>> #" >>> [(set_attr_alternative "mnemonic" [(const_string "foo") >>> (const_string "specialcase") >>> (const_string "bar") >>> (const_string "unknown")])]) >>> >>> If there exist a lot of alternatives, then setting the mnemonic attribute like >>> this feels repetitive and is error prone. Furthermore, if there exists no >>> other insn with an output template containing foo/bar, then I would have to >>> declare foo/bar via >>> >>> (define_attr "mnemonic" "...,foo,bar,..." (const_string "unknown")) >>> >>> which again is repetitive. Thus, I'm wondering if there exists a more elegant >>> way to achieve this? Ultimately, I would like to set the mnemonic >>> attribute only manually for the alternative which is implemented via C >>> code and let the mnemonic attribute for the remaining alternatives be >>> set automagically. Not sure whether this is supported? >>> >>> If all fails, I have another idea how to solve this by utilizing PRINT_OPERAND. >>> However, now I'm curious whether my current attempt is feasible or not. >>> >>> Cheers, >>> Stefan >> >> It's a bit unclear to me what you are trying to do, as you are not only >> adding an insn alternative, but also are adding insn attribute >> "mnemonic", which the original insn did not have. > > My take so far is that every insn has a mnemonic attribute which is set > either explicitly or implicitly (assuming that the target requested this > via define_attr "mnemonic" "..."). This is done in function > gen_mnemonic_attr() from gensupport.cc. Thus, something like > > (define_insn "foobar" > [(set (match_operand ...) > (match_operand ...))] > "" > "@ > foo > bar > #") > > and > > (define_insn "foobar" > [(set (match_operand ...) > (match_operand ...))] > "" > "@ > foo > bar > #" > [(set_attr_alternative "mnemonic" [(const_string "foo") > (const_string "bar") > (const_string "unknown")])]) > > should be equivalent. > > Of course, the implicit method fails if the pattern is generated via C > statements which is way I set it manually in the initial example. The > initial example contained 3 alternatives plus 1 for the generated one. > Setting it manually there might be feasible, however, for my actual > problem I have an insn with 27 alternatives where I do not want to set > and maintain it manually. A side effect of setting the attribute > implicitly is that each mnemonic is added automatically to the mnemonic > hash table which I would have to do manually for my 27 alternatives > which I would like to avoid, too. > >> >> Also, it's unclear how PRINT_OPERAND would help with setting the attribute. > > For my particular problem I think one can also utilize PRINT_OPERAND > which I should have elaborated a bit more but feared to make the example > unnecessarily complicated. The C code > > foobar_helper (operands[0], operands[1]) > > emits actually an extended mnemonic "specialcase$VAR\t%0,%1" where $VAR > can be either A, B, or C. The extended mnemonic is just syntactic sugar > for the base mnemonic "specialcase\t%0,%1,$IMM" which is why we can lie > and hard code the mnemonic attribute to specialcase since this won't > effect scheduling. Since the choice which extended mnemonic should be > used depends only on operands[1] I thought about rewriting all this into > > (define_insn "foobar" > [(set (match_operand ...) > (match_operand ...))] > "" > "@ > foo > specialcase\t%0,%1,%X1 > bar > #") > > Obviously we have to sacrifice the usage of an extended mnemonic but > more problematic is that we have to allocate one of those very few codes > X just for this insn. So this doesn't scale either if one has to come > up with many different codes. Furthermore, this only works in my very > particular case since I can split the extended mnemonic into a base > mnemonic and an immediate which only depends on one operand, i.e., it > would fail if it depended on operands[0] and operands[1]. > > I hope this makes it a bit more clear, if not just let me know. > > Cheers, > Stefan Maybe the following syntax for setting an attribute is a better fit in your case? [(set (attr "length") (symbol_ref ("4 + reg_overlap_mentioned_p (operands[0], operands[1])"))) So you can hook in some function that spits out the attributes, and it could also provide mnemonics. Johann ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Setting insn mnemonic partly automagically 2024-06-22 11:00 ` Georg-Johann Lay @ 2024-06-22 15:24 ` Stefan Schulze Frielinghaus 0 siblings, 0 replies; 5+ messages in thread From: Stefan Schulze Frielinghaus @ 2024-06-22 15:24 UTC (permalink / raw) To: Georg-Johann Lay; +Cc: gcc On Sat, Jun 22, 2024 at 01:00:54PM +0200, Georg-Johann Lay wrote: > Am 22.06.24 um 10:46 schrieb Stefan Schulze Frielinghaus: > > On Fri, Jun 21, 2024 at 09:50:43PM +0200, Georg-Johann Lay wrote: > > > > > > > > > Am 17.06.24 um 21:13 schrieb Stefan Schulze Frielinghaus via Gcc: > > > > Hi all, > > > > > > > > I'm trying to add an alternative to an existing insn foobar: > > > > > > > > (define_insn "foobar" > > > > [(set (match_operand ...) > > > > (match_operand ...))] > > > > "" > > > > "@ > > > > foo > > > > bar > > > > #") > > > > > > > > Since the asm output depends on the operands in a non-trivial way which isn't > > > > easily solved via iterators, I went for a general C function and came up with: > > > > > > > > (define_insn "foobar" > > > > [(set (match_operand ...) > > > > (match_operand ...))] > > > > "" > > > > "@ > > > > foo > > > > * return foobar_helper (operands[0], operands[1]); > > > > bar > > > > #" > > > > [(set_attr_alternative "mnemonic" [(const_string "foo") > > > > (const_string "specialcase") > > > > (const_string "bar") > > > > (const_string "unknown")])]) > > > > > > > > If there exist a lot of alternatives, then setting the mnemonic attribute like > > > > this feels repetitive and is error prone. Furthermore, if there exists no > > > > other insn with an output template containing foo/bar, then I would have to > > > > declare foo/bar via > > > > > > > > (define_attr "mnemonic" "...,foo,bar,..." (const_string "unknown")) > > > > > > > > which again is repetitive. Thus, I'm wondering if there exists a more elegant > > > > way to achieve this? Ultimately, I would like to set the mnemonic > > > > attribute only manually for the alternative which is implemented via C > > > > code and let the mnemonic attribute for the remaining alternatives be > > > > set automagically. Not sure whether this is supported? > > > > > > > > If all fails, I have another idea how to solve this by utilizing PRINT_OPERAND. > > > > However, now I'm curious whether my current attempt is feasible or not. > > > > > > > > Cheers, > > > > Stefan > > > > > > It's a bit unclear to me what you are trying to do, as you are not only > > > adding an insn alternative, but also are adding insn attribute > > > "mnemonic", which the original insn did not have. > > > > My take so far is that every insn has a mnemonic attribute which is set > > either explicitly or implicitly (assuming that the target requested this > > via define_attr "mnemonic" "..."). This is done in function > > gen_mnemonic_attr() from gensupport.cc. Thus, something like > > > > (define_insn "foobar" > > [(set (match_operand ...) > > (match_operand ...))] > > "" > > "@ > > foo > > bar > > #") > > > > and > > > > (define_insn "foobar" > > [(set (match_operand ...) > > (match_operand ...))] > > "" > > "@ > > foo > > bar > > #" > > [(set_attr_alternative "mnemonic" [(const_string "foo") > > (const_string "bar") > > (const_string "unknown")])]) > > > > should be equivalent. > > > > Of course, the implicit method fails if the pattern is generated via C > > statements which is way I set it manually in the initial example. The > > initial example contained 3 alternatives plus 1 for the generated one. > > Setting it manually there might be feasible, however, for my actual > > problem I have an insn with 27 alternatives where I do not want to set > > and maintain it manually. A side effect of setting the attribute > > implicitly is that each mnemonic is added automatically to the mnemonic > > hash table which I would have to do manually for my 27 alternatives > > which I would like to avoid, too. > > > > > > > > Also, it's unclear how PRINT_OPERAND would help with setting the attribute. > > > > For my particular problem I think one can also utilize PRINT_OPERAND > > which I should have elaborated a bit more but feared to make the example > > unnecessarily complicated. The C code > > > > foobar_helper (operands[0], operands[1]) > > > > emits actually an extended mnemonic "specialcase$VAR\t%0,%1" where $VAR > > can be either A, B, or C. The extended mnemonic is just syntactic sugar > > for the base mnemonic "specialcase\t%0,%1,$IMM" which is why we can lie > > and hard code the mnemonic attribute to specialcase since this won't > > effect scheduling. Since the choice which extended mnemonic should be > > used depends only on operands[1] I thought about rewriting all this into > > > > (define_insn "foobar" > > [(set (match_operand ...) > > (match_operand ...))] > > "" > > "@ > > foo > > specialcase\t%0,%1,%X1 > > bar > > #") > > > > Obviously we have to sacrifice the usage of an extended mnemonic but > > more problematic is that we have to allocate one of those very few codes > > X just for this insn. So this doesn't scale either if one has to come > > up with many different codes. Furthermore, this only works in my very > > particular case since I can split the extended mnemonic into a base > > mnemonic and an immediate which only depends on one operand, i.e., it > > would fail if it depended on operands[0] and operands[1]. > > > > I hope this makes it a bit more clear, if not just let me know. > > > > Cheers, > > Stefan > > Maybe the following syntax for setting an attribute is a better > fit in your case? > > [(set (attr "length") > (symbol_ref ("4 + reg_overlap_mentioned_p (operands[0], > operands[1])"))) > > So you can hook in some function that spits out the attributes, > and it could also provide mnemonics. I have been thinking about a symbel_ref hook, too. However, came to the conclusion that this would involve manual book keeping, too, i.e., I would have to set and keep in sync in my symbol_ref expression for my 27 alternative insn all 26 static mnemonics manually only in order to generate the 27th mnemonic. Maybe my case is a bit too special. Ultimately, I was hoping for something like (define_insn "foobar" [(set (match_operand ...) (match_operand ...))] "" "@ foo * return foobar_helper (operands[0], operands[1], insn); bar #") where the function which generates the mnemonic is also able to set the mnemonic attribute e.g. by passing the current insn reference as a parameter. Then function gen_mnemonic_attr() could deal with alternatives 0 and 2 as usual and alternative 1 would have been dealt with via C code. However, the more I dig into the generation pipeline I realize that this is not easily possible. Function foobar_helper is called during the final pass where scheduling is already done. Too late to set the mnemonic attribute. Cheers, Stefan ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2024-06-22 16:11 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2024-06-17 19:13 Setting insn mnemonic partly automagically Stefan Schulze Frielinghaus 2024-06-21 19:50 ` Georg-Johann Lay 2024-06-22 8:46 ` Stefan Schulze Frielinghaus 2024-06-22 11:00 ` Georg-Johann Lay 2024-06-22 15:24 ` Stefan Schulze Frielinghaus
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