Where is LDSA created?

Jul 02, 2020

Denis Feklushkin

Jul 02, 2020

Jul 02, 2020

Jul 02, 2020

Jul 05, 2020

Jul 05, 2020

Jul 06, 2020

Jul 06, 2020

Jul 18, 2020

Jul 18, 2020

Jul 18, 2020

Jul 18, 2020

Jul 18, 2020

Jul 18, 2020

Jul 19, 2020

Jul 19, 2020

Hi! Faced with wrong unwinding behaviour: if exception is occured _d_eh_personality can't find appropriate catcher because TType == 0x00 Before debug this I consider to find where is LDSA is created. I see it in DMD sources (dmd/src/dmd/backend/dwarfeh.d) but this file is removed from LDC. Where is LDSA created? (--mtriple=thumbv7m-unknown-none-eabi is used)

On Thursday, 2 July 2020 at 10:13:38 UTC, Denis Feklushkin wrote: > Hi! > > Faced with wrong unwinding behaviour: if exception is occured _d_eh_personality can't find appropriate catcher because TType == 0x00 > > Before debug this I consider to find where is LDSA is created. I see it in DMD sources (dmd/src/dmd/backend/dwarfeh.d) but this file is removed from LDC. > > Where is LDSA created? Typo: LSDA, of course!

On Thursday, 2 July 2020 at 10:14:34 UTC, Denis Feklushkin wrote: > On Thursday, 2 July 2020 at 10:13:38 UTC, Denis Feklushkin wrote: >> Hi! >> >> Faced with wrong unwinding behaviour: if exception is occured _d_eh_personality can't find appropriate catcher because TType == 0x00 >> >> Before debug this I consider to find where is LDSA is created. I see it in DMD sources (dmd/src/dmd/backend/dwarfeh.d) but this file is removed from LDC. >> >> Where is LDSA created? > > > Typo: LSDA, of course! The exception tables are generated by LLVM (it is safe to assume that everything that is done by `dmd/src/dmd/backend/...` is done by LLVM for LDC). -Johan

On Thursday, 2 July 2020 at 10:36:58 UTC, Johan wrote: > The exception tables are generated by LLVM (it is safe to assume that everything that is done by `dmd/src/dmd/backend/...` is done by LLVM for LDC). LSDA is about language-specific data. It is generated by LLVM too? You mean that LLVM calls some callback to druntime for LSDA creation? grep isn't displays anything related to LSDA creation in ldc sources. Only druntime's scanLSDA.

On Thursday, 2 July 2020 at 11:29:45 UTC, Denis Feklushkin wrote: > On Thursday, 2 July 2020 at 10:36:58 UTC, Johan wrote: > >> The exception tables are generated by LLVM (it is safe to assume that everything that is done by `dmd/src/dmd/backend/...` is done by LLVM for LDC). > > LSDA is about language-specific data. It is generated by LLVM too? > You mean that LLVM calls some callback to druntime for LSDA creation? > > grep isn't displays anything related to LSDA creation in ldc sources. Only druntime's scanLSDA. LSDA is generated at compile-time, yes? Or I understand something wrong?

On Sunday, 5 July 2020 at 09:31:25 UTC, Denis Feklushkin wrote: > On Thursday, 2 July 2020 at 11:29:45 UTC, Denis Feklushkin wrote: >> On Thursday, 2 July 2020 at 10:36:58 UTC, Johan wrote: >> >>> The exception tables are generated by LLVM (it is safe to assume that everything that is done by `dmd/src/dmd/backend/...` is done by LLVM for LDC). >> >> LSDA is about language-specific data. It is generated by LLVM too? >> You mean that LLVM calls some callback to druntime for LSDA creation? >> >> grep isn't displays anything related to LSDA creation in ldc sources. Only druntime's scanLSDA. > > LSDA is generated at compile-time, yes? Or I understand something wrong? The EH tables (yes, that's what LSDA is, don't be fooled by its name) are static and generated by LLVM as Johan already mentioned, quite obviously without any druntime involvement. [The -exception-model you've been playing with probably affect their format.] Traversing these EH tables during stack unwinding (at runtime) is the job of the EH personality function associated with a function.

On Sunday, 5 July 2020 at 11:19:44 UTC, kinke wrote: > The EH tables (yes, that's what LSDA is, don't be fooled by its name) are static and generated by LLVM as Johan already mentioned, quite obviously without any druntime involvement. [The -exception-model you've been playing with probably affect their format.] Yes I think D personality data for EH ABI can be corrupt. > Traversing these EH tables during stack unwinding (at runtime) is the job of the EH personality function associated with a function. Oh thanks!

On Monday, 6 July 2020 at 20:43:33 UTC, Denis Feklushkin wrote: > I think D personality data for EH ABI can be corrupt. LLVM generating wrong tables is *extremely* unlikely. The D (and LDC) specific EH personality function (and catch hooks) in druntime seems to be quite okay too, because as I've already told you, we haven't seen any big issues for 32-bit ARM's EHABI a few years back, with both armv6-linux-gnueabihf and armv7a-linux-android. I don't know of any more recent test results, but I also don't remember any recent relevant changes in this part of druntime.