digitalmars.D.bugs - [Issue 3822] New: alloca() can return the same address inside a function
- d-bugmail puremagic.com (25/25) Feb 18 2010 http://d.puremagic.com/issues/show_bug.cgi?id=3822
- d-bugmail puremagic.com (13/13) Feb 18 2010 http://d.puremagic.com/issues/show_bug.cgi?id=3822
- d-bugmail puremagic.com (14/19) Feb 18 2010 http://d.puremagic.com/issues/show_bug.cgi?id=3822
- d-bugmail puremagic.com (9/9) Jun 07 2010 http://d.puremagic.com/issues/show_bug.cgi?id=3822
- d-bugmail puremagic.com (17/17) Jun 07 2010 http://d.puremagic.com/issues/show_bug.cgi?id=3822
- d-bugmail puremagic.com (13/13) Jun 26 2010 http://d.puremagic.com/issues/show_bug.cgi?id=3822
- d-bugmail puremagic.com (16/16) Feb 10 2012 http://d.puremagic.com/issues/show_bug.cgi?id=3822
- d-bugmail puremagic.com (14/14) Feb 10 2012 http://d.puremagic.com/issues/show_bug.cgi?id=3822
- d-bugmail puremagic.com (7/8) Feb 11 2012 http://d.puremagic.com/issues/show_bug.cgi?id=3822
- d-bugmail puremagic.com (7/8) Feb 11 2012 http://d.puremagic.com/issues/show_bug.cgi?id=3822
- d-bugmail puremagic.com (9/9) Feb 18 2012 http://d.puremagic.com/issues/show_bug.cgi?id=3822
- d-bugmail puremagic.com (8/8) Feb 18 2012 http://d.puremagic.com/issues/show_bug.cgi?id=3822
- d-bugmail puremagic.com (10/10) Feb 18 2012 http://d.puremagic.com/issues/show_bug.cgi?id=3822
http://d.puremagic.com/issues/show_bug.cgi?id=3822 Summary: alloca() can return the same address inside a function Product: D Version: 2.040 Platform: Other OS/Version: Windows Status: NEW Severity: normal Priority: P2 Component: druntime AssignedTo: sean invisibleduck.org ReportedBy: bearophile_hugs eml.cc import std.stdio: printf; import std.c.stdlib: alloca; void main() { const int n = 8; for (int i; i < 2; i++) printf("%p\n", alloca(n)); } It prints two times the same address, I don't know why, I think this can be wrong. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Feb 18 2010
http://d.puremagic.com/issues/show_bug.cgi?id=3822 BCS <shro8822 vandals.uidaho.edu> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |shro8822 vandals.uidaho.edu --- I've never used alloca so I'm not sure, so this is a guess: alloca does stack allocation and the body of the for statement forms a scope on the stack (this in this case contains no named variables). I'm guessing that when that scope is exited, the allocation automatically gets deallocated. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Feb 18 2010
http://d.puremagic.com/issues/show_bug.cgi?id=3822I've never used alloca so I'm not sure, so this is a guess: alloca does stack allocation and the body of the for statement forms a scope on the stack (this in this case contains no named variables). I'm guessing that when that scope is exited, the allocation automatically gets deallocated.You can be right, thank you. Then it's very good for Phobos docs to say that alloca is relative to a scope and not to a function. The description of alloca() that I have seen says: The alloca() function allocates space in the stack frame of the caller, and returns a pointer to the allocated block. This temporary space is automatically freed when the function from which alloca() is called returns. While if you are right D alloca frees space when the scope of alloca ends and not when the function ends. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Feb 18 2010
http://d.puremagic.com/issues/show_bug.cgi?id=3822 Maybe the alloca() used by dmd frees memory as soon as the current scope is left, instead of deferring all deallocation until function exit. See: http://compilers.iecc.com/comparch/article/91-12-079 D documentation has to explain how exactly its alloca() works. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jun 07 2010
http://d.puremagic.com/issues/show_bug.cgi?id=3822 nfxjfg gmail.com changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |wrong-code CC| |nfxjfg gmail.com Summary|alloca() can return the |Memory allocated with |same address inside a |alloca() is freed at end of |function |scope instead at end of | |function C code that compiles in D without modification should work exactly as it does in C. This means this is a rather bad code gen bug. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jun 07 2010
http://d.puremagic.com/issues/show_bug.cgi?id=3822 nfxjfg gmail.com changed: What |Removed |Added ---------------------------------------------------------------------------- Severity|normal |critical There's D code in druntime that assumes memory allocated by alloca() is valid until the end of the function: http://dsource.org/projects/druntime/browser/trunk/src/rt/adi.d#L242 Maybe the codegen for alloca() within loops is broken, or something. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jun 26 2010
http://d.puremagic.com/issues/show_bug.cgi?id=3822 yebblies <yebblies gmail.com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |yebblies gmail.com Platform|Other |All Version|2.040 |D1 & D2 AssignedTo|nobody puremagic.com |yebblies gmail.com OS/Version|Windows |All The issue here is that n is a compile-time constant, so the call to alloca is optimized away completely, and always reserving the extra space. This optimization is not valid if the call to alloca might be repeated. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Feb 10 2012
http://d.puremagic.com/issues/show_bug.cgi?id=3822 yebblies <yebblies gmail.com> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |pull Summary|Memory allocated with |Invalid optimization of |alloca() is freed at end of |alloca called with constant |scope instead at end of |size |function | https://github.com/D-Programming-Language/dmd/pull/707 -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Feb 10 2012
http://d.puremagic.com/issues/show_bug.cgi?id=3822https://github.com/D-Programming-Language/dmd/pull/707Thank you for your patch, yebblies! -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Feb 11 2012
http://d.puremagic.com/issues/show_bug.cgi?id=3822Thank you for your patch, yebblies!You're welcome. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Feb 11 2012
http://d.puremagic.com/issues/show_bug.cgi?id=3822 Commit pushed to master at https://github.com/D-Programming-Language/dmd https://github.com/D-Programming-Language/dmd/commit/3fc9ee7064c05d4c8db6f1aac0a8896caa954e44 Issue 3822 - Invalid optimization of alloca called with constant size -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Feb 18 2012
http://d.puremagic.com/issues/show_bug.cgi?id=3822 Commit pushed to dmd-1.x at https://github.com/D-Programming-Language/dmd https://github.com/D-Programming-Language/dmd/commit/c492323b6edc44a2bac4ea0edaed1e757854b9d0 fix Issue 3822 - Invalid optimization of alloca called with constant size -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Feb 18 2012
http://d.puremagic.com/issues/show_bug.cgi?id=3822 Walter Bright <bugzilla digitalmars.com> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |RESOLVED CC| |bugzilla digitalmars.com Resolution| |FIXED -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Feb 18 2012