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* [Bug inline-asm/101438] New: Compiler hang on inline asm with local register and VLA operands @ 2021-07-13 14:36 andrey.vihrov at gmail dot com 2021-07-14 6:07 ` [Bug inline-asm/101438] " rguenth at gcc dot gnu.org ` (4 more replies) 0 siblings, 5 replies; 6+ messages in thread From: andrey.vihrov at gmail dot com @ 2021-07-13 14:36 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101438 Bug ID: 101438 Summary: Compiler hang on inline asm with local register and VLA operands Product: gcc Version: 11.1.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: inline-asm Assignee: unassigned at gcc dot gnu.org Reporter: andrey.vihrov at gmail dot com Target Milestone: --- Target: x86_64-pc-linux-gnu Compiling this C source: int main(void) { register long long rax __asm__("rax") = 0; register long long rbx __asm__("rbx") = 0; register long long rcx __asm__("rcx") = 0; register long long rdx __asm__("rdx") = 0; register long long rsi __asm__("rsi") = 0; register long long rdi __asm__("rdi") = 0; register long long r8 __asm__("r8") = 0; register long long r9 __asm__("r9") = 0; register long long r10 __asm__("r10") = 0; register long long r11 __asm__("r11") = 0; register long long r12 __asm__("r12") = 0; register long long r13 __asm__("r13") = 0; register long long r14 __asm__("r14") = 0; register long long r15 __asm__("r15") = 0; volatile int x = 1; char arr[x]; __asm__ ("" : : "r"(rax), "r"(rbx), "r"(rcx), "r"(rdx), "r"(rsi), "r"(rdi), "r"(r8), "r"(r9), "r"(r10), "r"(r11), "r"(r12), "r"(r13), "r"(r14), "r"(r15), "m"(arr) ); } with "gcc -O1 test.c" causes the compiler to hang in an infinite loop. Note: This code could possibly be formally incorrect, as [1] warns about potential clobbering after initialization of local register variables. [1] https://gcc.gnu.org/onlinedocs/gcc/Local-Register-Variables.html ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug inline-asm/101438] Compiler hang on inline asm with local register and VLA operands 2021-07-13 14:36 [Bug inline-asm/101438] New: Compiler hang on inline asm with local register and VLA operands andrey.vihrov at gmail dot com @ 2021-07-14 6:07 ` rguenth at gcc dot gnu.org 2021-07-14 18:26 ` pinskia at gcc dot gnu.org ` (3 subsequent siblings) 4 siblings, 0 replies; 6+ messages in thread From: rguenth at gcc dot gnu.org @ 2021-07-14 6:07 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101438 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |accepts-invalid, | |compile-time-hog, ra Status|UNCONFIRMED |NEW Last reconfirmed| |2021-07-14 Ever confirmed|0 |1 --- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> --- At -O0 we get t3.c: In function 'main': t3.c:21:5: error: 'asm' operand has impossible constraints 21 | __asm__ ("" | ^~~~~~~ likely because there's not enough registers to pass in 'arr' (and we need a FP to allocate arr). At -O1 it looks like we think we can manage but do not make progress reloading. So confirmed, a diagnostic would be nice. ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug inline-asm/101438] Compiler hang on inline asm with local register and VLA operands 2021-07-13 14:36 [Bug inline-asm/101438] New: Compiler hang on inline asm with local register and VLA operands andrey.vihrov at gmail dot com 2021-07-14 6:07 ` [Bug inline-asm/101438] " rguenth at gcc dot gnu.org @ 2021-07-14 18:26 ` pinskia at gcc dot gnu.org 2021-07-14 19:11 ` andrey.vihrov at gmail dot com ` (2 subsequent siblings) 4 siblings, 0 replies; 6+ messages in thread From: pinskia at gcc dot gnu.org @ 2021-07-14 18:26 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101438 --- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> --- This code is almost definitely invalid: "m"(arr) You are asigning the array/pointer that the VLA is. This is very much related to PR 71572 for similar reasons. ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug inline-asm/101438] Compiler hang on inline asm with local register and VLA operands 2021-07-13 14:36 [Bug inline-asm/101438] New: Compiler hang on inline asm with local register and VLA operands andrey.vihrov at gmail dot com 2021-07-14 6:07 ` [Bug inline-asm/101438] " rguenth at gcc dot gnu.org 2021-07-14 18:26 ` pinskia at gcc dot gnu.org @ 2021-07-14 19:11 ` andrey.vihrov at gmail dot com 2022-07-30 11:26 ` [Bug target/101438] Compiler hang on inline asm with local register and alloca andrey.vihrov at gmail dot com 2022-08-02 6:18 ` andrey.vihrov at gmail dot com 4 siblings, 0 replies; 6+ messages in thread From: andrey.vihrov at gmail dot com @ 2021-07-14 19:11 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101438 --- Comment #3 from Andrey Vihrov <andrey.vihrov at gmail dot com> --- Created attachment 51152 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51152&action=edit Alternative testcase using __builtin_alloca() Thanks. This code is the result of minimization. It seems that it is sufficient to make inline asm depend on arr in any form. "m"(arr[0]) (and initializing the array element) reproduces the issue as well. I've also attached a similar testcase that compiles and runs at -O0, but hangs the compiler at -O1 (and which likewise references the pointer itself with "m"). ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug target/101438] Compiler hang on inline asm with local register and alloca 2021-07-13 14:36 [Bug inline-asm/101438] New: Compiler hang on inline asm with local register and VLA operands andrey.vihrov at gmail dot com ` (2 preceding siblings ...) 2021-07-14 19:11 ` andrey.vihrov at gmail dot com @ 2022-07-30 11:26 ` andrey.vihrov at gmail dot com 2022-08-02 6:18 ` andrey.vihrov at gmail dot com 4 siblings, 0 replies; 6+ messages in thread From: andrey.vihrov at gmail dot com @ 2022-07-30 11:26 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101438 --- Comment #4 from Andrey Vihrov <andrey.vihrov at gmail dot com> --- Looks like this is a duplicate of bug 105032 (or vice versa). Both samples from this bug succeed for me with GCC 11.3 and GCC 12. ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug target/101438] Compiler hang on inline asm with local register and alloca 2021-07-13 14:36 [Bug inline-asm/101438] New: Compiler hang on inline asm with local register and VLA operands andrey.vihrov at gmail dot com ` (3 preceding siblings ...) 2022-07-30 11:26 ` [Bug target/101438] Compiler hang on inline asm with local register and alloca andrey.vihrov at gmail dot com @ 2022-08-02 6:18 ` andrey.vihrov at gmail dot com 4 siblings, 0 replies; 6+ messages in thread From: andrey.vihrov at gmail dot com @ 2022-08-02 6:18 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101438 Andrey Vihrov <andrey.vihrov at gmail dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |RESOLVED Resolution|--- |DUPLICATE --- Comment #5 from Andrey Vihrov <andrey.vihrov at gmail dot com> --- Closing as a duplicate. *** This bug has been marked as a duplicate of bug 105032 *** ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2022-08-02 6:18 UTC | newest] Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-07-13 14:36 [Bug inline-asm/101438] New: Compiler hang on inline asm with local register and VLA operands andrey.vihrov at gmail dot com 2021-07-14 6:07 ` [Bug inline-asm/101438] " rguenth at gcc dot gnu.org 2021-07-14 18:26 ` pinskia at gcc dot gnu.org 2021-07-14 19:11 ` andrey.vihrov at gmail dot com 2022-07-30 11:26 ` [Bug target/101438] Compiler hang on inline asm with local register and alloca andrey.vihrov at gmail dot com 2022-08-02 6:18 ` andrey.vihrov at gmail dot com
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