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* [Bug other/61979] New: Why float variable loading twice into the FTU Stack during condition checking ? @ 2014-07-31 16:52 nasika.srikanth1 at gmail dot com 2014-08-01 8:26 ` [Bug other/61979] " rguenth at gcc dot gnu.org ` (6 more replies) 0 siblings, 7 replies; 8+ messages in thread From: nasika.srikanth1 at gmail dot com @ 2014-07-31 16:52 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61979 Bug ID: 61979 Summary: Why float variable loading twice into the FTU Stack during condition checking ? Product: gcc Version: unknown Status: UNCONFIRMED Severity: minor Priority: P3 Component: other Assignee: unassigned at gcc dot gnu.org Reporter: nasika.srikanth1 at gmail dot com Actually its not a bug. But i identified that float variables are loading twice into the FTU STACK during the condition checking ,that's actually my doubt and i check without loading it again i remove repeated code and getting the same output . But why gcc complier loads the float variable again into the FTU Stack ? For checking the condition it first checks the parity flags(whether NAN ,INF )then it again loads the float variable into FTU stack and check for the zero flag( whether non zero) set or not. But we can directly check the zero flag after checking parity flag with out loading the variable into the FTU stack. ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug other/61979] Why float variable loading twice into the FTU Stack during condition checking ? 2014-07-31 16:52 [Bug other/61979] New: Why float variable loading twice into the FTU Stack during condition checking ? nasika.srikanth1 at gmail dot com @ 2014-08-01 8:26 ` rguenth at gcc dot gnu.org 2014-08-02 6:19 ` nasika.srikanth1 at gmail dot com ` (5 subsequent siblings) 6 siblings, 0 replies; 8+ messages in thread From: rguenth at gcc dot gnu.org @ 2014-08-01 8:26 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61979 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |WAITING Last reconfirmed| |2014-08-01 Ever confirmed|0 |1 --- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> --- Testcase that shows the problem? On what architecture? What's a FTU stack? ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug other/61979] Why float variable loading twice into the FTU Stack during condition checking ? 2014-07-31 16:52 [Bug other/61979] New: Why float variable loading twice into the FTU Stack during condition checking ? nasika.srikanth1 at gmail dot com 2014-08-01 8:26 ` [Bug other/61979] " rguenth at gcc dot gnu.org @ 2014-08-02 6:19 ` nasika.srikanth1 at gmail dot com 2014-08-02 6:37 ` [Bug other/61979] Why float variable loading twice into the FPU " nasika.srikanth1 at gmail dot com ` (4 subsequent siblings) 6 siblings, 0 replies; 8+ messages in thread From: nasika.srikanth1 at gmail dot com @ 2014-08-02 6:19 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61979 --- Comment #2 from Srikanth <nasika.srikanth1 at gmail dot com> --- Created attachment 33225 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33225&action=edit In this assemble code line number at 22-25 and after 27-30 both are same instructions repeated for conditional checking. In this assemble code line number at 22-25 and after 27-30 both are same instructions repeated for conditional checking. Architecture ---- Intel® Core™ i3-2350M CPU @ 2.30GHz × 4 Sorry its my mistype *not FTU*,its actually FPU Stack means Floating point unit stack I just patch the above code by removing the repeated code file "testcondition.c" .section .rodata .LC2: .string "true" .LC3: .string "false" .text .globl main .type main, @function main: .LFB0: .cfi_startproc pushl %ebp .cfi_def_cfa_offset 8 .cfi_offset 5, -8 movl %esp, %ebp .cfi_def_cfa_register 5 andl $-16, %esp subl $32, %esp movl .LC0, %eax movl %eax, 28(%esp) flds 28(%esp) fldz fucomip %st(1), %st fstp %st(0) jp .L6 je .L7 .L6: movl $.LC2, (%esp) call printf jmp .L4 .L7: movl $.LC3, (%esp) call printf .L4: movl $0, %eax leave .cfi_restore 5 .cfi_def_cfa 4, 4 ret .cfi_endproc .LFE0: .size main, .-main .section .rodata .align 4 .LC0: .long 1094713344 .ident "GCC: (Ubuntu/Linaro 4.8.1-10ubuntu9) 4.8.1" .section .note.GNU-stack,"",@progbits >From gcc-bugs-return-457603-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Sat Aug 02 06:21:59 2014 Return-Path: <gcc-bugs-return-457603-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org> Delivered-To: listarch-gcc-bugs@gcc.gnu.org Received: (qmail 31461 invoked by alias); 2 Aug 2014 06:21:58 -0000 Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: <gcc-bugs.gcc.gnu.org> List-Archive: <http://gcc.gnu.org/ml/gcc-bugs/> List-Post: <mailto:gcc-bugs@gcc.gnu.org> List-Help: <mailto:gcc-bugs-help@gcc.gnu.org> Sender: gcc-bugs-owner@gcc.gnu.org Delivered-To: mailing list gcc-bugs@gcc.gnu.org Received: (qmail 31413 invoked by uid 48); 2 Aug 2014 06:21:53 -0000 From: "nasika.srikanth1 at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug other/61979] Why float variable loading twice into the FTU Stack during condition checking ? Date: Sat, 02 Aug 2014 06:21:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: other X-Bugzilla-Version: unknown X-Bugzilla-Keywords: X-Bugzilla-Severity: minor X-Bugzilla-Who: nasika.srikanth1 at gmail dot com X-Bugzilla-Status: WAITING X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: <bug-61979-4-mx2RaHZs58@http.gcc.gnu.org/bugzilla/> In-Reply-To: <bug-61979-4@http.gcc.gnu.org/bugzilla/> References: <bug-61979-4@http.gcc.gnu.org/bugzilla/> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-SW-Source: 2014-08/txt/msg00100.txt.bz2 Content-length: 1197 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61979 --- Comment #3 from Srikanth <nasika.srikanth1 at gmail dot com> --- Comment on attachment 33225 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33225 In this assemble code line number at 22-25 and after 27-30 both are same instructions repeated for conditional checking. > file "testcondition.c" > .section .rodata >.LC2: > .string "true" >.LC3: > .string "false" > .text > .globl main > .type main, @function >main: >.LFB0: > .cfi_startproc > pushl %ebp > .cfi_def_cfa_offset 8 > .cfi_offset 5, -8 > movl %esp, %ebp > .cfi_def_cfa_register 5 > andl $-16, %esp > subl $32, %esp > movl .LC0, %eax > movl %eax, 28(%esp) > flds 28(%esp) > fldz > fucomip %st(1), %st > fstp %st(0) > jp .L6 flds 28(%esp) fldz fucomip %st(1), %st fstp %st(0) > je .L7 >.L6: > movl $.LC2, (%esp) > call printf > jmp .L4 >.L7: > movl $.LC3, (%esp) > call printf >.L4: > movl $0, %eax > leave > .cfi_restore 5 > .cfi_def_cfa 4, 4 > ret > .cfi_endproc >.LFE0: > .size main, .-main > .section .rodata > .align 4 >.LC0: > .long 1094713344 > .ident "GCC: (Ubuntu/Linaro 4.8.1-10ubuntu9) 4.8.1" > .section .note.GNU-stack,"",@progbits >From gcc-bugs-return-457604-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Sat Aug 02 06:23:56 2014 Return-Path: <gcc-bugs-return-457604-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org> Delivered-To: listarch-gcc-bugs@gcc.gnu.org Received: (qmail 768 invoked by alias); 2 Aug 2014 06:23:56 -0000 Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: <gcc-bugs.gcc.gnu.org> List-Archive: <http://gcc.gnu.org/ml/gcc-bugs/> List-Post: <mailto:gcc-bugs@gcc.gnu.org> List-Help: <mailto:gcc-bugs-help@gcc.gnu.org> Sender: gcc-bugs-owner@gcc.gnu.org Delivered-To: mailing list gcc-bugs@gcc.gnu.org Received: (qmail 750 invoked by uid 48); 2 Aug 2014 06:23:53 -0000 From: "q.gcc@rsn-tech.co.uk" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c++/61993] constexpr static member function "is not constant" Date: Sat, 02 Aug 2014 06:23:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: c++ X-Bugzilla-Version: 4.8.3 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: q.gcc@rsn-tech.co.uk X-Bugzilla-Status: RESOLVED X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: <bug-61993-4-qLSMH7Df1X@http.gcc.gnu.org/bugzilla/> In-Reply-To: <bug-61993-4@http.gcc.gnu.org/bugzilla/> References: <bug-61993-4@http.gcc.gnu.org/bugzilla/> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-SW-Source: 2014-08/txt/msg00101.txt.bz2 Content-length: 153 https://gcc.gnu.org/bugzilla/show_bug.cgi?ida993 --- Comment #2 from steveren <q.gcc@rsn-tech.co.uk> --- Ah, it is a dupe; sorry, I missed that one. ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug other/61979] Why float variable loading twice into the FPU Stack during condition checking ? 2014-07-31 16:52 [Bug other/61979] New: Why float variable loading twice into the FTU Stack during condition checking ? nasika.srikanth1 at gmail dot com 2014-08-01 8:26 ` [Bug other/61979] " rguenth at gcc dot gnu.org 2014-08-02 6:19 ` nasika.srikanth1 at gmail dot com @ 2014-08-02 6:37 ` nasika.srikanth1 at gmail dot com 2014-08-02 6:42 ` pinskia at gcc dot gnu.org ` (3 subsequent siblings) 6 siblings, 0 replies; 8+ messages in thread From: nasika.srikanth1 at gmail dot com @ 2014-08-02 6:37 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61979 --- Comment #4 from Srikanth <nasika.srikanth1 at gmail dot com> --- In the Above comment-3 assembly code with black color letter are the repeated code i.e storing the float variable twice in FPU stack during conditional checking for parity flag and zero flag. I just patch that one by removing repeated code ,after checking the parity flag i just check the zero flag with out loading it again into the FPU Stack and again compare with zero . ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug other/61979] Why float variable loading twice into the FPU Stack during condition checking ? 2014-07-31 16:52 [Bug other/61979] New: Why float variable loading twice into the FTU Stack during condition checking ? nasika.srikanth1 at gmail dot com ` (2 preceding siblings ...) 2014-08-02 6:37 ` [Bug other/61979] Why float variable loading twice into the FPU " nasika.srikanth1 at gmail dot com @ 2014-08-02 6:42 ` pinskia at gcc dot gnu.org 2014-08-02 11:12 ` nasika.srikanth1 at gmail dot com ` (2 subsequent siblings) 6 siblings, 0 replies; 8+ messages in thread From: pinskia at gcc dot gnu.org @ 2014-08-02 6:42 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61979 --- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Where is the testcase, this is only the assembly output. ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug other/61979] Why float variable loading twice into the FPU Stack during condition checking ? 2014-07-31 16:52 [Bug other/61979] New: Why float variable loading twice into the FTU Stack during condition checking ? nasika.srikanth1 at gmail dot com ` (3 preceding siblings ...) 2014-08-02 6:42 ` pinskia at gcc dot gnu.org @ 2014-08-02 11:12 ` nasika.srikanth1 at gmail dot com 2014-08-02 11:33 ` glisse at gcc dot gnu.org 2014-08-02 16:29 ` nasika.srikanth1 at gmail dot com 6 siblings, 0 replies; 8+ messages in thread From: nasika.srikanth1 at gmail dot com @ 2014-08-02 11:12 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61979 --- Comment #6 from Srikanth <nasika.srikanth1 at gmail dot com> --- int main() { float m=12 m?printf("true"):printf("false"); m=0; m?printf("true"):printf("false"); } and above is the assemble code generated from the source file .. when i seeing the assemble code i just recognize that float variable was loading twice during the conditional checking that's what my doubt ? please tell me why after comparison of parity flag for NAN or not,directly we can check for zero flag for zero or not.But the generated assemble code in #comment 3 ,after comparison of parity flag it again loading the same variable into the FPU stack and again comparing with zero and checking for zero flag and goes to true or false statment why? ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug other/61979] Why float variable loading twice into the FPU Stack during condition checking ? 2014-07-31 16:52 [Bug other/61979] New: Why float variable loading twice into the FTU Stack during condition checking ? nasika.srikanth1 at gmail dot com ` (4 preceding siblings ...) 2014-08-02 11:12 ` nasika.srikanth1 at gmail dot com @ 2014-08-02 11:33 ` glisse at gcc dot gnu.org 2014-08-02 16:29 ` nasika.srikanth1 at gmail dot com 6 siblings, 0 replies; 8+ messages in thread From: glisse at gcc dot gnu.org @ 2014-08-02 11:33 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61979 Marc Glisse <glisse at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|WAITING |RESOLVED Resolution|--- |INVALID --- Comment #7 from Marc Glisse <glisse at gcc dot gnu.org> --- Your testcase is missing a ';', a #include and a return. You don't say how you compiled, but clearly you didn't pass any optimization flag (-O2 for instance), so you shouldn't expect optimized code. ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug other/61979] Why float variable loading twice into the FPU Stack during condition checking ? 2014-07-31 16:52 [Bug other/61979] New: Why float variable loading twice into the FTU Stack during condition checking ? nasika.srikanth1 at gmail dot com ` (5 preceding siblings ...) 2014-08-02 11:33 ` glisse at gcc dot gnu.org @ 2014-08-02 16:29 ` nasika.srikanth1 at gmail dot com 6 siblings, 0 replies; 8+ messages in thread From: nasika.srikanth1 at gmail dot com @ 2014-08-02 16:29 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61979 --- Comment #8 from Srikanth <nasika.srikanth1 at gmail dot com> --- #include<stdio.h> int main() { float m=12; m?printf("true"):printf("false"); m=0; m?printf("true"):printf("false"); return 0; } complied : gcc -S testcase.c -o testcase.s ^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2014-08-02 16:29 UTC | newest] Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2014-07-31 16:52 [Bug other/61979] New: Why float variable loading twice into the FTU Stack during condition checking ? nasika.srikanth1 at gmail dot com 2014-08-01 8:26 ` [Bug other/61979] " rguenth at gcc dot gnu.org 2014-08-02 6:19 ` nasika.srikanth1 at gmail dot com 2014-08-02 6:37 ` [Bug other/61979] Why float variable loading twice into the FPU " nasika.srikanth1 at gmail dot com 2014-08-02 6:42 ` pinskia at gcc dot gnu.org 2014-08-02 11:12 ` nasika.srikanth1 at gmail dot com 2014-08-02 11:33 ` glisse at gcc dot gnu.org 2014-08-02 16:29 ` nasika.srikanth1 at gmail dot com
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