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From: "sebastian.huber@embedded-brains.de" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/49641] New: [ARM] Wrong code for ARMv4T and stmia Date: Tue, 05 Jul 2011 12:19:00 -0000 [thread overview] Message-ID: <bug-49641-4@http.gcc.gnu.org/bugzilla/> (raw) http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49641 Summary: [ARM] Wrong code for ARMv4T and stmia Product: gcc Version: 4.6.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: target AssignedTo: unassigned@gcc.gnu.org ReportedBy: sebastian.huber@embedded-brains.de Target: arm-rtemseabi4.11 Created attachment 24689 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=24689 Sample code. The attached source code generates the following assembler code: 00000000 <_Watchdog_Handler_initialization>: 0: 2200 movs r2, #0 2: 4b06 ldr r3, [pc, #24] ; (1c <_Watchdog_Handler_initialization+0x1c>) 4: 601a str r2, [r3, #0] 6: 4b06 ldr r3, [pc, #24] ; (20 <_Watchdog_Handler_initialization+0x20>) 8: 601a str r2, [r3, #0] a: 4b06 ldr r3, [pc, #24] ; (24 <_Watchdog_Handler_initialization+0x24>) c: 601a str r2, [r3, #0] e: 4b06 ldr r3, [pc, #24] ; (28 <_Watchdog_Handler_initialization+0x28>) 10: 1d19 adds r1, r3, #4 12: c30e stmia r3!, {r1, r2, r3} 14: 4b05 ldr r3, [pc, #20] ; (2c <_Watchdog_Handler_initialization+0x2c>) 16: 1d19 adds r1, r3, #4 18: c30e stmia r3!, {r1, r2, r3} 1a: 4770 bx lr In particular it generates: stmia r3!, {r1, r2, r3} This instruction leads to UNPREDICTABLE behavior. According to "ARM Architecture Reference Manual, Issue I" we have in section "A7.1.57 STMIA", "Operand restrictions": "If <Rn> is specified in <registers>: o If <Rn> is the lowest-numbered register specified in <registers>, the original value of <Rn> is stored. o Otherwise, the stored value of <Rn> is UNPREDICTABLE." Since r3 is not the lowest-numbered register specified in {r1, r2, r3} the stored value of r3 is UNPREDICTABLE.
next reply other threads:[~2011-07-05 12:19 UTC|newest] Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top 2011-07-05 12:19 sebastian.huber@embedded-brains.de [this message] 2011-07-06 6:27 ` [Bug target/49641] " sebastian.huber@embedded-brains.de 2011-07-06 8:32 ` [Bug target/49641] [4.6 Regression] " rearnsha at gcc dot gnu.org 2011-08-01 14:32 ` rguenth at gcc dot gnu.org 2011-08-01 14:42 ` rguenth at gcc dot gnu.org 2011-08-02 13:11 ` bernds at gcc dot gnu.org 2011-08-22 11:10 ` sebastian.huber@embedded-brains.de 2011-09-12 9:23 ` sebastian.huber@embedded-brains.de 2011-10-26 17:22 ` jakub at gcc dot gnu.org 2011-11-16 17:20 ` rearnsha at gcc dot gnu.org 2011-11-16 18:00 ` rearnsha at gcc dot gnu.org 2011-11-16 18:23 ` rearnsha at gcc dot gnu.org 2013-02-19 20:38 ` LpSolit at netscape dot net
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