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* Re: inline-asm/10857: Inlining a function with inline-asm: "error: impossible constraint in `asm'"
@ 2003-05-19 12:46 ehrhardt
2003-05-19 17:16 ` Bernd Trog
0 siblings, 1 reply; 5+ messages in thread
From: ehrhardt @ 2003-05-19 12:46 UTC (permalink / raw)
To: berndtrog, gcc-bugs, gcc-prs, nobody
Synopsis: Inlining a function with inline-asm: "error: impossible constraint in `asm'"
State-Changed-From-To: open->closed
State-Changed-By: cae
State-Changed-When: Mon May 19 12:23:16 2003
State-Changed-Why:
Not a bug. An immediate value must be a compile time constant. A
procedure parameter is definitly NOT a compile time constant. gcc
can deduce its value for an inline function if certain optimizations
are done. You can request these optimizations with the various -O
flags and in this case the code compiles. Note that there is no
guarantee that this will remain true in the future.
Also note that the `I' constraint has this description on the avr
architecture:
| `I'
| Constant greater than -1, less than 64
regards Christian
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=10857
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: inline-asm/10857: Inlining a function with inline-asm: "error: impossible constraint in `asm'"
2003-05-19 12:46 inline-asm/10857: Inlining a function with inline-asm: "error: impossible constraint in `asm'" ehrhardt
@ 2003-05-19 17:16 ` Bernd Trog
0 siblings, 0 replies; 5+ messages in thread
From: Bernd Trog @ 2003-05-19 17:16 UTC (permalink / raw)
To: ehrhardt, gcc-bugs, gcc-prs, nobody, gcc-gnats
> You can request these optimizations with the various -O
> flags and in this case the code compiles.
Not for me. (gcc-3.3.0, tried: -Os, -O1, -O3)
Would you please describe your environment?
The code compiles on gcc version 3.3 20030127 (prerelease). (with
inline-asm warnings)
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: inline-asm/10857: Inlining a function with inline-asm: "error: impossible constraint in `asm'"
2003-05-19 19:37 ehrhardt
@ 2003-05-21 9:48 ` Bernd Trog
0 siblings, 0 replies; 5+ messages in thread
From: Bernd Trog @ 2003-05-21 9:48 UTC (permalink / raw)
To: jh, ehrhardt, gcc-bugs, gcc-prs, nobody, gcc-gnats
--- ehrhardt@mathematik.uni-ulm.de wrote:
> The patch the prevented this from compiling at -O3 went into gcc-3.4
> between 20030331 and 20030519.
After spending some CPU cycles on compiling gcc, it looks like:
+Fri Apr 11 00:12:14 CEST 2003 Jan Hubicka <jh@suse.cz>
+
+ PR inline-asm/8803
+ * function.c (instantate_virtual_regs): Verify that all ASM
statements
+ match after the virutal regs instantiation.
+
gcc/gcc/function.c:
instantiate_virtual_regs_1 (&CALL_INSN_FUNCTION_USAGE (insn),
NULL_RTX, 0);
+
+ /* Past this point all ASM statements should match. Verify that
+ to avoid failures later in the compilation process. */
+ if (asm_noperands (PATTERN (insn)) >= 0
+ && ! check_asm_operands (PATTERN (insn)))
+ instantiate_virtual_regs_lossage (insn);
}
triggered my regression.
Removing that patch from 3.3.0 makes my code compile
again - I'm happy :-)
Maybe its possible to add another condition to that if statement?
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: inline-asm/10857: Inlining a function with inline-asm: "error: impossible constraint in `asm'"
@ 2003-05-19 19:37 ehrhardt
2003-05-21 9:48 ` Bernd Trog
0 siblings, 1 reply; 5+ messages in thread
From: ehrhardt @ 2003-05-19 19:37 UTC (permalink / raw)
To: berndtrog, gcc-bugs, gcc-prs, nobody
Synopsis: Inlining a function with inline-asm: "error: impossible constraint in `asm'"
State-Changed-From-To: closed->open
State-Changed-By: cae
State-Changed-When: Mon May 19 17:53:20 2003
State-Changed-Why:
Reopened based on submitter's comment. This is rejected by 3.3 at all
optimization levels. I still don't think this should compile but previous
versions of gcc accepted it. An arch independant example is below. Could
someone please clarify if this supposed to compile at e.g. -S -O3?
----------------- cut -------------------------------
#define PORTD 0x12
static
void
write_byte(unsigned char adr, unsigned char data )
{
__asm__ ("blah %0" : : "i" (adr));
}
int main(void)
{
write_byte( PORTD, 4);
return 0;
}
----------------- cut -------------------------------
Both gcc-3.2 and older versions of gcc-3.4 accepted this if
optimization level was high enough. It is rejected by gcc 3.3
nomatter what. Note that __builtin_constant_p (adr) holds for
the inlined copy of write_byte.
The patch the prevented this from compiling at -O3 went into gcc-3.4
between 20030331 and 20030519.
regards Christian
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=10857
^ permalink raw reply [flat|nested] 5+ messages in thread
* inline-asm/10857: Inlining a function with inline-asm: "error: impossible constraint in `asm'"
@ 2003-05-19 12:25 berndtrog
0 siblings, 0 replies; 5+ messages in thread
From: berndtrog @ 2003-05-19 12:25 UTC (permalink / raw)
To: gcc-gnats
>Number: 10857
>Category: inline-asm
>Synopsis: Inlining a function with inline-asm: "error: impossible constraint in `asm'"
>Confidential: no
>Severity: critical
>Priority: medium
>Responsible: unassigned
>State: open
>Class: sw-bug
>Submitter-Id: net
>Arrival-Date: Mon May 19 11:16:00 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator: Bernd Trog
>Release: gcc-3.3.0
>Organization:
>Environment:
avr-gcc -v
Reading specs from /src/build/gcc-330/lib/gcc-lib/avr/3.3/specs
Configured with: /src/gcc-330/configure -v --target=avr --prefix=/src/build/gcc-330 --with-gnu-ld --with-gnu-as --disable-nls --enable-languages=c,ada
Thread model: single
gcc version 3.3
>Description:
$ avr-gcc test.c
test.c: In function `write_byte':
test.c:8: warning: asm operand 0 probably doesn't match constraints
test.c:8: error: impossible constraint in `asm'
Note: The information for operand 0 is available
at compile-time(#define PORTD 0x12)!
>How-To-Repeat:
#define PORTD 0x12
static
inline
void
write_byte( unsigned char adr, unsigned char data )
{
asm("out %0, %1" : : "I" (adr), "r" (data) );
}
int main(void)
{
write_byte( PORTD, 4);
return 0;
}
>Fix:
unknown
>Release-Note:
>Audit-Trail:
>Unformatted:
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2003-05-21 9:38 UTC | newest]
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2003-05-19 12:46 inline-asm/10857: Inlining a function with inline-asm: "error: impossible constraint in `asm'" ehrhardt
2003-05-19 17:16 ` Bernd Trog
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2003-05-19 19:37 ehrhardt
2003-05-21 9:48 ` Bernd Trog
2003-05-19 12:25 berndtrog
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