dlmalloc: remove manual reloc alias warning

PATCH New Andreas Bießmann 5 participants 10 messages Aug 13, 2012 – Sep 1, 2012

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Andreas Bießmann

author

2012-08-13 09:02 UTC #0 lore raw

PATCH 1/1 dlmalloc: remove manual reloc alias warning

From: Andreas Bie?mann <[email protected]>

The avr32 architecture (and some others) require manual relocation. Due to the previous error all avr32 boards gave warnings in MAKEALL wich makes it hard to find new warnings.

This patch fixes following warning:
---8<---
dlmalloc.c: In function 'malloc_bin_reloc':
dlmalloc.c:1493: warning: dereferencing pointer 'p' does break strict-aliasing rules dlmalloc.c:1493: warning: dereferencing pointer 'p' does break strict-aliasing rules dlmalloc.c:1490: note: initialized from here
dlmalloc.c:1493: note: initialized from here
--->8---

Signed-off-by Andreas Bie?mann <[email protected]>

---
A question to all the other related arches, namely m68k, mips, nds32 and
sparc: Do you encounter the same warnings or is this warning due to my outdated compiler (4.4.3 currently, unfortunately atmel do not bother to send their patches mainline)?

 common/dlmalloc.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

common/dlmalloc.c +2 -1

index c645d73..78b1885 100644
@@ -1485,9 +1485,10 @@ static mbinptr av_[NAV * 2 + 2] = {
 };
 
 #ifdef CONFIG_NEEDS_MANUAL_RELOC
+typedef unsigned long __attribute__((__may_alias__)) ulong_aliased;
 void malloc_bin_reloc (void)
 {
-	unsigned long *p = (unsigned long *)(&av_[2]);
+	ulong_aliased *p = (ulong_aliased *)(&av_[2]);
 	int i;
 	for (i=2; i<(sizeof(av_)/sizeof(mbinptr)); ++i) {
 		*p++ += gd->reloc_off;

Signature · 1 line

1.7.10.4

Mike Frysinger

2012-08-13 14:54 UTC #1 lore raw

PATCH 1/1 dlmalloc: remove manual reloc alias warning

Quoted 16 lines · On Monday 13 August 2012 05:02:03 Andreas Bie?mann wrote:

From: Andreas Bie?mann <[email protected]>
The avr32 architecture (and some others) require manual relocation. Due to the previous error all avr32 boards gave warnings in MAKEALL wich makes it hard to find new warnings.
This patch fixes following warning:
---8<---
dlmalloc.c: In function 'malloc_bin_reloc':
dlmalloc.c:1493: warning: dereferencing pointer 'p' does break strict-aliasing rules dlmalloc.c:1493: warning: dereferencing pointer 'p' does break strict-aliasing rules dlmalloc.c:1490: note: initialized from here
dlmalloc.c:1493: note: initialized from here
--->8---

Quoted 6 lines

Signed-off-by Andreas Bie?mann <[email protected]>
---
A question to all the other related arches, namely m68k, mips, nds32 and
sparc: Do you encounter the same warnings or is this warning due to my outdated compiler (4.4.3 currently, unfortunately atmel do not bother to send their patches mainline)?

previous thread (and i think there was one before this):
http://patchwork.ozlabs.org/patch/134597/
-mike
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Andreas Bießmann

author

2012-08-13 15:14 UTC #2 lore raw

PATCH 1/1 dlmalloc: remove manual reloc alias warning

Dear Mike Frysinger,

Quoted 24 lines · Mike Frysinger

Quoted 16 lines · On Monday 13 August 2012 05:02:03 Andreas Bie?mann wrote:
From: Andreas Bie?mann <[email protected]>
The avr32 architecture (and some others) require manual relocation. Due to the previous error all avr32 boards gave warnings in MAKEALL wich makes it hard to find new warnings.
This patch fixes following warning:
---8<---
dlmalloc.c: In function 'malloc_bin_reloc':
dlmalloc.c:1493: warning: dereferencing pointer 'p' does break strict-aliasing rules dlmalloc.c:1493: warning: dereferencing pointer 'p' does break strict-aliasing rules dlmalloc.c:1490: note: initialized from here
dlmalloc.c:1493: note: initialized from here
--->8---
Quoted 6 lines
Signed-off-by Andreas Bie?mann <[email protected]>
---
A question to all the other related arches, namely m68k, mips, nds32 and
sparc: Do you encounter the same warnings or is this warning due to my outdated compiler (4.4.3 currently, unfortunately atmel do not bother to send their patches mainline)?

Quoted 2 lines

previous thread (and i think there was one before this):
http://patchwork.ozlabs.org/patch/134597/

thank you for the hint. I think this is a better solution so I will test it and try to force the other patch as the correct solution.

Best regards

Andreas Bie?mann

Andreas Bießmann

2012-08-13 15:31 UTC #3 lore raw

PATCH 1/1 dlmalloc: remove manual reloc alias warning

Quoted 27 lines · Andreas Bie?mann

Dear Mike Frysinger,
Quoted 24 lines · Mike Frysinger
Quoted 22 lines · On Monday 13 August 2012 05:02:03 Andreas Bie?mann wrote:
From: Andreas Bie?mann <[email protected]>
The avr32 architecture (and some others) require manual relocation. Due to the previous error all avr32 boards gave warnings in MAKEALL wich makes it hard to find new warnings.
This patch fixes following warning:
---8<---
dlmalloc.c: In function 'malloc_bin_reloc':
dlmalloc.c:1493: warning: dereferencing pointer 'p' does break strict-aliasing rules dlmalloc.c:1493: warning: dereferencing pointer 'p' does break strict-aliasing rules dlmalloc.c:1490: note: initialized from here
dlmalloc.c:1493: note: initialized from here
--->8---
Signed-off-by Andreas Bie?mann <[email protected]>
---
A question to all the other related arches, namely m68k, mips, nds32 and
sparc: Do you encounter the same warnings or is this warning due to my outdated compiler (4.4.3 currently, unfortunately atmel do not bother to send their patches mainline)?

Quoted 5 lines

Quoted 2 lines
previous thread (and i think there was one before this):
http://patchwork.ozlabs.org/patch/134597/
thank you for the hint. I think this is a better solution so I will test it and try to force the other patch as the correct solution.

well, looks nice but is broken at runtime ;(

Quoted 6 lines

Best regards
Andreas Bie?mann

Andreas Bießmann

author

2012-08-14 08:50 UTC #4 lore raw

PATCH 1/1 dlmalloc: remove manual reloc alias warning

In reply to Andreas Bießmann

Dear all,

Quoted 32 lines · Andreas Bie?mann

From: Andreas Bie?mann <[email protected]>
The avr32 architecture (and some others) require manual relocation. Due to the previous error all avr32 boards gave warnings in MAKEALL wich makes it hard to find new warnings.
This patch fixes following warning:
---8<---
dlmalloc.c: In function 'malloc_bin_reloc':
dlmalloc.c:1493: warning: dereferencing pointer 'p' does break strict-aliasing rules dlmalloc.c:1493: warning: dereferencing pointer 'p' does break strict-aliasing rules dlmalloc.c:1490: note: initialized from here
dlmalloc.c:1493: note: initialized from here
--->8---
Signed-off-by Andreas Bie?mann <[email protected]>
---
A question to all the other related arches, namely m68k, mips, nds32 and
sparc: Do you encounter the same warnings or is this warning due to my outdated compiler (4.4.3 currently, unfortunately atmel do not bother to send their patches mainline)?
 common/dlmalloc.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
common/dlmalloc.c +0 -0
index c645d73..78b1885 100644
@@ -1485,9 +1485,10 @@ static mbinptr av_[NAV * 2 + 2] = {
 };

common/dlmalloc.c static mbinptr av_[NAV * 2 + 2] = { · line 1494

Quoted 10 lines

common/dlmalloc.c +2 -1

 
 #ifdef CONFIG_NEEDS_MANUAL_RELOC
+typedef unsigned long __attribute__((__may_alias__)) ulong_aliased;
 void malloc_bin_reloc (void)
 {
-	unsigned long *p = (unsigned long *)(&av_[2]);
+	ulong_aliased *p = (ulong_aliased *)(&av_[2]);
 	int i;
 	for (i=2; i<(sizeof(av_)/sizeof(mbinptr)); ++i) {
 		*p++ += gd->reloc_off;

this seems to be related to
http://thread.gmane.org/gmane.comp.boot-loaders.u-boot/121848/focus=121849
can you Wolfgang and/or Simon please comment.

best regards

Andreas Bie?mann

Simon Glass

2012-08-15 00:15 UTC #5 lore raw

PATCH 1/1 dlmalloc: remove manual reloc alias warning

Hi,

Quoted 35 lines · Andreas Bie?mann

Dear all,
Quoted 32 lines · Andreas Bie?mann
From: Andreas Bie?mann <[email protected]>
The avr32 architecture (and some others) require manual relocation. Due to the previous error all avr32 boards gave warnings in MAKEALL wich makes it hard to find new warnings.
This patch fixes following warning:
---8<---
dlmalloc.c: In function 'malloc_bin_reloc':
dlmalloc.c:1493: warning: dereferencing pointer 'p' does break strict-aliasing rules dlmalloc.c:1493: warning: dereferencing pointer 'p' does break strict-aliasing rules dlmalloc.c:1490: note: initialized from here
dlmalloc.c:1493: note: initialized from here
--->8---
Signed-off-by Andreas Bie?mann <[email protected]>
---
A question to all the other related arches, namely m68k, mips, nds32 and
sparc: Do you encounter the same warnings or is this warning due to my outdated compiler (4.4.3 currently, unfortunately atmel do not bother to send their patches mainline)?
 common/dlmalloc.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
common/dlmalloc.c +0 -0
index c645d73..78b1885 100644
@@ -1485,9 +1485,10 @@ static mbinptr av_[NAV * 2 + 2] = {
 };
 

Quoted 14 lines

common/dlmalloc.c static mbinptr av_[NAV * 2 + 2] = { · line 1494
Quoted 10 lines
common/dlmalloc.c +2 -1
 #ifdef CONFIG_NEEDS_MANUAL_RELOC
+typedef unsigned long __attribute__((__may_alias__)) ulong_aliased;
 void malloc_bin_reloc (void)
 {
-     unsigned long *p = (unsigned long *)(&av_[2]);
+     ulong_aliased *p = (ulong_aliased *)(&av_[2]);
      int i;
      for (i=2; i<(sizeof(av_)/sizeof(mbinptr)); ++i) {
              *p++ += gd->reloc_off;
this seems to be related to
http://thread.gmane.org/gmane.comp.boot-loaders.u-boot/121848/focus=121849
can you Wolfgang and/or Simon please comment.

My only comment is that I created that patch due to errors I saw at the time, and still see with the toolchain I use for avr32.

Regards,
Simon

Quoted 4 lines

best regards
Andreas Bie?mann

Andreas Bießmann

author

2012-08-15 06:29 UTC #6 lore raw

PATCH 1/1 dlmalloc: remove manual reloc alias warning

Dear Simon Glass,

Quoted 54 lines · Simon Glass

Hi,
Quoted 35 lines · Andreas Bie?mann
Dear all,
Quoted 32 lines · Andreas Bie?mann
From: Andreas Bie?mann <[email protected]>
The avr32 architecture (and some others) require manual relocation. Due to the previous error all avr32 boards gave warnings in MAKEALL wich makes it hard to find new warnings.
This patch fixes following warning:
---8<---
dlmalloc.c: In function 'malloc_bin_reloc':
dlmalloc.c:1493: warning: dereferencing pointer 'p' does break strict-aliasing rules dlmalloc.c:1493: warning: dereferencing pointer 'p' does break strict-aliasing rules dlmalloc.c:1490: note: initialized from here
dlmalloc.c:1493: note: initialized from here
--->8---
Signed-off-by Andreas Bie?mann <[email protected]>
---
A question to all the other related arches, namely m68k, mips, nds32 and
sparc: Do you encounter the same warnings or is this warning due to my outdated compiler (4.4.3 currently, unfortunately atmel do not bother to send their patches mainline)?
 common/dlmalloc.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
common/dlmalloc.c +0 -0
index c645d73..78b1885 100644
@@ -1485,9 +1485,10 @@ static mbinptr av_[NAV * 2 + 2] = {
 };
 
Quoted 14 lines
common/dlmalloc.c static mbinptr av_[NAV * 2 + 2] = { · line 1494
Quoted 10 lines
common/dlmalloc.c +2 -1
 #ifdef CONFIG_NEEDS_MANUAL_RELOC
+typedef unsigned long __attribute__((__may_alias__)) ulong_aliased;
 void malloc_bin_reloc (void)
 {
-     unsigned long *p = (unsigned long *)(&av_[2]);
+     ulong_aliased *p = (ulong_aliased *)(&av_[2]);
      int i;
      for (i=2; i<(sizeof(av_)/sizeof(mbinptr)); ++i) {
              *p++ += gd->reloc_off;
this seems to be related to
http://thread.gmane.org/gmane.comp.boot-loaders.u-boot/121848/focus=121849
can you Wolfgang and/or Simon please comment.

Quoted 2 lines

My only comment is that I created that patch due to errors I saw at the time, and still see with the toolchain I use for avr32.

So you also want to remove this annoying warning. Sorry that I didn't test your patch from January earlier, but it is broken at runtime.

I would really like to remove the alias warning in 2012.10. My patch is straight forward, maybe there are better solutions.
However I would like to see tested by from other affected arches (m68k, mips, nds32 and sparc).

Best regards

Andreas Bie?mann

Wolfgang Denk

2012-09-01 10:10 UTC #7 lore raw

PATCH 1/1 dlmalloc: remove manual reloc alias warning

In reply to Andreas Bießmann

Dear =?UTF-8?q?Andreas=20Bie=C3=9Fmann?=,

Quoted 8 lines · In message <[email protected]>…

This patch fixes following warning:
---8<---
dlmalloc.c: In function 'malloc_bin_reloc':
dlmalloc.c:1493: warning: dereferencing pointer 'p' does break strict-aliasing rules dlmalloc.c:1493: warning: dereferencing pointer 'p' does break strict-aliasing rules dlmalloc.c:1490: note: initialized from here
dlmalloc.c:1493: note: initialized from here

...

common/dlmalloc.c static mbinptr av_[NAV * 2 + 2] = { · line 1491

Quoted 5 lines

common/dlmalloc.c +2 -1

+typedef unsigned long __attribute__((__may_alias__)) ulong_aliased;
 void malloc_bin_reloc (void)
 {
-	unsigned long *p = (unsigned long *)(&av_[2]);
+	ulong_aliased *p = (ulong_aliased *)(&av_[2]);

I dislike this typedef, especially as it's used only a single time. But even so - why cannot we avoid the __may_alias__ thing alltogether?

You wrote in http://article.gmane.org/gmane.comp.boot-loaders.u-boot/137770
that Simon's patch breaks avr32 boards at runtime.

The implementation is indeed broken. I wonder if it ever worked:

	mbinptr *p = &av_[2];
	int i;

	for (i = 2; i < ARRAY_SIZE(av_); ++i)
		*p = (mbinptr)((ulong)*p + gd->reloc_off);

i. e. this has the offset 2 added twice, so it is missing the first two real entries, env writing beyond the end of the array.

Can you please test this code instead:

	mbinptr *p = &av_;
	int i;

	for (i = 2; i < ARRAY_SIZE(av_); ++i)
		*p = (mbinptr)((ulong)*p + gd->reloc_off);

Best regards,

Wolfgang Denk

Signature · 6 lines

DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
"Don't try to outweird me, three-eyes. I get stranger things than you
free with my breakfast cereal."
           - Zaphod Beeblebrox in  "Hitchhiker's Guide to the Galaxy"

Wolfgang Denk

2012-09-01 12:02 UTC #8 lore raw

PATCH 1/1 dlmalloc: remove manual reloc alias warning

Dear Andreas,

Quoted 3 lines · In message <[email protected]> I wrote:

i. e. this has the offset 2 added twice, so it is missing the first two real entries, env writing beyond the end of the array.

Please ignore me. Seems my brain is still in vacation mode.

However, I really wonder why you say this code would be causing runtime errors for you:

Quoted 5 lines

	mbinptr *p = &av_[2];
	int i;

	for (i = 2; i < ARRAY_SIZE(av_); ++i)
		*p = (mbinptr)((ulong)*p + gd->reloc_off);

It looks good to me.

Can you please add some debug printf()s to find out how the old code and this one differ in their results?

Best regards,

Wolfgang Denk

Signature · 5 lines

DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
All your people must learn before you can reach for the stars.
	-- Kirk, "The Gamesters of Triskelion", stardate 3259.2

Andreas Bießmann

author

2012-09-01 13:20 UTC #9 lore raw

PATCH 1/1 dlmalloc: remove manual reloc alias warning

Dera Wolfgang Denk,

Quoted 12 lines · Wolfgang Denk

Dear Andreas,
Quoted 3 lines · In message <[email protected]> I wrote:
i. e. this has the offset 2 added twice, so it is missing the first two real entries, env writing beyond the end of the array.
Please ignore me. Seems my brain is still in vacation mode.
However, I really wonder why you say this code would be causing runtime errors for you:

Quoted 7 lines

Quoted 5 lines

	mbinptr *p = &av_[2];
	int i;

	for (i = 2; i < ARRAY_SIZE(av_); ++i)
		*p = (mbinptr)((ulong)*p + gd->reloc_off);

It looks good to me.

Well, I did not investigate it further, but I can do this weekend (after merging/testing/pull request the atmel arm stuff). Hopefully we get a solution for the annoying alias warning in upcoming release.

Best regards

Andreas Bie?mann

Quoted 7 lines

Can you please add some debug printf()s to find out how the old code and this one differ in their results?
Best regards,
Wolfgang Denk