[Bug rtl-optimization/18628] [4.0/4.1 regression] miscompilation of switch statement in loop

2005-03-14 Thread cvs-commit at gcc dot gnu dot org 

--- Additional Comments From cvs-commit at gcc dot gnu dot org  2005-03-14 
20:06 ---
Subject: Bug 18628

CVSROOT:/cvs/gcc
Module name:gcc
Changes by: [EMAIL PROTECTED]   2005-03-14 20:06:23

Modified files:
gcc: ChangeLog cse.c 
gcc/testsuite  : ChangeLog 
Added files:
gcc/testsuite/gcc.dg: pr18628.c 

Log message:
gcc/ChangeLog:
PR middle-end/18628
* cse.c (fold_rtx_mem): Don't fold a load from a jumptable into a
register.
gcc/testsuite/ChangeLog:
* gcc.dg/pr18628.c: New.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gccr1=2.7849r2=2.7850
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cse.c.diff?cvsroot=gccr1=1.349r2=1.350
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/ChangeLog.diff?cvsroot=gccr1=1.5166r2=1.5167
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.dg/pr18628.c.diff?cvsroot=gccr1=NONEr2=1.1



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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18628

[Bug rtl-optimization/18628] [4.0/4.1 regression] miscompilation of switch statement in loop

2005-03-14 Thread cvs-commit at gcc dot gnu dot org 

--- Additional Comments From cvs-commit at gcc dot gnu dot org  2005-03-14 
20:32 ---
Subject: Bug 18628

CVSROOT:/cvs/gcc
Module name:gcc
Branch: gcc-4_0-branch
Changes by: [EMAIL PROTECTED]   2005-03-14 20:32:50

Modified files:
gcc: ChangeLog cse.c 
gcc/testsuite  : ChangeLog 
Added files:
gcc/testsuite/gcc.dg: pr18628.c 

Log message:
gcc/ChangeLog:
PR middle-end/18628
* cse.c (fold_rtx_mem): Don't fold a load from a jumptable into a
register.
gcc/testsuite/ChangeLog:
* gcc.dg/pr18628.c: New.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcconly_with_tag=gcc-4_0-branchr1=2.7592.2.49r2=2.7592.2.50
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cse.c.diff?cvsroot=gcconly_with_tag=gcc-4_0-branchr1=1.345r2=1.345.2.1
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/ChangeLog.diff?cvsroot=gcconly_with_tag=gcc-4_0-branchr1=1.5084.2.44r2=1.5084.2.45
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.dg/pr18628.c.diff?cvsroot=gcconly_with_tag=gcc-4_0-branchr1=NONEr2=1.1.2.1



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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18628

[Bug rtl-optimization/18628] [4.0/4.1 regression] miscompilation of switch statement in loop

2005-03-14 Thread aoliva at gcc dot gnu dot org 

--- Additional Comments From aoliva at gcc dot gnu dot org  2005-03-14 
23:43 ---
Fixed

-- 
   What|Removed |Added

 Status|ASSIGNED|RESOLVED
 Resolution||FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18628

[Bug rtl-optimization/18628] [4.0/4.1 regression] miscompilation of switch statement in loop

2005-03-11 Thread rth at gcc dot gnu dot org 

--- Additional Comments From rth at gcc dot gnu dot org  2005-03-11 12:45 
---
Subject: Re: [PR middle-end/18628] do not fold to label load from tablejump to 
reg

On Thu, Mar 10, 2005 at 05:37:48PM -0300, Alexandre Oliva wrote:
   * cse.c (fold_rtx_mem): Don't fold a load from a jumptable into a
   register.

Ok.


r~


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18628

[Bug rtl-optimization/18628] [4.0/4.1 regression] miscompilation of switch statement in loop

2005-03-10 Thread rth at gcc dot gnu dot org 

--- Additional Comments From rth at gcc dot gnu dot org  2005-03-10 13:46 
---
Subject: Re: [PR middle-end/18628] do not fold to label load from tablejump to 
reg

On Wed, Mar 09, 2005 at 07:26:37AM -0300, Alexandre Oliva wrote:
 + /* If it's not a REG, the REG_EQUAL note is inappropriate.  */
 + if (REG_P (SET_DEST (set)))
 +   set_unique_reg_note (insn, REG_EQUAL, label);

I don't think this is a good idea at all.  This is just
asking for reload to recreate a reference to the deleted label.


r~


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18628

[Bug rtl-optimization/18628] [4.0/4.1 regression] miscompilation of switch statement in loop

2005-03-10 Thread aoliva at redhat dot com 

--- Additional Comments From aoliva at gcc dot gnu dot org  2005-03-10 
20:38 ---
Subject: Re: [PR middle-end/18628] do not fold to label load from tablejump to 
reg

On Mar 10, 2005, Richard Henderson [EMAIL PROTECTED] wrote:

 On Wed, Mar 09, 2005 at 07:26:37AM -0300, Alexandre Oliva wrote:
 +/* If it's not a REG, the REG_EQUAL note is inappropriate.  */
 +if (REG_P (SET_DEST (set)))
 +  set_unique_reg_note (insn, REG_EQUAL, label);

 I don't think this is a good idea at all.  This is just
 asking for reload to recreate a reference to the deleted label.

Here's a patch with that bit removed, along with the change in
cse_init that it required.  Ok?

Index: gcc/ChangeLog
from  Alexandre Oliva  [EMAIL PROTECTED]

PR middle-end/18628
* cse.c (fold_rtx_mem): Don't fold a load from a jumptable into a
register.

Index: gcc/cse.c
===
RCS file: /cvs/gcc/gcc/gcc/cse.c,v
retrieving revision 1.349
diff -u -p -r1.349 cse.c
--- gcc/cse.c 8 Mar 2005 13:56:56 - 1.349
+++ gcc/cse.c 10 Mar 2005 20:36:36 -
@@ -3515,8 +3515,30 @@ fold_rtx_mem (rtx x, rtx insn)
if (offset = 0
 (offset / GET_MODE_SIZE (GET_MODE (table))
 XVECLEN (table, 0)))
- return XVECEXP (table, 0,
- offset / GET_MODE_SIZE (GET_MODE (table)));
+ {
+   rtx label = XVECEXP
+ (table, 0, offset / GET_MODE_SIZE (GET_MODE (table)));
+   rtx set;
+
+   /* If we have an insn that loads the label from the
+  jumptable into a reg, we don't want to set the reg
+  to the label, because this may cause a reference to
+  the label to remain after the label is removed in
+  some very obscure cases (PR middle-end/18628).  */
+   if (!insn)
+ return label;
+
+   set = single_set (insn);
+
+   if (! set || SET_SRC (set) != x)
+ return x;
+
+   /* If it's a jump, it's safe to reference the label.  */
+   if (SET_DEST (set) == pc_rtx)
+ return label;
+
+   return x;
+ }
  }
if (table_insn  JUMP_P (table_insn)
 GET_CODE (PATTERN (table_insn)) == ADDR_DIFF_VEC)
Index: gcc/testsuite/ChangeLog
from  Alexandre Oliva  [EMAIL PROTECTED]

* gcc.dg/pr18628.c: New.

Index: gcc/testsuite/gcc.dg/pr18628.c
===
RCS file: gcc/testsuite/gcc.dg/pr18628.c
diff -N gcc/testsuite/gcc.dg/pr18628.c
--- /dev/null   1 Jan 1970 00:00:00 -
+++ gcc/testsuite/gcc.dg/pr18628.c 10 Mar 2005 20:36:52 -
@@ -0,0 +1,31 @@
+/* { dg-do link } */
+/* { dg-options -O2 } */
+
+/* PR middle-end/18628 exposed a problem in which cse folded a load
+   from a jump table into the label that was the target of the branch.
+   Unfortunately, the indirect jump was moved to a different basic
+   block, and the LABEL_REF copied to the register wasn't enough to
+   keep the cfg from optimizing the otherwise-unused label away.  So
+   we ended up with a dangling reference to the label.  */
+
+int i;
+
+int main()
+{
+  for (;;)
+  {
+switch (i)
+{
+  case 0:
+  case 1:
+return 1;
+
+  case 2:
+  case 3:
+return 0;
+
+  case 5:
+--i;
+}
+  }
+}

-- 
Alexandre Oliva http://www.ic.unicamp.br/~oliva/
Red Hat Compiler Engineer   [EMAIL PROTECTED], gcc.gnu.org}
Free Software Evangelist  [EMAIL PROTECTED], gnu.org}


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18628

[Bug rtl-optimization/18628] [4.0/4.1 regression] miscompilation of switch statement in loop

2005-03-10 Thread pluto at pld-linux dot org 

--- Additional Comments From pluto at pld-linux dot org  2005-03-10 23:00 
---
I've just built qt334/kde340(core) with -march=i686 -O/-O2. 
They are totally broken (damaged grahpics/widgets) :/ 
I don't have a testcase at this moment but gcc4 has a serious bug. 
 

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18628

[Bug rtl-optimization/18628] [4.0/4.1 regression] miscompilation of switch statement in loop

2005-03-10 Thread pinskia at gcc dot gnu dot org 

--- Additional Comments From pinskia at gcc dot gnu dot org  2005-03-10 
23:13 ---
(In reply to comment #27)
 I've just built qt334/kde340(core) with -march=i686 -O/-O2. 
 They are totally broken (damaged grahpics/widgets) :/ 
 I don't have a testcase at this moment but gcc4 has a serious bug. 
That is most likely PR 19317.

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18628

[Bug rtl-optimization/18628] [4.0/4.1 regression] miscompilation of switch statement in loop

2005-03-10 Thread law at redhat dot com 

--- Additional Comments From law at redhat dot com  2005-03-11 00:51 ---
Subject: Re: [PR middle-end/18628] do not fold to label load from tablejump
to reg

On Thu, 2005-03-10 at 17:37 -0300, Alexandre Oliva wrote:
 On Mar 10, 2005, Richard Henderson [EMAIL PROTECTED] wrote:
 
  On Wed, Mar 09, 2005 at 07:26:37AM -0300, Alexandre Oliva wrote:
  +  /* If it's not a REG, the REG_EQUAL note is inappropriate.  */
  +  if (REG_P (SET_DEST (set)))
  +set_unique_reg_note (insn, REG_EQUAL, label);
 
  I don't think this is a good idea at all.  This is just
  asking for reload to recreate a reference to the deleted label.
 
 Here's a patch with that bit removed, along with the change in
 cse_init that it required.  Ok?
BTW, can you open a new bug with the same testcase and attach it to the
things CSE still catches meta-bug.  I'd like to catch this at the
tree level if we can rather than wait for our friend CSE.

jeff



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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18628