[Bug target/38900] New: ICE: unable to find a register to spill

[Bug target/38900] New: ICE: unable to find a register to spill

[d dot g dot gorbachev at gmail dot com]

gcc -S -O1 -foptimize-sibling-calls bug.c

bug.c: In function 'f':
bug.c:9: error: unable to find a register to spill in class 'CREG'
bug.c:9: error: this is the insn:
(call_insn/j 11 9 12 2 bug.c:8 (call (mem:QI (reg/f:SI 3 bx [59]) [0 S1 A8])
        (const_int 0 [0x0])) 468 {*sibcall_1} (expr_list:REG_DEAD (reg/f:SI 3
bx [59])
        (expr_list:REG_DEAD (reg:SI 2 cx)
            (nil)))
    (expr_list:REG_DEP_TRUE (use (reg:SI 2 cx))
        (nil)))
bug.c:9: internal compiler error: in spill_failure, at reload1.c:2093


-- 
           Summary: ICE: unable to find a register to spill
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: d dot g dot gorbachev at gmail dot com
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i386-pc-mingw32


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38900

[Bug target/38900] ICE: unable to find a register to spill

[d dot g dot gorbachev at gmail dot com]

------- Comment #1 from d dot g dot gorbachev at gmail dot com  2009-01-17 23:19 -------
bug.c:

void __attribute__((dllimport,fastcall)) h(int);

void f(int i)
{
    static void (__attribute__((fastcall)) *g)(int) = h;

    g(i);
    g(i);
}


-- 

d dot g dot gorbachev at gmail dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to fail|                            |4.3.2 4.4.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38900

[Bug target/38900] ICE: unable to find a register to spill

[d dot g dot gorbachev at gmail dot com]

------- Comment #2 from d dot g dot gorbachev at gmail dot com  2009-01-17 23:20 -------
ok.c:

void __attribute__((dllimport,fastcall)) h(int);

void f(int i)
{
    static void (__attribute__((fastcall)) *g)(int);

    g = h;

    g(i);
    g(i);
}


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38900

[Bug target/38900] ICE: unable to find a register to spill

[fxcoudert at gcc dot gnu dot org]

------- Comment #3 from fxcoudert at gcc dot gnu dot org  2009-05-13 20:04 -------
Simpler testcase, confirmed on native i386-pc-mingw32 (trunk, SVN rev. 147441):

$ cat a.c
void __attribute__((dllimport,fastcall)) h(int);

void f()
{
  h(2);
  h(1);
}

$ gcc -S -O1 a.c -foptimize-sibling-calls
a.c: In function 'f':
a.c:7: error: unable to find a register to spill in class 'CREG'
a.c:7: error: this is the insn:
(call_insn/j 10 8 11 2 a.c:6 (call (mem:QI (reg/f:SI 3 bx [58]) [0 S1 A8])
        (const_int 0 [0x0])) 468 {*sibcall_1} (expr_list:REG_DEAD (reg/f:SI 3
bx [58])
        (expr_list:REG_DEAD (reg:SI 2 cx)
            (nil)))
    (expr_list:REG_DEP_TRUE (use (reg:SI 2 cx))
        (nil)))
a.c:7: internal compiler error: in spill_failure, at reload1.c:2094


-- 

fxcoudert at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
  GCC build triplet|i686-pc-linux-gnu           |
   GCC host triplet|i686-pc-linux-gnu           |
   Last reconfirmed|0000-00-00 00:00:00         |2009-05-13 20:04:31
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38900

[Bug target/38900] ICE: unable to find a register to spill

[ivmai at mail dot ru]

------- Comment #4 from ivmai at mail dot ru  2009-06-25 10:31 -------
Bug confirmed in mingw-w64 gcc v4.5.0 (32-bit target).
Bug also observed in MinGW gcc v3.4.5 and v4.2.1


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38900

[Bug target/38900] ICE: unable to find a register to spill

[d dot g dot gorbachev at gmail dot com]

------- Comment #5 from d dot g dot gorbachev at gmail dot com  2009-06-26 14:57 -------
Perhaps there are two bugs, not one, as my more elaborate testcases show.
Though they are seemingly equivalent, one triggers the bug, while another
don't.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38900

[Bug target/38900] ICE: unable to find a register to spill

[ktietz at gcc dot gnu dot org]

------- Comment #6 from ktietz at gcc dot gnu dot org  2009-07-06 10:33 -------
(In reply to comment #5)
> Perhaps there are two bugs, not one, as my more elaborate testcases show.
> Though they are seemingly equivalent, one triggers the bug, while another
> don't.
> 

Ok, is the same issue occurring, when the attributes are set separately in
different __attribute__ statements?

Cheers,
Kai 


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38900

[Bug target/38900] ICE: unable to find a register to spill

[ktietz at gcc dot gnu dot org]

------- Comment #7 from ktietz at gcc dot gnu dot org  2009-07-06 11:54 -------
Ok, I think I found the issue. The following patch solved the ICE here. The ebx
register wasn't allowed for sibcall_1 in i386.md, but for fastcall it can be
used for sibcalling.

I have to do a regression test for it, but it seems to work well.

Index: config/i386/i386.md
===================================================================
--- config/i386/i386.md (revision 149152)
+++ config/i386/i386.md (working copy)
@@ -15536,7 +15536,7 @@
   [(set_attr "type" "call")])

 (define_insn "*sibcall_1"
-  [(call (mem:QI (match_operand:SI 0 "sibcall_insn_operand" "s,c,d,a"))
+  [(call (mem:QI (match_operand:SI 0 "sibcall_insn_operand" "s,c,d,a,b"))
         (match_operand 1 "" ""))]
   "SIBLING_CALL_P (insn) && !TARGET_64BIT"
 {
@@ -22183,7 +22183,7 @@

 (define_insn "*sibcall_value_1"
   [(set (match_operand 0 "" "")
-       (call (mem:QI (match_operand:SI 1 "sibcall_insn_operand" "s,c,d,a"))
+       (call (mem:QI (match_operand:SI 1 "sibcall_insn_operand" "s,c,d,a,b"))
              (match_operand:SI 2 "" "")))]
   "SIBLING_CALL_P (insn) && !TARGET_64BIT"
 {


-- 

ktietz at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|2009-05-13 20:04:31         |2009-07-06 11:54:21
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38900

[Bug target/38900] ICE: unable to find a register to spill

[ktietz at gcc dot gnu dot org]

-- 

ktietz at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |ktietz at gcc dot gnu dot
                   |dot org                     |org
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2009-07-06 11:54:21         |2009-07-06 12:38:34
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38900

[Bug target/38900] ICE: unable to find a register to spill

[ebotcazou at gcc dot gnu dot org]

------- Comment #8 from ebotcazou at gcc dot gnu dot org  2009-07-06 12:49 -------
 > Index: config/i386/i386.md
> ===================================================================
> --- config/i386/i386.md (revision 149152)
> +++ config/i386/i386.md (working copy)
> @@ -15536,7 +15536,7 @@
>    [(set_attr "type" "call")])
> 
>  (define_insn "*sibcall_1"
> -  [(call (mem:QI (match_operand:SI 0 "sibcall_insn_operand" "s,c,d,a"))
> +  [(call (mem:QI (match_operand:SI 0 "sibcall_insn_operand" "s,c,d,a,b"))
>          (match_operand 1 "" ""))]
>    "SIBLING_CALL_P (insn) && !TARGET_64BIT"
>  {
> @@ -22183,7 +22183,7 @@
> 
>  (define_insn "*sibcall_value_1"
>    [(set (match_operand 0 "" "")
> -       (call (mem:QI (match_operand:SI 1 "sibcall_insn_operand" "s,c,d,a"))
> +       (call (mem:QI (match_operand:SI 1 "sibcall_insn_operand" "s,c,d,a,b"))
>               (match_operand:SI 2 "" "")))]
>    "SIBLING_CALL_P (insn) && !TARGET_64BIT"
>  {

This cannot be correct in the general case as %ebx is call-saved, you cannot
clobber it through a function call.  A solution could be to disparage the 'c'
alternative, but a x86 maintainer will know better.


-- 

ebotcazou at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ebotcazou at gcc dot gnu dot
                   |                            |org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38900

[Bug target/38900] ICE: unable to find a register to spill

[ktietz at gcc dot gnu dot org]

------- Comment #9 from ktietz at gcc dot gnu dot org  2009-07-06 13:17 -------
(In reply to comment #8)
> This cannot be correct in the general case as %ebx is call-saved, you cannot
> clobber it through a function call.  A solution could be to disparage the 'c'
> alternative, but a x86 maintainer will know better.
> 

Well, why? For save or called saved registers the functions epilogue/prologue
takes care. The reason why gcc tries to choose ebx for call address register
here, is exactly this reason, as it can be sure that after the sibcall, the
register is still valid.

Cheers,
Kai


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38900

[Bug target/38900] ICE: unable to find a register to spill

[ebotcazou at gcc dot gnu dot org]

------- Comment #10 from ebotcazou at gcc dot gnu dot org  2009-07-06 15:31 -------
> Well, why? For save or called saved registers the functions epilogue/prologue
> takes care. The reason why gcc tries to choose ebx for call address register
> here, is exactly this reason, as it can be sure that after the sibcall, the
> register is still valid.

What's the assembly code generated with your patch?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38900

[Bug target/38900] ICE: unable to find a register to spill

[ktietz at gcc dot gnu dot org]

------- Comment #11 from ktietz at gcc dot gnu dot org  2009-07-06 16:12 -------
(In reply to comment #10)
> > Well, why? For save or called saved registers the functions epilogue/prologue
> > takes care. The reason why gcc tries to choose ebx for call address register
> > here, is exactly this reason, as it can be sure that after the sibcall, the
> > register is still valid.
> 
> What's the assembly code generated with your patch?
> 

Compiling the test case with -O2

        .file   "c_impfast.c"
        .text
        .p2align 4,,15
.globl _f
        .def    _f;     .scl    2;      .type   32;     .endef
_f:
        pushl   %ebp
        movl    $2, %ecx
        movl    %esp, %ebp
        pushl   %ebx
        subl    $4, %esp
        movl    __imp_@h@4, %ebx
        call    *%ebx
        addl    $4, %esp
        movl    $1, %ecx
        popl    %ebx
        popl    %ebp
        jmp     *%ebx


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38900

[Bug target/38900] ICE: unable to find a register to spill

[ktietz at gcc dot gnu dot org]

------- Comment #12 from ktietz at gcc dot gnu dot org  2009-07-06 16:13 -------
And this is pretty wrong :}


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38900

[Bug target/38900] ICE: unable to find a register to spill

[ktietz at gcc dot gnu dot org]

------- Comment #13 from ktietz at gcc dot gnu dot org  2009-07-06 16:41 -------
By simply re-ording of arguments fos sibcall_1 and sibcall_value_1, so that c
is last element, produced code is ok and no ICE I've seen. The ebx issue is
pretty wrong here.

Index: gcc/gcc/config/i386/i386.md
===================================================================
--- gcc.orig/gcc/config/i386/i386.md    2009-07-06 18:14:36.155670000 +0200
+++ gcc/gcc/config/i386/i386.md 2009-07-06 18:36:54.453670100 +0200
@@ -15536,7 +15536,7 @@
   [(set_attr "type" "call")])

 (define_insn "*sibcall_1"
-  [(call (mem:QI (match_operand:SI 0 "sibcall_insn_operand" "s,c,d,a"))
+  [(call (mem:QI (match_operand:SI 0 "sibcall_insn_operand" "s,d,a,c"))
         (match_operand 1 "" ""))]
   "SIBLING_CALL_P (insn) && !TARGET_64BIT"
 {
@@ -22183,7 +22183,7 @@

 (define_insn "*sibcall_value_1"
   [(set (match_operand 0 "" "")
-       (call (mem:QI (match_operand:SI 1 "sibcall_insn_operand" "s,c,d,a"))
+       (call (mem:QI (match_operand:SI 1 "sibcall_insn_operand" "s,d,a,c"))
              (match_operand:SI 2 "" "")))]
   "SIBLING_CALL_P (insn) && !TARGET_64BIT"
 {


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38900

[Bug target/38900] ICE: unable to find a register to spill

[ebotcazou at gcc dot gnu dot org]

------- Comment #14 from ebotcazou at gcc dot gnu dot org  2009-07-06 16:43 -------
> By simply re-ording of arguments fos sibcall_1 and sibcall_value_1, so that c
> is last element, produced code is ok and no ICE I've seen.

Disparaging it ("s,!c,d,a") would be even more robust I think.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38900

[Bug target/38900] ICE: unable to find a register to spill

[ktietz at gcc dot gnu dot org]

------- Comment #15 from ktietz at gcc dot gnu dot org  2009-07-06 17:02 -------
(In reply to comment #14)
> > By simply re-ording of arguments fos sibcall_1 and sibcall_value_1, so that c
> > is last element, produced code is ok and no ICE I've seen.
> 
> Disparaging it ("s,!c,d,a") would be even more robust I think.
> 

yeah, this works, too. But the d needs the !, too. As when I alter my testcase
by giving the dllimport'ed fastcall a second argument, it ICEs again.

$ /usr/local/bin/i686-pc-mingw32-gcc.exe -o t.s -S c_impfast2.c -O2
c_impfast2.c: In function 'f':
c_impfast2.c:7:1: error: unable to find a register to spill in class 'DREG'
c_impfast2.c:7:1: error: this is the insn:
(call_insn/j 12 10 13 2 c_impfast2.c:6 (call (mem:QI (reg/f:SI 3 bx [58]) [0 S1
A8])
        (const_int 0 [0x0])) 462 {*sibcall_1} (expr_list:REG_DEAD (reg/f:SI 3
bx [58])
        (expr_list:REG_DEAD (reg:SI 2 cx)
            (expr_list:REG_DEAD (reg:SI 1 dx)
                (nil))))
    (expr_list:REG_DEP_TRUE (use (reg:SI 2 cx))
        (expr_list:REG_DEP_TRUE (use (reg:SI 1 dx))
            (nil))))
c_impfast2.c:7:1: internal compiler error: in spill_failure, at reload1.c:2094
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.

So with both c and d changed to !c and !d for sibcall_1 and sibcall_value_1 it
translates without ICE to:

        .file   "c_impfast2.c"
        .text
        .p2align 4,,15
.globl _f
        .def    _f;     .scl    2;      .type   32;     .endef
_f:
        pushl   %ebp
        movl    $1, %edx
        movl    %esp, %ebp
        movl    $2, %ecx
        pushl   %ebx
        subl    $4, %esp
        movl    __imp_@h@8, %ebx
        call    *%ebx
        addl    $4, %esp
        movl    $2, %edx
        movl    $1, %ecx
        movl    %ebx, %eax
        popl    %ebx
        popl    %ebp
        jmp     *%eax

New patch for i386.md (and you are right the !c,!d is more robust here) is:

Index: gcc/gcc/config/i386/i386.md
===================================================================
--- gcc.orig/gcc/config/i386/i386.md    2009-07-06 18:14:36.155670000 +0200
+++ gcc/gcc/config/i386/i386.md 2009-07-06 18:53:10.459670100 +0200
@@ -15536,7 +15536,7 @@
   [(set_attr "type" "call")])

 (define_insn "*sibcall_1"
-  [(call (mem:QI (match_operand:SI 0 "sibcall_insn_operand" "s,c,d,a"))
+  [(call (mem:QI (match_operand:SI 0 "sibcall_insn_operand" "s,!c,!d,a"))
         (match_operand 1 "" ""))]
   "SIBLING_CALL_P (insn) && !TARGET_64BIT"
 {
@@ -22183,7 +22183,7 @@

 (define_insn "*sibcall_value_1"
   [(set (match_operand 0 "" "")
-       (call (mem:QI (match_operand:SI 1 "sibcall_insn_operand" "s,c,d,a"))
+       (call (mem:QI (match_operand:SI 1 "sibcall_insn_operand" "s,!c,!d,a"))
              (match_operand:SI 2 "" "")))]
   "SIBLING_CALL_P (insn) && !TARGET_64BIT"
 {


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38900

[Bug target/38900] ICE: unable to find a register to spill

[rth at gcc dot gnu dot org]

------- Comment #16 from rth at gcc dot gnu dot org  2009-07-08 16:41 -------
Subject: Bug 38900

Author: rth
Date: Wed Jul  8 16:41:23 2009
New Revision: 149373

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=149373
Log:
        PR target/38900
        * config/i386/i386.h (CONDITIONAL_REGISTER_USAGE): Move to i386.c.
        (enum reg_class): Add CLOBBERED_REGS.
        (REG_CLASS_NAMES, REG_CLASS_CONTENTS): Likewise.
        * config/i386/i386.c (ix86_conditional_register_usage): Moved
        from CONDITIONAL_REGISTER_USAGE; build CLOBBERED_REGS for 64-bit.
        (ix86_function_ok_for_sibcall): Tidy.  Disallow MS->SYSV sibcalls.
        (ix86_expand_call): Use sibcall_insn_operand when needed.  Don't
        force 64-bit sibcalls into R11.
        * config/i386/constraints.md (U): New constraint.
        * config/i386/i386.md (sibcall_1, sibcall_value_1): Use it.
        (sibcall_1_rex64, sibcall_value_1_rex64): Likewise.
        (sibcall_1_rex64_v, sibcall_value_1_rex64_v): Remove.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/config/i386/constraints.md
    trunk/gcc/config/i386/i386-protos.h
    trunk/gcc/config/i386/i386.c
    trunk/gcc/config/i386/i386.h
    trunk/gcc/config/i386/i386.md


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38900

[Bug target/38900] ICE: unable to find a register to spill

[rth at gcc dot gnu dot org]

------- Comment #17 from rth at gcc dot gnu dot org  2009-07-08 16:59 -------
Subject: Bug 38900

Author: rth
Date: Wed Jul  8 16:59:15 2009
New Revision: 149374

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=149374
Log:
        PR target/38900
        * config/i386/i386.h (CONDITIONAL_REGISTER_USAGE): Move to i386.c.
        (enum reg_class): Add CLOBBERED_REGS.
        (REG_CLASS_NAMES, REG_CLASS_CONTENTS): Likewise.
        * config/i386/i386.c (ix86_conditional_register_usage): Moved
        from CONDITIONAL_REGISTER_USAGE; build CLOBBERED_REGS for 64-bit.
        (ix86_function_ok_for_sibcall): Tidy.  Disallow MS->SYSV sibcalls.
        (ix86_expand_call): Use sibcall_insn_operand when needed.  Don't
        force 64-bit sibcalls into R11.
        * config/i386/constraints.md (U): New constraint.
        * config/i386/i386.md (sibcall_1, sibcall_value_1): Use it.
        (sibcall_1_rex64, sibcall_value_1_rex64): Likewise.
        (sibcall_1_rex64_v, sibcall_value_1_rex64_v): Remove.

Modified:
    branches/gcc-4_4-branch/gcc/ChangeLog
    branches/gcc-4_4-branch/gcc/config/i386/constraints.md
    branches/gcc-4_4-branch/gcc/config/i386/i386-protos.h
    branches/gcc-4_4-branch/gcc/config/i386/i386.c
    branches/gcc-4_4-branch/gcc/config/i386/i386.h
    branches/gcc-4_4-branch/gcc/config/i386/i386.md


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38900

[Bug target/38900] ICE: unable to find a register to spill

[rth at gcc dot gnu dot org]

------- Comment #18 from rth at gcc dot gnu dot org  2009-07-08 17:03 -------
Fixed.


-- 

rth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38900