[Bug target/50193] New: ARM: ICE on a | (b << negative-constant)

[Bug target/50193] New: ARM: ICE on a | (b << negative-constant)

[michael.hope at linaro dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50193

             Bug #: 50193
           Summary: ARM: ICE on a | (b << negative-constant)
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: michael.hope@linaro.org


trunk r178025, 4.6.1, and 4.5.3 all ICE with unsatisfied constraints on the
following code:

int foo(int a, int b)
{
    return a | (b << -3);
}

shift.c: In function 'foo':
shift.c:3:5: warning: left shift count is negative [enabled by default]
shift.c:4:1: error: insn does not satisfy its constraints:
(insn 14 9 17 2 (set (reg/i:SI 0 r0)
        (ior:SI (ashift:SI (reg:SI 1 r1 [ b ])
                (const_int -3 [0xfffffffffffffffd]))
            (reg:SI 0 r0 [ a ]))) shift.c:4 259 {*arith_shiftsi}
     (expr_list:REG_DEAD (reg:SI 1 r1 [ b ])
        (nil)))
shift.c:4:1: internal compiler error: in extract_constrain_insn_cached, at
recog.c:2030

This happens with -mcpu=cortex-a9 -mthumb.  With -marm, GCC recognises that the
shift is unusual, loads it into a register, then uses this in the
register-shifted-register form of ORR.  This form isn't available in Thumb-2.

The problem was originally seen in libtheora:lib/mathops.c when built with -O3
-funroll-loops when a shift by negative 8 is generated.

[Bug target/50193] ARM: ICE on a | (b << negative-constant)

[michael.hope at linaro dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50193

--- Comment #1 from Michael Hope <michael.hope at linaro dot org> 2011-08-28 21:40:01 UTC ---
Also occurs when building LLVM trunk.  See:

http://builds.linaro.org/toolchain/llvm-3.0~svn138625/logs/armv7l-natty-cbuild172-ursa1-cortexa9r1/llvm-build.txt

/scratch/cbuild/slave/slaves/ursa1/llvm-3.0~svn138625/llvm/llvm-3.0~/tools/clang/unittests/AST/APValueTest.cpp:
In member function 'virtual void
{anonymous}::APValue_Diagnostics_Test::TestBody()':
/scratch/cbuild/slave/slaves/ursa1/llvm-3.0~svn138625/llvm/llvm-3.0~/tools/clang/unittests/AST/APValueTest.cpp:77:1:
error: insn does not satisfy its constraints:
(insn 1267 1266 1269 72 (set (subreg:SI (reg:DI 1327) 0)
        (ior:SI (ashift:SI (reg:SI 1330)
                (const_int -16 [0xfffffffffffffff0]))
            (subreg:SI (reg:DI 1327) 0)))
/scratch/cbuild/slave/slaves/ursa1/llvm-3.0~svn138625/llvm/llvm-3.0~/include/llvm/ADT/APInt.h:140
257 {*arith_shiftsi}
     (nil))
/scratch/cbuild/slave/slaves/ursa1/llvm-3.0~svn138625/llvm/llvm-3.0~/tools/clang/unittests/AST/APValueTest.cpp:77:1:
internal compiler error: in extract_constrain_insn_cached, at recog.c:2028

[Bug target/50193] ARM: ICE on a | (b << negative-constant)

[ams at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50193

Andrew Stubbs <ams at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2011-09-01
                 CC|                            |ams at gcc dot gnu.org
         AssignedTo|unassigned at gcc dot       |ams at gcc dot gnu.org
                   |gnu.org                     |
     Ever Confirmed|0                           |1

--- Comment #2 from Andrew Stubbs <ams at gcc dot gnu.org> 2011-09-01 10:19:03 UTC ---
The problem appears to be that the predicate accepts any constant, without
checking the range.

I'll post a patch shortly.

[Bug target/50193] ARM: ICE on a | (b << negative-constant)

[ams at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50193

Andrew Stubbs <ams at gcc dot gnu.org> changed:

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

--- Comment #3 from Andrew Stubbs <ams at gcc dot gnu.org> 2011-10-10 11:39:22 UTC ---
This has now been fixed. The patch was posted here:

http://gcc.gnu.org/ml/gcc-patches/2011-10/msg00594.html

[Bug target/50193] ARM: ICE on a | (b << negative-constant)

[doko at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50193

Matthias Klose <doko at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |konstantinos.margaritis at
                   |                            |linaro dot org

--- Comment #4 from Matthias Klose <doko at gcc dot gnu.org> 2011-12-03 15:58:45 UTC ---
*** Bug 50947 has been marked as a duplicate of this bug. ***