[Bug rtl-optimization/63365] New: [ARM] Incorrect copy propagation for vclz intrinsic

[michael.collison at linaro dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63365

            Bug ID: 63365
           Summary: [ARM] Incorrect copy propagation for vclz intrinsic
           Product: gcc
           Version: 4.9.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: michael.collison at linaro dot org

Created attachment 33558
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33558&action=edit
Test case demonstrating incorrect code generation for vclz

Compiling and executing the attached testcase at -O2 produces incorrect code
and execution results. Instead of code being generated for the vclz instruction
the compiler propagates an incorrect constant value for what it believes will
be the result of the instruction. The attached test case is part of a proposed
set of DejaGnu tests for neon intrinsics.

------------------------------------------------------------------------------
Target: arm-linux-gnueabihf

Configured with:
'/home/michael-collison/neon-intrinsic-build/snapshots/gcc.git~neon-intrinsic-christophe/configure'
--with-bugurl=https://bugs.launchpad.net/gcc-linaro
--with-mpc=/home/michael-collison/neon-intrinsic-build/builds/destdir/x86_64-unknown-linux-gnu
--with-mpfr=/home/michael-collison/neon-intrinsic-build/builds/destdir/x86_64-unknown-linux-gnu
--with-gmp=/home/michael-collison/neon-intrinsic-build/builds/destdir/x86_64-unknown-linux-gnu
--with-gnu-as --with-gnu-ld --disable-libstdcxx-pch --disable-libmudflap
--with-cloog=no --with-ppl=no --with-isl=no --disable-nls --enable-multiarch
--disable-multilib --enable-c99 --with-arch=armv7-a --with-fpu=vfpv3-d16
--with-float=hard --with-mode=thumb
--with-sysroot=/opt/linaro/sysroot-linaro_eglibc-2_19-arm-clean-linux-gnueabihf
--with-build-sysroot=/home/michael-collison/neon-intrinsic-build/sysroots/arm-clean-linux-gnueabihf
--enable-lto --enable-linker-build-id --enable-long-long
--enable-languages=c,c++,fortran,go,lto
--with-bugurl=https://bugs.launchpad.net/gcc-linaro --with-pkgversion='Linaro
GCC 2014.08' --build=x86_64-unknown-linux-gnu --host=x86_64-unknown-linux-gnu
--target=arm-clean-linux-gnueabihf
--prefix=/home/michael-collison/neon-intrinsic-build/builds/destdir/x86_64-unknown-linux-gnu

Thread model: posix

gcc version 4.10.0 20140812 (experimental) (Linaro GCC 2014.08)