Re: ICE in gcc/libgcc2.c:566 (gcc trunk)

["H. J. Lu" <hjl at lucon dot org>]

On Sun, Feb 11, 2007 at 05:11:15PM +0100, Hanno Meyer-Thurow wrote:
> On 07 Feb 2007 15:36:14 -0800
> Ian Lance Taylor <iant@google.com> wrote:
> 
> > Can anybody else out there recreate this on their x86_64 system?
> 
> Not that I could not recreate the segfault but I found a way to hide the
> segfault. Instead of optimizing with nocona
> 
> 	make \
> 		LDFLAGS="-Wl,-O1 -Wl,--as-needed -Wl,--sort-common" \
> 		STAGE1_CFLAGS="-O" \
> 		LIBPATH="/usr/lib/gcj-4.3.0_alpha20070209/lib64" \
> 		BOOT_CFLAGS=" -O2 -mtune=nocona -march=nocona -pipe -msse3 -mfpmath=sse" \
> 		bootstrap
> 

-mtune=nocona seems to miscompile the stage3 compiler. I got

bash-3.1$ make compare
Comparing stages 2 and 3
warning: ./cc1-checksum.o differs
Bootstrap comparison failure!
./tree-vrp.o differs
./tree-ssa-operands.o differs
./build/genpreds.o differs
./build/gengtype-yacc.o differs
./build/genattrtab.o differs
./tree-ssa-alias.o differs
./tree-eh.o differs
./tree-tailcall.o differs
./ipa-reference.o differs
./c-common.o differs
./sched-rgn.o differs
./dominance.o differs
./reload1.o differs
./tree-cfg.o differs
./flow.o differs
./fold-const.o differs
./gcc.o differs
./c-decl.o differs
./tree-ssa-dce.o differs
./bt-load.o differs
./tree-ssa-ter.o differs
./function.o differs
./ddg.o differs
./tree.o differs
./tree-ssa.o differs
./loop-unroll.o differs
./expmed.o differs
./df-scan.o differs
./tree-sra.o differs
./resource.o differs
./except.o differs
./predict.o differs
./tree-ssa-dse.o differs
./df-core.o differs
./cfgloopmanip.o differs
./calls.o differs
./real.o differs
./gcse.o differs
./bitmap.o differs
./c-pragma.o differs
./explow.o differs
./loop-invariant.o differs
./tree-object-size.o differs
./tree-ssa-structalias.o differs
./sched-deps.o differs
./tree-ssa-threadupdate.o differs
./pretty-print.o differs
./tree-pretty-print.o differs
./tree-ssa-sink.o differs
./df-problems.o differs
./tree-into-ssa.o differs
./lower-subreg.o differs
./caller-save.o differs
./loop-iv.o differs
./tree-nested.o differs
./combine.o differs
./tree-ssa-loop-ivopts.o differs
./c-parser.o differs
./cfgrtl.o differs
./tree-scalar-evolution.o differs
./tree-ssa-live.o differs
./ifcvt.o differs
./expr.o differs
./ipa-type-escape.o differs
./i386.o differs
./local-alloc.o differs
./tree-ssa-dom.o differs
./c-typeck.o differs
./bb-reorder.o differs
./tree-ssa-pre.o differs
./global.o differs
./see.o differs
./tree-ssa-loop-manip.o differs
./cfgcleanup.o differs
./cfgexpand.o differs
./tree-ssa-coalesce.o differs
./stor-layout.o differs
make: *** [compare] Error 1

when passed I BOOT_CFLAGS="-O2 -g -mtune=nocona -pipe" to bootstrap.

"make bootstrap" should have checked it. Due to a gcc regression:

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30767

"make bootstrap" didn't stop when the stage3 compiler was bad.

H.J.