Improvement to constant propagation

[Toon Moene]

Richard Kenner wrote:
> 
> Having cprop call simplify_replace_rtx allows more constants to be
> propagated.  This is further increased by looking at REG_EQUAL and
> REG_EQUIV notes on insns that generate available expressions.
> 
> Tested on alphaev56.

[ Patch elided ]

Unfortunately, with this patch I can't bootstrap on
alphaev6-unknown-linux-gnu.

With it, the bootstrap fails in:

/home/toon/compilers/snapshots/obj/gcc/g++
-B/home/toon/compilers/snapshots/obj/gcc/ -nostdinc++
-L/home/toon/compilers/snapshots/obj/alphaev6-unknown-linux-gnu/libstdc++-v3/src
-L/home/toon/compilers/snapshots/obj/alphaev6-unknown-linux-gnu/libstdc++-v3/src/.libs
-B/usr/snp/alphaev6-unknown-linux-gnu/bin/
-B/usr/snp/alphaev6-unknown-linux-gnu/lib/ -isystem
/usr/snp/alphaev6-unknown-linux-gnu/include -nostdinc++
-I../../../../gcc/libstdc++-v3/include
-I../../../../gcc/libstdc++-v3/include/std
-I../../../../gcc/libstdc++-v3/include/c_std -I../include
-I../../../../gcc/libstdc++-v3/libsupc++ -I../libio
-I../../../../gcc/libstdc++-v3/libio
-I../../../../gcc/libstdc++-v3/libmath -g -O2 -fvtable-thunks
-D_GNU_SOURCE -mieee -fno-implicit-templates -Wall -Wno-format -W
-Wwrite-strings -Winline -fdiagnostics-show-location=once
-ffunction-sections -fdata-sections -g -c c++locale.cc  -fPIC -DPIC -o
.libs/c++locale.o
c++locale.cc: In member function `void std::moneypunct<_CharT, 
   _Intl>::_M_initialize_moneypunct(int*) [with _CharT = char, bool
_Intl = 
   false]':
c++locale.cc:88: Internal compiler error in validate_replace_src, at
recog.c:
   754
Please submit a full bug report, with preprocessed source if
appropriate.
See <URL: http://www.gnu.org/software/gcc/bugs.html > for instructions.

If I patch -R it - no problem ...

Sorry, no explanation, yet.

-- 
Toon Moene - mailto:toon@moene.indiv.nluug.nl - phoneto: +31 346 214290
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