Re: Frozen

[Vladimir 'φ-coder/phcoder' Serbinenko]

On 01.03.2012 20:15, Lennart Sorensen wrote:
> On Thu, Mar 01, 2012 at 01:37:10PM -0500, Lennart Sorensen wrote:
> > gcc-4.4 -DHAVE_CONFIG_H -I. -I../../../grub-core -I..  -Wall -W -I../../../include 
> > -I../include  -DGRUB_MACHINE_EMU=1 -DGRUB_MACHINE=POWERPC_EMU -DGRUB_TARGET_CPU_POWERPC=1 
> > -m32 -DGRUB_FILE=\"normal/charset.c\" -I. -I../../../grub-core -I.. -I../../.. 
> > -I../../../include -I../include   -I../../../grub-core/lib/posix_wrap   -Os -Wall -W 
> > -Wshadow -Wold-style-declaration -Wold-style-definition -Wpointer-arith -Wundef -Wextra 
> > -Waddress -Warray-bounds -Wattributes -Wbuiltin-macro-redefined -Wcast-align 
> > -Wchar-subscripts -Wclobbered -Wcomment -Wcoverage-mismatch -Wdeprecated 
> > -Wdeprecated-declarations -Wdisabled-optimization -Wdiv-by-zero -Wempty-body 
> > -Wendif-labels -Wfloat-equal -Wformat-contains-nul -Wformat-extra-args -Wformat-security 
> > -Wformat-y2k -Wignored-qualifiers -Wimplicit -Wimplicit-function-declaration 
> > -Wimplicit-int -Winit-self -Wint-to-pointer-cast -Winvalid-pch 
> > -Wunsafe-loop-optimizations -Wlogical-op -Wmain -Wmissing-braces 
> > -Wmissing-field-initializers -Wmissing-format-attribute -Wmissing-noreturn -W
> > mudflap -Wmultichar -Wnonnull -Woverflow -Wpacked-bitfield-compat -Wparentheses 
> > -Wpointer-arith -Wpointer-to-int-cast -Wreturn-type -Wsequence-point -Wshadow 
> > -Wsign-compare -Wstrict-aliasing -Wswitch -Wsync-nand -Wtrigraphs  
> > -Wtype-limits -Wundef -Wuninitialized -Wunknown-pragmas -Wunused 
> > -Wunused-function -Wunused-label -Wunused-parameter -Wunused-value  
> > -Wunused-variable -Wvariadic-macros -Wvolatile-register-var -Wwrite-strings 
> > -Wmissing-parameter-type -Wnested-externs -Wstrict-prototypes -Wpointer-sign -g 
> > -Wredundant-decls -Wmissing-prototypes -Wmissing-declarations 
> > -fno-dwarf2-cfi-asm -fno-asynchronous-unwind-tables -m32 -fno-stack-protector 
> > -Werror -DUSE_ASCII_FAILBACK=1 -DHAVE_UNIFONT_WIDTHSPEC=1         
> > -ffreestanding -fno-builtin -Wno-redundant-decls   -c -o 
> > normal/normal_module-charset.o `test -f 'normal/charset.c' || echo 
> > '../../../grub-core/'`normal/charset.c
> > cc1: warnings being treated as errors
> > ../../../grub-core/normal/charset.c: In function 
> > 'grub_bidi_line_logical_to_visual':
> > ../../../grub-core/normal/charset.c:636: error: cannot optimize possibly 
> > infinite loops
> Would using this instead work:
>
> for (i = k - 1; i>= 0&&  (unsigned) i>  line_start - 1;
>
> After all if i already had to be>=0 then casting it to unsigned has no
> harm, whereas casting line_start to signed could potentially generate
> a very negative number if line_start was very big.
You forget the case line_start = 0. Please try:
-        for (i = k - 1; i > (signed) line_start - 1 && i >= 0;
+        for (i = k - 1; i >= 0 && (unsigned) i >= line_start;
> The compiler approves.


--
Regards
Vladimir 'φ-coder/phcoder' Serbinenko