On 2014-03-17 14:28:13 +0200, Martin Storsjö wrote:
> This does some rudimentary conversions of instructions that aren't
> available in thumb mode.
>
> This allows building OpenH264 for Windows Phone 8 (and Windows RT),
> which only supports thumb mode, and the OpenH264 arm assembly is
> hardcoded for arm mode.
>
> This is similar to how libvpx supports assembling in thumb mode - the
> source itself is arm mode only, but a perl script can replace
> instruction combinations that aren't supported in thumb mode. This
> is a small subset of those conversions.
> ---
> gas-preprocessor.pl | 28 ++++++++++++++++++++++++++++
> 1 file changed, 28 insertions(+)
>
> diff --git a/gas-preprocessor.pl b/gas-preprocessor.pl
> index eefe571..36cef69 100755
> --- a/gas-preprocessor.pl
> +++ b/gas-preprocessor.pl
> @@ -27,6 +27,7 @@ my $arch;
> my $as_type = "apple-gas";
>
> my $fix_unreq = $^O eq "darwin";
> +my $force_thumb = 0;
>
> my $arm_cond_codes = "eq|ne|cs|cc|mi|pl|vs|vc|hi|ls|ge|lt|gt|le|al|hs|lo";
>
> @@ -45,6 +46,9 @@ command. Following options are currently supported:
> -as-type - one value out of {{,apple-}{gas,clang},armasm}
> -fix-unreq
> -no-fix-unreq
> + -force-thumb - assemble as thumb regardless of the input source
> + (note, this is incomplete and only works for sources
> + it explicitly was tested with)
> ";
>
> sub usage() {
> @@ -76,6 +80,8 @@ while (@options) {
> my $opt = shift @options;
> if ($opt =~ /^-(no-)?fix-unreq$/) {
> $fix_unreq = $1 ne "no-";
> + } elsif ($opt eq "-force-thumb") {
> + $force_thumb = 1;
> } elsif ($opt eq "-arch") {
> $arch = shift @options;
> die "unknown arch: '$arch'\n" if not exists $comments{$arch};
> @@ -215,6 +221,10 @@ my @ifstack;
>
> my %symbols;
>
> +if ($force_thumb) {
> + parse_line(".thumb\n");
> +}
> +
> # pass 1: parse .macro
> # note that the handling of arguments is probably overly permissive vs. gas
> # but it should be the same for valid cases
> @@ -885,6 +895,24 @@ sub handle_serialized_line {
> $line =~ s/&0x/& 0x/g;
> }
>
> + if ($force_thumb) {
> + # Convert register post indexing to a separate add instruction.
> + # This converts e.g. "ldr r0, [r1], r2" into "ldr r0, [r1]",
> + # "add r1, r1, r2".
> + $line =~ s/(ldr|str)\s+(\w+),\s*\[(\w+)\],\s*(\w+)/$1 $2,
> [$3]\n\tadd $3, $3, $4/g;
yes, that's much better. thanks
> +
> + # Convert "mov pc, lr" into "bx lr", since the former only works
> + # for switching from arm to thumb (and only in armv7), but not
> + # from thumb to arm.
> + s/mov\s*pc\s*,\s*lr/bx lr/g;
> +
> + # Convert stmdb/ldmia with only one register into a plain str/ldr
> with post-increment/decrement
> + $line =~ s/stmdb\s+sp!\s*,\s*\{([^,-]+)\}/str $1, [sp, #-4]!/g;
> + $line =~ s/ldmia\s+sp!\s*,\s*\{([^,-]+)\}/ldr $1, [sp], #4/g;
> +
> + $line =~ s/\.arm/.thumb/x;
> + }
> +
> # comment out unsupported directives
> $line =~ s/\.type/$comm$&/x if $as_type =~ /^(apple-|armasm)/;
> $line =~ s/\.func/$comm$&/x if $as_type =~ /^(apple-|clang)/;
ok
Janne
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