Move rewriting of bs_match from beam_clean to beam_z

The actual bs_match_string instruction has four operands:

   bs_match_string {f,Lbl} Ctxt NumBits {string,ListOfBytes}

However, v3_codegen emits a more compact representation where
the bits to match are packaged in a bitstring:

   bs_match_string {f,Lbl} Ctxt Bitstring

Currently, beam_clean:clean_labels/1 will rewrite the compact
representation to the final representation. That is unfortunate
since clean_labels/1 is called by beam_dead, which means that
the less compact representation will be introduced long before
it is actually needed by beam_asm. It will also complicate any
optimizations that we might want to do.

Move the rewriting of bs_match_string from beam_clean:clean_labels/1
to the beam_z pass, which is the last pass executed before
beam_validator and beam_asm.

1 files changed, 2 insertions, 2 deletions

diff --git a/lib/compiler/src/beam_dead.erl b/lib/compiler/src/beam_dead.erl
index f4515ba2a7..adc3cebc62 100644
--- a/lib/compiler/src/beam_dead.erl
+++ b/lib/compiler/src/beam_dead.erl
@@ -459,8 +459,8 @@ count_bits_matched([{test,_,_,_,[_,Sz,U,{field_flags,_}],_}|Is], SavePoint, Bits
 	{integer,N} -> count_bits_matched(Is, SavePoint, Bits+N*U);
 	_ -> count_bits_matched(Is, SavePoint, Bits)
     end;
-count_bits_matched([{test,bs_match_string,_,[_,Bits,_]}|Is], SavePoint, Bits0) ->
-    count_bits_matched(Is, SavePoint, Bits0+Bits);
+count_bits_matched([{test,bs_match_string,_,[_,Bs]}|Is], SavePoint, Bits) ->
+    count_bits_matched(Is, SavePoint, Bits+bit_size(Bs));
 count_bits_matched([{test,_,_,_}|Is], SavePoint, Bits) ->
     count_bits_matched(Is, SavePoint, Bits);
 count_bits_matched([{bs_save2,Reg,SavePoint}|_], {Reg,SavePoint}, Bits) ->