Commit b44b3449 authored by Richard Henderson's avatar Richard Henderson
Browse files

decodetree: Allow group covering the entire insn space 



This is an edge case for sure, but the logic that disallowed
this case was faulty.  Further, a few fixes scattered about
can allow this to work.

Reviewed-by: default avatarPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: default avatarRichard Henderson <richard.henderson@linaro.org>
parent df63044d

scripts/decodetree.py

+11 −3
Original line number Diff line number Diff line
@@ -124,6 +124,7 @@ def is_pow2(x): 


def ctz(x):

    """Return the number of times 2 factors into X."""

    assert x != 0

    r = 0

    while ((x >> r) & 1) == 0:

        r += 1
@@ -131,6 +132,8 @@ def ctz(x): 




def is_contiguous(bits):

    if bits == 0:

        return -1

    shift = ctz(bits)

    if is_pow2((bits >> shift) + 1):

        return shift
@@ -793,9 +796,8 @@ def build_incmulti_pattern(lineno, pats): 
            error(lineno, 'width mismatch in patterns within braces')



    repeat = True

    while repeat:

        if fixedmask == 0:

            error(lineno, 'no overlap in patterns within braces')

    fixedbits = 0

    while repeat and fixedmask != 0:

        fixedbits = None

        for p in pats:

            thisbits = p.fixedbits & fixedmask
@@ -978,6 +980,12 @@ def build_tree(pats, outerbits, outermask): 
        innermask &= i.fixedmask



    if innermask == 0:

        # Edge condition: One pattern covers the entire insnmask

        if len(pats) == 1:

            t = Tree(outermask, innermask)

            t.subs.append((0, pats[0]))

            return t



        text = 'overlapping patterns:'

        for p in pats:

            text += '\n' + p.file + ':' + str(p.lineno) + ': ' + str(p)

tests/decode/err_pattern_group_nest1.decode→tests/decode/succ_pattern_group_nest2.decode

+1 −1
Original line number Diff line number Diff line
@@ -6,7 +6,7 @@ 
%sub3 16:8

%sub4 24:8



# Groups with no overlap are supposed to fail

# Group with complete overlap of the two patterns

{

  top  00000000 00000000 00000000 00000000

  sub4 ........ ........ ........ ........ %sub1 %sub2 %sub3 %sub4