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ARM: allow for reverse pointer addition #191

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Merged
sipma merged 1 commit into from
Dec 18, 2024
Merged

ARM: allow for reverse pointer addition #191

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31 changes: 28 additions & 3 deletions chb/arm/opcodes/ARMAdd.py
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Original file line number Diff line number Diff line change
Expand Up @@ -214,14 +214,39 @@ def pointer_arithmetic_expr() -> AST.ASTExpr:
hl_rhs1_type = hl_rhs1.ctype(astree.ctyper)
hl_rhs2_type = hl_rhs2.ctype(astree.ctyper)

if hl_rhs1_type is None:
if hl_rhs1_type is None and hl_rhs2_type is None:
chklogger.logger.error(
"Unable to lift pointer arithmetic without type for "
+ "%s at address %s",
str(rhs3), iaddr)
return astree.mk_temp_lval_expression()

if hl_rhs1_type.is_pointer:
if hl_rhs2_type is not None and hl_rhs2_type.is_pointer:
rhs2tgttyp = cast(AST.ASTTypPtr, hl_rhs2_type).tgttyp
tgttypsize = astree.type_size_in_bytes(rhs2tgttyp)
if tgttypsize is None:
chklogger.logger.warning(
"Unable to lift pointer arithmetic without size for "
+ "%s at address %s; set type size to 1",
str(hl_rhs2_type), iaddr)
# return astree.mk_temp_lval_expression()
tgttypsize = 1

if tgttypsize == 1:
return XU.xxpr_to_ast_def_expr(rhs3, xdata, iaddr, astree)

if hl_rhs1.is_integer_constant:
addend = cast(AST.ASTIntegerConstant, hl_rhs1).cvalue
addend = addend // tgttypsize
astaddend: AST.ASTExpr = astree.mk_integer_constant(addend)
annotations.append("scaled by " + str(tgttypsize))
return astree.mk_binary_op("plus", hl_rhs2, astaddend)

scale = astree.mk_integer_constant(tgttypsize)
scaled = astree.mk_binary_op("div", hl_rhs1, scale)
return astree.mk_binary_op("plus", hl_rhs2, scaled)

if hl_rhs1_type is not None and hl_rhs1_type.is_pointer:
rhs1tgttyp = cast(AST.ASTTypPtr, hl_rhs1_type).tgttyp
tgttypsize = astree.type_size_in_bytes(rhs1tgttyp)
if tgttypsize is None:
Expand Down Expand Up @@ -250,7 +275,7 @@ def pointer_arithmetic_expr() -> AST.ASTExpr:
if hl_rhs2.is_integer_constant:
addend = cast(AST.ASTIntegerConstant, hl_rhs2).cvalue
addend = addend // tgttypsize
astaddend: AST.ASTExpr = astree.mk_integer_constant(addend)
astaddend = astree.mk_integer_constant(addend)
annotations.append("scaled by " + str(tgttypsize))
return astree.mk_binary_op("plus", hl_rhs1, astaddend)

Expand Down