ARM: add support for tail call returning a value (Issue:223)

Author: sipma

chb/app/CHVersion.py

@@ -1 +1 @@
-chbversion: str = "0.3.0-20250502"
+chbversion: str = "0.3.0-20250608"

chb/arm/ARMCallOpcode.py

@@ -331,7 +331,11 @@ def ast_call_prov(
             # Note that defuses[0] may be None even when defuseshigh[0] is not
             # None. This happens when the return value's only use is as a
             # return value of the caller's function itself.
-            if rtype.is_void or ((defuses[0] is None) and (defuseshigh[0] is None)):
+            if (
+                    rtype.is_void
+                    or ((defuses[0] is None)
+                        and (defuseshigh[0] is None)
+                        and not self.return_value)):
                 chklogger.logger.info(
                     "Unused: introduced ssa-variable: %s for return value of %s "
                     + "at address %s",

chb/arm/opcodes/ARMAdd.py

@@ -259,6 +259,12 @@ def ast_prov(
 
         annotations: List[str] = [iaddr, "ADD"]
 
+        if xdata.is_aggregate_jumptable:
+            chklogger.logger.warning(
+                "ADD: aggregate jumptable at address %s not yet handled",
+                iaddr)
+            return ([], [])
+
         # low-level assignment
 
         (ll_lhs, _, _) = self.operands[0].ast_lvalue(astree)

chb/arm/opcodes/ARMBranch.py

@@ -149,6 +149,21 @@ def is_xtgt_ok(self) -> bool:
         else:
             return self.is_xpr_ok(4)
 
+    def has_return_xpr(self) -> bool:
+        return self.xdata.has_return_xpr()
+
+    def returnval(self) -> "XXpr":
+        return self.xdata.get_return_xpr()
+
+    def rreturnval(self) -> "XXpr":
+        return self.xdata.get_return_xxpr()
+
+    def has_creturnval(self) -> bool:
+        return self.xdata.has_return_cxpr()
+
+    def creturnval(self) -> "XXpr":
+        return self.xdata.get_return_cxpr()
+
     @property
     def annotation(self) -> str:
         if self.is_conditional:
@@ -234,6 +249,19 @@ def jump_target(self, xdata: InstrXData) -> Optional["XXpr"]:
         else:
             return xdata.xprs[0]
 
+    def is_return_instruction(self, xdata: InstrXData) -> bool:
+        return ARMBranchXData(xdata).has_return_xpr()
+
+    def return_value(self, xdata: InstrXData) -> Optional[XXpr]:
+        xd = ARMBranchXData(xdata)
+        if xd.has_return_xpr():
+            if xd.has_creturnval():
+                return xd.creturnval()
+            else:
+                return xd.rreturnval()
+        else:
+            return None
+
     def annotation(self, xdata: InstrXData) -> str:
         xd = ARMBranchXData(xdata)
         if xd.is_ok: