Allow to force loop type

* Helps in case of ambigous loop types and makes the operation more predictable.

example.py

@@ -738,6 +738,23 @@ def core(self,slothy):
         slothy.config.variable_size=True
         slothy.config.outputs = ["r6"]
         slothy.optimize_loop("start")
+
+class Armv7mLoopVmovCmpForced(Example):
+    def __init__(self, var="", arch=Arch_Armv7M, target=Target_CortexM7):
+        name = "loop_vmov_cmp_forced"
+        infile = name
+
+        if var != "":
+            name += f"_{var}"
+            infile += f"_{var}"
+        name += f"_{target_label_dict[target]}"
+
+        super().__init__(infile, name, rename=True, arch=arch, target=target)
+
+    def core(self,slothy):
+        slothy.config.variable_size=True
+        slothy.config.outputs = ["r5", "r6"]
+        slothy.optimize_loop("start", forced_loop_type=Arch_Armv7M.CmpLoop)
 
 class AArch64IfElse(Example):
     def __init__(self, var="", arch=AArch64_Neon, target=Target_CortexA55):
@@ -1561,6 +1578,7 @@ def main():
                  Armv7mLoopSubs(),
                  Armv7mLoopCmp(),
                  Armv7mLoopVmovCmp(),
+                 Armv7mLoopVmovCmpForced(),
 
                  CRT(),
 

examples/naive/armv7m/loop_vmov_cmp_forced.s

@@ -0,0 +1,15 @@
+/* For example, r5 represents an address where we will stop iterating and r6 is
+the actual pointer which is incremented inside the loop.
+
+In this specific example, the vmov shall not be accounted towards the loop
+boundary but rather the body. */
+
+mov.w r6, #0
+add.w r5, r6, #64
+vmov s0, r5
+
+start:
+    add r6, r6, #4
+    vmov r5, s0
+    cmp r6, r5
+    bne start

examples/opt/armv7m/loop_vmov_cmp_forced_opt_m7.s

@@ -0,0 +1,35 @@
+/* For example, r5 represents an address where we will stop iterating and r6 is
+the actual pointer which is incremented inside the loop.
+
+In this specific example, the vmov shall not be accounted towards the loop
+boundary but rather the body. */
+
+mov.w r6, #0
+add.w r5, r6, #64
+vmov s0, r5
+
+1:
+                              // Instructions:    2
+                              // Expected cycles: 1
+                              // Expected IPC:    2.00
+                              //
+                              // Cycle bound:     1.0
+                              // IPC bound:       2.00
+                              //
+                              // Wall time:     0.04s
+                              // User time:     0.04s
+                              //
+                              // ----- cycle (expected) ------>
+                              // 0                        25
+                              // |------------------------|----
+        add r6, r6, #4        // *.............................
+        vmov r5, s0           // *.............................
+
+                               // ------ cycle (expected) ------>
+                               // 0                        25
+                               // |------------------------|-----
+        // add r6, r6, #4      // *..............................
+        // vmov r5, s0         // *..............................
+
+        cmp r6, r5
+        bne 1b

slothy/core/slothy.py

@@ -355,10 +355,15 @@ def indented(code):
         self.source = pre + optimized_source + post
         assert SourceLine.is_source(self.source)
 
-    def get_loop_input_output(self, loop_lbl):
-        """Find all registers that a loop body depends on"""
+    def get_loop_input_output(self, loop_lbl, forced_loop_type=None):
+        """Find all registers that a loop body depends on
+        
+            Args:
+                loop_lbl: Label of loop to process.
+                forced_loop_type: Forces the loop to be parsed as a certain type.
+        """
         logger = self.logger.getChild(loop_lbl)
-        _, body, _, _, _ = self.arch.Loop.extract(self.source, loop_lbl)
+        _, body, _, _, _ = self.arch.Loop.extract(self.source, loop_lbl, forced_loop_type=forced_loop_type)
 
         c = self.config.copy()
         dfgc = DFGConfig(c)
@@ -432,18 +437,19 @@ def fusion_region(self, start, end, **kwargs):
         self.source = pre + body_ssa + post
         assert SourceLine.is_source(self.source)
 
-    def fusion_loop(self, loop_lbl, **kwargs):
+    def fusion_loop(self, loop_lbl, forced_loop_type=None, **kwargs):
         """Run fusion callbacks on loop body replacing certain instruction
         (sequences) with an alternative. These replacements are defined in the
         architectural model by setting an instruction class' global_fusion_cb.
         
         Args:
             loop_lbl: Label of loop to which the fusions are applied to. 
+            forced_loop_type: Forces the loop to be parsed as a certain type.
         """
         logger = self.logger.getChild(f"ssa_loop_{loop_lbl}")
 
         pre , body, post, _, other_data, loop = \
-            self.arch.Loop.extract(self.source, loop_lbl)
+            self.arch.Loop.extract(self.source, loop_lbl, forced_loop_type=forced_loop_type)
         loop_cnt = other_data['cnt']
         indentation = AsmHelper.find_indentation(body)
 
@@ -454,15 +460,18 @@ def fusion_loop(self, loop_lbl, **kwargs):
         self.source = pre + body_ssa + post
         assert SourceLine.is_source(self.source)
 
-    def optimize_loop(self, loop_lbl, postamble_label=None):
+    def optimize_loop(self, loop_lbl, postamble_label=None, forced_loop_type=None):
         """Optimize the loop starting at a given label
-            The postamble_label marks the end of the loop kernel.
+            
+            Args:
+                postamble_label: Marks end of loop kernel.
+                forced_loop_type: Forces the loop to be parsed as a certain type.
         """
 
         logger = self.logger.getChild(loop_lbl)
 
         early, body, late, _, other_data, loop = \
-            self.arch.Loop.extract(self.source, loop_lbl)
+            self.arch.Loop.extract(self.source, loop_lbl, forced_loop_type=forced_loop_type)
         loop_cnt = other_data['cnt']
 
         # Check if the body has a dominant indentation

slothy/helper.py

@@ -1559,8 +1559,21 @@ def _extract(self, source, lbl):
         return pre, body, post, lbl, self.additional_data
 
     @staticmethod
-    def extract(source, lbl):
-        for loop_type in Loop.__subclasses__():
+    def extract(source, lbl, forced_loop_type=None):
+        """
+        Find a loop with start label `lbl` in `source` and return it together
+        with its type.
+        
+            Args:
+                source: list of SourceLine objects
+                lbl: label of the loop to extract
+                forced_loop_type: if not None, only try to extract this type of loop
+        """
+        if forced_loop_type is not None:
+            loop_types = [forced_loop_type]
+        else:
+            loop_types = Loop.__subclasses__()
+        for loop_type in loop_types:
             try:
                 l = loop_type(lbl)
                 # concatenate the extracted loop with an instance of the