CM7: Simplify Dilithium iNTT code

* This commit simplifies the Dilithium iNTT naive implementations to revert modifications to the code originally taken from pqm4 that were only introduced to accomodate for shortcomings of slothy's abilities.
* We can also enable the fixup in more cases due to switching of the loop-type + using `before` tag which is done here, too. This aids with performance.

example.py

@@ -1605,7 +1605,7 @@ def __init__(self, var="", arch=Arch_Armv7M, target=Target_CortexM7, timeout=Non
     def core(self, slothy):
         slothy.config.constraints.stalls_first_attempt = 16
 
-        slothy.config.unsafe_address_offset_fixup = False
+        slothy.config.unsafe_address_offset_fixup = True
 
 
         slothy.config.variable_size = True
@@ -1616,12 +1616,12 @@ def core(self, slothy):
         slothy.config.sw_pipelining.optimize_postamble = True
         slothy.config.sw_pipelining.allow_pre = True
 
-        slothy.optimize_loop("layer123_loop")
+        slothy.optimize_loop("layer123_loop", forced_loop_type=Arch_Armv7M.BranchLoop)
         slothy.optimize_loop("layer456_first_loop")
         slothy.optimize_loop("layer456_loop")
 
         slothy.config.inputs_are_outputs = True
-        slothy.optimize_loop("layer78_loop")
+        slothy.optimize_loop("layer78_loop", forced_loop_type=Arch_Armv7M.BranchLoop)
 
 class pointwise_montgomery_dilithium(Example):
     def __init__(self, var="", arch=Arch_Armv7M, target=Target_CortexM7, timeout=None):

examples/naive/armv7m/intt_dilithium_123_456_78.s

@@ -221,9 +221,9 @@ pqcrystals_dilithium_invntt_tomont:
     str.w pol5, [ptr_p, #5*distance/4]
     str.w pol6, [ptr_p, #6*distance/4]
     str.w pol7, [ptr_p, #7*distance/4]
-    str.w pol0, [ptr_p], #strincr
+    str.w pol0, [ptr_p], #strincr // @slothy:before=cmp
     vmov temp_l, s9
-    cmp.w ptr_p, temp_l
+    cmp.w ptr_p, temp_l // @slothy:id=cmp
   bne.w layer123_loop
 
   sub ptr_p, #32*strincr
@@ -248,21 +248,21 @@ pqcrystals_dilithium_invntt_tomont:
     ldr.w pol3, [ptr_p, #7*distance2/4]
     _3_layer_inv_butterfly_light_fast_first pol0, pol1, pol2, pol3, pol4, pol5, pol6, pol7, s2, s3, s4, s5, s6, s7, s8, zeta, qinv, q, temp_h, temp_l
 
-    ldr.w pol0, [ptr_p], #128
-    ldr pol1, [ptr_p, #1*distance2/4-128]
-    ldr pol2, [ptr_p, #2*distance2/4-128]
-    ldr pol3, [ptr_p, #3*distance2/4-128]
+    ldr.w pol0, [ptr_p]
+    ldr pol1, [ptr_p, #1*distance2/4]
+    ldr pol2, [ptr_p, #2*distance2/4]
+    ldr pol3, [ptr_p, #3*distance2/4]
     _3_layer_inv_butterfly_light_fast_second pol0, pol1, pol2, pol3, pol4, pol5, pol6, pol7, s2, s3, s4, s5, s6, s7, s8, zeta, qinv, q, temp_h, temp_l
 
-    str pol1, [ptr_p, #1*distance2/4-128]
-    str pol2, [ptr_p, #2*distance2/4-128]
-    str pol3, [ptr_p, #3*distance2/4-128]
-    str.w pol5, [ptr_p, #5*distance2/4-128]
-    str.w pol6, [ptr_p, #6*distance2/4-128]
-    str.w pol7, [ptr_p, #7*distance2/4-128]
-    str pol0, [ptr_p, #-128]
-    str.w pol4, [ptr_p], #128
-    //add.w ptr_p, #strincr2
+    str pol1, [ptr_p, #1*distance2/4]
+    str pol2, [ptr_p, #2*distance2/4]
+    str pol3, [ptr_p, #3*distance2/4]
+    str.w pol4, [ptr_p, #4*distance2/4]
+    str.w pol5, [ptr_p, #5*distance2/4]
+    str.w pol6, [ptr_p, #6*distance2/4]
+    str.w pol7, [ptr_p, #7*distance2/4]
+    str pol0, [ptr_p]
+    add.w ptr_p, ptr_p, #strincr2
 
     vmov temp_l, s10
     cmp.w ptr_p, temp_l
@@ -281,26 +281,26 @@ pqcrystals_dilithium_invntt_tomont:
     vldm ptr_zeta!, {s2-s8}
     vmov s0, ptr_zeta
     layer456_loop:
-	    ldr.w pol0, [ptr_p], #128
-	    ldr pol1, [ptr_p, #1*distance2/4-128]
-	    ldr pol2, [ptr_p, #2*distance2/4-128]
-	    ldr pol3, [ptr_p, #3*distance2/4-128]
-	    ldr.w pol4, [ptr_p, #4*distance2/4-128]
-	    ldr.w pol5, [ptr_p, #5*distance2/4-128]
-	    ldr.w pol6, [ptr_p, #6*distance2/4-128]
-	    ldr.w pol7, [ptr_p, #7*distance2/4-128]
+	    ldr.w pol0, [ptr_p]
+	    ldr pol1, [ptr_p, #1*distance2/4]
+	    ldr pol2, [ptr_p, #2*distance2/4]
+	    ldr pol3, [ptr_p, #3*distance2/4]
+	    ldr.w pol4, [ptr_p, #4*distance2/4]
+	    ldr.w pol5, [ptr_p, #5*distance2/4]
+	    ldr.w pol6, [ptr_p, #6*distance2/4]
+	    ldr.w pol7, [ptr_p, #7*distance2/4]
 
 	    _3_layer_inv_CT_32 pol0, pol1, pol2, pol3, pol4, pol5, pol6, pol7, s2, s3, s4, s5, s6, s7, s8, zeta, qinv, q, temp_h, temp_l
 
-	    str pol1, [ptr_p, #1*distance2/4-128]
-	    str pol2, [ptr_p, #2*distance2/4-128]
-	    str pol3, [ptr_p, #3*distance2/4-128]
-	    str.w pol5, [ptr_p, #5*distance2/4-128]
-	    str.w pol6, [ptr_p, #6*distance2/4-128]
-	    str.w pol7, [ptr_p, #7*distance2/4-128]
-	    str pol0, [ptr_p, #-128]
-      str.w pol4, [ptr_p], #128
-	    //add.w ptr_p, #strincr2
+	    str pol1, [ptr_p, #1*distance2/4]
+	    str pol2, [ptr_p, #2*distance2/4]
+	    str pol3, [ptr_p, #3*distance2/4]
+      str.w pol4, [ptr_p, #4*distance2/4]
+	    str.w pol5, [ptr_p, #5*distance2/4]
+	    str.w pol6, [ptr_p, #6*distance2/4]
+	    str.w pol7, [ptr_p, #7*distance2/4]
+	    str pol0, [ptr_p]
+	    add.w ptr_p, ptr_p, #strincr2
 
       vmov temp_l, s10
       cmp.w ptr_p, temp_l
@@ -342,10 +342,10 @@ pqcrystals_dilithium_invntt_tomont:
     str.w pol1, [ptr_p, #256]
     str.w pol2, [ptr_p, #512]
     str.w pol3, [ptr_p, #768]
-    str pol0, [ptr_p], #strincr3 // @slothy:core
+    str pol0, [ptr_p], #strincr3 // @slothy:core // @slothy:before=cmp
 
     vmov cntr, s9
-    cmp.w ptr_p, cntr
+    cmp.w ptr_p, cntr // @slothy:id=cmp
     bne.w layer78_loop
 
     //restore registers