Fix: TrashedRegisterFinder wasn't working correctly.

Sometimes, registers that really were being preserved across a function call were not. This fix looks at variables in the exit block of the procedure and marks them as preserved if the reaching definition for the variables is a `def` instruction from the entry block.
uxmal · Feb 13, 2024 · 15e5066 · 15e5066
1 parent c5c1221
commit 15e5066
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Showing 79 changed files with 442,320 additions and 445,293 deletions.
diff --git a/src/Core/Types/TypeStore.cs b/src/Core/Types/TypeStore.cs
@@ -141,15 +141,16 @@ public void BuildEquivalenceClassDataTypes(TypeFactory factory)
                 DataType dt = tv.OriginalDataType;
                 EquivalenceClass c = tv.Class;
                 DataType dtOld = c.DataType;
+                var dtNew = dt;
                 if (dtOld != null)
                 {
-                    dt = u.Unify(dt, dtOld)!;
+                    dtNew = u.Unify(dt, dtOld)!;
                 }
                 else if (dt != null)
                 {
-                    dt = dt.Clone();        // why clone???
+                    dtNew = dt.Clone();        // why clone???
                 }
-                c.DataType = dt!;
+                c.DataType = dtNew;
             }
         }
 

diff --git a/src/Decompiler/Analysis/TrashedRegisterFinder.cs b/src/Decompiler/Analysis/TrashedRegisterFinder.cs
@@ -556,12 +556,17 @@ public bool VisitUseInstruction(UseInstruction use)
                         }
                         else if (idV.Storage == id.Storage)
                         {
-                            if (sid.OriginalIdentifier == idV &&
-                                sid.OriginalIdentifier != id)
+                            var sidV = ssas[block!.Procedure].Identifiers[idV];
+                            if (block!.Procedure.Name == "__IOERROR" &&
+                                ( id.Name.Contains("si") ||
+                                id.Name.Contains("bp")))
+                                _ = this; //$DEBUG
+
+                            if (sidV.DefStatement?.Instruction is DefInstruction)
                             {
                                 ctx.ProcFlow.Preserved.Add(stg);
+                                return true;
                             }
-                            return true;
                         }
                     }
                     ctx.ProcFlow.Trashed.Add(stg);

diff --git a/src/Decompiler/Typing/ExpressionTypeDescender.cs b/src/Decompiler/Typing/ExpressionTypeDescender.cs
@@ -543,9 +543,10 @@ public DataType MeetDataType(TypeVariable tvExp, DataType dt)
                 seg.IsSegment = true;
                 var ptr = factory.CreatePointer(seg, dt.BitSize);
                 dt = ptr;
-            } 
+            }
             tvExp.DataType = unifier.Unify(tvExp.DataType, dt)!;
-            tvExp.OriginalDataType = unifier.Unify(tvExp.OriginalDataType, dt)!;
+            var u = unifier.Unify(tvExp.OriginalDataType, dt)!;
+            tvExp.OriginalDataType = u;
             return tvExp.DataType;
         }
 

diff --git a/src/tests/Analysis/CrwIpLiveness.exp b/src/tests/Analysis/CrwIpLiveness.exp
@@ -4,7 +4,7 @@ void fn0C00_0000(Register selector ds)
 //   ds: (ptr16 (segment 0106))
 // LiveOut:
 // Trashed: SCZO ax bx di si Top
-// Preserved: sp
+// Preserved: ds sp
 // fn0C00_0000
 // Return size: 0
 // Mem0:Mem
@@ -53,7 +53,7 @@ Register word16 fn0C00_0026(Sequence segptr32 ds_si)
 //   Sequence ds:si: segptr32
 // LiveOut: ax
 // Trashed: SCZO ax Top
-// Preserved: di sp
+// Preserved: di ds si sp
 // fn0C00_0026
 // Return size: 0
 // Mem0:Mem

diff --git a/src/tests/Analysis/CrwParameters.exp b/src/tests/Analysis/CrwParameters.exp
@@ -4,7 +4,7 @@ void fn0C00_0000(Register selector ds)
 //   ds: (ptr16 (segment 0402))
 // LiveOut:
 // Trashed: SCZO ax si Top
-// Preserved: sp
+// Preserved: ds sp
 // fn0C00_0000
 // Return size: 0
 // Mem0:Mem
@@ -164,7 +164,7 @@ Register word16 fn0C00_0036(Sequence segptr32 ds_si, Register out ptr16 siOut)
 //   Sequence ds:si: segptr32
 // LiveOut: ax si
 // Trashed: ax si Top
-// Preserved: sp
+// Preserved: ds sp
 // fn0C00_0036
 // Return size: 0
 // Mem0:Mem

diff --git a/src/tests/Analysis/CrwProcIsolation.exp b/src/tests/Analysis/CrwProcIsolation.exp
@@ -4,7 +4,7 @@ void fn0C00_0000(Sequence segptr32 ds_di)
 //   Sequence ds:di: segptr32
 // LiveOut:
 // Trashed: SCZO ax Top
-// Preserved: di sp
+// Preserved: di ds sp
 // fn0C00_0000
 // Return size: 0
 // Mem0:Mem

diff --git a/src/tests/Analysis/CrwSliceReturn.exp b/src/tests/Analysis/CrwSliceReturn.exp
@@ -4,7 +4,7 @@ void fn0C00_0000(Register selector ds)
 //   ds: (ptr16 (segment 0303))
 // LiveOut:
 // Trashed: ax si Top
-// Preserved: sp
+// Preserved: ds sp
 // fn0C00_0000
 // Return size: 0
 // Mem0:Mem

diff --git a/src/tests/Analysis/CrwVoidFunctions.exp b/src/tests/Analysis/CrwVoidFunctions.exp
@@ -4,7 +4,7 @@ void fn0C00_0000(Sequence segptr32 ds_di)
 //   Sequence ds:di: segptr32
 // LiveOut:
 // Trashed: SCZO ax bx si Top
-// Preserved: sp
+// Preserved: di ds sp
 // fn0C00_0000
 // Return size: 0
 // Mem0:Mem
@@ -43,7 +43,7 @@ void fn0C00_0010(Sequence segptr32 ds_di, Register word16 si)
 //   si: (memptr (ptr16 (segment)) (struct 0004))
 // LiveOut:
 // Trashed: ax Top
-// Preserved: sp
+// Preserved: di ds sp
 // fn0C00_0010
 // Return size: 0
 // Mem0:Mem
@@ -78,7 +78,7 @@ void fn0C00_0017(Sequence segptr32 ds_di, Stack word16 wArg02)
 //   Stack +0002: (memptr (ptr16 (segment)) (struct 0004))
 // LiveOut:
 // Trashed: SCZO ax bx Top
-// Preserved: bp sp
+// Preserved: bp di ds sp
 // fn0C00_0017
 // Return size: 0
 // Mem0:Mem

diff --git a/src/tests/Analysis/DfaFpuStackReturn.exp b/src/tests/Analysis/DfaFpuStackReturn.exp
@@ -3,7 +3,7 @@
 // MayUse:  ds:[0..15]
 // LiveOut:
 // Trashed: bx FPU -1 Top
-// Preserved: sp
+// Preserved: ds sp
 // fn0C00_0000
 // Return size: 0
 void fn0C00_0000(selector ds)

diff --git a/src/tests/Analysis/DfaReadFile.exp b/src/tests/Analysis/DfaReadFile.exp
@@ -2,7 +2,7 @@
 // stackDelta: 2; fpuStackDelta: 0; fpuMaxParam: -1
 // MayUse: 
 // LiveOut:
-// Trashed: SCZO bx cx ds dx Top
+// Trashed: SCZO ax bx cx ds dx Top
 // Preserved: sp
 // fn0C00_0000
 // Return size: 0
@@ -42,7 +42,7 @@ fn0C00_001F_exit:
 // MayUse:  bx:[0..15] cx:[0..15] Sequence ds:dx:[0..31]
 // LiveOut: ax
 // Trashed: C ax Top
-// Preserved: sp
+// Preserved: ds dx sp
 // fn0C00_0023
 // Return size: 0
 word16 fn0C00_0023(word32 ds_dx, word16 cx, word16 bx)

diff --git a/src/tests/Analysis/DfaReg00010.exp b/src/tests/Analysis/DfaReg00010.exp
@@ -20,7 +20,7 @@ fn0C00_0000_exit:
 // MayUse:  bp:[0..15] ds:[0..15] si:[0..15]
 // LiveOut:
 // Trashed: SCZO ax bp bx cx dx si Top
-// Preserved: sp
+// Preserved: ds sp
 // fn0C00_0004
 // Return size: 0
 void fn0C00_0004(word16 bp, word16 si, selector ds)

diff --git a/src/tests/Analysis/DfaRemoveSpaces.exp b/src/tests/Analysis/DfaRemoveSpaces.exp
@@ -11,7 +11,7 @@ fn0C00_0000_entry:
 	// succ:  l0C00_0000
 l0C00_0000:
 	fn0C00_0015(SEQ(cs, 0x46<16>))
-	Mem31[ds:0x63<16>:word16] = fn0C00_002F(SEQ(cs, 0x46<16>))
+	Mem32[ds:0x63<16>:word16] = fn0C00_002F(SEQ(cs, 0x46<16>))
 	return
 	// succ:  fn0C00_0000_exit
 fn0C00_0000_exit:
@@ -20,7 +20,7 @@ fn0C00_0000_exit:
 // stackDelta: 2; fpuStackDelta: 0; fpuMaxParam: -1
 // MayUse:  Stack +0002:[0..31]
 // LiveOut:
-// Trashed: SCZO di es si Top
+// Trashed: SCZO al di es si Top
 // Preserved: bp ds sp
 // fn0C00_0015
 // Return size: 0

diff --git a/src/tests/Analysis/RlCalleeSave.exp b/src/tests/Analysis/RlCalleeSave.exp
@@ -2,7 +2,7 @@
 	LiveOut:  
 	BitsUsed:  ds:[0..15]
 	Trashed:   ax si Top
-	Preserved: sp
+	Preserved: ds sp
 // fn0C00_0000
 define fn0C00_0000
 fn0C00_0000_entry:

diff --git a/src/tests/Analysis/RlDeepNest.exp b/src/tests/Analysis/RlDeepNest.exp
@@ -2,7 +2,7 @@
 	LiveOut:  
 	BitsUsed:  ds:[0..15]
 	Trashed:   ax si Top
-	Preserved: sp
+	Preserved: ds sp
 // fn0C00_0000
 define fn0C00_0000
 fn0C00_0000_entry:
@@ -19,7 +19,7 @@ fn0C00_0000_exit:
 	LiveOut:   ax:[0..15]
 	BitsUsed:  Sequence ds:si:[0..31]
 	Trashed:   ax Top
-	Preserved: si sp
+	Preserved: ds si sp
 // fn0C00_000B
 define fn0C00_000B
 fn0C00_000B_entry:

diff --git a/src/tests/Analysis/RlIpLiveness.exp b/src/tests/Analysis/RlIpLiveness.exp
@@ -2,7 +2,7 @@
 	LiveOut:  
 	BitsUsed:  ds:[0..15]
 	Trashed:   SCZO ax bx di si Top
-	Preserved: sp
+	Preserved: ds sp
 // fn0C00_0000
 define fn0C00_0000
 fn0C00_0000_entry:
@@ -36,7 +36,7 @@ fn0C00_0000_exit:
 	LiveOut:   ax:[0..15]
 	BitsUsed:  Sequence ds:si:[0..31]
 	Trashed:   SCZO ax Top
-	Preserved: di sp
+	Preserved: di ds si sp
 // fn0C00_0026
 define fn0C00_0026
 fn0C00_0026_entry:

diff --git a/src/tests/Analysis/RlProcIsolation.exp b/src/tests/Analysis/RlProcIsolation.exp
@@ -2,7 +2,7 @@
 	LiveOut:  
 	BitsUsed:  Sequence ds:di:[0..31]
 	Trashed:   SCZO ax Top
-	Preserved: di sp
+	Preserved: di ds sp
 // fn0C00_0000
 define fn0C00_0000
 fn0C00_0000_entry:

diff --git a/src/tests/Analysis/RlReg00010.exp b/src/tests/Analysis/RlReg00010.exp
@@ -18,7 +18,7 @@ fn0C00_0000_exit:
 	LiveOut:  
 	BitsUsed:  bp:[0..15] ds:[0..15] si:[0..15]
 	Trashed:   SCZO ax bp bx cx dx si Top
-	Preserved: sp
+	Preserved: ds sp
 // fn0C00_0004
 define fn0C00_0004
 fn0C00_0004_entry:

diff --git a/src/tests/Analysis/RlSequence.exp b/src/tests/Analysis/RlSequence.exp
@@ -2,7 +2,7 @@
 	LiveOut:  
 	BitsUsed:  ds:[0..15] es:[0..15]
 	Trashed:   SCZO ax di si Top
-	Preserved: sp
+	Preserved: ds sp
 // fn0C00_0000
 define fn0C00_0000
 fn0C00_0000_entry:
@@ -20,7 +20,7 @@ fn0C00_0000_exit:
 	LiveOut:   ax:[0..15]
 	BitsUsed:  es:[0..15] Sequence ds:si:[0..31]
 	Trashed:   SCZO ax di Top
-	Preserved: si sp
+	Preserved: ds si sp
 // fn0C00_000B
 define fn0C00_000B
 fn0C00_000B_entry:

diff --git a/src/tests/Analysis/RlSliceReturn.exp b/src/tests/Analysis/RlSliceReturn.exp
@@ -2,7 +2,7 @@
 	LiveOut:  
 	BitsUsed:  ds:[0..15]
 	Trashed:   ax si Top
-	Preserved: sp
+	Preserved: ds sp
 // fn0C00_0000
 define fn0C00_0000
 fn0C00_0000_entry:

diff --git a/subjects/Elf/ARM/angr-685/RTOSDemo.reko/RTOSDemo.globals.c b/subjects/Elf/ARM/angr-685/RTOSDemo.reko/RTOSDemo.globals.c