Improve block ordering in ConditionDetection using the ILOffsets of Leave instruction arguments

ICSharpCode.Decompiler.Tests/TestCases/Pretty/ShortCircuit.cs

@@ -252,6 +252,14 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 			return 2;
 		}
 
+		public int InferCorrectOrder()
+		{
+			if (F(1) || F(2)) {
+				return 1;
+			}
+			return 2;
+		}
+
 #if !OPT
 		public void EmptyIf()
 		{

ICSharpCode.Decompiler.Tests/TestCases/Pretty/ShortCircuit.il

@@ -1257,6 +1257,45 @@
     IL_003d:  ret
   } // end of method ShortCircuit::StmtComplex6
 
+  .method public hidebysig instance int32 
+          InferCorrectOrder() cil managed
+  {
+    // Code size       39 (0x27)
+    .maxstack  2
+    .locals init (int32 V_0,
+             bool V_1)
+    IL_0000:  nop
+    IL_0001:  ldarg.0
+    IL_0002:  ldc.i4.1
+    IL_0003:  callvirt   instance bool ICSharpCode.Decompiler.Tests.TestCases.Pretty.ShortCircuit::F(int32)
+    IL_0008:  brtrue.s   IL_0016
+
+    IL_000a:  ldarg.0
+    IL_000b:  ldc.i4.2
+    IL_000c:  callvirt   instance bool ICSharpCode.Decompiler.Tests.TestCases.Pretty.ShortCircuit::F(int32)
+    IL_0011:  ldc.i4.0
+    IL_0012:  ceq
+    IL_0014:  br.s       IL_0017
+
+    IL_0016:  ldc.i4.0
+    IL_0017:  nop
+    IL_0018:  stloc.1
+    IL_0019:  ldloc.1
+    IL_001a:  brtrue.s   IL_0021
+
+    IL_001c:  nop
+    IL_001d:  ldc.i4.1
+    IL_001e:  stloc.0
+    IL_001f:  br.s       IL_0025
+
+    IL_0021:  ldc.i4.2
+    IL_0022:  stloc.0
+    IL_0023:  br.s       IL_0025
+
+    IL_0025:  ldloc.0
+    IL_0026:  ret
+  } // end of method ShortCircuit::InferCorrectOrder
+
   .method public hidebysig instance void 
           EmptyIf() cil managed
   {

ICSharpCode.Decompiler.Tests/TestCases/Pretty/ShortCircuit.opt.il

@@ -879,6 +879,28 @@
     IL_0024:  ret
   } // end of method ShortCircuit::StmtComplex6
 
+  .method public hidebysig instance int32 
+          InferCorrectOrder() cil managed
+  {
+    // Code size       22 (0x16)
+    .maxstack  8
+    IL_0000:  ldarg.0
+    IL_0001:  ldc.i4.1
+    IL_0002:  callvirt   instance bool ICSharpCode.Decompiler.Tests.TestCases.Pretty.ShortCircuit::F(int32)
+    IL_0007:  brtrue.s   IL_0012
+
+    IL_0009:  ldarg.0
+    IL_000a:  ldc.i4.2
+    IL_000b:  callvirt   instance bool ICSharpCode.Decompiler.Tests.TestCases.Pretty.ShortCircuit::F(int32)
+    IL_0010:  brfalse.s  IL_0014
+
+    IL_0012:  ldc.i4.1
+    IL_0013:  ret
+
+    IL_0014:  ldc.i4.2
+    IL_0015:  ret
+  } // end of method ShortCircuit::InferCorrectOrder
+
   .method public hidebysig instance void 
           PreferLogicalToBitwise(bool a,
                                  bool b,

ICSharpCode.Decompiler.Tests/TestCases/Pretty/ShortCircuit.opt.roslyn.il

@@ -883,6 +883,28 @@
     IL_0024:  ret
   } // end of method ShortCircuit::StmtComplex6
 
+  .method public hidebysig instance int32 
+          InferCorrectOrder() cil managed
+  {
+    // Code size       22 (0x16)
+    .maxstack  8
+    IL_0000:  ldarg.0
+    IL_0001:  ldc.i4.1
+    IL_0002:  callvirt   instance bool ICSharpCode.Decompiler.Tests.TestCases.Pretty.ShortCircuit::F(int32)
+    IL_0007:  brtrue.s   IL_0012
+
+    IL_0009:  ldarg.0
+    IL_000a:  ldc.i4.2
+    IL_000b:  callvirt   instance bool ICSharpCode.Decompiler.Tests.TestCases.Pretty.ShortCircuit::F(int32)
+    IL_0010:  brfalse.s  IL_0014
+
+    IL_0012:  ldc.i4.1
+    IL_0013:  ret
+
+    IL_0014:  ldc.i4.2
+    IL_0015:  ret
+  } // end of method ShortCircuit::InferCorrectOrder
+
   .method public hidebysig instance void 
           PreferLogicalToBitwise(bool a,
                                  bool b,

ICSharpCode.Decompiler.Tests/TestCases/Pretty/ShortCircuit.roslyn.il

@@ -1193,6 +1193,42 @@
     IL_0036:  ret
   } // end of method ShortCircuit::StmtComplex6
 
+  .method public hidebysig instance int32 
+          InferCorrectOrder() cil managed
+  {
+    // Code size       35 (0x23)
+    .maxstack  2
+    .locals init (bool V_0,
+             int32 V_1)
+    IL_0000:  nop
+    IL_0001:  ldarg.0
+    IL_0002:  ldc.i4.1
+    IL_0003:  callvirt   instance bool ICSharpCode.Decompiler.Tests.TestCases.Pretty.ShortCircuit::F(int32)
+    IL_0008:  brtrue.s   IL_0013
+
+    IL_000a:  ldarg.0
+    IL_000b:  ldc.i4.2
+    IL_000c:  callvirt   instance bool ICSharpCode.Decompiler.Tests.TestCases.Pretty.ShortCircuit::F(int32)
+    IL_0011:  br.s       IL_0014
+
+    IL_0013:  ldc.i4.1
+    IL_0014:  stloc.0
+    IL_0015:  ldloc.0
+    IL_0016:  brfalse.s  IL_001d
+
+    IL_0018:  nop
+    IL_0019:  ldc.i4.1
+    IL_001a:  stloc.1
+    IL_001b:  br.s       IL_0021
+
+    IL_001d:  ldc.i4.2
+    IL_001e:  stloc.1
+    IL_001f:  br.s       IL_0021
+
+    IL_0021:  ldloc.1
+    IL_0022:  ret
+  } // end of method ShortCircuit::InferCorrectOrder
+
   .method public hidebysig instance void 
           EmptyIf() cil managed
   {

ICSharpCode.Decompiler/IL/ControlFlow/ConditionDetection.cs

@@ -514,12 +514,15 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow
 
 			if (strongly)
 				return 0;
-
-			if (exit1.MatchBranch(out var block1) && exit2.MatchBranch(out var block2)) {
-				// prefer arranging stuff in IL order
-				return block1.ILRange.Start.CompareTo(block2.ILRange.Start);
-			}
+			
 			// prefer arranging stuff in IL order
+			if (exit1.MatchBranch(out var block1) && exit2.MatchBranch(out var block2))
+				return block1.ILRange.Start.CompareTo(block2.ILRange.Start);
+
+			// use the IL offsets of the arguments of leave instructions instead of the leaves themselves if possible
+			if (exit1.MatchLeave(out var _, out var arg1) && exit2.MatchLeave(out var _, out var arg2))
+				return arg1.ILRange.Start.CompareTo(arg2.ILRange.Start);
+				
 			return exit1.ILRange.Start.CompareTo(exit2.ILRange.Start);
 		}