Fix: bugs in TrashedRegisterFinder and DistributedConversionRule.

Reko was generating invalid CONVERT() expression.
uxmal · Jun 5, 2024 · ccee2ab · ccee2ab
1 parent 14e8046
commit ccee2ab
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Showing 26 changed files with 238,646 additions and 238,448 deletions.
diff --git a/src/Decompiler/Analysis/TrashedRegisterFinder.cs b/src/Decompiler/Analysis/TrashedRegisterFinder.cs
@@ -741,8 +741,20 @@ public Expression GetValue(MemoryAccess access, IMemory memory)
  return StackState!.Get(stack.StackOffset);
  if (!IdState.TryGetValue(id, out (Expression, BitRange) value))
  return null;
+ else if (value.Item1 is { })
+ return MaybeSlice(value.Item1, id.DataType);
  else
- return value.Item1;
+ return null;
+ }
+
+ private static Expression MaybeSlice(Expression exp, DataType dt)
+ {
+ var wantedBitsize = dt.BitSize;
+ if (exp.DataType.BitSize > wantedBitsize)
+ {
+ exp = new Slice(dt, exp, 0);
+ }
+ return exp;
  }
 
  public BitRange GetBitRange(Identifier id)

diff --git a/src/Decompiler/Evaluation/DistributedConversionRule.cs b/src/Decompiler/Evaluation/DistributedConversionRule.cs
@@ -18,15 +18,8 @@
  */
 #endregion
 
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-using Reko.Core;
 using Reko.Core.Expressions;
 using Reko.Core.Operators;
-using Reko.Core.Types;
 
 namespace Reko.Evaluation
 {
@@ -54,7 +47,7 @@ public DistributedConversionRule()
  return new Conversion(
  new BinaryExpression(op, dt, eLeft, eRight),
  dtSrc,
- dt);
+ cLeft.DataType);
  }
  }
  }

diff --git a/src/UnitTests/Decompiler/Analysis/TrashedRegisterFinderTests.cs b/src/UnitTests/Decompiler/Analysis/TrashedRegisterFinderTests.cs
@@ -915,6 +915,29 @@ public void TrfLoop()
  RunTest();
  }
 
+ [Test]
+ public void TrfSliceNeeded()
+ {
+ var arch = new Reko.Arch.X86.X86ArchitectureFlat32(new ServiceContainer(), "x86-protected-32", new Dictionary<string, object>());
+ Given_Architecture(arch);
+
+ Expect(
+ "TrfSliceNeeded",
+ "Preserved: ",
+ "Trashed: rax",
+ "");
 
+ builder.Add(nameof(TrfSliceNeeded), m =>
+ {
+ var rax = m.Frame.EnsureRegister(arch.GetRegister("rax"));
+ var eax = m.Frame.EnsureRegister(arch.GetRegister("eax"));
+ var fp = m.Frame.FramePointer;
+ m.MStore(m.IAddS(fp, 30), rax);
+ m.Assign(eax, m.Mem32(m.IAddS(fp, 30)));
+ m.Assign(rax, m.Convert(eax, PrimitiveType.Word32, PrimitiveType.UInt64));
+ m.Return();
+ });
+ RunTest();
+ }
  }
 }
diff --git a/src/UnitTests/Decompiler/Evaluation/ExpressionSimplifierTests.cs b/src/UnitTests/Decompiler/Evaluation/ExpressionSimplifierTests.cs
@@ -1328,5 +1328,25 @@ public void Exs_SliceMemPtrIdPlusIntConst()
 
  Assert.AreEqual("Mem0[id_3 + 2<32>:word32]", exp.ToString());
  }
+
+ [Test]
+ public void Exs_DistributedConversion()
+ {
+ Given_ExpressionSimplifier();
+ var rax_6 = Given_Tmp("id", PrimitiveType.Ptr64);
+ Expression exp =
+ m.IAdd(
+ m.Convert(
+ m.Mem16(m.IAddS(rax_6, 14)),
+ PrimitiveType.Word16,
+ PrimitiveType.Word32),
+ m.Convert(
+ m.Mem16(m.IAddS(rax_6, 12)),
+ PrimitiveType.Word16,
+ PrimitiveType.Word32));
+ exp = RunExpressionSimplifier(exp);
+
+ Assert.AreEqual("CONVERT(Mem0[id_3 + 14<i64>:word16] + Mem0[id_3 + 12<i64>:word16], word16, word32)", exp.ToString());
+ }
  }
 }