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translator/tests/Translator.Tests/StackAddressFactsTests.cs

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+using Translator.Core.Analysis;
+using Translator.Core.Ir;
+
+namespace Translator.Tests;
+
+public sealed class StackAddressFactsTests
+{
+    [Fact]
+    public void TracksFramePointerCopiesAndSubtractions()
+    {
+        var function = new IrFunction("stack_facts", "entry", new[]
+        {
+            new IrBasicBlock("entry", new IrInstruction[]
+            {
+                new IrBinary("r11", IrValue.Register("r1"), IrValue.Imm(64), "add"),
+                new IrAssign("save_area", IrValue.Register("r11")),
+                new IrBinary("slot", IrValue.Register("save_area"), IrValue.Imm(8), "sub")
+            })
+        });
+
+        var facts = StackAddressFacts.Build(function);
+
+        Assert.True(facts.TryResolve(new IrAddress("r11", -28), out var frameOffset));
+        Assert.Equal(36, frameOffset);
+        Assert.True(facts.TryResolve(new IrAddress("slot", 0), out var slotOffset));
+        Assert.Equal(56, slotOffset);
+        Assert.True(facts.ContainsTemporary("r11"));
+        Assert.True(facts.ContainsTemporary("save_area"));
+    }
+
+    [Fact]
+    public void TreatsEveryR1VersionAsTheCurrentStackRoot()
+    {
+        var facts = StackAddressFacts.Build(new IrFunction("r1_versions", "entry", new[]
+        {
+            new IrBasicBlock("entry", new IrInstruction[]
+            {
+                new IrAssign("r1_7", IrValue.Register("r4"))
+            })
+        }));
+
+        Assert.True(facts.TryResolve(new IrAddress("r1_7", 12), out var offset));
+        Assert.Equal(12, offset);
+    }
+
+    [Fact]
+    public void DoesNotAddCfgOrCommutedExpressionSemantics()
+    {
+        var facts = StackAddressFacts.Build(new IrFunction("simple_only", "entry", new[]
+        {
+            new IrBasicBlock("entry", new IrInstruction[]
+            {
+                new IrBinary("commuted", IrValue.Imm(8), IrValue.Register("r1"), "add"),
+                new IrPhi("joined", new Dictionary<string, string>
+                {
+                    ["entry"] = "r1",
+                    ["other"] = "r1"
+                })
+            })
+        }));
+
+        Assert.False(facts.ContainsTemporary("commuted"));
+        Assert.False(facts.ContainsTemporary("joined"));
+        Assert.False(facts.TryResolve(new IrAddress("commuted", 0), out _));
+    }
+}