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X86 Debug Stack offsets are encoded divided by 4 #58070

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Merged
davidwrighton merged 1 commit into from
Aug 25, 2021
Merged

X86 Debug Stack offsets are encoded divided by 4 #58070

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2 changes: 1 addition & 1 deletion src/coreclr/tools/Common/JitInterface/CorInfoImpl.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -392,7 +392,7 @@ private void PublishCode()
_methodCodeNode.InitializeEHInfo(ehInfo);

_methodCodeNode.InitializeDebugLocInfos(_debugLocInfos);
_methodCodeNode.InitializeDebugVarInfos(_debugVarInfos);
_methodCodeNode.InitializeDebugVarInfos(_debugVarInfos, _compilation.TypeSystemContext.Target);
#if READYTORUN
_methodCodeNode.InitializeInliningInfo(_inlinedMethods.ToArray());

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26 changes: 21 additions & 5 deletions ...ls/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRun/DebugInfoTableNode.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;

using Internal.JitInterface;
Expand Down Expand Up @@ -149,11 +150,13 @@ public static byte[] CreateBoundsBlobForMethod(OffsetMapping[] offsetMapping)
return writer.ToArray();
}

public static byte[] CreateVarBlobForMethod(NativeVarInfo[] varInfos)
public static byte[] CreateVarBlobForMethod(NativeVarInfo[] varInfos, TargetDetails target)
{
if (varInfos == null || varInfos.Length == 0)
return null;

bool isX86 = target.Architecture == TargetArchitecture.X86;

NibbleWriter writer = new NibbleWriter();
writer.WriteUInt((uint)varInfos.Length);

Expand All @@ -177,7 +180,7 @@ public static byte[] CreateVarBlobForMethod(NativeVarInfo[] varInfos)
case VarLocType.VLT_STK:
case VarLocType.VLT_STK_BYREF:
writer.WriteUInt((uint)nativeVarInfo.varLoc.B);
writer.WriteInt(nativeVarInfo.varLoc.C);
WriteEncodedStackOffset(writer, nativeVarInfo.varLoc.C, assume4ByteAligned : isX86);
break;
case VarLocType.VLT_REG_REG:
writer.WriteUInt((uint)nativeVarInfo.varLoc.B);
Expand All @@ -186,16 +189,16 @@ public static byte[] CreateVarBlobForMethod(NativeVarInfo[] varInfos)
case VarLocType.VLT_REG_STK:
writer.WriteUInt((uint)nativeVarInfo.varLoc.B);
writer.WriteUInt((uint)nativeVarInfo.varLoc.C);
writer.WriteInt(nativeVarInfo.varLoc.D);
WriteEncodedStackOffset(writer, nativeVarInfo.varLoc.D, assume4ByteAligned : isX86);
break;
case VarLocType.VLT_STK_REG:
writer.WriteInt(nativeVarInfo.varLoc.B);
WriteEncodedStackOffset(writer, nativeVarInfo.varLoc.B, assume4ByteAligned : isX86);
writer.WriteUInt((uint)nativeVarInfo.varLoc.C);
writer.WriteUInt((uint)nativeVarInfo.varLoc.D);
break;
case VarLocType.VLT_STK2:
writer.WriteUInt((uint)nativeVarInfo.varLoc.B);
writer.WriteInt(nativeVarInfo.varLoc.C);
WriteEncodedStackOffset(writer, nativeVarInfo.varLoc.C, assume4ByteAligned : isX86);
break;
case VarLocType.VLT_FPSTK:
writer.WriteUInt((uint)nativeVarInfo.varLoc.B);
Expand All @@ -206,6 +209,19 @@ public static byte[] CreateVarBlobForMethod(NativeVarInfo[] varInfos)
default:
throw new BadImageFormatException("Unexpected var loc type");
}

static void WriteEncodedStackOffset(NibbleWriter _writer, int offset, bool assume4ByteAligned)
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@trylek trylek Aug 24, 2021

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Nit - if at some point we considered expanding this behavior to other architectures, the name of the argument (assume4ByteAligned) would probably need to change to e.g. something like encodeUsingPointerSizeUnits or some such. If we believe this to be limited to X86 forever, it's probably OK.

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@davidwrighton davidwrighton Aug 24, 2021

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I just checked to see how valuable this really is, and we could save something like 0.08% of System.Private.CoreLib.dll size if we applied a similar size optimization on X64. I don't see that as worthwhile given the complexity it would impose on the reader in the runtime.

{
if (assume4ByteAligned)
{
Debug.Assert(offset % 4 == 0);
_writer.WriteInt(offset / 4);
}
else
{
_writer.WriteInt(offset);
}
}
}

return writer.ToArray();
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4 changes: 2 additions & 2 deletions ...ools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRun/MethodWithGCInfo.cs
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Expand Up @@ -296,12 +296,12 @@ public void InitializeDebugLocInfos(OffsetMapping[] debugLocInfos)
_debugLocInfos = DebugInfoTableNode.CreateBoundsBlobForMethod(debugLocInfos);
}

public void InitializeDebugVarInfos(NativeVarInfo[] debugVarInfos)
public void InitializeDebugVarInfos(NativeVarInfo[] debugVarInfos, TargetDetails target)
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@MichalStrehovsky MichalStrehovsky Aug 27, 2021

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TargetDetails are available in _method.Context.Target. The additional parameter caused an unnecessary NativeAOT build break.

{
Debug.Assert(_debugVarInfos == null);
// Process the debug info from JIT format to R2R format immediately as it is large
// and not used in the rest of the process except to emit.
_debugVarInfos = DebugInfoTableNode.CreateVarBlobForMethod(debugVarInfos);
_debugVarInfos = DebugInfoTableNode.CreateVarBlobForMethod(debugVarInfos, target);
}

public void InitializeDebugEHClauseInfos(DebugEHClauseInfo[] debugEHClauseInfos)
Expand Down