Add support for string constructors to the interpreter #115914

kg · 2025-05-22T22:26:28Z

Updates the compiler to identify NEWOBJ opcodes that are operating on string or multidim arrays, and generates a different specialized newobj opcode for them.
Updates the callstub generator to know how to generate the appropriate type of stub for those constructors.
Adds a specialized newobj opcode for strings and md arrays (md arrays not actually implemented in this PR.)
Modifies InvokeCompiledMethod to accept the code address from outside.

Copilot

Pull Request Overview

This PR adds support for string constructors in the interpreter and updates the associated call stub generation.

Added a new test case (TestStringCtor) to verify string constructor functionality
Updated interpreter execution logic to correctly handle fcalls for string constructors
Adjusted call stub generation to account for special string constructors

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
src/tests/JIT/interpreter/Interpreter.cs	Added test method for string constructor support
src/coreclr/vm/interpexec.cpp	Updated interpreter method call to support special string constructors
src/coreclr/vm/callstubgenerator.cpp	Modified call stub generation for special constructor handling

Copilot · 2025-05-22T22:26:59Z

src/coreclr/vm/interpexec.cpp

@@ -1186,15 +1186,46 @@ void InterpExecMethod(InterpreterFrame *pInterpreterFrame, InterpMethodContextFr
                    callArgsOffset = ip[2];
                    methodSlot = ip[3];

-                    OBJECTREF objRef = AllocateObject((MethodTable*)pMethod->pDataItems[ip[4]]);
+                    MethodTable *pClass = (MethodTable*)pMethod->pDataItems[ip[4]];
+                    // FIXME: Duplicated code from CALL_INTERP_SLOT


Consider refactoring the duplicated code block for handling string constructor invocations to improve maintainability.

Suggested change

// FIXME: Duplicated code from CALL_INTERP_SLOT

src/coreclr/vm/callstubgenerator.cpp

dotnet-policy-service · 2025-05-22T22:27:11Z

Tagging subscribers to this area: @dotnet/interop-contrib
See info in area-owners.md if you want to be subscribed.

src/coreclr/vm/callstubgenerator.cpp

Co-authored-by: Aaron Robinson <[email protected]>

kg · 2025-05-23T00:06:30Z

Anyone know what's up with this crossdac failure on CI?

  [458/464] Linking CXX static library unwinder\unwinder_dac.lib
  [459/464] Building RC object dlls\mscordbi\CMakeFiles\mscordbi.dir\Native.rc.res
  [460/464] Building C object D:\a\_work\1\s\artifacts\obj\external\libunwind\CMakeFiles\libunwind_xdac.dir\D_\a\_work\1\s\src\native\external\libunwind\src\dwarf\Gparser.c.obj
  FAILED: D:/a/_work/1/s/artifacts/obj/external/libunwind/CMakeFiles/libunwind_xdac.dir/D_/a/_work/1/s/src/native/external/libunwind/src/dwarf/Gparser.c.obj 
  C:\PROGRA~1\MICROS~1\2022\ENTERP~1\VC\Tools\MSVC\1443~1.348\bin\Hostx64\x64\cl.exe  /nologo -DBUILDENV_CHECKED=1 -DCROSS_COMPILE -DDEBUG -DDISABLE_CONTRACTS -DHAVE_CONFIG_H=1 -DHAVE_DL_ITERATE_PHDR=1 -DHAVE_UNW_GET_ACCESSORS -DHAVE___THREAD=0 -DHOST_64BIT -DHOST_AMD64 -DHOST_WINDOWS -DPACKAGE_BUGREPORT=\"\" -DPACKAGE_STRING=\"\" -DTARGET_64BIT -DTARGET_AMD64 -DTARGET_LINUX -DTARGET_UNIX -DUNW_REMOTE_ONLY -DURTBLDENV_FRIENDLY=Checked -D_CRT_DECLARE_NONSTDC_NAMES -D_CRT_SECURE_NO_WARNINGS -D_DBG -D_DEBUG -D_FILE_OFFSET_BITS=64 -D_GNU_SOURCE -D_TIME_BITS=64 -D_Thread_local="" -D__amd64__ -D__linux__ -D__x86_64__ -ID:\a\_work\1\s\artifacts\obj\external\libunwind -ID:\a\_work\1\s\src\native\external\libunwind_extras -ID:\a\_work\1\s\src\native -ID:\a\_work\1\s\src\native\inc -ID:\a\_work\1\s\src\native\external\libunwind\include\tdep -ID:\a\_work\1\s\src\native\external\libunwind\include -ID:\a\_work\1\s\artifacts\obj\external\libunwind\include\tdep -ID:\a\_work\1\s\artifacts\obj\external\libunwind\include -ID:\a\_work\1\s\src\native\external\libunwind\include\remote -ID:\a\_work\1\s\src\native\external\libunwind\include\remote\win -ID:\a\_work\1\s\src\native\external\libunwind\src /DWIN32 /D_WINDOWS -std:c11 -MTd /O2 /nologo /W4 /WX /Oi /Oy- /Gm- /Zp8 /Gy /GS /fp:precise /FC /MP /Zm200 /Zc:strictStrings /Zc:wchar_t /Zc:inline /Zc:forScope /wd4065 /wd4100 /wd4127 /wd4131 /wd4189 /wd4200 /wd4201 /wd4206 /wd4239 /wd4245 /wd4291 /wd4310 /wd4324 /wd4366 /wd4456 /wd4457 /wd4458 /wd4459 /wd4463 /wd4505 /wd4702 /wd4706 /wd4733 /wd4815 /wd4838 /wd4918 /wd4960 /wd4961 /wd5105 /wd5205 /we4007 /we4013 /we4102 /we4551 /we4640 /we4806 /we4055 /we4146 /we4242 /we4244 /we4267 /we4302 /we4308 /we4509 /we4510 /we4532 /we4533 /we4610 /we4611 /we4700 /we4701 /we4703 /we4789 /we4995 /we4996 /w34092 /w34121 /w34125 /w34130 /w34132 /w34212 /w34530 /w35038 /w44177 /Zi /ZH:SHA_256 /source-charset:utf-8 /guard:cf /guard:ehcont /permissive- -wd4068 -wd4334 -wd4311 -wd4475 -wd4477 /TC /showIncludes /FoD:\a\_work\1\s\artifacts\obj\external\libunwind\CMakeFiles\libunwind_xdac.dir\D_\a\_work\1\s\src\native\external\libunwind\src\dwarf\Gparser.c.obj /FdD:\a\_work\1\s\artifacts\obj\external\libunwind\CMakeFiles\libunwind_xdac.dir\ /FS -c D:\a\_work\1\s\src\native\external\libunwind\src\dwarf\Gparser.c
  D:\a\_work\1\s\src\native\external\libunwind\src\dwarf\Gparser.c(1181): fatal error C1090: PDB API call failed, error code '23': (0x00000005)
  [461/464] Building CXX object dlls\mscordbi\CMakeFiles\mscordbi.dir\mscordbi.cpp.obj
  ninja: build stopped: subcommand failed.
##[error]BUILD: Error: native component build failed. Refer to the build log files for details.

EDIT: Looks like https://developercommunity.visualstudio.com/t/C1090-PDB-API-call-failed-error-code-2/48897

jkotas · 2025-05-23T00:19:04Z

Also tracked here: #48070 . Build analysis should flag it for you.

jkotas · 2025-05-23T00:55:36Z

src/coreclr/vm/interpexec.cpp

+                    //  fcall that is basically a static method that returns the new instance.
+                    if (pMD && pClass->HasComponentSize())
+                    {
+                        // The compiler didn't know about this so it reserved space for a this-reference. We need to skip


This sounds like a temporary workaround. The compiler can know about this (by checking CORINFO_FLG_VAROBJSIZE flag). What needs to happen to move this logic to the compiler?

m_compHnd didn't appear to expose the things I needed to determine this. I can take another look.

That's the flag CORINFO_FLG_VAROBJSIZE that @jkotas mentioned offline yesterday:

runtime/src/coreclr/jit/importercalls.cpp

Lines 1010 to 1026 in fc85a87

if (opcode == CEE_NEWOBJ)

{

if (clsFlags & CORINFO_FLG_VAROBJSIZE)

{

assert(!(clsFlags & CORINFO_FLG_ARRAY)); // arrays handled separately

// This is a 'new' of a variable sized object, wher

// the constructor is to return the object. In this case

// the constructor claims to return VOID but we know it

// actually returns the new object

assert(callRetTyp == TYP_VOID);

callRetTyp = TYP_REF;

call->gtType = TYP_REF;

impSpillSpecialSideEff();

impPushOnStack(call, typeInfo(clsHnd));

}

else

You can get it by getClassAttribs or by the getCallInfo in the CORINFO_CALL_INFO::classFlags.

Fixing this on the compiler side complicates it a lot. Could we just keep the extra slot allocation we ignore?

Updated. 0298d2e
Not sure how I feel about it.

src/coreclr/vm/callstubgenerator.cpp

src/coreclr/vm/interpexec.cpp

BrzVlad · 2025-05-27T16:51:32Z

src/coreclr/vm/interpexec.cpp

+                    callArgsOffset = ip[2];
+                    methodSlot = ip[3];
+
+                    // FIXME: Duplicated code from CALL_INTERP_SLOT


I don't really understand why this opcode is not a normal call like the others. Could we avoid having this code duplication here ?

generating the call and getting everything to work right given the way we do the tagged method pointer and then cache the call target looked like a pain.

right now we rely on being able to cache the call target and then use CodeInfo to figure out whether it is interp code or jit code. the helpers for this are a third category so we would need another different tag for them or would need to generate a generic helper opcode.

if we're not ok with a special opcode for arrays and strings i can figure something out, but i don't know how long it will take

md arrays make it worse because you have to do a weird thing to adapt the array of dimensions to its actual call signature, so that one would need additional setup opcodes before a regular call. you can see that in the mdarray draft, look for an array called dims

Add support for string constructors to the interpreter

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Copilot AI review requested due to automatic review settings May 22, 2025 22:26

kg requested review from BrzVlad and janvorli as code owners May 22, 2025 22:26

github-actions bot added the area-Interop-coreclr label May 22, 2025

dotnet-policy-service bot assigned kg May 22, 2025

Copilot AI reviewed May 22, 2025

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AaronRobinsonMSFT reviewed May 22, 2025

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Update src/coreclr/vm/callstubgenerator.cpp

ad311ac

Co-authored-by: Aaron Robinson <[email protected]>

kg mentioned this pull request May 22, 2025

Add multi-dim array support to the interpreter #115916

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jkotas reviewed May 23, 2025

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janvorli reviewed May 23, 2025

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BrzVlad reviewed May 23, 2025

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src/coreclr/vm/interpexec.cpp Show resolved Hide resolved

kg added 3 commits May 23, 2025 07:19

Update isSpecialConstructor to match other parts of the runtime

b040e0d

Migrate some string/array ctor smarts from interpexec to compiler

0298d2e

Separate newobj opcode for string and mdarray

e1e5efd

BrzVlad reviewed May 27, 2025

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Add support for string constructors to the interpreter #115914

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kg commented May 22, 2025 •

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	if (opcode == CEE_NEWOBJ)
	{
	if (clsFlags & CORINFO_FLG_VAROBJSIZE)
	{
	assert(!(clsFlags & CORINFO_FLG_ARRAY)); // arrays handled separately
	// This is a 'new' of a variable sized object, wher
	// the constructor is to return the object. In this case
	// the constructor claims to return VOID but we know it
	// actually returns the new object
	assert(callRetTyp == TYP_VOID);
	callRetTyp = TYP_REF;
	call->gtType = TYP_REF;
	impSpillSpecialSideEff();

	impPushOnStack(call, typeInfo(clsHnd));
	}
	else

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kg commented May 22, 2025 •

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