Replace FEATURE_EH_FUNCLETS in JIT with runtime switch #99191

filipnavara · 2024-03-02T16:50:51Z

Everything but win-x86 already had FEATURE_EH_FUNCLETS defined unconditionally. For win-x86 there's a new FEATURE_EH_X86_FRAMES switch defined in targetx86.h (shortcut for TARGET_X86 && !UNIX_X86_ABI). Funclet code is always compiled in and controlled at runtime with Compiler::UsesFunclets(). On win-x86 it's controlled by NativeAOT ABI, everywhere else it's unconditionally true.

ghost · 2024-03-02T16:51:00Z

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Issue Details

Everything but win-x86 already had FEATURE_EH_FUNCLETS defined unconditionally. For win-x86 there's a new FEATURE_EH_X86_FRAMES switch defined in targetx86.h. Funclet code is always compiled in and controlled at runtime with Compiler::UsesFunclets(). On win-x86 it's controlled by NativeAOT ABI, everywhere else it's unconditionally true.

Author:	filipnavara
Assignees:	-
Labels:	`area-CodeGen-coreclr`
Milestone:	-

src/coreclr/jit/compiler.h

filipnavara · 2024-03-02T19:49:07Z

src/coreclr/jit/codegencommon.cpp

@@ -1503,10 +1503,11 @@ void CodeGen::genExitCode(BasicBlock* block)
 void CodeGen::genJumpToThrowHlpBlk(emitJumpKind jumpKind, SpecialCodeKind codeKind, BasicBlock* failBlk)
 {
    bool useThrowHlpBlk = compiler->fgUseThrowHelperBlocks();
-#if defined(UNIX_X86_ABI) && defined(FEATURE_EH_FUNCLETS)
+#if defined(UNIX_X86_ABI)
+    // TODO: Is this really UNIX_X86_ABI specific? Should we guard with compiler->UsesFunclets() instead?


This should be double-checked along with

runtime/src/coreclr/jit/morph.cpp

Lines 14299 to 14304 in ce6cf4b

if (info.compXcptnsCount > 0)

{

assert(!codeGen->isGCTypeFixed());

// Enforce fully interruptible codegen for funclet unwinding

SetInterruptible(true);

}

Is any of that relevant for win-x86 with funclets?

filipnavara · 2024-03-02T19:51:55Z

cc @jakobbotsch @SingleAccretion since you seemed to favor this over having a separate JIT flavor.

jkotas · 2024-03-03T06:44:23Z

Ideally, we would switch win-x86 to the funclet plan and delete !FEATURE_EH_FUNCLETS code everywhere. @janvorli Have you thought about what it would take?

jakobbotsch · 2024-03-04T09:04:13Z

It would be good to check where the throughput cost is coming from (perhaps some of the new runtime funclet checks can be hoisted out).

jakobbotsch · 2024-03-04T09:05:18Z

cc @dotnet/jit-contrib

janvorli · 2024-03-04T19:52:11Z

Ideally, we would switch win-x86 to the funclet plan and delete !FEATURE_EH_FUNCLETS code everywhere. @janvorli Have you thought about what it would take?

The original plan was to leave the win x86 on the old plan and not to spend time porting that to the new EH. Is there a reason for modernizing this almost obsolete platform?

jkotas · 2024-03-04T20:11:05Z

Windows x86 support is here to stay for many years. The reason for switching over to the unified model would be code base simplification. We keep spending time on dealing with the difference, as this PR demonstrates.

@filipnavara has been working on enabling native AOT for Windows x86 that uses the funclet model. Our testing strategy for native AOT assumes that the codegen differences are kept to absolute minimum. Switching regular Windows x86 to the funclet model would help with that.

jakobbotsch · 2024-03-06T15:38:48Z

I checked the methods that are contributing to the TP regression in Tier0 for benchmarks.run_pgo. The breakdown looks like:

Base: 17457576750, Diff: 17528444068, +0.4059%

20569264  : +6.76%   : 17.35% : +0.1178% : public: unsigned int __thiscall emitter::emitOutputInstr(struct insGroup *, struct emitter::instrDesc *, unsigned char **)                                                                     
14592023  : NA       : 12.31% : +0.0836% : private: struct insGroup * __thiscall emitter::emitAllocIG(void)                                                                                                                               
14141188  : NA       : 11.93% : +0.0810% : public: void __thiscall CodeGen::siOpenScopesForNonTrackedVars(struct BasicBlock const *, unsigned int)                                                                                        
7645212   : NA       : 6.45%  : +0.0438% : public: void __thiscall emitter::emitBegFN(bool)                                                                                                                                               
3468762   : +5.70%   : 2.93%  : +0.0199% : public: unsigned int __thiscall GCInfo::gcMakeRegPtrTable(unsigned char *, int, struct InfoHdr const &, unsigned int, unsigned int *)                                                          
3332472   : NA       : 2.81%  : +0.0191% : public: bool __thiscall Compiler::UsesFunclets(void)                                                                                                                                           
3085243   : +40.50%  : 2.60%  : +0.0177% : public: void __thiscall emitter::emitCreatePlaceholderIG(enum insGroupPlaceholderType, struct BasicBlock *, unsigned int *const &, unsigned int, unsigned int, bool)                           
2923051   : +24.12%  : 2.47%  : +0.0167% : public: void __thiscall GCInfo::gcCountForHeader(unsigned int *, unsigned int *)                                                                                                               
2415660   : +3.65%   : 2.04%  : +0.0138% : protected: void __thiscall CodeGen::genCall(struct GenTreeCall *)                                                                                                                              
2128950   : +147.06% : 1.80%  : +0.0122% : private: void __thiscall emitter::emitNxtIG(bool)                                                                                                                                              
1950494   : +4.12%   : 1.65%  : +0.0112% : private: unsigned int __thiscall GCInfo::gcInfoBlockHdrSave(unsigned char *, int, unsigned int, unsigned int, unsigned int, struct InfoHdr *, int *)                                           
1760517   : NA       : 1.48%  : +0.0101% : public: void __thiscall Compiler::funSetCurrentFunc(unsigned int)                                                                                                                              
1701900   : +14.19%  : 1.44%  : +0.0097% : private: void * __thiscall emitter::emitAddLabel(unsigned int *const &, unsigned int, unsigned int)                                                                                            
1597287   : +2.00%   : 1.35%  : +0.0091% : private: void __thiscall LinearScan::setBlockSequence(void)                                                                                                                                    
1414600   : NA       : 1.19%  : +0.0081% : public: struct FuncInfoDsc * __thiscall Compiler::funCurrentFunc(void)                                                                                                                         
1332289   : +3.57%   : 1.12%  : +0.0076% : public: void __thiscall Compiler::lvaAssignVirtualFrameOffsetsToLocals(void)                                                                                                                   
1253994   : +39.81%  : 1.06%  : +0.0072% : public: enum PhaseStatus __thiscall Compiler::lvaMarkLocalVars(void)                                                                                                                           
1060950   : +22.73%  : 0.89%  : +0.0061% : public: void __thiscall CodeGen::genEmitMachineCode(void)                                                                                                                                      
1057289   : +5.74%   : 0.89%  : +0.0061% : public: void __thiscall CodeGen::genEmitUnwindDebugGCandEH(void)                                                                                                                               
979839    : NA       : 0.83%  : +0.0056% : protected: void __thiscall Compiler::impImportLeaveEHRegions(struct BasicBlock *)                                                                                                              
926607    : +1.81%   : 0.78%  : +0.0053% : protected: void __thiscall CodeGen::genFnProlog(void)                                                                                                                                          
919488    : +12.16%  : 0.78%  : +0.0053% : public: void __thiscall emitter::emitGeneratePrologEpilog(void)                                                                                                                                
535926    : +8.21%   : 0.45%  : +0.0031% : protected: void __thiscall CodeGen::genExitCode(struct BasicBlock *)                                                                                                                           
512478    : NA       : 0.43%  : +0.0029% : public: unsigned int __thiscall Compiler::bbThrowIndex(struct BasicBlock *)                                                                                                                    
391775    : +0.28%   : 0.33%  : +0.0022% : public: unsigned int __thiscall emitter::emitEndCodeGen(class Compiler *, bool, bool, bool, unsigned int, unsigned int *, unsigned int *, void **, void **, void **, void **, void **, void **)
390696    : +6.24%   : 0.33%  : +0.0022% : public: void __thiscall Compiler::fgFindBasicBlocks(void)                                                                                                                                      
289133    : NA       : 0.24%  : +0.0017% : public: enum PhaseStatus __thiscall Compiler::fgMergeFinallyChains(void)                                                                                                                       
283556    : +0.91%   : 0.24%  : +0.0016% : protected: void __thiscall Compiler::compCompile(void **, unsigned int *, class JitFlags *)                                                                                                    
267951    : +4.55%   : 0.23%  : +0.0015% : public: void __thiscall emitter::emitBegPrologEpilog(struct insGroup *)                                                                                                                        
240221    : +0.98%   : 0.20%  : +0.0014% : protected: void __thiscall CodeGen::genCheckUseBlockInit(void)                                                                                                                                 
218487    : +0.84%   : 0.18%  : +0.0013% : public: void __thiscall Compiler::compInit(class ArenaAllocator *, struct CORINFO_METHOD_STRUCT_*, class ICorJitInfo *, struct CORINFO_METHOD_INFO *, struct InlineInfo *)                     
208706    : +1.19%   : 0.18%  : +0.0012% : protected: void __thiscall CodeGen::genInitialize(void)                                                                                                                                        
182117    : +2.21%   : 0.15%  : +0.0010% : public: enum PhaseStatus __thiscall Compiler::fgAddInternal(void)                                                                                                                              
-141778   : -33.31%  : 0.12%  : -0.0008% : __scrt_stub_for_is_c_termination_complete                                                                                                                                                      
-141848   : -100.00% : 0.12%  : -0.0008% : public: void __thiscall Compiler::fgNormalizeEH(void)                                                                                                                                          
-923488   : -89.05%  : 0.78%  : -0.0053% : protected: void __thiscall Compiler::impImportLeave(struct BasicBlock *)                                                                                                                       
-2406826  : -20.66%  : 2.03%  : -0.0138% : private: void __thiscall emitter::emitGenIG(struct insGroup *)                                                                                                                                 
-2627780  : -1.42%   : 2.22%  : -0.0151% : protected: void __thiscall CodeGen::genCodeForBBlist(void)                                                                                                                                     
-4615901  : -29.00%  : 3.89%  : -0.0264% : public: void __thiscall CodeGen::genGenerateMachineCode(void)                                                                                                                                  
-12943600 : -100.00% : 10.92% : -0.0741% : private: void __thiscall emitter::emitNewIG(void)

A number of cases in the top look like different inlining decisions that we'd expect to change regardless with native PGO.

BruceForstall · 2024-03-06T23:31:16Z

We should update the documentation that states that Windows/x86 does not use funclets: https://github.com/dotnet/runtime/blob/main/docs/design/coreclr/botr/clr-abi.md#funclets

MichalPetryka · 2024-03-07T00:01:42Z

We should update the documentation that states that Windows/x86 does not use funclets: https://github.com/dotnet/runtime/blob/main/docs/design/coreclr/botr/clr-abi.md#funclets

Aren't they still used in CoreCLR? I though this only disabled them for NativeAOT.

BruceForstall · 2024-03-07T00:15:11Z

Aren't they still used in CoreCLR? I though this only disabled them for NativeAOT.

That document covers NativeAOT as well as CoreCLR.

jkotas · 2024-03-11T01:11:33Z

@filipnavara has been working on enabling native AOT for Windows x86 that uses the funclet model. Our testing strategy for native AOT assumes that the codegen differences are kept to absolute minimum. Switching regular Windows x86 to the funclet model would help with that.

I have done a bit of work towards this: https://github.com/jkotas/runtime/tree/x86funclets (compiles, does not work and needs cleanup of NYIs)

src/coreclr/jit/compiler.h

BruceForstall

Can you update this PR to fix the merge conflicts, and so the testing + asmdiffs/TP diffs can run again?

src/coreclr/jit/targetx86.h

src/coreclr/jit/compiler.h

BruceForstall · 2024-03-28T22:28:43Z

src/coreclr/jit/compiler.h

+        return UsesFunclets();
+    }
+#else
+    bool UsesFunclets()


nit

Suggested change

bool UsesFunclets()

static bool UsesFunclets()

This is semi-intentional. The compiler will inline it for non-x86 configurations anyway, so the static doesn't have an effect on the resulting code. The absence of static does, however, prevent it from calling Compiler:: UsesFunclets() by accident and only discovering it when the x86 JIT is built on CI.

BruceForstall · 2024-03-28T22:29:02Z

src/coreclr/jit/compiler.h

+        return true;
+    }
+
+    bool UsesCallfinallyThunks()


nit

Suggested change

bool UsesCallfinallyThunks()

static bool UsesCallFinallyThunks()

Same reason as #99191 (comment)

filipnavara · 2024-03-28T22:53:29Z

Can you update this PR to fix the merge conflicts, and so the testing + asmdiffs/TP diffs can run again?

I'll do it first thing tomorrow morning along with applying your suggestions.

BruceForstall · 2024-03-29T19:52:44Z

Diffs

No asm diffs (expected).

Small TP diffs on all non-x86 platforms, mostly improvements. Surprising there is any change here?

Big TP regressions on x86, especially MinOpts: up to almost 0.5%.

I wonder if this could be significantly improved by changing:

    bool UsesFunclets()
    {
        return IsTargetAbi(CORINFO_NATIVEAOT_ABI);
    }

such that we compute the result early (maybe in compInit?), cache it on Compiler, and then have:

    bool UsesFunclets()
    {
        return eeIsNativeAotAbi;
    }

filipnavara · 2024-03-29T19:59:18Z

The TP diff on x86 are mostly inlining decisions that would like be reduced with a new PGO profile. At least that was the conclusion when @jakobbotsch looked into it. I can try some variations to see if it makes a difference but other unrelated PRs saw similar patterns on small changes.

BruceForstall · 2024-04-05T05:22:01Z

The TP diff on x86 are mostly inlining decisions that would like be reduced with a new PGO profile.

Our superpmi-diffs pipeline disables native PGO (otherwise we'd never get "apples-to-apples" comparison).

I tried the small suggestion I made above here:

#100655

(after rebasing this PR on top of upstream/main, and fixing the conflicts) and it seemed to greatly reduce the x86 TP regression.

… runtime switch

filipnavara · 2024-04-05T08:13:24Z

Thanks for testing it. I did another rebase and cherry-picked your change.

BruceForstall · 2024-04-05T18:42:36Z

Diffs

The notable win-x86 TP diffs:

BruceForstall

LGTM

* Replace FEATURE_EH_FUNCLETS/FEATURE_EH_CALLFINALLY_THUNKS in JIT with runtime switch * Cache Native AOT ABI check to see if TP improves --------- Co-authored-by: Bruce Forstall <brucefo@microsoft.com>

dotnet-issue-labeler bot added the area-CodeGen-coreclr CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI label Mar 2, 2024

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This was referenced Mar 11, 2024

Cleanup ifdefs #99511

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[NativeAot] win-x86: Funclets getting double called #99687

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System.IO.Tests crash in CI (Linux arm64) #100441

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slow macOS - "##[error]The job running on agent Azure Pipelines 9 ran longer than the maximum time of 60 minutes." dotnet/dnceng#1883

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filipnavara and others added 2 commits April 5, 2024 10:12

Replace FEATURE_EH_FUNCLETS/FEATURE_EH_CALLFINALLY_THUNKS in JIT with…

4daf5e1

… runtime switch

Cache Native AOT ABI check to see if TP improves

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filipnavara force-pushed the jit-funclets branch from 7d37a01 to 4671c3c Compare April 5, 2024 08:12

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Checkout failure: "Git fetch failed with exit code 128" dotnet/arcade#9009

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Exclude win_aot JIT binaries from Crossgen2 packages #99157

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Add type-specialized vectorized hash table container #100386

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Replace FEATURE_EH_FUNCLETS in JIT with runtime switch #99191

Replace FEATURE_EH_FUNCLETS in JIT with runtime switch #99191

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	if (info.compXcptnsCount > 0)
	{
	assert(!codeGen->isGCTypeFixed());
	// Enforce fully interruptible codegen for funclet unwinding
	SetInterruptible(true);
	}

	bool UsesCallfinallyThunks()
	static bool UsesCallFinallyThunks()

Replace FEATURE_EH_FUNCLETS in JIT with runtime switch #99191

Replace FEATURE_EH_FUNCLETS in JIT with runtime switch #99191

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