[mono] Intrinsify API's in SpanHelpers.ByteMemOps.cs

[fanyang-mono]

Two new API's were added and intrinsified by CoreCLR. They are used in the library which caused Performance regression in Mono. See dotnet/perf-autofiling-issues#29872. These new API's were added via #98623

The API's to intrinsify are

• SpanHelpers.Memmove -> Update existing intrinsics support for Buffer.Memmove. See the code below
  

  runtime/src/mono/mono/mini/intrinsics.c

  Lines 288 to 310 in fd48b6f

  	if (in_corlib && !strcmp (m_class_get_name (cmethod->klass), "Buffer")) {
  	if (!strcmp (cmethod->name, "Memmove") && fsig->param_count == 3 && m_type_is_byref (fsig->params [0]) && m_type_is_byref (fsig->params [1]) && !cmethod->is_inflated) {
  	MonoBasicBlock *end_bb;
  	NEW_BBLOCK (cfg, end_bb);
  	// do nothing if len == 0 (even if src or dst are nulls)
  	MONO_EMIT_NEW_BIALU_IMM (cfg, OP_COMPARE_IMM, -1, args [2]->dreg, 0);
  	MONO_EMIT_NEW_BRANCH_BLOCK (cfg, OP_IBEQ, end_bb);
  	// throw NRE if src or dst are nulls
  	MONO_EMIT_NEW_BIALU_IMM (cfg, OP_COMPARE_IMM, -1, args [0]->dreg, 0);
  	MONO_EMIT_NEW_COND_EXC (cfg, EQ, "NullReferenceException");
  	MONO_EMIT_NEW_BIALU_IMM (cfg, OP_COMPARE_IMM, -1, args [1]->dreg, 0);
  	MONO_EMIT_NEW_COND_EXC (cfg, EQ, "NullReferenceException");
  	MONO_INST_NEW (cfg, ins, OP_MEMMOVE);
  	ins->sreg1 = args [0]->dreg; // i1* dst
  	ins->sreg2 = args [1]->dreg; // i1* src
  	ins->sreg3 = args [2]->dreg; // i32/i64 len
  	MONO_ADD_INS (cfg->cbb, ins);
  	MONO_START_BB (cfg, end_bb);
  	}
  	}

• SpanHelpers.ClearWithoutReferences
• SpanHelpers.Fill

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Issue Details

---

Two new API's were added and intrinsified by CoreCLR. They are used in the library which caused Performance regression in Mono. See dotnet/perf-autofiling-issues#29872. These new API's were added via #98623

The API's to intrinsify are

• SpanHelpers.Memmove -> Update existing intrinsics support for Buffer.Memmove. See the code below
  

  runtime/src/mono/mono/mini/intrinsics.c

  Lines 288 to 310 in fd48b6f

  	if (in_corlib && !strcmp (m_class_get_name (cmethod->klass), "Buffer")) {
  	if (!strcmp (cmethod->name, "Memmove") && fsig->param_count == 3 && m_type_is_byref (fsig->params [0]) && m_type_is_byref (fsig->params [1]) && !cmethod->is_inflated) {
  	MonoBasicBlock *end_bb;
  	NEW_BBLOCK (cfg, end_bb);
  	// do nothing if len == 0 (even if src or dst are nulls)
  	MONO_EMIT_NEW_BIALU_IMM (cfg, OP_COMPARE_IMM, -1, args [2]->dreg, 0);
  	MONO_EMIT_NEW_BRANCH_BLOCK (cfg, OP_IBEQ, end_bb);
  	// throw NRE if src or dst are nulls
  	MONO_EMIT_NEW_BIALU_IMM (cfg, OP_COMPARE_IMM, -1, args [0]->dreg, 0);
  	MONO_EMIT_NEW_COND_EXC (cfg, EQ, "NullReferenceException");
  	MONO_EMIT_NEW_BIALU_IMM (cfg, OP_COMPARE_IMM, -1, args [1]->dreg, 0);
  	MONO_EMIT_NEW_COND_EXC (cfg, EQ, "NullReferenceException");
  	MONO_INST_NEW (cfg, ins, OP_MEMMOVE);
  	ins->sreg1 = args [0]->dreg; // i1* dst
  	ins->sreg2 = args [1]->dreg; // i1* src
  	ins->sreg3 = args [2]->dreg; // i32/i64 len
  	MONO_ADD_INS (cfg->cbb, ins);
  	MONO_START_BB (cfg, end_bb);
  	}
  	}

• SpanHelpers.ClearWithoutReferences

Author:	fanyang-mono
Assignees:	-
Labels:	area-Codegen-Intrinsics-mono
Milestone:	9.0.0

[lewing]

This is one of the regressions in dotnet/perf-autofiling-issues#30686 so it is potentially quite impactful on wasm
cc @steveisok

[lewing]

dotnet/perf-autofiling-issues#30686 (comment)

[lewing]

cc @EgorBo @JulieLeeMSFT

[EgorBo]

cc @EgorBo @JulieLeeMSFT

It was decided that it should be handled on Mono side #99059

[lewing]

cc @EgorBo @JulieLeeMSFT

It was decided that it should be handled on Mono side #99059

Yes, this issue is about fixing it in mono. I pinged you because this is a ship blocking regression for wasm and I wanted to make sure that was clear.

[lewing]

It is probably worth understanding why the other mono-AOT-llvm runtimes were not impacted in the same way.

[lewing]

Iinterpreter changes were added in #99115