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Enable BCR for kernels with low register pressure
Adding IGCRegisterPressurePublisher pass to make register pressure estimation available in CISABuilder. Enable BCR for kernels with low register pressure.
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8 files changed

+145
-5
lines changed

8 files changed

+145
-5
lines changed

‎IGC/Compiler/CISACodeGen/CISABuilder.cpp‎

Lines changed: 7 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -4042,7 +4042,13 @@ void CEncoder::InitVISABuilderOptions(TARGET_PLATFORM VISAPlatform, bool canAbor
40424042
if (IGC_IS_FLAG_ENABLED(EnableBCR)) {
40434043
SaveOption(vISA_enableBCR, true);
40444044
}
4045-
if (context->type == ShaderType::OPENCL_SHADER && m_program->m_Platform->limitedBCR()) {
4045+
4046+
auto funcInfoMD = context->getMetaDataUtils()->getFunctionsInfoItem(m_program->entry);
4047+
uint32_t MaxRegPressure = funcInfoMD->getMaxRegPressure()->getMaxPressure();
4048+
uint32_t RegPressureThreshold = (uint32_t) (context->getNumGRFPerThread(true) * 0.6);
4049+
4050+
if (context->type == ShaderType::OPENCL_SHADER &&
4051+
(m_program->m_Platform->limitedBCR() || MaxRegPressure < RegPressureThreshold)) {
40464052
SaveOption(vISA_enableBCR, true);
40474053
}
40484054
if (context->type == ShaderType::OPENCL_SHADER && m_program->m_Platform->supportDpasInstruction()) {

‎IGC/Compiler/CISACodeGen/IGCLivenessAnalysis.cpp‎

Lines changed: 38 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -572,3 +572,41 @@ bool IGCRegisterPressurePrinter::runOnFunction(llvm::Function &F) {
572572

573573
return false;
574574
}
575+
576+
577+
char IGCRegisterPressurePublisher::ID = 0;
578+
// Register pass to igc-opt
579+
#define PASS_FLAG3 "igc-pressure-publisher"
580+
#define PASS_DESCRIPTION3 "puts metadata with register pressure estimation"
581+
#define PASS_CFG_ONLY1 false
582+
#define PASS_ANALYSIS1 false
583+
IGC_INITIALIZE_PASS_BEGIN(IGCRegisterPressurePublisher, PASS_FLAG3, PASS_DESCRIPTION3, PASS_CFG_ONLY1, PASS_ANALYSIS1)
584+
IGC_INITIALIZE_PASS_DEPENDENCY(WIAnalysis)
585+
IGC_INITIALIZE_PASS_DEPENDENCY(CodeGenContextWrapper)
586+
IGC_INITIALIZE_PASS_DEPENDENCY(IGCFunctionExternalRegPressureAnalysis)
587+
IGC_INITIALIZE_PASS_DEPENDENCY(IGCLivenessAnalysis)
588+
IGC_INITIALIZE_PASS_END(IGCRegisterPressurePublisher, PASS_FLAG3, PASS_DESCRIPTION3, PASS_CFG_ONLY1, PASS_ANALYSIS1)
589+
590+
IGCRegisterPressurePublisher::IGCRegisterPressurePublisher() : FunctionPass(ID) {
591+
initializeIGCRegisterPressurePublisherPass(*PassRegistry::getPassRegistry());
592+
};
593+
594+
bool IGCRegisterPressurePublisher::runOnFunction(llvm::Function &F) {
595+
596+
ExternalPressure = getAnalysis<IGCFunctionExternalRegPressureAnalysis>().getExternalPressureForFunction(&F);
597+
RPE = &getAnalysis<IGCLivenessAnalysis>();
598+
WI = &getAnalysis<WIAnalysis>();
599+
CGCtx = getAnalysis<CodeGenContextWrapper>().getCodeGenContext();
600+
MaxPressureInFunction = 0;
601+
602+
unsigned int SIMD = numLanes(RPE->bestGuessSIMDSize(&F));
603+
604+
// if we have some published metadata already don't do anything
605+
bool NotPublishedAlready = RPE->checkPublishRegPressureMetadata(F) == 0;
606+
607+
if (NotPublishedAlready) {
608+
MaxPressureInFunction = RPE->getMaxRegCountForFunction(F, SIMD, &WI->Runner);
609+
RPE->publishRegPressureMetadata(F, MaxPressureInFunction + ExternalPressure);
610+
}
611+
return true;
612+
}

‎IGC/Compiler/CISACodeGen/IGCLivenessAnalysis.h‎

Lines changed: 37 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -88,9 +88,19 @@ class IGCLivenessAnalysis : public llvm::FunctionPass, public IGCLivenessAnalysi
8888
if (MDUtils->findFunctionsInfoItem(&F) != MDUtils->end_FunctionsInfo()) {
8989
IGC::IGCMD::FunctionInfoMetaDataHandle funcInfoMD = MDUtils->getFunctionsInfoItem(&F);
9090
funcInfoMD->getMaxRegPressure()->setMaxPressure(MaxPressure);
91+
MDUtils->save(F.getContext());
9192
}
9293
}
9394

95+
unsigned checkPublishRegPressureMetadata(llvm::Function &F) {
96+
unsigned Result = 0;
97+
if (MDUtils->findFunctionsInfoItem(&F) != MDUtils->end_FunctionsInfo()) {
98+
IGC::IGCMD::FunctionInfoMetaDataHandle funcInfoMD = MDUtils->getFunctionsInfoItem(&F);
99+
Result = funcInfoMD->getMaxRegPressure()->getMaxPressure();
100+
}
101+
return Result;
102+
}
103+
94104
unsigned int getMaxRegCountForBB(llvm::BasicBlock &BB, unsigned int SIMD, WIAnalysisRunner *WI = nullptr) {
95105
InsideBlockPressureMap PressureMap;
96106
collectPressureForBB(BB, PressureMap, SIMD, WI);
@@ -269,6 +279,7 @@ class IGCRegisterPressurePrinter : public llvm::FunctionPass {
269279
virtual bool runOnFunction(llvm::Function &F) override;
270280
virtual void getAnalysisUsage(llvm::AnalysisUsage &AU) const override {
271281
AU.setPreservesAll();
282+
AU.addRequired<MetaDataUtilsWrapper>();
272283
AU.addRequired<IGCLivenessAnalysis>();
273284
AU.addRequired<CodeGenContextWrapper>();
274285
AU.addRequired<WIAnalysis>();
@@ -279,4 +290,30 @@ class IGCRegisterPressurePrinter : public llvm::FunctionPass {
279290
static char ID;
280291
};
281292

293+
294+
class IGCRegisterPressurePublisher : public llvm::FunctionPass {
295+
296+
IGCLivenessAnalysis *RPE = nullptr;
297+
WIAnalysis *WI = nullptr;
298+
CodeGenContext *CGCtx = nullptr;
299+
300+
unsigned int ExternalPressure = 0;
301+
unsigned int MaxPressureInFunction = 0;
302+
303+
public:
304+
llvm::StringRef getPassName() const override { return "IGCRegPressurePublisher"; }
305+
virtual ~IGCRegisterPressurePublisher() {}
306+
virtual bool runOnFunction(llvm::Function &F) override;
307+
virtual void getAnalysisUsage(llvm::AnalysisUsage &AU) const override {
308+
AU.setPreservesAll();
309+
AU.addRequired<MetaDataUtilsWrapper>();
310+
AU.addRequired<IGCLivenessAnalysis>();
311+
AU.addRequired<CodeGenContextWrapper>();
312+
AU.addRequired<WIAnalysis>();
313+
AU.addRequired<IGCFunctionExternalRegPressureAnalysis>();
314+
}
315+
IGCRegisterPressurePublisher();
316+
static char ID;
317+
};
318+
282319
}; // namespace IGC

‎IGC/Compiler/CISACodeGen/ShaderCodeGen.cpp‎

Lines changed: 6 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -365,6 +365,12 @@ void AddAnalysisPasses(CodeGenContext &ctx, IGCPassManager &mpm) {
365365
mpm.add(createCleanPHINodePass());
366366
if (IGC_IS_FLAG_SET(DumpRegPressureEstimate))
367367
mpm.add(new IGCRegisterPressurePrinter("final"));
368+
369+
// save RPE results in metadata
370+
if (ctx.type == ShaderType::OPENCL_SHADER) {
371+
mpm.add(new IGCRegisterPressurePublisher());
372+
}
373+
368374
// Let Layout be the last pass before Emit Pass
369375
mpm.add(new Layout());
370376
if(IGC_IS_FLAG_ENABLED(EnableDropTargetBBs)) {

‎IGC/Compiler/InitializePasses.h‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -270,6 +270,7 @@ void initializeRematChainsAnalysisPass(llvm::PassRegistry &);
270270
void initializeVectorShuffleAnalysisPass(llvm::PassRegistry &);
271271
void initializeIGCLivenessAnalysisPass(llvm::PassRegistry &);
272272
void initializeIGCRegisterPressurePrinterPass(llvm::PassRegistry &);
273+
void initializeIGCRegisterPressurePublisherPass(llvm::PassRegistry &);
273274
void initializeIGCVectorizerPass(llvm::PassRegistry &);
274275
void initializeIGCFunctionExternalRegPressureAnalysisPass(llvm::PassRegistry &);
275276
void initializePromoteConstantStructsPass(llvm::PassRegistry &);

‎IGC/Compiler/MetaDataApi/MetaDataApi.cpp‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -306,7 +306,7 @@ FunctionInfoMetaData::FunctionInfoMetaData(const llvm::MDNode *pNode, bool hasId
306306
m_ThreadGroupSize(new ThreadGroupSizeMetaData(getNamedNode(pNode, "thread_group_size"), true)),
307307
m_ThreadGroupSizeHint(new ThreadGroupSizeMetaData(getNamedNode(pNode, "thread_group_size_hint"), true)),
308308
m_SubGroupSize(new SubGroupSizeMetaData(getNamedNode(pNode, "sub_group_size"), true)),
309-
m_MaxRegPressure(new MaxRegPressureMetaData(getNamedNode(pNode, "max_reg_pressure"), true)),
309+
m_MaxRegPressure(new MaxRegPressureMetaDataHandle::ObjectType("max_reg_pressure")),
310310
m_OpenCLVectorTypeHint(new VectorTypeHintMetaData(getNamedNode(pNode, "opencl_vec_type_hint"), true)),
311311
m_pNode(pNode) {}
312312

‎IGC/Compiler/tests/RegPressureEstimator/RegisterPressurePublisher.ll‎

Lines changed: 52 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,52 @@
1+
;=========================== begin_copyright_notice ============================
2+
;
3+
; Copyright (C) 2025 Intel Corporation
4+
;
5+
; SPDX-License-Identifier: MIT
6+
;
7+
;============================ end_copyright_notice =============================
8+
9+
; REQUIRES: llvm-14-plus, regkeys
10+
; RUN: igc_opt --opaque-pointers -igc-pressure-publisher -S %s | FileCheck %s
11+
; RUN: igc_opt --typed-pointers -igc-pressure-publisher -S %s | FileCheck %s
12+
13+
; Test checks that RegisterPressurePublisher writes max_reg_pressure in metadata
14+
15+
; CHECK: "max_reg_pressure", i32 {{[0-9]+}}
16+
17+
define spir_kernel void @testNoUnif(float addrspace(1)* %out, float addrspace(1)* %in, <8 x i32> %r0, <8 x i32> %payloadHeader, <3 x i32> %localSize, i16 %localIdX, i16 %localIdY, i16 %localIdZ, i32 %bufferOffset, i32 %bufferOffset1) {
18+
entry:
19+
%0 = extractelement <3 x i32> %localSize, i64 0
20+
%1 = extractelement <3 x i32> %localSize, i64 1
21+
%localIdZ2 = zext i16 %localIdZ to i32
22+
%mul.i.i = mul i32 %1, %localIdZ2
23+
%localIdY4 = zext i16 %localIdY to i32
24+
%add.i.i = add i32 %mul.i.i, %localIdY4
25+
%mul4.i.i = mul i32 %0, %add.i.i
26+
%localIdX6 = zext i16 %localIdX to i32
27+
%add6.i.i = add i32 %mul4.i.i, %localIdX6
28+
%conv.i = zext i32 %add6.i.i to i64
29+
%arrayidx = getelementptr inbounds float, float addrspace(1)* %in, i64 %conv.i
30+
%2 = load float, float addrspace(1)* %arrayidx, align 4
31+
%arrayidx1 = getelementptr inbounds float, float addrspace(1)* %out, i64 %conv.i
32+
store float %2, float addrspace(1)* %arrayidx1, align 4
33+
ret void
34+
}
35+
36+
!igc.functions = !{!1}
37+
38+
!1 = !{void (float addrspace(1)*, float addrspace(1)*, <8 x i32>, <8 x i32>, <3 x i32>, i16, i16, i16, i32, i32)* @testNoUnif, !2}
39+
!2 = !{!3, !4, !5}
40+
!3 = !{!"function_type", i32 0}
41+
!4 = !{!"implicit_arg_desc", !7, !8, !9, !10, !11, !12, !13, !15}
42+
!5 = !{!"thread_group_size", i32 16, i32 32, i32 32}
43+
!7 = !{i32 0}
44+
!8 = !{i32 1}
45+
!9 = !{i32 6}
46+
!10 = !{i32 8}
47+
!11 = !{i32 9}
48+
!12 = !{i32 10}
49+
!13 = !{i32 15, !14}
50+
!14 = !{!"explicit_arg_num", i32 0}
51+
!15 = !{i32 15, !16}
52+
!16 = !{!"explicit_arg_num", i32 1}

‎IGC/ocloc_tests/retry/final_test_pytorch3.ll‎

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -10,14 +10,14 @@
1010
; RUN: ocloc compile -llvm_input -file %t.bc -device mtl -options "-igc_opts 'DisableCodeScheduling=1,VISAOptions=-asmToConsole'" &> %t_output.ll
1111
; RUN: FileCheck --input-file %t_output.ll %s
1212

13-
; CHECK://.kernel _ZTSN2at15AtenIpexTypeXPU4impl35FastGroupRadixSortImplKernelFunctorIbxLi1024ELb0ELb1EtLi32ELi4ENS0_19GroupRadixProcesserIbLi1024ELi32ELi4ELb0EttjLi4EEEbEE
14-
; CHECK://.spill size {{([5-6][0-9]{3})}}
15-
; CHECK: end of thread
13+
; This test checks that after kernel recompilation there is no more spills
1614

1715
; CHECK://.kernel _ZTSN2at15AtenIpexTypeXPU4impl35FastGroupRadixSortImplKernelFunctorIbxLi1024ELb0ELb1EtLi32ELi4ENS0_19GroupRadixProcesserIbLi1024ELi32ELi4ELb0EttjLi4EEEbEE
1816
; CHECK-NOT://.spill size
1917
; CHECK: end of thread
2018

19+
; CHECK: warning: [RetryManager] Start recompilation of the kernel
20+
2121
; ModuleID = 'reduced.ll'
2222
source_filename = "reduced.ll"
2323

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