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Re-order some blocks in runtimelookup #83453

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EgorBo wants to merge 8 commits into from
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Re-order some blocks in runtimelookup #83453

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8894243
Re-order some blocks in runtimelookup
EgorBo Mar 15, 2023
65a2e0b
Update runtimelookup.cpp
EgorBo Mar 15, 2023
05293dc
Update runtimelookup.cpp
EgorBo Mar 15, 2023
61b02a5
Merge branch 'main' of github.com:dotnet/runtime into runtimelookup-r…
EgorBo Mar 21, 2023
4f2b996
Merge branch 'main' of github.com:dotnet/runtime into runtimelookup-r…
EgorBo Mar 28, 2023
9311a11
mark blocks cold
EgorBo Mar 29, 2023
73b458b
Restore fgReorderBlocks
EgorBo Mar 29, 2023
2505631
actually we don't need them, let's rely on OptimizeLayout phase
EgorBo Mar 29, 2023
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Re-order some blocks in runtimelookup
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@EgorBo
EgorBo committed Mar 15, 2023
commit 889424325931da53d84710adae699ab7cb371c90
39 changes: 15 additions & 24 deletions src/coreclr/jit/runtimelookup.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -239,12 +239,12 @@ PhaseStatus Compiler::fgExpandRuntimeLookups()
// if (*fastPathValue == null)
// goto fallbackBb;
//
// fastPathBb(BBJ_ALWAYS): [weight: 0.8]
// rtLookupLcl = *fastPathValue;
// fallbackBb(BBJ_ALWAYS): [weight: 0.2]
// rtLookupLcl = HelperCall();
// goto block;
//
// fallbackBb(BBJ_NONE): [weight: 0.2]
// rtLookupLcl = HelperCall();
// fastPathBb(BBJ_NONE): [weight: 0.8]
// rtLookupLcl = *fastPathValue;
//
// block(...): [weight: 1.0]
// use(rtLookupLcl);
Expand All @@ -262,15 +262,14 @@ PhaseStatus Compiler::fgExpandRuntimeLookups()
CreateBlockFromTree(this, prevBb, BBJ_COND, gtNewOperNode(GT_JTRUE, TYP_VOID, nullcheckOp),
debugInfo);

// Fast-path basic block
GenTree* asgFastpathValue = gtNewAssignNode(gtClone(rtLookupLcl), fastPathValueClone);
BasicBlock* fastPathBb = CreateBlockFromTree(this, nullcheckBb, BBJ_NONE, asgFastpathValue, debugInfo);

// Fallback basic block
GenTree* asgFallbackValue = gtNewAssignNode(gtClone(rtLookupLcl), call);
BasicBlock* fallbackBb =
CreateBlockFromTree(this, nullcheckBb, BBJ_NONE, asgFallbackValue, debugInfo, true);

// Fast-path basic block
GenTree* asgFastpathValue = gtNewAssignNode(gtClone(rtLookupLcl), fastPathValueClone);
BasicBlock* fastPathBb =
CreateBlockFromTree(this, nullcheckBb, BBJ_ALWAYS, asgFastpathValue, debugInfo);
CreateBlockFromTree(this, nullcheckBb, BBJ_ALWAYS, asgFallbackValue, debugInfo, true);

BasicBlock* sizeCheckBb = nullptr;
if (needsSizeCheck)
Expand All @@ -288,12 +287,12 @@ PhaseStatus Compiler::fgExpandRuntimeLookups()
// if (*fastPathValue == null)
// goto fallbackBb;
//
// fastPathBb(BBJ_ALWAYS): [weight: 0.64]
// rtLookupLcl = *fastPathValue;
// fallbackBb(BBJ_ALWAYS): [weight: 0.36]
// rtLookupLcl = HelperCall();
// goto block;
//
// fallbackBb(BBJ_NONE): [weight: 0.36]
// rtLookupLcl = HelperCall();
// fastPathBb(BBJ_NONE): [weight: 0.64]
// rtLookupLcl = *fastPathValue;
//
// block(...): [weight: 1.0]
// use(rtLookupLcl);
Expand Down Expand Up @@ -322,8 +321,8 @@ PhaseStatus Compiler::fgExpandRuntimeLookups()
fgRemoveRefPred(block, prevBb);
fgAddRefPred(block, fastPathBb);
fgAddRefPred(block, fallbackBb);
nullcheckBb->bbJumpDest = fallbackBb;
fastPathBb->bbJumpDest = block;
nullcheckBb->bbJumpDest = fastPathBb;
fallbackBb->bbJumpDest = block;
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@kunalspathak kunalspathak Mar 28, 2023 •
edited
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What if you mark fallBackBb->bbSetRunRarely()? I had to do similar thing to re-arrange in #80297.

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@kunalspathak kunalspathak Mar 28, 2023

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G_M10050_IG01:
       sub      rsp, 40
                                                ;; size=4 bbWeight=1 PerfScore 0.25
G_M10050_IG02:
       mov      rcx, qword ptr GS:[0x0058]
       mov      rcx, qword ptr [rcx+30H]
       mov      edx, dword ptr [rcx+48H]
       cmp      edx, 2
       jl       SHORT G_M10050_IG04
                                                ;; size=21 bbWeight=1 PerfScore 6.25
G_M10050_IG03:
       mov      rcx, qword ptr [rcx+50H]
       cmp      qword ptr [rcx+10H], 0
       jne      SHORT G_M10050_IG05
                                                ;; size=11 bbWeight=0.90 PerfScore 5.42
G_M10050_IG04:
       mov      rcx, 0xD1FFAB1E
       mov      edx, 29
       mov      r8d, 2
       call     CORINFO_HELP_GETSHARED_NONGCTHREADSTATIC_BASE_NOCTOR_OPTIMIZED
       mov      qword ptr [rsp+20H], rax
                                                ;; size=31 bbWeight=0.09 PerfScore 0.25
G_M10050_IG05:
       mov      rax, qword ptr [rsp+20H]
       mov      eax, dword ptr [rax+8CH]
                                                ;; size=11 bbWeight=1 PerfScore 3.00
G_M10050_IG06:
       add      rsp, 40
       ret
                                                ;; size=5 bbWeight=1 PerfScore 1.25

vs.

G_M10050_IG01:
       sub      rsp, 40
                                                ;; size=4 bbWeight=1 PerfScore 0.25
G_M10050_IG02:
       mov      rax, qword ptr GS:[0x0058]
       mov      rax, qword ptr [rax+30H]
       mov      ecx, dword ptr [rax+48H]
       cmp      ecx, 2
       jl       SHORT G_M10050_IG06
                                                ;; size=21 bbWeight=1 PerfScore 6.25
G_M10050_IG03:
       mov      rax, qword ptr [rax+50H]
       cmp      qword ptr [rax+10H], 0
       je       SHORT G_M10050_IG06
                                                ;; size=11 bbWeight=0.90 PerfScore 5.42
G_M10050_IG04:
       mov      r9, qword ptr [rsp+20H]
       mov      eax, dword ptr [r9+8CH]
                                                ;; size=12 bbWeight=1 PerfScore 3.00
G_M10050_IG05:
       add      rsp, 40
       ret
                                                ;; size=5 bbWeight=1 PerfScore 1.25
G_M10050_IG06:
       mov      rcx, 0xD1FFAB1E
       mov      edx, 29
       mov      r8d, 2
       call     CORINFO_HELP_GETSHARED_NONGCTHREADSTATIC_BASE_NOCTOR_OPTIMIZED
       mov      r9, rax
       mov      qword ptr [rsp+20H], r9
       jmp      SHORT G_M10050_IG04
                                                ;; size=36 bbWeight=0 PerfScore 0.00


if (needsSizeCheck)
{
Expand Down Expand Up @@ -412,13 +411,5 @@ PhaseStatus Compiler::fgExpandRuntimeLookups()
}
}

if (result == PhaseStatus::MODIFIED_EVERYTHING)
{
if (opts.OptimizationEnabled())
{
fgReorderBlocks(/* useProfileData */ false);
fgUpdateChangedFlowGraph(FlowGraphUpdates::COMPUTE_BASICS);
}
}
Comment on lines -451 to -458
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@jakobbotsch jakobbotsch Mar 15, 2023

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W.r.t. the confusing diffs, maybe try with this change reverted?

return result;
}