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Constant folding for RuntimeInformation.IsOSPlatform(OSPlatform) #83308

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merged 3 commits into from
Mar 13, 2023
Merged

Constant folding for RuntimeInformation.IsOSPlatform(OSPlatform) #83308

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b69d735
Fold RuntimeInformation.IsOSPlatform
EgorBo Mar 11, 2023
568f3d6
Update importervectorization.cpp
EgorBo Mar 12, 2023
642585c
Update morph.cpp
EgorBo Mar 13, 2023
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4 changes: 1 addition & 3 deletions src/coreclr/jit/importervectorization.cpp
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Expand Up @@ -731,10 +731,8 @@ GenTree* Compiler::impStringEqualsOrStartsWith(bool startsWith, CORINFO_SIG_INFO
GenTreeLclVar* varStrLcl = gtNewLclvNode(varStrTmp, varStr->TypeGet());

// Create a tree representing string's Length:
// TODO-Unroll-CQ: Consider using ARR_LENGTH here, but we'll have to modify QMARK to propagate BBF_HAS_IDX_LEN
int strLenOffset = OFFSETOF__CORINFO_String__stringLen;
GenTree* lenOffset = gtNewIconNode(strLenOffset, TYP_I_IMPL);
GenTree* lenNode = gtNewIndir(TYP_INT, gtNewOperNode(GT_ADD, TYP_BYREF, varStrLcl, lenOffset));
GenTree* lenNode = gtNewArrLen(TYP_INT, varStrLcl, strLenOffset, compCurBB);
varStrLcl = gtClone(varStrLcl)->AsLclVar();

GenTree* unrolled = impExpandHalfConstEquals(varStrLcl, lenNode, needsNullcheck, startsWith, (WCHAR*)str, cnsLength,
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12 changes: 9 additions & 3 deletions src/coreclr/jit/morph.cpp
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Expand Up @@ -14544,8 +14544,10 @@ void Compiler::fgExpandQmarkStmt(BasicBlock* block, Statement* stmt)
// if they are going to be cleared by fgSplitBlockAfterStatement(). We currently only do this only
// for the GC safe point bit, the logic being that if 'block' was marked gcsafe, then surely
// remainderBlock will still be GC safe.
BasicBlockFlags propagateFlags = block->bbFlags & BBF_GC_SAFE_POINT;
BasicBlock* remainderBlock = fgSplitBlockAfterStatement(block, stmt);
BasicBlockFlags propagateFlagsToRemainder = block->bbFlags & BBF_GC_SAFE_POINT;
// Conservatively mark all blocks as having IDX_LEN since we don't know where exactly it went
BasicBlockFlags propagateFlagsToAll = block->bbFlags & BBF_HAS_IDX_LEN;
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This should use BBF_COPY_PROPAGATE

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@EgorBo EgorBo Mar 13, 2023 •
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This should use BBF_COPY_PROPAGATE

That will decrease throughput at this moment for no benefit - e.g. we'll mark 4 blocks with "has nullcheck" and will have to visit them all in earlyprop. Ideally, QmarkGenTree should store BB flags it needs to propagate IMO. I propose we add flags on demand here since we use QMARK only in a few specific cases (none of them need to propagate flags atm except string-unrolling)

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@jakobbotsch jakobbotsch Mar 13, 2023 •
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How bad is it?

If that's the case I think we should have comment about it. Also, can you add asserts that check for GT_NULLCHECK, GT_MDARR_LENGTH, GT_ALLOCOBJ at least then (can use gtTreeContainsOper for this)?

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@EgorBo EgorBo Mar 13, 2023 •
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can you add asserts that check for GT_NULLCHECK, GT_MDARR_LENGTH, GT_ALLOCOBJ at least then (can use gtTreeContainsOper for this)?

It will assert anyway if we have a block without e.g. HAS_NULLCHECK with an actuall nullcheck, so no need in an extra assert - if someone adds a new kind of qmark with a need to propagate a new block flag (prior my PR it was never needed) they will hit it. The extra regression from BBF_COPY_PROPAGATE is another +0.02% or so

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Ok, will leave it up to you -- although I don't think 0.02% is that much to have this be always correct

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It's not urgent, let's have a CI run with BBF_COPY_PROPAGATE

BasicBlock* remainderBlock = fgSplitBlockAfterStatement(block, stmt);
fgRemoveRefPred(remainderBlock, block); // We're going to put more blocks between block and remainderBlock.

BasicBlock* condBlock = fgNewBBafter(BBJ_COND, block, true);
Expand All @@ -14561,14 +14563,17 @@ void Compiler::fgExpandQmarkStmt(BasicBlock* block, Statement* stmt)
elseBlock->bbFlags |= BBF_IMPORTED;
}

remainderBlock->bbFlags |= propagateFlags;
remainderBlock->bbFlags |= (propagateFlagsToRemainder | propagateFlagsToAll);

condBlock->inheritWeight(block);

fgAddRefPred(condBlock, block);
fgAddRefPred(elseBlock, condBlock);
fgAddRefPred(remainderBlock, elseBlock);

condBlock->bbFlags |= propagateFlagsToAll;
elseBlock->bbFlags |= propagateFlagsToAll;

BasicBlock* thenBlock = nullptr;
if (hasTrueExpr && hasFalseExpr)
{
Expand All @@ -14585,6 +14590,7 @@ void Compiler::fgExpandQmarkStmt(BasicBlock* block, Statement* stmt)

thenBlock = fgNewBBafter(BBJ_ALWAYS, condBlock, true);
thenBlock->bbJumpDest = remainderBlock;
thenBlock->bbFlags |= propagateFlagsToAll;
if ((block->bbFlags & BBF_INTERNAL) == 0)
{
thenBlock->bbFlags &= ~BBF_INTERNAL;
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2 changes: 2 additions & 0 deletions src/libraries/System.Private.CoreLib/src/System/OperatingSystem.cs
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Expand Up @@ -2,6 +2,7 @@
// The .NET Foundation licenses this file to you under the MIT license.

using System.Diagnostics;
using System.Runtime.CompilerServices;
using System.Runtime.Serialization;
using System.Runtime.Versioning;

Expand Down Expand Up @@ -115,6 +116,7 @@ public string VersionString
/// Indicates whether the current application is running on the specified platform.
/// </summary>
/// <param name="platform">Case-insensitive platform name. Examples: Browser, Linux, FreeBSD, Android, iOS, macOS, tvOS, watchOS, Windows.</param>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static bool IsOSPlatform(string platform)
{
ArgumentNullException.ThrowIfNull(platform);
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