Revert "[llvm][IR] Extend BranchWeightMetadata to track provenance of weights" #95060
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… weights…" This reverts commit c5978f1.
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@llvm/pr-subscribers-llvm-ir @llvm/pr-subscribers-pgo Author: Paul Kirth (ilovepi) ChangesReverts llvm/llvm-project#86609 This change causes compile-time regressions for stage2 builds (https://llvm-compile-time-tracker.com/compare.php?from=3254f31a66263ea9647c9547f1531c3123444fcd&to=c5978f1eb5eeca8610b9dfce1fcbf1f473911cd8&stat=instructions:u). It also introduced unintended changes to Patch is 38.70 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/95060.diff 30 Files Affected:
diff --git a/clang/test/CodeGenCXX/attr-likelihood-if-vs-builtin-expect.cpp b/clang/test/CodeGenCXX/attr-likelihood-if-vs-builtin-expect.cpp
index 81d9334356520..fb236aeb982e0 100644
--- a/clang/test/CodeGenCXX/attr-likelihood-if-vs-builtin-expect.cpp
+++ b/clang/test/CodeGenCXX/attr-likelihood-if-vs-builtin-expect.cpp
@@ -221,5 +221,5 @@ void tu2(int &i) {
}
}
-// CHECK: [[BW_LIKELY]] = !{!"branch_weights", !"expected", i32 2000, i32 1}
-// CHECK: [[BW_UNLIKELY]] = !{!"branch_weights", !"expected", i32 1, i32 2000}
+// CHECK: [[BW_LIKELY]] = !{!"branch_weights", i32 2000, i32 1}
+// CHECK: [[BW_UNLIKELY]] = !{!"branch_weights", i32 1, i32 2000}
diff --git a/llvm/docs/BranchWeightMetadata.rst b/llvm/docs/BranchWeightMetadata.rst
index 62204753e29b0..522f37cdad4fc 100644
--- a/llvm/docs/BranchWeightMetadata.rst
+++ b/llvm/docs/BranchWeightMetadata.rst
@@ -28,14 +28,11 @@ Supported Instructions
Metadata is only assigned to the conditional branches. There are two extra
operands for the true and the false branch.
-We optionally track if the metadata was added by ``__builtin_expect`` or
-``__builtin_expect_with_probability`` with an optional field ``!"expected"``.
.. code-block:: none
!0 = !{
!"branch_weights",
- [ !"expected", ]
i32 <TRUE_BRANCH_WEIGHT>,
i32 <FALSE_BRANCH_WEIGHT>
}
@@ -50,7 +47,6 @@ is always case #0).
!0 = !{
!"branch_weights",
- [ !"expected", ]
i32 <DEFAULT_BRANCH_WEIGHT>
[ , i32 <CASE_BRANCH_WEIGHT> ... ]
}
@@ -64,7 +60,6 @@ Branch weights are assigned to every destination.
!0 = !{
!"branch_weights",
- [ !"expected", ]
i32 <LABEL_BRANCH_WEIGHT>
[ , i32 <LABEL_BRANCH_WEIGHT> ... ]
}
@@ -80,7 +75,6 @@ block and entry counts which may not be accurate with sampling.
!0 = !{
!"branch_weights",
- [ !"expected", ]
i32 <CALL_BRANCH_WEIGHT>
}
@@ -101,7 +95,6 @@ is used.
!0 = !{
!"branch_weights",
- [ !"expected", ]
i32 <INVOKE_NORMAL_WEIGHT>
[ , i32 <INVOKE_UNWIND_WEIGHT> ]
}
diff --git a/llvm/include/llvm/IR/MDBuilder.h b/llvm/include/llvm/IR/MDBuilder.h
index e02ec8f5a3d8b..3265589b7c8df 100644
--- a/llvm/include/llvm/IR/MDBuilder.h
+++ b/llvm/include/llvm/IR/MDBuilder.h
@@ -59,11 +59,7 @@ class MDBuilder {
//===------------------------------------------------------------------===//
/// Return metadata containing two branch weights.
- /// @param TrueWeight the weight of the true branch
- /// @param FalseWeight the weight of the false branch
- /// @param Do these weights come from __builtin_expect*
- MDNode *createBranchWeights(uint32_t TrueWeight, uint32_t FalseWeight,
- bool IsExpected = false);
+ MDNode *createBranchWeights(uint32_t TrueWeight, uint32_t FalseWeight);
/// Return metadata containing two branch weights, with significant bias
/// towards `true` destination.
@@ -74,10 +70,7 @@ class MDBuilder {
MDNode *createUnlikelyBranchWeights();
/// Return metadata containing a number of branch weights.
- /// @param Weights the weights of all the branches
- /// @param Do these weights come from __builtin_expect*
- MDNode *createBranchWeights(ArrayRef<uint32_t> Weights,
- bool IsExpected = false);
+ MDNode *createBranchWeights(ArrayRef<uint32_t> Weights);
/// Return metadata specifying that a branch or switch is unpredictable.
MDNode *createUnpredictable();
diff --git a/llvm/include/llvm/IR/ProfDataUtils.h b/llvm/include/llvm/IR/ProfDataUtils.h
index 1d7c97d9be953..88fbad4d6b9d8 100644
--- a/llvm/include/llvm/IR/ProfDataUtils.h
+++ b/llvm/include/llvm/IR/ProfDataUtils.h
@@ -55,17 +55,6 @@ MDNode *getBranchWeightMDNode(const Instruction &I);
/// Nullptr otherwise.
MDNode *getValidBranchWeightMDNode(const Instruction &I);
-/// Check if Branch Weight Metadata has an "expected" field from an llvm.expect*
-/// intrinsic
-bool hasBranchWeightOrigin(const Instruction &I);
-
-/// Check if Branch Weight Metadata has an "expected" field from an llvm.expect*
-/// intrinsic
-bool hasBranchWeightOrigin(const MDNode *ProfileData);
-
-/// Return the offset to the first branch weight data
-unsigned getBranchWeightOffset(const MDNode *ProfileData);
-
/// Extract branch weights from MD_prof metadata
///
/// \param ProfileData A pointer to an MDNode.
@@ -122,11 +111,7 @@ bool extractProfTotalWeight(const Instruction &I, uint64_t &TotalWeights);
/// Create a new `branch_weights` metadata node and add or overwrite
/// a `prof` metadata reference to instruction `I`.
-/// \param I the Instruction to set branch weights on.
-/// \param Weights an array of weights to set on instruction I.
-/// \param IsExpected were these weights added from an llvm.expect* intrinsic.
-void setBranchWeights(Instruction &I, ArrayRef<uint32_t> Weights,
- bool IsExpected);
+void setBranchWeights(Instruction &I, ArrayRef<uint32_t> Weights);
/// Scaling the profile data attached to 'I' using the ratio of S/T.
void scaleProfData(Instruction &I, uint64_t S, uint64_t T);
diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
index 0e01080bd75cc..339a1f1f2f002 100644
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -8866,8 +8866,7 @@ bool CodeGenPrepare::splitBranchCondition(Function &F, ModifyDT &ModifiedDT) {
scaleWeights(NewTrueWeight, NewFalseWeight);
Br1->setMetadata(LLVMContext::MD_prof,
MDBuilder(Br1->getContext())
- .createBranchWeights(TrueWeight, FalseWeight,
- hasBranchWeightOrigin(*Br1)));
+ .createBranchWeights(TrueWeight, FalseWeight));
NewTrueWeight = TrueWeight;
NewFalseWeight = 2 * FalseWeight;
diff --git a/llvm/lib/IR/Instruction.cpp b/llvm/lib/IR/Instruction.cpp
index aec927a8cf31d..29272e627a1d1 100644
--- a/llvm/lib/IR/Instruction.cpp
+++ b/llvm/lib/IR/Instruction.cpp
@@ -1268,23 +1268,12 @@ Instruction *Instruction::cloneImpl() const {
void Instruction::swapProfMetadata() {
MDNode *ProfileData = getBranchWeightMDNode(*this);
- if (!ProfileData)
- return;
- unsigned FirstIdx = getBranchWeightOffset(ProfileData);
- if (ProfileData->getNumOperands() != 2 + FirstIdx)
+ if (!ProfileData || ProfileData->getNumOperands() != 3)
return;
- unsigned SecondIdx = FirstIdx + 1;
- SmallVector<Metadata *, 4> Ops;
- // If there are more weights past the second, we can't swap them
- if (ProfileData->getNumOperands() > SecondIdx + 1)
- return;
- for (unsigned Idx = 0; Idx < FirstIdx; ++Idx) {
- Ops.push_back(ProfileData->getOperand(Idx));
- }
- // Switch the order of the weights
- Ops.push_back(ProfileData->getOperand(SecondIdx));
- Ops.push_back(ProfileData->getOperand(FirstIdx));
+ // The first operand is the name. Fetch them backwards and build a new one.
+ Metadata *Ops[] = {ProfileData->getOperand(0), ProfileData->getOperand(2),
+ ProfileData->getOperand(1)};
setMetadata(LLVMContext::MD_prof,
MDNode::get(ProfileData->getContext(), Ops));
}
diff --git a/llvm/lib/IR/Instructions.cpp b/llvm/lib/IR/Instructions.cpp
index de369bd62a617..1213f078d05ec 100644
--- a/llvm/lib/IR/Instructions.cpp
+++ b/llvm/lib/IR/Instructions.cpp
@@ -5199,11 +5199,7 @@ void SwitchInstProfUpdateWrapper::init() {
if (!ProfileData)
return;
- // FIXME: This check belongs in ProfDataUtils. Its almost equivalent to
- // getValidBranchWeightMDNode(), but the need to use llvm_unreachable
- // makes them slightly different.
- if (ProfileData->getNumOperands() !=
- SI.getNumSuccessors() + getBranchWeightOffset(ProfileData)) {
+ if (ProfileData->getNumOperands() != SI.getNumSuccessors() + 1) {
llvm_unreachable("number of prof branch_weights metadata operands does "
"not correspond to number of succesors");
}
diff --git a/llvm/lib/IR/MDBuilder.cpp b/llvm/lib/IR/MDBuilder.cpp
index 000027754d13e..bd68db3a6f961 100644
--- a/llvm/lib/IR/MDBuilder.cpp
+++ b/llvm/lib/IR/MDBuilder.cpp
@@ -35,8 +35,8 @@ MDNode *MDBuilder::createFPMath(float Accuracy) {
}
MDNode *MDBuilder::createBranchWeights(uint32_t TrueWeight,
- uint32_t FalseWeight, bool IsExpected) {
- return createBranchWeights({TrueWeight, FalseWeight}, IsExpected);
+ uint32_t FalseWeight) {
+ return createBranchWeights({TrueWeight, FalseWeight});
}
MDNode *MDBuilder::createLikelyBranchWeights() {
@@ -49,19 +49,15 @@ MDNode *MDBuilder::createUnlikelyBranchWeights() {
return createBranchWeights(1, (1U << 20) - 1);
}
-MDNode *MDBuilder::createBranchWeights(ArrayRef<uint32_t> Weights,
- bool IsExpected) {
+MDNode *MDBuilder::createBranchWeights(ArrayRef<uint32_t> Weights) {
assert(Weights.size() >= 1 && "Need at least one branch weights!");
- unsigned int Offset = IsExpected ? 2 : 1;
- SmallVector<Metadata *, 4> Vals(Weights.size() + Offset);
+ SmallVector<Metadata *, 4> Vals(Weights.size() + 1);
Vals[0] = createString("branch_weights");
- if (IsExpected)
- Vals[1] = createString("expected");
Type *Int32Ty = Type::getInt32Ty(Context);
for (unsigned i = 0, e = Weights.size(); i != e; ++i)
- Vals[i + Offset] = createConstant(ConstantInt::get(Int32Ty, Weights[i]));
+ Vals[i + 1] = createConstant(ConstantInt::get(Int32Ty, Weights[i]));
return MDNode::get(Context, Vals);
}
diff --git a/llvm/lib/IR/Metadata.cpp b/llvm/lib/IR/Metadata.cpp
index 5f42ce22f72fe..b6c932495a145 100644
--- a/llvm/lib/IR/Metadata.cpp
+++ b/llvm/lib/IR/Metadata.cpp
@@ -1196,10 +1196,10 @@ MDNode *MDNode::mergeDirectCallProfMetadata(MDNode *A, MDNode *B,
StringRef AProfName = AMDS->getString();
StringRef BProfName = BMDS->getString();
if (AProfName == "branch_weights" && BProfName == "branch_weights") {
- ConstantInt *AInstrWeight = mdconst::dyn_extract<ConstantInt>(
- A->getOperand(getBranchWeightOffset(A)));
- ConstantInt *BInstrWeight = mdconst::dyn_extract<ConstantInt>(
- B->getOperand(getBranchWeightOffset(B)));
+ ConstantInt *AInstrWeight =
+ mdconst::dyn_extract<ConstantInt>(A->getOperand(1));
+ ConstantInt *BInstrWeight =
+ mdconst::dyn_extract<ConstantInt>(B->getOperand(1));
assert(AInstrWeight && BInstrWeight && "verified by LLVM verifier");
return MDNode::get(Ctx,
{MDHelper.createString("branch_weights"),
diff --git a/llvm/lib/IR/ProfDataUtils.cpp b/llvm/lib/IR/ProfDataUtils.cpp
index c4b1ed55de8a2..51e78dc5e6c00 100644
--- a/llvm/lib/IR/ProfDataUtils.cpp
+++ b/llvm/lib/IR/ProfDataUtils.cpp
@@ -40,6 +40,9 @@ namespace {
// We maintain some constants here to ensure that we access the branch weights
// correctly, and can change the behavior in the future if the layout changes
+// The index at which the weights vector starts
+constexpr unsigned WeightsIdx = 1;
+
// the minimum number of operands for MD_prof nodes with branch weights
constexpr unsigned MinBWOps = 3;
@@ -72,7 +75,6 @@ static void extractFromBranchWeightMD(const MDNode *ProfileData,
assert(isBranchWeightMD(ProfileData) && "wrong metadata");
unsigned NOps = ProfileData->getNumOperands();
- unsigned WeightsIdx = getBranchWeightOffset(ProfileData);
assert(WeightsIdx < NOps && "Weights Index must be less than NOps.");
Weights.resize(NOps - WeightsIdx);
@@ -80,8 +82,8 @@ static void extractFromBranchWeightMD(const MDNode *ProfileData,
ConstantInt *Weight =
mdconst::dyn_extract<ConstantInt>(ProfileData->getOperand(Idx));
assert(Weight && "Malformed branch_weight in MD_prof node");
- assert(Weight->getValue().getActiveBits() <= (sizeof(T) * 8) &&
- "Too many bits for MD_prof branch_weight");
+ assert(Weight->getValue().getActiveBits() <= 32 &&
+ "Too many bits for uint32_t");
Weights[Idx - WeightsIdx] = Weight->getZExtValue();
}
}
@@ -121,26 +123,6 @@ bool hasValidBranchWeightMD(const Instruction &I) {
return getValidBranchWeightMDNode(I);
}
-bool hasBranchWeightOrigin(const Instruction &I) {
- auto *ProfileData = I.getMetadata(LLVMContext::MD_prof);
- return hasBranchWeightOrigin(ProfileData);
-}
-
-bool hasBranchWeightOrigin(const MDNode *ProfileData) {
- if (!isBranchWeightMD(ProfileData))
- return false;
- auto *ProfDataName = dyn_cast<MDString>(ProfileData->getOperand(1));
- // NOTE: if we ever have more types of branch weight provenance,
- // we need to check the string value is "expected". For now, we
- // supply a more generic API, and avoid the spurious comparisons.
- assert(ProfDataName == nullptr || ProfDataName->getString() == "expected");
- return ProfDataName != nullptr;
-}
-
-unsigned getBranchWeightOffset(const MDNode *ProfileData) {
- return hasBranchWeightOrigin(ProfileData) ? 2 : 1;
-}
-
MDNode *getBranchWeightMDNode(const Instruction &I) {
auto *ProfileData = I.getMetadata(LLVMContext::MD_prof);
if (!isBranchWeightMD(ProfileData))
@@ -150,9 +132,7 @@ MDNode *getBranchWeightMDNode(const Instruction &I) {
MDNode *getValidBranchWeightMDNode(const Instruction &I) {
auto *ProfileData = getBranchWeightMDNode(I);
- auto Offset = getBranchWeightOffset(ProfileData);
- if (ProfileData &&
- ProfileData->getNumOperands() == Offset + I.getNumSuccessors())
+ if (ProfileData && ProfileData->getNumOperands() == 1 + I.getNumSuccessors())
return ProfileData;
return nullptr;
}
@@ -211,8 +191,7 @@ bool extractProfTotalWeight(const MDNode *ProfileData, uint64_t &TotalVal) {
return false;
if (ProfDataName->getString() == "branch_weights") {
- unsigned Offset = getBranchWeightOffset(ProfileData);
- for (unsigned Idx = Offset; Idx < ProfileData->getNumOperands(); ++Idx) {
+ for (unsigned Idx = 1; Idx < ProfileData->getNumOperands(); Idx++) {
auto *V = mdconst::dyn_extract<ConstantInt>(ProfileData->getOperand(Idx));
assert(V && "Malformed branch_weight in MD_prof node");
TotalVal += V->getValue().getZExtValue();
@@ -233,10 +212,9 @@ bool extractProfTotalWeight(const Instruction &I, uint64_t &TotalVal) {
return extractProfTotalWeight(I.getMetadata(LLVMContext::MD_prof), TotalVal);
}
-void setBranchWeights(Instruction &I, ArrayRef<uint32_t> Weights,
- bool IsExpected) {
+void setBranchWeights(Instruction &I, ArrayRef<uint32_t> Weights) {
MDBuilder MDB(I.getContext());
- MDNode *BranchWeights = MDB.createBranchWeights(Weights, IsExpected);
+ MDNode *BranchWeights = MDB.createBranchWeights(Weights);
I.setMetadata(LLVMContext::MD_prof, BranchWeights);
}
diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp
index fe2253dd04eb3..e5927203f33a2 100644
--- a/llvm/lib/IR/Verifier.cpp
+++ b/llvm/lib/IR/Verifier.cpp
@@ -104,7 +104,6 @@
#include "llvm/IR/Module.h"
#include "llvm/IR/ModuleSlotTracker.h"
#include "llvm/IR/PassManager.h"
-#include "llvm/IR/ProfDataUtils.h"
#include "llvm/IR/Statepoint.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/Use.h"
@@ -4809,10 +4808,8 @@ void Verifier::visitProfMetadata(Instruction &I, MDNode *MD) {
// Check consistency of !prof branch_weights metadata.
if (ProfName == "branch_weights") {
- unsigned int Offset = getBranchWeightOffset(MD);
if (isa<InvokeInst>(&I)) {
- Check(MD->getNumOperands() == (1 + Offset) ||
- MD->getNumOperands() == (2 + Offset),
+ Check(MD->getNumOperands() == 2 || MD->getNumOperands() == 3,
"Wrong number of InvokeInst branch_weights operands", MD);
} else {
unsigned ExpectedNumOperands = 0;
@@ -4832,10 +4829,10 @@ void Verifier::visitProfMetadata(Instruction &I, MDNode *MD) {
CheckFailed("!prof branch_weights are not allowed for this instruction",
MD);
- Check(MD->getNumOperands() == Offset + ExpectedNumOperands,
+ Check(MD->getNumOperands() == 1 + ExpectedNumOperands,
"Wrong number of operands", MD);
}
- for (unsigned i = Offset; i < MD->getNumOperands(); ++i) {
+ for (unsigned i = 1; i < MD->getNumOperands(); ++i) {
auto &MDO = MD->getOperand(i);
Check(MDO, "second operand should not be null", MD);
Check(mdconst::dyn_extract<ConstantInt>(MDO),
diff --git a/llvm/lib/Transforms/IPO/SampleProfile.cpp b/llvm/lib/Transforms/IPO/SampleProfile.cpp
index 7e6a8817b7a67..92ad4c34da6e7 100644
--- a/llvm/lib/Transforms/IPO/SampleProfile.cpp
+++ b/llvm/lib/Transforms/IPO/SampleProfile.cpp
@@ -1662,8 +1662,7 @@ void SampleProfileLoader::generateMDProfMetadata(Function &F) {
else if (OverwriteExistingWeights)
I.setMetadata(LLVMContext::MD_prof, nullptr);
} else if (!isa<IntrinsicInst>(&I)) {
- setBranchWeights(I, {static_cast<uint32_t>(BlockWeights[BB])},
- /*IsExpected=*/false);
+ setBranchWeights(I, {static_cast<uint32_t>(BlockWeights[BB])});
}
}
} else if (OverwriteExistingWeights || ProfileSampleBlockAccurate) {
@@ -1674,7 +1673,7 @@ void SampleProfileLoader::generateMDProfMetadata(Function &F) {
if (cast<CallBase>(I).isIndirectCall()) {
I.setMetadata(LLVMContext::MD_prof, nullptr);
} else {
- setBranchWeights(I, {uint32_t(0)}, /*IsExpected=*/false);
+ setBranchWeights(I, {uint32_t(0)});
}
}
}
@@ -1757,7 +1756,7 @@ void SampleProfileLoader::generateMDProfMetadata(Function &F) {
if (MaxWeight > 0 &&
(!TI->extractProfTotalWeight(TempWeight) || OverwriteExistingWeights)) {
LLVM_DEBUG(dbgs() << "SUCCESS. Found non-zero weights.\n");
- setBranchWeights(*TI, Weights, /*IsExpected=*/false);
+ setBranchWeights(*TI, Weights);
ORE->emit([&]() {
return OptimizationRemark(DEBUG_TYPE, "PopularDest", MaxDestInst)
<< "most popular destination for conditional branches at "
diff --git a/llvm/lib/Transforms/Instrumentation/ControlHeightReduction.cpp b/llvm/lib/Transforms/Instrumentation/ControlHeightReduction.cpp
index 731104d4fcef0..0a3d8d6000cf4 100644
--- a/llvm/lib/Transforms/Instrumentation/ControlHeightReduction.cpp
+++ b/llvm/lib/Transforms/Instrumentation/ControlHeightReduction.cpp
@@ -1878,7 +1878,7 @@ void CHR::fixupBranchesAndSelects(CHRScope *Scope,
static_cast<uint32_t>(CHRBranchBias.scale(1000)),
static_cast<uint32_t>(CHRBranchBias.getCompl().scale(1000)),
};
- setBranchWeights(*MergedBR, Weights, /*IsExpected=*/false);
+ setBranchWeights(*MergedBR, Weights);
CHR_DEBUG(dbgs() << "CHR branch bias " << Weights[0] << ":" << Weights[1]
<< "\n");
}
diff --git a/llvm/lib/Transforms/Instrumentation/IndirectCallPromotion.cpp b/llvm/lib/Transforms/Instrumentation/IndirectCallPromotion.cpp
index 6db76ca78b218..23a7c6a20aecb 100644
--- a/llvm/lib/Transforms/Instrumentation/IndirectCallPromotion.cpp
+++ b/llvm/lib/Transforms/Instrumentation/IndirectCallPromotion.cpp
@@ -259,8 +259,7 @@ CallBase &llvm::pgo::promoteIndirectCall(CallBase &CB, Function *DirectCallee,
promoteCallWithIfThenElse(CB, DirectCallee, BranchWeights);
if (AttachProfToDirectCall) {
- setBranchWeights(NewInst, {static_cast<uint32_t>(Count)},
- /*IsExpected=*/false);
+ setBranchWeights(NewInst, {static_cast<uint32_t>(Count)});
}
using namespace ore;
diff --git a/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp b/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
index ac6d3348b3db9..2269c2e0fffae 100644
--- a/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
+++ b/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
@@ -1474,8 +1474,7 @@ void PGOUseFunc::populateCoverage(IndexedInstrProfReader *PGOReader) {
for (auto *Succ : successors(&BB))
Weights.push_back((Coverage[Succ] || !Coverage[&BB]) ? 1 : 0);
if (Weights.size() >= 2)
- llvm::setBranchWeights(*BB.getTerminator(), Weights,
- /*IsExpected=*/false);
+ llvm::setBranchWeights(*BB.getTerminator(), Weights);
}
unsigned NumCorruptCoverage = 0;
@@ -2261,7 +2260,7 @@ void llvm::setProfMetadata(Module *M, Instruction *TI,
misexpect::checkExpectAnnotations(*TI, Weights, /*IsFrontend=*...
[truncated]
|
nikic
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Jun 11, 2024
nikic
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revert-86609-users/ilovepi/spr/llvmir-extend-branchweightmetadata-to-track-provenance-of-weights
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…f weights" llvm#95136 Reverts llvm#95060, and relands llvm#86609, with the unintended code generation changes addressed. This patch implements the changes to LLVM IR discussed in https://discourse.llvm.org/t/rfc-update-branch-weights-metadata-to-allow-tracking-branch-weight-origins/75032 In this patch, we add an optional field to MD_prof meatdata nodes for branch weights, which can be used to distinguish weights added from llvm.expect* intrinsics from those added via other methods, e.g. from profiles or inserted by the compiler. One of the major motivations, is for use with MisExpect diagnostics, which need to know if branch_weight metadata originates from an llvm.expect intrinsic. Without that information, we end up checking branch weights multiple times in the case if ThinLTO + SampleProfiling, leading to some inaccuracy in how we report MisExpect related diagnostics to users. Since we change the format of MD_prof metadata in a fundamental way, we need to update code handling branch weights in a number of places. We also update the lang ref for branch weights to reflect the change.
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Jun 12, 2024
… weights" (llvm#95060) Reverts llvm#86609 This change causes compile-time regressions for stage2 builds (https://llvm-compile-time-tracker.com/compare.php?from=3254f31a66263ea9647c9547f1531c3123444fcd&to=c5978f1eb5eeca8610b9dfce1fcbf1f473911cd8&stat=instructions:u). It also introduced unintended changes to `.text` which should be addressed before relanding.
nikic
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to nikic/llvm-project
that referenced
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Jun 12, 2024
…f weights" llvm#95136 Reverts llvm#95060, and relands llvm#86609, with the unintended code generation changes addressed. This patch implements the changes to LLVM IR discussed in https://discourse.llvm.org/t/rfc-update-branch-weights-metadata-to-allow-tracking-branch-weight-origins/75032 In this patch, we add an optional field to MD_prof meatdata nodes for branch weights, which can be used to distinguish weights added from llvm.expect* intrinsics from those added via other methods, e.g. from profiles or inserted by the compiler. One of the major motivations, is for use with MisExpect diagnostics, which need to know if branch_weight metadata originates from an llvm.expect intrinsic. Without that information, we end up checking branch weights multiple times in the case if ThinLTO + SampleProfiling, leading to some inaccuracy in how we report MisExpect related diagnostics to users. Since we change the format of MD_prof metadata in a fundamental way, we need to update code handling branch weights in a number of places. We also update the lang ref for branch weights to reflect the change.
ilovepi
added a commit
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this pull request
Jun 12, 2024
#95281) …f weights" #95136 Reverts #95060, and relands #86609, with the unintended code generation changes addressed. This patch implements the changes to LLVM IR discussed in https://discourse.llvm.org/t/rfc-update-branch-weights-metadata-to-allow-tracking-branch-weight-origins/75032 In this patch, we add an optional field to MD_prof meatdata nodes for branch weights, which can be used to distinguish weights added from llvm.expect* intrinsics from those added via other methods, e.g. from profiles or inserted by the compiler. One of the major motivations, is for use with MisExpect diagnostics, which need to know if branch_weight metadata originates from an llvm.expect intrinsic. Without that information, we end up checking branch weights multiple times in the case if ThinLTO + SampleProfiling, leading to some inaccuracy in how we report MisExpect related diagnostics to users. Since we change the format of MD_prof metadata in a fundamental way, we need to update code handling branch weights in a number of places. We also update the lang ref for branch weights to reflect the change.
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Reverts #86609
This change causes compile-time regressions for stage2 builds (https://llvm-compile-time-tracker.com/compare.php?from=3254f31a66263ea9647c9547f1531c3123444fcd&to=c5978f1eb5eeca8610b9dfce1fcbf1f473911cd8&stat=instructions:u). It also introduced unintended changes to
.textwhich should be addressed before relanding.