Reapply "[llvm][IR] Extend BranchWeightMetadata to track provenance of weights" #95136
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…nance of…" This reverts commit 607afa0.
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@llvm/pr-subscribers-llvm-ir @llvm/pr-subscribers-clang Author: Paul Kirth (ilovepi) ChangesReverts llvm/llvm-project#95060, and relands #86609, with the unintended code generation changes addressed. This patch implements the changes to LLVM IR discussed in In this patch, we add an optional field to MD_prof meatdata nodes for One of the major motivations, is for use with MisExpect diagnostics, Since we change the format of MD_prof metadata in a fundamental way, we We also update the lang ref for branch weights to reflect the change. Patch is 38.70 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/95136.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 fb236aeb982e0..81d9334356520 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", i32 2000, i32 1}
-// CHECK: [[BW_UNLIKELY]] = !{!"branch_weights", i32 1, i32 2000}
+// CHECK: [[BW_LIKELY]] = !{!"branch_weights", !"expected", i32 2000, i32 1}
+// CHECK: [[BW_UNLIKELY]] = !{!"branch_weights", !"expected", i32 1, i32 2000}
diff --git a/llvm/docs/BranchWeightMetadata.rst b/llvm/docs/BranchWeightMetadata.rst
index 522f37cdad4fc..62204753e29b0 100644
--- a/llvm/docs/BranchWeightMetadata.rst
+++ b/llvm/docs/BranchWeightMetadata.rst
@@ -28,11 +28,14 @@ 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>
}
@@ -47,6 +50,7 @@ is always case #0).
!0 = !{
!"branch_weights",
+ [ !"expected", ]
i32 <DEFAULT_BRANCH_WEIGHT>
[ , i32 <CASE_BRANCH_WEIGHT> ... ]
}
@@ -60,6 +64,7 @@ Branch weights are assigned to every destination.
!0 = !{
!"branch_weights",
+ [ !"expected", ]
i32 <LABEL_BRANCH_WEIGHT>
[ , i32 <LABEL_BRANCH_WEIGHT> ... ]
}
@@ -75,6 +80,7 @@ block and entry counts which may not be accurate with sampling.
!0 = !{
!"branch_weights",
+ [ !"expected", ]
i32 <CALL_BRANCH_WEIGHT>
}
@@ -95,6 +101,7 @@ 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 3265589b7c8df..e02ec8f5a3d8b 100644
--- a/llvm/include/llvm/IR/MDBuilder.h
+++ b/llvm/include/llvm/IR/MDBuilder.h
@@ -59,7 +59,11 @@ class MDBuilder {
//===------------------------------------------------------------------===//
/// Return metadata containing two branch weights.
- MDNode *createBranchWeights(uint32_t TrueWeight, uint32_t FalseWeight);
+ /// @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);
/// Return metadata containing two branch weights, with significant bias
/// towards `true` destination.
@@ -70,7 +74,10 @@ class MDBuilder {
MDNode *createUnlikelyBranchWeights();
/// Return metadata containing a number of branch weights.
- MDNode *createBranchWeights(ArrayRef<uint32_t> 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);
/// 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 88fbad4d6b9d8..1d7c97d9be953 100644
--- a/llvm/include/llvm/IR/ProfDataUtils.h
+++ b/llvm/include/llvm/IR/ProfDataUtils.h
@@ -55,6 +55,17 @@ 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.
@@ -111,7 +122,11 @@ 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`.
-void setBranchWeights(Instruction &I, ArrayRef<uint32_t> Weights);
+/// \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);
/// 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 339a1f1f2f002..0e01080bd75cc 100644
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -8866,7 +8866,8 @@ bool CodeGenPrepare::splitBranchCondition(Function &F, ModifyDT &ModifiedDT) {
scaleWeights(NewTrueWeight, NewFalseWeight);
Br1->setMetadata(LLVMContext::MD_prof,
MDBuilder(Br1->getContext())
- .createBranchWeights(TrueWeight, FalseWeight));
+ .createBranchWeights(TrueWeight, FalseWeight,
+ hasBranchWeightOrigin(*Br1)));
NewTrueWeight = TrueWeight;
NewFalseWeight = 2 * FalseWeight;
diff --git a/llvm/lib/IR/Instruction.cpp b/llvm/lib/IR/Instruction.cpp
index 29272e627a1d1..aec927a8cf31d 100644
--- a/llvm/lib/IR/Instruction.cpp
+++ b/llvm/lib/IR/Instruction.cpp
@@ -1268,12 +1268,23 @@ Instruction *Instruction::cloneImpl() const {
void Instruction::swapProfMetadata() {
MDNode *ProfileData = getBranchWeightMDNode(*this);
- if (!ProfileData || ProfileData->getNumOperands() != 3)
+ if (!ProfileData)
+ return;
+ unsigned FirstIdx = getBranchWeightOffset(ProfileData);
+ if (ProfileData->getNumOperands() != 2 + FirstIdx)
return;
- // 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)};
+ 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));
setMetadata(LLVMContext::MD_prof,
MDNode::get(ProfileData->getContext(), Ops));
}
diff --git a/llvm/lib/IR/Instructions.cpp b/llvm/lib/IR/Instructions.cpp
index 1213f078d05ec..de369bd62a617 100644
--- a/llvm/lib/IR/Instructions.cpp
+++ b/llvm/lib/IR/Instructions.cpp
@@ -5199,7 +5199,11 @@ void SwitchInstProfUpdateWrapper::init() {
if (!ProfileData)
return;
- if (ProfileData->getNumOperands() != SI.getNumSuccessors() + 1) {
+ // 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)) {
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 bd68db3a6f961..000027754d13e 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) {
- return createBranchWeights({TrueWeight, FalseWeight});
+ uint32_t FalseWeight, bool IsExpected) {
+ return createBranchWeights({TrueWeight, FalseWeight}, IsExpected);
}
MDNode *MDBuilder::createLikelyBranchWeights() {
@@ -49,15 +49,19 @@ MDNode *MDBuilder::createUnlikelyBranchWeights() {
return createBranchWeights(1, (1U << 20) - 1);
}
-MDNode *MDBuilder::createBranchWeights(ArrayRef<uint32_t> Weights) {
+MDNode *MDBuilder::createBranchWeights(ArrayRef<uint32_t> Weights,
+ bool IsExpected) {
assert(Weights.size() >= 1 && "Need at least one branch weights!");
- SmallVector<Metadata *, 4> Vals(Weights.size() + 1);
+ unsigned int Offset = IsExpected ? 2 : 1;
+ SmallVector<Metadata *, 4> Vals(Weights.size() + Offset);
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 + 1] = createConstant(ConstantInt::get(Int32Ty, Weights[i]));
+ Vals[i + Offset] = 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 b6c932495a145..5f42ce22f72fe 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(1));
- ConstantInt *BInstrWeight =
- mdconst::dyn_extract<ConstantInt>(B->getOperand(1));
+ ConstantInt *AInstrWeight = mdconst::dyn_extract<ConstantInt>(
+ A->getOperand(getBranchWeightOffset(A)));
+ ConstantInt *BInstrWeight = mdconst::dyn_extract<ConstantInt>(
+ B->getOperand(getBranchWeightOffset(B)));
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 51e78dc5e6c00..c4b1ed55de8a2 100644
--- a/llvm/lib/IR/ProfDataUtils.cpp
+++ b/llvm/lib/IR/ProfDataUtils.cpp
@@ -40,9 +40,6 @@ 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;
@@ -75,6 +72,7 @@ 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);
@@ -82,8 +80,8 @@ 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() <= 32 &&
- "Too many bits for uint32_t");
+ assert(Weight->getValue().getActiveBits() <= (sizeof(T) * 8) &&
+ "Too many bits for MD_prof branch_weight");
Weights[Idx - WeightsIdx] = Weight->getZExtValue();
}
}
@@ -123,6 +121,26 @@ 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))
@@ -132,7 +150,9 @@ MDNode *getBranchWeightMDNode(const Instruction &I) {
MDNode *getValidBranchWeightMDNode(const Instruction &I) {
auto *ProfileData = getBranchWeightMDNode(I);
- if (ProfileData && ProfileData->getNumOperands() == 1 + I.getNumSuccessors())
+ auto Offset = getBranchWeightOffset(ProfileData);
+ if (ProfileData &&
+ ProfileData->getNumOperands() == Offset + I.getNumSuccessors())
return ProfileData;
return nullptr;
}
@@ -191,7 +211,8 @@ bool extractProfTotalWeight(const MDNode *ProfileData, uint64_t &TotalVal) {
return false;
if (ProfDataName->getString() == "branch_weights") {
- for (unsigned Idx = 1; Idx < ProfileData->getNumOperands(); Idx++) {
+ unsigned Offset = getBranchWeightOffset(ProfileData);
+ for (unsigned Idx = Offset; 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();
@@ -212,9 +233,10 @@ bool extractProfTotalWeight(const Instruction &I, uint64_t &TotalVal) {
return extractProfTotalWeight(I.getMetadata(LLVMContext::MD_prof), TotalVal);
}
-void setBranchWeights(Instruction &I, ArrayRef<uint32_t> Weights) {
+void setBranchWeights(Instruction &I, ArrayRef<uint32_t> Weights,
+ bool IsExpected) {
MDBuilder MDB(I.getContext());
- MDNode *BranchWeights = MDB.createBranchWeights(Weights);
+ MDNode *BranchWeights = MDB.createBranchWeights(Weights, IsExpected);
I.setMetadata(LLVMContext::MD_prof, BranchWeights);
}
diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp
index e5927203f33a2..fe2253dd04eb3 100644
--- a/llvm/lib/IR/Verifier.cpp
+++ b/llvm/lib/IR/Verifier.cpp
@@ -104,6 +104,7 @@
#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"
@@ -4808,8 +4809,10 @@ 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() == 2 || MD->getNumOperands() == 3,
+ Check(MD->getNumOperands() == (1 + Offset) ||
+ MD->getNumOperands() == (2 + Offset),
"Wrong number of InvokeInst branch_weights operands", MD);
} else {
unsigned ExpectedNumOperands = 0;
@@ -4829,10 +4832,10 @@ void Verifier::visitProfMetadata(Instruction &I, MDNode *MD) {
CheckFailed("!prof branch_weights are not allowed for this instruction",
MD);
- Check(MD->getNumOperands() == 1 + ExpectedNumOperands,
+ Check(MD->getNumOperands() == Offset + ExpectedNumOperands,
"Wrong number of operands", MD);
}
- for (unsigned i = 1; i < MD->getNumOperands(); ++i) {
+ for (unsigned i = Offset; 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 92ad4c34da6e7..7e6a8817b7a67 100644
--- a/llvm/lib/Transforms/IPO/SampleProfile.cpp
+++ b/llvm/lib/Transforms/IPO/SampleProfile.cpp
@@ -1662,7 +1662,8 @@ 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])});
+ setBranchWeights(I, {static_cast<uint32_t>(BlockWeights[BB])},
+ /*IsExpected=*/false);
}
}
} else if (OverwriteExistingWeights || ProfileSampleBlockAccurate) {
@@ -1673,7 +1674,7 @@ void SampleProfileLoader::generateMDProfMetadata(Function &F) {
if (cast<CallBase>(I).isIndirectCall()) {
I.setMetadata(LLVMContext::MD_prof, nullptr);
} else {
- setBranchWeights(I, {uint32_t(0)});
+ setBranchWeights(I, {uint32_t(0)}, /*IsExpected=*/false);
}
}
}
@@ -1756,7 +1757,7 @@ void SampleProfileLoader::generateMDProfMetadata(Function &F) {
if (MaxWeight > 0 &&
(!TI->extractProfTotalWeight(TempWeight) || OverwriteExistingWeights)) {
LLVM_DEBUG(dbgs() << "SUCCESS. Found non-zero weights.\n");
- setBranchWeights(*TI, Weights);
+ setBranchWeights(*TI, Weights, /*IsExpected=*/false);
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 0a3d8d6000cf4..731104d4fcef0 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);
+ setBranchWeights(*MergedBR, Weights, /*IsExpected=*/false);
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 23a7c6a20aecb..6db76ca78b218 100644
--- a/llvm/lib/Transforms/Instrumentation/IndirectCallPromotion.cpp
+++ b/llvm/lib/Transforms/Instrumentation/IndirectCallPromotion.cpp
@@ -259,7 +259,8 @@ CallBase &llvm::pgo::promoteIndirectCall(CallBase &CB, Function *DirectCallee,
promoteCallWithIfThenElse(CB, DirectCallee, BranchWeights);
if (AttachProfToDirectCall) {
- setBranchWeights(NewInst, {static_cast<uint32_t>(Count)});
+ setBranchWeights(NewInst, {static_cast<uint32_t>(Count)},
+ /*IsExpected=*/false);
}
using namespace ore;
diff --git a/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp b/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
index 2269c2e0fffae..ac6d3348b3db9 100644
--- a/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
+++ b/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
@@ -1474,7 +1474,8 @@ 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);
+ llvm::setBranchWeights(*BB.getTerminator(), Weights,
+ /*IsExpected=*/false);
}
unsigned NumCorruptCoverage = 0;
@@ -2260,7 +2261,7 @@ void llvm::setProfMetadata(Module *M, Instruction *TI,
misexpect::checkExpectAnnotations(*TI, Weights, /*IsFrontend=*...
[truncated]
|
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Still looking into the codegen issue, but I'd expect there's probably just 1-2 cases where I failed to update a pass to use APIs from ProfDataUtils. |
|
What is the summary of the new changes that address the compile time issue? |
ilovepi
added a commit
to ilovepi/llvm-project
that referenced
this pull request
Jun 11, 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.
I'm still looking at that, that's why I marked it as a draft, but I suspect I just missed updating llvm-project/llvm/lib/IR/ProfDataUtils.cpp Line 244 in 163d036 .text
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So, I think I made a mistake when I started the revert w/ the I'm about 80% sure I'm much more confident in my ability to update using a PR started from my fork, so I'm closing in favor of #95281 |
nikic
pushed a commit
to nikic/llvm-project
that referenced
this pull request
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
that referenced
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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 #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.