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[MC/DC] Create dedicated MCDCCondBitmapAddr for each Decision #125411

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[MC/DC] Create dedicated MCDCCondBitmapAddr for each Decision #125411

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c74e5af
[MC/DC] Create dedicated MCDCCondBitmapAddr for each Decision
chapuni Feb 2, 2025
4d531f3
Prune mcdc-single-cond.cpp
chapuni Mar 1, 2025
d6cb61a
Merge branch 'users/chapuni/mcdc/nest/tests' into users/chapuni/mcdc/…
chapuni Mar 1, 2025
7ee8e06
Merge branch 'users/chapuni/mcdc/nest/mcdcstate' into users/chapuni/m…
chapuni Mar 1, 2025
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17 changes: 9 additions & 8 deletions clang/lib/CodeGen/CodeGenFunction.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1671,9 +1671,6 @@ class CodeGenFunction : public CodeGenTypeCache {

CodeGenPGO PGO;

/// Bitmap used by MC/DC to track condition outcomes of a boolean expression.
Address MCDCCondBitmapAddr = Address::invalid();

/// Calculate branch weights appropriate for PGO data
llvm::MDNode *createProfileWeights(uint64_t TrueCount,
uint64_t FalseCount) const;
Expand Down Expand Up @@ -1712,8 +1709,12 @@ class CodeGenFunction : public CodeGenTypeCache {
void maybeCreateMCDCCondBitmap() {
if (isMCDCCoverageEnabled()) {
PGO.emitMCDCParameters(Builder);
MCDCCondBitmapAddr =
CreateIRTemp(getContext().UnsignedIntTy, "mcdc.addr");

// Set up MCDCCondBitmapAddr for each Decision.
// Note: This doesn't initialize Addrs in invalidated Decisions.
for (auto *MCDCCondBitmapAddr : PGO.getMCDCCondBitmapAddrArray(Builder))
*MCDCCondBitmapAddr =
CreateIRTemp(getContext().UnsignedIntTy, "mcdc.addr");
}
}

Expand All @@ -1725,7 +1726,7 @@ class CodeGenFunction : public CodeGenTypeCache {
/// Zero-init the MCDC temp value.
void maybeResetMCDCCondBitmap(const Expr *E) {
if (isMCDCCoverageEnabled() && isBinaryLogicalOp(E)) {
PGO.emitMCDCCondBitmapReset(Builder, E, MCDCCondBitmapAddr);
PGO.emitMCDCCondBitmapReset(Builder, E);
PGO.setCurrentStmt(E);
}
}
Expand All @@ -1734,15 +1735,15 @@ class CodeGenFunction : public CodeGenTypeCache {
/// If \p StepV is null, the default increment is 1.
void maybeUpdateMCDCTestVectorBitmap(const Expr *E) {
if (isMCDCCoverageEnabled() && isBinaryLogicalOp(E)) {
PGO.emitMCDCTestVectorBitmapUpdate(Builder, E, MCDCCondBitmapAddr, *this);
PGO.emitMCDCTestVectorBitmapUpdate(Builder, E, *this);
PGO.setCurrentStmt(E);
}
}

/// Update the MCDC temp value with the condition's evaluated result.
void maybeUpdateMCDCCondBitmap(const Expr *E, llvm::Value *Val) {
if (isMCDCCoverageEnabled()) {
PGO.emitMCDCCondBitmapUpdate(Builder, E, MCDCCondBitmapAddr, Val, *this);
PGO.emitMCDCCondBitmapUpdate(Builder, E, Val, *this);
PGO.setCurrentStmt(E);
}
}
Expand Down
41 changes: 35 additions & 6 deletions clang/lib/CodeGen/CodeGenPGO.cpp
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Expand Up @@ -1245,9 +1245,29 @@ void CodeGenPGO::emitMCDCParameters(CGBuilderTy &Builder) {
CGM.getIntrinsic(llvm::Intrinsic::instrprof_mcdc_parameters), Args);
}

/// Fill mcdc.addr order by ID.
std::vector<Address *>
CodeGenPGO::getMCDCCondBitmapAddrArray(CGBuilderTy &Builder) {
std::vector<Address *> Result;

if (!canEmitMCDCCoverage(Builder) || !RegionMCDCState)
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should we ever call this function if canEmitMCDCCoverage is false?

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It seems that many parts of the code already follow this pattern. Therefore, I think I'm fine with this for now. I think it should be cleaned up eventually though.

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I'll take a look in the future. Please be patient. :)

return Result;

SmallVector<std::pair<unsigned, Address *>> SortedPair;
for (auto &[_, V] : RegionMCDCState->DecisionByStmt)
if (V.isValid())
SortedPair.emplace_back(V.ID, &V.MCDCCondBitmapAddr);

llvm::sort(SortedPair);

for (auto &[_, MCDCCondBitmapAddr] : SortedPair)
Result.push_back(MCDCCondBitmapAddr);

return Result;
}

void CodeGenPGO::emitMCDCTestVectorBitmapUpdate(CGBuilderTy &Builder,
const Expr *S,
Address MCDCCondBitmapAddr,
CodeGenFunction &CGF) {
if (!canEmitMCDCCoverage(Builder) || !RegionMCDCState)
return;
Expand All @@ -1258,6 +1278,10 @@ void CodeGenPGO::emitMCDCTestVectorBitmapUpdate(CGBuilderTy &Builder,
if (DecisionStateIter == RegionMCDCState->DecisionByStmt.end())
return;

auto &MCDCCondBitmapAddr = DecisionStateIter->second.MCDCCondBitmapAddr;
if (!MCDCCondBitmapAddr.isValid())
return;

// Don't create tvbitmap_update if the record is allocated but excluded.
// Or `bitmap |= (1 << 0)` would be wrongly executed to the next bitmap.
if (DecisionStateIter->second.Indices.size() == 0)
Expand All @@ -1280,22 +1304,23 @@ void CodeGenPGO::emitMCDCTestVectorBitmapUpdate(CGBuilderTy &Builder,
CGM.getIntrinsic(llvm::Intrinsic::instrprof_mcdc_tvbitmap_update), Args);
}

void CodeGenPGO::emitMCDCCondBitmapReset(CGBuilderTy &Builder, const Expr *S,
Address MCDCCondBitmapAddr) {
void CodeGenPGO::emitMCDCCondBitmapReset(CGBuilderTy &Builder, const Expr *S) {
if (!canEmitMCDCCoverage(Builder) || !RegionMCDCState)
return;

S = S->IgnoreParens();
auto I = RegionMCDCState->DecisionByStmt.find(S->IgnoreParens());
if (I == RegionMCDCState->DecisionByStmt.end())
return;

if (!RegionMCDCState->DecisionByStmt.contains(S))
auto &MCDCCondBitmapAddr = I->second.MCDCCondBitmapAddr;
if (!MCDCCondBitmapAddr.isValid())
return;

// Emit intrinsic that resets a dedicated temporary value on the stack to 0.
Builder.CreateStore(Builder.getInt32(0), MCDCCondBitmapAddr);
}

void CodeGenPGO::emitMCDCCondBitmapUpdate(CGBuilderTy &Builder, const Expr *S,
Address MCDCCondBitmapAddr,
llvm::Value *Val,
CodeGenFunction &CGF) {
if (!canEmitMCDCCoverage(Builder) || !RegionMCDCState)
Expand Down Expand Up @@ -1325,6 +1350,10 @@ void CodeGenPGO::emitMCDCCondBitmapUpdate(CGBuilderTy &Builder, const Expr *S,
if (DecisionIter == RegionMCDCState->DecisionByStmt.end())
return;

auto &MCDCCondBitmapAddr = DecisionIter->second.MCDCCondBitmapAddr;
if (!MCDCCondBitmapAddr.isValid())
return;

const auto &TVIdxs = DecisionIter->second.Indices[Branch.ID];

auto *CurTV = Builder.CreateLoad(MCDCCondBitmapAddr,
Expand Down
8 changes: 3 additions & 5 deletions clang/lib/CodeGen/CodeGenPGO.h
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Expand Up @@ -114,14 +114,12 @@ class CodeGenPGO {
void emitCounterSetOrIncrement(CGBuilderTy &Builder, const Stmt *S,
llvm::Value *StepV);
void emitMCDCTestVectorBitmapUpdate(CGBuilderTy &Builder, const Expr *S,
Address MCDCCondBitmapAddr,
CodeGenFunction &CGF);
void emitMCDCParameters(CGBuilderTy &Builder);
void emitMCDCCondBitmapReset(CGBuilderTy &Builder, const Expr *S,
Address MCDCCondBitmapAddr);
std::vector<Address *> getMCDCCondBitmapAddrArray(CGBuilderTy &Builder);
void emitMCDCCondBitmapReset(CGBuilderTy &Builder, const Expr *S);
void emitMCDCCondBitmapUpdate(CGBuilderTy &Builder, const Expr *S,
Address MCDCCondBitmapAddr, llvm::Value *Val,
CodeGenFunction &CGF);
llvm::Value *Val, CodeGenFunction &CGF);

void markStmtAsUsed(bool Skipped, const Stmt *S) {
// Do nothing.
Expand Down
2 changes: 2 additions & 0 deletions clang/lib/CodeGen/MCDCState.h
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,7 @@
#ifndef LLVM_CLANG_LIB_CODEGEN_MCDCSTATE_H
#define LLVM_CLANG_LIB_CODEGEN_MCDCSTATE_H

#include "Address.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ProfileData/Coverage/MCDCTypes.h"
Expand All @@ -38,6 +39,7 @@ struct State {
unsigned BitmapIdx;
IndicesTy Indices;
unsigned ID = InvalidID;
Address MCDCCondBitmapAddr = Address::invalid();

bool isValid() const { return ID != InvalidID; }

Expand Down
18 changes: 10 additions & 8 deletions clang/test/Profile/c-mcdc-logicalop-ternary.c
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Expand Up @@ -13,12 +13,14 @@ int test(int a, int b, int c, int d, int e, int f) {

// ALLOCATE MCDC TEMP AND ZERO IT.
// MCDC-LABEL: @test(
// MCDC: %mcdc.addr = alloca i32, align 4
// MCDC: store i32 0, ptr %mcdc.addr, align 4
// MCDC: %[[ADDR0:mcdc.+]] = alloca i32, align 4
// MCDC: %[[ADDR1:mcdc.+]] = alloca i32, align 4
// MCDC: %[[ADDR2:mcdc.+]] = alloca i32, align 4
// MCDC: store i32 0, ptr %[[ADDR0]], align 4

// TERNARY TRUE SHOULD UPDATE THE BITMAP WITH RESULT AT ELEMENT 0.
// MCDC-LABEL: cond.true:
// MCDC-DAG: %[[TEMP0:mcdc.temp[0-9]*]] = load i32, ptr %mcdc.addr, align 4
// MCDC-DAG: %[[TEMP0:mcdc.temp[0-9]*]] = load i32, ptr %[[ADDR0]], align 4
// MCDC: %[[TEMP:[0-9]+]] = add i32 %[[TEMP0]], 0
// MCDC: %[[LAB1:[0-9]+]] = lshr i32 %[[TEMP]], 3
// MCDC: %[[LAB4:[0-9]+]] = getelementptr inbounds i8, ptr @__profbm_test, i32 %[[LAB1]]
Expand All @@ -30,12 +32,12 @@ int test(int a, int b, int c, int d, int e, int f) {
// MCDC: store i8 %[[LAB9]], ptr %[[LAB4]], align 1

// CHECK FOR ZERO OF MCDC TEMP
// MCDC: store i32 0, ptr %mcdc.addr, align 4
// MCDC: store i32 0, ptr %[[ADDR1]], align 4

// TERNARY TRUE YIELDS TERNARY LHS LOGICAL-AND.
// TERNARY LHS LOGICAL-AND SHOULD UPDATE THE BITMAP WITH RESULT AT ELEMENT 1.
// MCDC-LABEL: land.end:
// MCDC-DAG: %[[TEMP0:mcdc.temp[0-9]*]] = load i32, ptr %mcdc.addr, align 4
// MCDC-DAG: %[[TEMP0:mcdc.temp[0-9]*]] = load i32, ptr %[[ADDR1]], align 4
// MCDC: %[[TEMP:[0-9]+]] = add i32 %[[TEMP0]], 3
// MCDC: %[[LAB1:[0-9]+]] = lshr i32 %[[TEMP]], 3
// MCDC: %[[LAB4:[0-9]+]] = getelementptr inbounds i8, ptr @__profbm_test, i32 %[[LAB1]]
Expand All @@ -48,7 +50,7 @@ int test(int a, int b, int c, int d, int e, int f) {

// TERNARY FALSE SHOULD UPDATE THE BITMAP WITH RESULT AT ELEMENT 0.
// MCDC-LABEL: cond.false:
// MCDC-DAG: %[[TEMP0:mcdc.temp[0-9]*]] = load i32, ptr %mcdc.addr, align 4
// MCDC-DAG: %[[TEMP0:mcdc.+]] = load i32, ptr %[[ADDR0]], align 4
// MCDC: %[[TEMP:[0-9]+]] = add i32 %[[TEMP0]], 0
// MCDC: %[[LAB1:[0-9]+]] = lshr i32 %[[TEMP]], 3
// MCDC: %[[LAB4:[0-9]+]] = getelementptr inbounds i8, ptr @__profbm_test, i32 %[[LAB1]]
Expand All @@ -60,12 +62,12 @@ int test(int a, int b, int c, int d, int e, int f) {
// MCDC: store i8 %[[LAB9]], ptr %[[LAB4]], align 1

// CHECK FOR ZERO OF MCDC TEMP
// MCDC: store i32 0, ptr %mcdc.addr, align 4
// MCDC: store i32 0, ptr %[[ADDR2]], align 4

// TERNARY FALSE YIELDS TERNARY RHS LOGICAL-OR.
// TERNARY RHS LOGICAL-OR SHOULD UPDATE THE BITMAP WITH RESULT AT ELEMENT 2.
// MCDC-LABEL: lor.end:
// MCDC-DAG: %[[TEMP0:mcdc.temp[0-9]*]] = load i32, ptr %mcdc.addr, align 4
// MCDC-DAG: %[[TEMP0:mcdc.temp[0-9]*]] = load i32, ptr %[[ADDR2]], align 4
// MCDC: %[[TEMP:[0-9]+]] = add i32 %[[TEMP0]], 6
// MCDC: %[[LAB1:[0-9]+]] = lshr i32 %[[TEMP]], 3
// MCDC: %[[LAB4:[0-9]+]] = getelementptr inbounds i8, ptr @__profbm_test, i32 %[[LAB1]]
Expand Down