[llvm] [X86] Support hoisting load/store with conditional faulting (PR #95515)
Shengchen Kan via llvm-commits
llvm-commits at lists.llvm.org
Wed Jun 19 01:32:18 PDT 2024
https://github.com/KanRobert updated https://github.com/llvm/llvm-project/pull/95515
>From 4856cbe8f0d3dbdf4140258af47b8aefaa6fa65c Mon Sep 17 00:00:00 2001
From: Shengchen Kan <shengchen.kan at intel.com>
Date: Wed, 5 Jun 2024 15:04:27 +0800
Subject: [PATCH] [X86] Support hoisting load/store with conditional faulting
1. Add TTI interface for conditional load/store
2. Hoist load/store from successors if the targets support conditional
faulting
3. Lower masked load/store to CFCMOV
---
.../llvm/Analysis/TargetTransformInfo.h | 8 +
.../llvm/Analysis/TargetTransformInfoImpl.h | 1 +
llvm/lib/Analysis/TargetTransformInfo.cpp | 5 +
.../lib/Target/X86/X86TargetTransformInfo.cpp | 17 +
llvm/lib/Target/X86/X86TargetTransformInfo.h | 1 +
llvm/lib/Transforms/Utils/SimplifyCFG.cpp | 186 ++++++++-
llvm/test/CodeGen/X86/apx/cf.ll | 51 +++
.../X86/hoist-load-store-with-cf.ll | 357 ++++++++++++++++++
8 files changed, 623 insertions(+), 3 deletions(-)
create mode 100644 llvm/test/CodeGen/X86/apx/cf.ll
create mode 100644 llvm/test/Transforms/SimplifyCFG/X86/hoist-load-store-with-cf.ll
diff --git a/llvm/include/llvm/Analysis/TargetTransformInfo.h b/llvm/include/llvm/Analysis/TargetTransformInfo.h
index f55f21c94a85a..37afda39a1c9c 100644
--- a/llvm/include/llvm/Analysis/TargetTransformInfo.h
+++ b/llvm/include/llvm/Analysis/TargetTransformInfo.h
@@ -1113,6 +1113,10 @@ class TargetTransformInfo {
/// \return the number of registers in the target-provided register class.
unsigned getNumberOfRegisters(unsigned ClassID) const;
+ /// \return true if the target supports load/store that enables fault
+ /// suppression of memory operands when the source condition is false.
+ bool hasConditionalFaultingLoadStoreForType(Type *Ty) const;
+
/// \return the target-provided register class ID for the provided type,
/// accounting for type promotion and other type-legalization techniques that
/// the target might apply. However, it specifically does not account for the
@@ -1956,6 +1960,7 @@ class TargetTransformInfo::Concept {
virtual bool preferToKeepConstantsAttached(const Instruction &Inst,
const Function &Fn) const = 0;
virtual unsigned getNumberOfRegisters(unsigned ClassID) const = 0;
+ virtual bool hasConditionalFaultingLoadStoreForType(Type *Ty) const = 0;
virtual unsigned getRegisterClassForType(bool Vector,
Type *Ty = nullptr) const = 0;
virtual const char *getRegisterClassName(unsigned ClassID) const = 0;
@@ -2543,6 +2548,9 @@ class TargetTransformInfo::Model final : public TargetTransformInfo::Concept {
unsigned getNumberOfRegisters(unsigned ClassID) const override {
return Impl.getNumberOfRegisters(ClassID);
}
+ bool hasConditionalFaultingLoadStoreForType(Type *Ty) const override {
+ return Impl.hasConditionalFaultingLoadStoreForType(Ty);
+ }
unsigned getRegisterClassForType(bool Vector,
Type *Ty = nullptr) const override {
return Impl.getRegisterClassForType(Vector, Ty);
diff --git a/llvm/include/llvm/Analysis/TargetTransformInfoImpl.h b/llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
index 7828bdc1f1f43..a4aa836ed82d3 100644
--- a/llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
+++ b/llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
@@ -457,6 +457,7 @@ class TargetTransformInfoImplBase {
}
unsigned getNumberOfRegisters(unsigned ClassID) const { return 8; }
+ bool hasConditionalFaultingLoadStoreForType(Type *Ty) const { return false; }
unsigned getRegisterClassForType(bool Vector, Type *Ty = nullptr) const {
return Vector ? 1 : 0;
diff --git a/llvm/lib/Analysis/TargetTransformInfo.cpp b/llvm/lib/Analysis/TargetTransformInfo.cpp
index 7e721cbc87f3f..46936f266bf46 100644
--- a/llvm/lib/Analysis/TargetTransformInfo.cpp
+++ b/llvm/lib/Analysis/TargetTransformInfo.cpp
@@ -722,6 +722,11 @@ unsigned TargetTransformInfo::getNumberOfRegisters(unsigned ClassID) const {
return TTIImpl->getNumberOfRegisters(ClassID);
}
+bool TargetTransformInfo::hasConditionalFaultingLoadStoreForType(
+ Type *Ty) const {
+ return TTIImpl->hasConditionalFaultingLoadStoreForType(Ty);
+}
+
unsigned TargetTransformInfo::getRegisterClassForType(bool Vector,
Type *Ty) const {
return TTIImpl->getRegisterClassForType(Vector, Ty);
diff --git a/llvm/lib/Target/X86/X86TargetTransformInfo.cpp b/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
index de0144331dba3..3dcfaf9ff98d5 100644
--- a/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
+++ b/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
@@ -176,6 +176,23 @@ unsigned X86TTIImpl::getNumberOfRegisters(unsigned ClassID) const {
return 8;
}
+bool X86TTIImpl::hasConditionalFaultingLoadStoreForType(Type *Ty) const {
+ // Conditional faulting is supported by CFCMOV, which only accepts
+ // 16/32/64-bit operands.
+ // NOTE: Though VMOVSS/VMOVSD suppresses memory fault with zero mask, it has
+ // performance penalty.
+ if (!ST->hasCF() || !Ty || !Ty->isIntegerTy())
+ return false;
+ switch (cast<IntegerType>(Ty)->getBitWidth()) {
+ default:
+ return false;
+ case 16:
+ case 32:
+ case 64:
+ return true;
+ }
+}
+
TypeSize
X86TTIImpl::getRegisterBitWidth(TargetTransformInfo::RegisterKind K) const {
unsigned PreferVectorWidth = ST->getPreferVectorWidth();
diff --git a/llvm/lib/Target/X86/X86TargetTransformInfo.h b/llvm/lib/Target/X86/X86TargetTransformInfo.h
index e14dc9fc09051..701648c6a2b3a 100644
--- a/llvm/lib/Target/X86/X86TargetTransformInfo.h
+++ b/llvm/lib/Target/X86/X86TargetTransformInfo.h
@@ -132,6 +132,7 @@ class X86TTIImpl : public BasicTTIImplBase<X86TTIImpl> {
/// @{
unsigned getNumberOfRegisters(unsigned ClassID) const;
+ bool hasConditionalFaultingLoadStoreForType(Type *Ty) const;
TypeSize getRegisterBitWidth(TargetTransformInfo::RegisterKind K) const;
unsigned getLoadStoreVecRegBitWidth(unsigned AS) const;
unsigned getMaxInterleaveFactor(ElementCount VF);
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index 4e2dc7f2b2f4e..73f382d8b5386 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -131,6 +131,12 @@ static cl::opt<bool> HoistCondStores(
"simplifycfg-hoist-cond-stores", cl::Hidden, cl::init(true),
cl::desc("Hoist conditional stores if an unconditional store precedes"));
+static cl::opt<bool> HoistLoadsStoresWithCondFaulting(
+ "simplifycfg-hoist-loads-stores-with-cond-faulting", cl::Hidden,
+ cl::init(true),
+ cl::desc("Hoist loads/stores if the target supports "
+ "conditional faulting"));
+
static cl::opt<bool> MergeCondStores(
"simplifycfg-merge-cond-stores", cl::Hidden, cl::init(true),
cl::desc("Hoist conditional stores even if an unconditional store does not "
@@ -275,6 +281,7 @@ class SimplifyCFGOpt {
bool hoistSuccIdenticalTerminatorToSwitchOrIf(
Instruction *TI, Instruction *I1,
SmallVectorImpl<Instruction *> &OtherSuccTIs);
+ bool hoistLoadStoreWithCondFaultingFromSuccessors(BasicBlock *BB);
bool SpeculativelyExecuteBB(BranchInst *BI, BasicBlock *ThenBB);
bool SimplifyTerminatorOnSelect(Instruction *OldTerm, Value *Cond,
BasicBlock *TrueBB, BasicBlock *FalseBB,
@@ -2960,6 +2967,173 @@ static bool validateAndCostRequiredSelects(BasicBlock *BB, BasicBlock *ThenBB,
return HaveRewritablePHIs;
}
+/// Hoist load/store instructions from the conditional successor blocks up into
+/// the block.
+///
+/// We are looking for code like the following:
+/// \code
+/// BB:
+/// ...
+/// %cond = icmp ult %x, %y
+/// br i1 %cond, label %TrueBB, label %FalseBB
+/// FalseBB:
+/// store i32 1, ptr %q, align 4
+/// ...
+/// TrueBB:
+/// %0 = load i32, ptr %b, align 4
+/// store i32 %0, ptr %p, align 4
+/// ...
+/// \endcode
+//
+/// We are going to transform this into:
+///
+/// \code
+/// BB:
+/// ...
+/// %cond = icmp ult %x, %y
+/// %0 = cload i32, ptr %b, %cond
+/// cstore i32 %0, ptr %p, %cond
+/// cstore i32 1, ptr %q, ~%cond
+/// br i1 %cond, label %TrueBB, label %FalseBB
+/// FalseBB:
+/// ...
+/// TrueBB:
+/// ...
+/// \endcode
+///
+/// where cload/cstore is represented by llvm.masked.load/store, e.g.
+///
+/// \code
+/// %vcond = insertelement <1 x i1> undef, i1 %cond, i32 0
+/// %v0 = call <1 x i32> @llvm.masked.load.v1i32.p0
+/// (ptr %b, i32 4, <1 x i1> %vcond, <1 x i32> poison)
+/// %0 = bitcast <1 x i32> %v0 to i32
+/// call void @llvm.masked.store.v1i32.p0
+// (<1 x i32> %v0, ptr %p, i32 4, <1 x i1> %vcond)
+/// %cond.not = xor i1 %cond, true
+/// %vcond.not = insertelement <1 x i1> undef, i1 %cond.not, i32 0
+/// call void @llvm.masked.store.v1i32.p0
+/// (<1 x i32> <i32 1>, ptr %q, i32 4, <1x i1> %vcond.not)
+/// \endcode
+///
+/// \returns true if any load/store is hosited.
+///
+/// Note that this tranform should be run
+/// * before SpeculativelyExecuteBB so that the latter can have more chance.
+/// * after hoistCommonCodeFromSuccessors to ensure unconditional loads/stores
+/// are handled first.
+bool SimplifyCFGOpt::hoistLoadStoreWithCondFaultingFromSuccessors(
+ BasicBlock *BB) {
+ auto *BI = dyn_cast<BranchInst>(BB->getTerminator());
+ if (!BI || !BI->isConditional())
+ return false;
+
+ BasicBlock *IfTrueBB = BI->getSuccessor(0);
+ BasicBlock *IfFalseBB = BI->getSuccessor(1);
+
+ // If either of the blocks has it's address taken, then we can't do this fold,
+ // because the code we'd hoist would no longer run when we jump into the block
+ // by it's address.
+ for (auto *Succ : {IfTrueBB, IfFalseBB})
+ if (Succ->hasAddressTaken() || !Succ->getSinglePredecessor())
+ return false;
+
+ // Collect hoisted loads/stores.
+ SmallSetVector<Instruction *, 4> HoistedInsts;
+ // Not hoist load/store if
+ // 1. target does not have corresponding conditional faulting load/store.
+ // 2. it's volatile or atomic.
+ // 3. there is a load/store that can not be hoisted in the same bb.
+ // 4. there is a non-load/store that may have side effects in the same bb.
+ // 5. any operand of it does not dominate the branch.
+ // 6. it's a store and a memory read is skipped.
+ auto HoistInstsInBB = [&](BasicBlock *BB) {
+ bool SkipMemoryRead = false;
+ // A more efficient way to check domination. An operand dominates the
+ // BranchInst if
+ // 1. it's not defined in the same bb as the instruction.
+ // 2. it's to be hoisted.
+ //
+ // b/c BB is only predecessor and BranchInst does not define any value.
+ auto OpsDominatesBranch = [&](Instruction &I) {
+ return llvm::none_of(I.operands(), [&](Value *Op) {
+ if (auto *J = dyn_cast<Instruction>(Op)) {
+ if (HoistedInsts.contains(J))
+ return false;
+ if (J->getParent() == I.getParent())
+ return true;
+ }
+ return false;
+ });
+ };
+ for (auto &I : *BB) {
+ auto *LI = dyn_cast<LoadInst>(&I);
+ auto *SI = dyn_cast<StoreInst>(&I);
+ if (LI || SI) {
+ auto *Type = LI ? I.getType() : I.getOperand(0)->getType();
+ bool IsSimple = (LI && LI->isSimple()) || (SI && SI->isSimple());
+ if (!TTI.hasConditionalFaultingLoadStoreForType(Type) || !IsSimple ||
+ !OpsDominatesBranch(I))
+ return false;
+ if (SI && SkipMemoryRead)
+ return false;
+ HoistedInsts.insert(&I);
+ } else if (I.mayHaveSideEffects())
+ return false;
+ else if (I.mayReadFromMemory())
+ SkipMemoryRead = true;
+ }
+ return true;
+ };
+
+ if (!HoistInstsInBB(IfTrueBB) || !HoistInstsInBB(IfFalseBB) ||
+ HoistedInsts.empty())
+ return false;
+
+ // Put newly added instructions before the BranchInst.
+ IRBuilder<> Builder(BI);
+ auto &Context = BB->getContext();
+ auto *VCondTy = FixedVectorType::get(Type::getInt1Ty(Context), 1);
+ auto *Cond = BI->getOperand(0);
+ auto *Undef = UndefValue::get(VCondTy);
+ constexpr uint64_t Zero = 0; // Defined to avoid ambiguous function call
+ auto *VCond = Builder.CreateInsertElement(Undef, Cond, Zero);
+ Value *VCondNot = nullptr;
+ for (auto *I : HoistedInsts) {
+ bool InvertCond = I->getParent() == IfFalseBB;
+ // Construct the inverted condition if need.
+ if (InvertCond && !VCondNot)
+ VCondNot = Builder.CreateInsertElement(
+ Undef, Builder.CreateXor(Cond, ConstantInt::getTrue(Context)), Zero);
+
+ auto *Mask = InvertCond ? VCondNot : VCond;
+ auto *Op0 = I->getOperand(0);
+ if (auto *LI = dyn_cast<LoadInst>(I)) {
+ // Load
+ auto *Ty = I->getType();
+ auto *V0 = Builder.CreateMaskedLoad(FixedVectorType::get(Ty, 1), Op0,
+ LI->getAlign(), Mask);
+ auto *S0 = Builder.CreateBitCast(V0, Ty);
+ V0->copyMetadata(*I);
+ I->replaceAllUsesWith(S0);
+ } else {
+ // Store
+ auto *StoredVal = Builder.CreateInsertElement(
+ UndefValue::get(FixedVectorType::get(Op0->getType(), 1)), Op0, Zero);
+ auto *VStore = Builder.CreateMaskedStore(
+ StoredVal, I->getOperand(1), cast<StoreInst>(I)->getAlign(), Mask);
+ VStore->copyMetadata(*I);
+ }
+ }
+
+ // Erase the hoisted instrutions in reverse order to avoid use-w/o-define
+ // error.
+ std::for_each(HoistedInsts.rbegin(), HoistedInsts.rend(),
+ [](auto I) { I->eraseFromParent(); });
+
+ return true;
+}
+
/// Speculate a conditional basic block flattening the CFG.
///
/// Note that this is a very risky transform currently. Speculating
@@ -7419,14 +7593,20 @@ bool SimplifyCFGOpt::simplifyCondBranch(BranchInst *BI, IRBuilder<> &Builder) {
return requestResimplify();
// We have a conditional branch to two blocks that are only reachable
- // from BI. We know that the condbr dominates the two blocks, so see if
- // there is any identical code in the "then" and "else" blocks. If so, we
- // can hoist it up to the branching block.
+ // from BI. We know that the condbr dominates the two blocks, so see
+ //
+ // * if there is any identical code in the "then" and "else" blocks.
+ // * if there is any different load/store in the "then" and "else" blocks.
+ //
+ // If so, we can hoist it up to the branching block.
if (BI->getSuccessor(0)->getSinglePredecessor()) {
if (BI->getSuccessor(1)->getSinglePredecessor()) {
if (HoistCommon && hoistCommonCodeFromSuccessors(
BI->getParent(), !Options.HoistCommonInsts))
return requestResimplify();
+ if (HoistLoadsStoresWithCondFaulting &&
+ hoistLoadStoreWithCondFaultingFromSuccessors(BI->getParent()))
+ return requestResimplify();
} else {
// If Successor #1 has multiple preds, we may be able to conditionally
// execute Successor #0 if it branches to Successor #1.
diff --git a/llvm/test/CodeGen/X86/apx/cf.ll b/llvm/test/CodeGen/X86/apx/cf.ll
new file mode 100644
index 0000000000000..cd8e76e9e4e43
--- /dev/null
+++ b/llvm/test/CodeGen/X86/apx/cf.ll
@@ -0,0 +1,51 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64 -mattr=+cf -verify-machineinstrs | FileCheck %s
+
+define void @test (i32 %a, ptr %b, ptr %p, ptr %q) {
+; CHECK-LABEL: test:
+; CHECK: # %bb.0: # %entry
+; CHECK-NEXT: testl %edi, %edi
+; CHECK-NEXT: sete %al
+; CHECK-NEXT: negb %al
+; CHECK-NEXT: testl %edi, %edi
+; CHECK-NEXT: # implicit-def: $r8d
+; CHECK-NEXT: je .LBB0_1
+; CHECK-NEXT: # %bb.2: # %else
+; CHECK-NEXT: testb $1, %al
+; CHECK-NEXT: jne .LBB0_3
+; CHECK-NEXT: .LBB0_4: # %else1
+; CHECK-NEXT: testl %edi, %edi
+; CHECK-NEXT: jne .LBB0_5
+; CHECK-NEXT: .LBB0_6: # %else3
+; CHECK-NEXT: retq
+; CHECK-NEXT: .LBB0_1: # %cond.load
+; CHECK-NEXT: movl (%rsi), %r8d
+; CHECK-NEXT: testb $1, %al
+; CHECK-NEXT: je .LBB0_4
+; CHECK-NEXT: .LBB0_3: # %cond.store
+; CHECK-NEXT: movl %r8d, (%rdx)
+; CHECK-NEXT: testl %edi, %edi
+; CHECK-NEXT: je .LBB0_6
+; CHECK-NEXT: .LBB0_5: # %cond.store2
+; CHECK-NEXT: movl $1, (%rcx)
+; CHECK-NEXT: retq
+entry:
+ %cond = icmp eq i32 %a, 0
+ %vcond = insertelement <1 x i1> undef, i1 %cond, i32 0
+ %v0 = call <1 x i32> @llvm.masked.load.v1i32.p0 (ptr %b, i32 4, <1 x i1> %vcond, <1 x i32> poison)
+ %0 = bitcast <1 x i32> %v0 to i32
+ call void @llvm.masked.store.v1i32.p0(<1 x i32> %v0, ptr %p, i32 4, <1 x i1> %vcond)
+ %cond.not = xor i1 %cond, true
+ %vcond.not = insertelement <1 x i1> undef, i1 %cond.not, i32 0
+ call void @llvm.masked.store.v1i32.p0(<1 x i32> <i32 1>, ptr %q, i32 4, <1 x i1> %vcond.not)
+ br i1 %cond, label %if.true, label %if.false
+
+if.false: ; preds = %entry
+ br label %if.end
+
+if.true: ; preds = %entry
+ br label %if.end
+
+if.end: ; preds = %if.true, %if.false
+ ret void
+}
diff --git a/llvm/test/Transforms/SimplifyCFG/X86/hoist-load-store-with-cf.ll b/llvm/test/Transforms/SimplifyCFG/X86/hoist-load-store-with-cf.ll
new file mode 100644
index 0000000000000..fac86df21f282
--- /dev/null
+++ b/llvm/test/Transforms/SimplifyCFG/X86/hoist-load-store-with-cf.ll
@@ -0,0 +1,357 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -mtriple=x86_64 -mattr=+cf -passes=simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S -simplifycfg-hoist-loads-stores-with-cond-faulting=true | FileCheck %s
+
+;; The redundant bitcast + insertelement will be opimized out in instcombine pass.
+define void @basic(i32 %a, ptr %b, ptr %p, ptr %q) {
+; CHECK-LABEL: @basic(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[COND:%.*]] = icmp eq i32 [[A:%.*]], 0
+; CHECK-NEXT: [[TMP0:%.*]] = insertelement <1 x i1> undef, i1 [[COND]], i64 0
+; CHECK-NEXT: [[TMP1:%.*]] = call <1 x i32> @llvm.masked.load.v1i32.p0(ptr [[B:%.*]], i32 4, <1 x i1> [[TMP0]], <1 x i32> poison), !dbg [[DBG8:![0-9]+]]
+; CHECK-NEXT: [[TMP2:%.*]] = bitcast <1 x i32> [[TMP1]] to i32
+; CHECK-NEXT: [[TMP3:%.*]] = insertelement <1 x i32> undef, i32 [[TMP2]], i64 0
+; CHECK-NEXT: call void @llvm.masked.store.v1i32.p0(<1 x i32> [[TMP3]], ptr [[P:%.*]], i32 4, <1 x i1> [[TMP0]])
+; CHECK-NEXT: [[TMP4:%.*]] = xor i1 [[COND]], true
+; CHECK-NEXT: [[TMP5:%.*]] = insertelement <1 x i1> undef, i1 [[TMP4]], i64 0
+; CHECK-NEXT: call void @llvm.masked.store.v1i64.p0(<1 x i64> <i64 1>, ptr [[P]], i32 8, <1 x i1> [[TMP5]]), !dbg [[DBG12:![0-9]+]]
+; CHECK-NEXT: call void @llvm.masked.store.v1i16.p0(<1 x i16> <i16 2>, ptr [[Q:%.*]], i32 8, <1 x i1> [[TMP5]]), !dbg [[DBG12]]
+; CHECK-NEXT: ret void
+;
+entry:
+ %cond = icmp eq i32 %a, 0
+ br i1 %cond, label %if.true, label %if.false
+
+if.false:
+ store i64 1, ptr %p, align 8, !dbg !8
+ store i16 2, ptr %q, align 8, !dbg !8
+ br label %if.end
+
+if.true:
+ %0 = load i32, ptr %b, align 4, !dbg !9
+ store i32 %0, ptr %p, align 4
+ br label %if.end
+
+if.end:
+ ret void
+}
+
+define void @not_supported_type(i8 %a, ptr %b, ptr %p, ptr %q) {
+; CHECK-LABEL: @not_supported_type(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[COND:%.*]] = icmp eq i8 [[A:%.*]], 0
+; CHECK-NEXT: br i1 [[COND]], label [[IF_TRUE:%.*]], label [[IF_FALSE:%.*]]
+; CHECK: if.false:
+; CHECK-NEXT: store i8 1, ptr [[Q:%.*]], align 1
+; CHECK-NEXT: br label [[IF_END:%.*]]
+; CHECK: if.true:
+; CHECK-NEXT: [[TMP0:%.*]] = load i8, ptr [[B:%.*]], align 1
+; CHECK-NEXT: store i8 [[TMP0]], ptr [[P:%.*]], align 1
+; CHECK-NEXT: br label [[IF_END]]
+; CHECK: if.end:
+; CHECK-NEXT: ret void
+;
+entry:
+ %cond = icmp eq i8 %a, 0
+ br i1 %cond, label %if.true, label %if.false
+
+if.false:
+ store i8 1, ptr %q
+ br label %if.end
+
+if.true:
+ %0 = load i8, ptr %b
+ store i8 %0, ptr %p
+ br label %if.end
+
+if.end:
+ ret void
+}
+
+define void @not_br_terminator(i32 %a, ptr %b, ptr %p, ptr %q) {
+; CHECK-LABEL: @not_br_terminator(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: switch i32 [[A:%.*]], label [[IF_END:%.*]] [
+; CHECK-NEXT: i32 1, label [[IF_FALSE:%.*]]
+; CHECK-NEXT: i32 2, label [[IF_TRUE:%.*]]
+; CHECK-NEXT: ]
+; CHECK: if.false:
+; CHECK-NEXT: store i32 1, ptr [[Q:%.*]], align 4
+; CHECK-NEXT: br label [[IF_END]]
+; CHECK: if.true:
+; CHECK-NEXT: [[TMP0:%.*]] = load i32, ptr [[B:%.*]], align 4
+; CHECK-NEXT: store i32 [[TMP0]], ptr [[P:%.*]], align 4
+; CHECK-NEXT: br label [[IF_FALSE]]
+; CHECK: if.end:
+; CHECK-NEXT: ret void
+;
+entry:
+ switch i32 %a, label %if.end [
+ i32 1, label %if.false
+ i32 2, label %if.true
+ ]
+
+if.false:
+ store i32 1, ptr %q, align 4
+ br label %if.end
+
+if.true:
+ %0 = load i32, ptr %b, align 4
+ store i32 %0, ptr %p, align 4
+ br label %if.false
+
+if.end:
+ ret void
+}
+
+define void @not_single_predecessor(i32 %a, ptr %b, ptr %p, ptr %q) {
+; CHECK-LABEL: @not_single_predecessor(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[COND:%.*]] = icmp eq i32 [[A:%.*]], 0
+; CHECK-NEXT: br i1 [[COND]], label [[IF_TRUE:%.*]], label [[IF_FALSE:%.*]]
+; CHECK: if.false:
+; CHECK-NEXT: store i32 1, ptr [[Q:%.*]], align 4
+; CHECK-NEXT: ret void
+; CHECK: if.true:
+; CHECK-NEXT: [[TMP0:%.*]] = load i32, ptr [[B:%.*]], align 4
+; CHECK-NEXT: store i32 [[TMP0]], ptr [[P:%.*]], align 4
+; CHECK-NEXT: br label [[IF_FALSE]]
+;
+entry:
+ %cond = icmp eq i32 %a, 0
+ br i1 %cond, label %if.true, label %if.false
+
+if.false:
+ store i32 1, ptr %q, align 4
+ br label %if.end
+
+if.true:
+ %0 = load i32, ptr %b, align 4
+ store i32 %0, ptr %p, align 4
+ br label %if.false
+
+if.end:
+ ret void
+}
+
+define void @not_simple(i32 %a, ptr %b, ptr %p, ptr %q) {
+; CHECK-LABEL: @not_simple(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[COND:%.*]] = icmp eq i32 [[A:%.*]], 0
+; CHECK-NEXT: br i1 [[COND]], label [[IF_TRUE:%.*]], label [[IF_FALSE:%.*]]
+; CHECK: if.false:
+; CHECK-NEXT: store atomic i32 1, ptr [[Q:%.*]] seq_cst, align 4
+; CHECK-NEXT: br label [[IF_END:%.*]]
+; CHECK: if.true:
+; CHECK-NEXT: [[TMP0:%.*]] = load i32, ptr [[B:%.*]], align 4
+; CHECK-NEXT: store i32 [[TMP0]], ptr [[P:%.*]], align 4
+; CHECK-NEXT: br label [[IF_END]]
+; CHECK: if.end:
+; CHECK-NEXT: ret void
+;
+entry:
+ %cond = icmp eq i32 %a, 0
+ br i1 %cond, label %if.true, label %if.false
+
+if.false:
+ store atomic i32 1, ptr %q seq_cst, align 4
+ br label %if.end
+
+if.true:
+ %0 = load i32, ptr %b, align 4
+ store i32 %0, ptr %p, align 4
+ br label %if.end
+
+if.end:
+ ret void
+}
+
+define void @not_hoistable_store(i32 %a, ptr %b, ptr %p, ptr %q) {
+; CHECK-LABEL: @not_hoistable_store(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[COND:%.*]] = icmp eq i32 [[A:%.*]], 0
+; CHECK-NEXT: br i1 [[COND]], label [[IF_TRUE:%.*]], label [[IF_FALSE:%.*]]
+; CHECK: if.false:
+; CHECK-NEXT: store i32 1, ptr [[Q:%.*]], align 4
+; CHECK-NEXT: br label [[IF_END:%.*]]
+; CHECK: if.true:
+; CHECK-NEXT: [[TMP0:%.*]] = load i32, ptr [[B:%.*]], align 4
+; CHECK-NEXT: store volatile i32 [[TMP0]], ptr [[P:%.*]], align 4
+; CHECK-NEXT: br label [[IF_END]]
+; CHECK: if.end:
+; CHECK-NEXT: ret void
+;
+entry:
+ %cond = icmp eq i32 %a, 0
+ br i1 %cond, label %if.true, label %if.false
+
+if.false:
+ store i32 1, ptr %q, align 4
+ br label %if.end
+
+if.true:
+ %0 = load i32, ptr %b, align 4
+ store volatile i32 %0, ptr %p, align 4
+ br label %if.end
+
+if.end:
+ ret void
+}
+
+define void @not_hoistable_sideeffect(i32 %a, ptr %b, ptr %p, ptr %q) {
+; CHECK-LABEL: @not_hoistable_sideeffect(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[COND:%.*]] = icmp eq i32 [[A:%.*]], 0
+; CHECK-NEXT: br i1 [[COND]], label [[IF_TRUE:%.*]], label [[IF_FALSE:%.*]]
+; CHECK: if.false:
+; CHECK-NEXT: store i32 1, ptr [[Q:%.*]], align 4
+; CHECK-NEXT: br label [[IF_END:%.*]]
+; CHECK: if.true:
+; CHECK-NEXT: [[TMP0:%.*]] = load i32, ptr [[B:%.*]], align 4
+; CHECK-NEXT: [[RMW:%.*]] = atomicrmw xchg ptr [[Q]], double 4.000000e+00 seq_cst, align 8
+; CHECK-NEXT: store i32 [[TMP0]], ptr [[P:%.*]], align 4
+; CHECK-NEXT: br label [[IF_END]]
+; CHECK: if.end:
+; CHECK-NEXT: ret void
+;
+entry:
+ %cond = icmp eq i32 %a, 0
+ br i1 %cond, label %if.true, label %if.false
+
+if.false:
+ store i32 1, ptr %q, align 4
+ br label %if.end
+
+if.true:
+ %0 = load i32, ptr %b, align 4
+ %rmw= atomicrmw xchg ptr %q, double 4.0 seq_cst
+ store i32 %0, ptr %p, align 4
+ br label %if.end
+
+if.end:
+ ret void
+}
+
+define void @not_ops_dominate_br(i32 %a, ptr %b, ptr %p, ptr %q) {
+; CHECK-LABEL: @not_ops_dominate_br(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[COND:%.*]] = icmp eq i32 [[A:%.*]], 0
+; CHECK-NEXT: br i1 [[COND]], label [[IF_TRUE:%.*]], label [[IF_FALSE:%.*]]
+; CHECK: if.false:
+; CHECK-NEXT: [[ADD:%.*]] = add i32 [[A]], 2
+; CHECK-NEXT: store i32 [[ADD]], ptr [[Q:%.*]], align 4
+; CHECK-NEXT: br label [[IF_END:%.*]]
+; CHECK: if.true:
+; CHECK-NEXT: [[TMP0:%.*]] = load i32, ptr [[B:%.*]], align 4
+; CHECK-NEXT: store i32 [[TMP0]], ptr [[P:%.*]], align 4
+; CHECK-NEXT: br label [[IF_END]]
+; CHECK: if.end:
+; CHECK-NEXT: ret void
+;
+entry:
+ %cond = icmp eq i32 %a, 0
+ br i1 %cond, label %if.true, label %if.false
+
+if.false:
+ %add = add i32 %a, 2
+ store i32 %add, ptr %q, align 4
+ br label %if.end
+
+if.true:
+ %1 = load i32, ptr %b, align 4
+ store i32 %1, ptr %p, align 4
+ br label %if.end
+
+if.end:
+ ret void
+}
+
+define void @load_skip_memory_read(i32 %a, ptr %b, ptr %p, ptr %q) {
+; CHECK-LABEL: @load_skip_memory_read(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[COND:%.*]] = icmp eq i32 [[A:%.*]], 0
+; CHECK-NEXT: [[TMP0:%.*]] = insertelement <1 x i1> undef, i1 [[COND]], i64 0
+; CHECK-NEXT: [[TMP1:%.*]] = call <1 x i32> @llvm.masked.load.v1i32.p0(ptr [[B:%.*]], i32 4, <1 x i1> [[TMP0]], <1 x i32> poison)
+; CHECK-NEXT: [[TMP2:%.*]] = bitcast <1 x i32> [[TMP1]] to i32
+; CHECK-NEXT: [[TMP3:%.*]] = insertelement <1 x i32> undef, i32 [[TMP2]], i64 0
+; CHECK-NEXT: call void @llvm.masked.store.v1i32.p0(<1 x i32> [[TMP3]], ptr [[P:%.*]], i32 4, <1 x i1> [[TMP0]])
+; CHECK-NEXT: [[TMP4:%.*]] = xor i1 [[COND]], true
+; CHECK-NEXT: [[TMP5:%.*]] = insertelement <1 x i1> undef, i1 [[TMP4]], i64 0
+; CHECK-NEXT: [[TMP6:%.*]] = call <1 x i32> @llvm.masked.load.v1i32.p0(ptr [[Q:%.*]], i32 4, <1 x i1> [[TMP5]], <1 x i32> poison)
+; CHECK-NEXT: [[TMP7:%.*]] = bitcast <1 x i32> [[TMP6]] to i32
+; CHECK-NEXT: br i1 [[COND]], label [[IF_END:%.*]], label [[IF_FALSE:%.*]]
+; CHECK: if.false:
+; CHECK-NEXT: call void @read_memory_only()
+; CHECK-NEXT: br label [[IF_END]]
+; CHECK: if.end:
+; CHECK-NEXT: ret void
+;
+entry:
+ %cond = icmp eq i32 %a, 0
+ br i1 %cond, label %if.true, label %if.false
+
+if.false:
+ call void @read_memory_only()
+ %0 = load i32, ptr %q, align 4
+ br label %if.end
+
+if.true:
+ %1 = load i32, ptr %b, align 4
+ store i32 %1, ptr %p, align 4
+ br label %if.end
+
+if.end:
+ ret void
+}
+
+define void @not_store_skip_memory_read(i32 %a, ptr %b, ptr %p, ptr %q) {
+; CHECK-LABEL: @not_store_skip_memory_read(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[COND:%.*]] = icmp eq i32 [[A:%.*]], 0
+; CHECK-NEXT: br i1 [[COND]], label [[IF_TRUE:%.*]], label [[IF_FALSE:%.*]]
+; CHECK: if.false:
+; CHECK-NEXT: call void @read_memory_only()
+; CHECK-NEXT: store i32 1, ptr [[Q:%.*]], align 4
+; CHECK-NEXT: br label [[IF_END:%.*]]
+; CHECK: if.true:
+; CHECK-NEXT: [[TMP0:%.*]] = load i32, ptr [[B:%.*]], align 4
+; CHECK-NEXT: store i32 [[TMP0]], ptr [[P:%.*]], align 4
+; CHECK-NEXT: br label [[IF_END]]
+; CHECK: if.end:
+; CHECK-NEXT: ret void
+;
+entry:
+ %cond = icmp eq i32 %a, 0
+ br i1 %cond, label %if.true, label %if.false
+
+if.false:
+ call void @read_memory_only()
+ store i32 1, ptr %q, align 4
+ br label %if.end
+
+if.true:
+ %1 = load i32, ptr %b, align 4
+ store i32 %1, ptr %p, align 4
+ br label %if.end
+
+if.end:
+ ret void
+}
+
+declare void @read_memory_only() readonly nounwind willreturn
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2, !3, !4, !5, !6, !7}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, producer: "clang", isOptimized: true, runtimeVersion: 0, emissionKind: LineTablesOnly, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "test.c", directory: "/tmp")
+!2 = !{i32 7, !"Dwarf Version", i32 5}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!4 = !{i32 1, !"wchar_size", i32 4}
+!5 = !{i32 8, !"PIC Level", i32 2}
+!6 = !{i32 7, !"PIE Level", i32 2}
+!7 = !{i32 7, !"uwtable", i32 2}
+!8 = !DILocation(line: 1, column: 2, scope: !10)
+!9 = !DILocation(line: 1, column: 3, scope: !10)
+!10 = distinct !DISubprogram(name: "basic", scope: !1, file: !1, line: 1, type: !11, scopeLine: 1, flags: DIFlagPrototyped, unit: !0)
+!11 = !DISubroutineType(types: !12)
+!12 = !{}
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