forked from OSchip/llvm-project
Resubmit "[CorrelatedValuePropagation] Fix prof branch_weights metadata handling for SwitchInst"
This reverts commit5b32f60ec3. The fix is in commit4f9e68148b. This patch fixes the CorrelatedValuePropagation pass to keep prof branch_weights metadata of SwitchInst consistent. It makes use of SwitchInstProfUpdateWrapper. New tests are added. Reviewed By: nikic Differential Revision: https://reviews.llvm.org/D62126 llvm-svn: 362583
This commit is contained in:
Yevgeny Rouban
parent
fa449a9bb2
commit
a3e16719c4
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@ -308,11 +308,11 @@ static bool processCmp(CmpInst *Cmp, LazyValueInfo *LVI) {
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/// that cannot fire no matter what the incoming edge can safely be removed. If
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/// that cannot fire no matter what the incoming edge can safely be removed. If
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/// a case fires on every incoming edge then the entire switch can be removed
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/// a case fires on every incoming edge then the entire switch can be removed
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/// and replaced with a branch to the case destination.
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/// and replaced with a branch to the case destination.
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static bool processSwitch(SwitchInst *SI, LazyValueInfo *LVI,
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static bool processSwitch(SwitchInst *I, LazyValueInfo *LVI,
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DominatorTree *DT) {
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DominatorTree *DT) {
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DomTreeUpdater DTU(*DT, DomTreeUpdater::UpdateStrategy::Lazy);
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DomTreeUpdater DTU(*DT, DomTreeUpdater::UpdateStrategy::Lazy);
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Value *Cond = SI->getCondition();
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Value *Cond = I->getCondition();
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BasicBlock *BB = SI->getParent();
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BasicBlock *BB = I->getParent();
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// If the condition was defined in same block as the switch then LazyValueInfo
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// If the condition was defined in same block as the switch then LazyValueInfo
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// currently won't say anything useful about it, though in theory it could.
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// currently won't say anything useful about it, though in theory it could.
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@ -329,67 +329,72 @@ static bool processSwitch(SwitchInst *SI, LazyValueInfo *LVI,
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for (auto *Succ : successors(BB))
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for (auto *Succ : successors(BB))
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SuccessorsCount[Succ]++;
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SuccessorsCount[Succ]++;
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for (auto CI = SI->case_begin(), CE = SI->case_end(); CI != CE;) {
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{ // Scope for SwitchInstProfUpdateWrapper. It must not live during
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ConstantInt *Case = CI->getCaseValue();
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// ConstantFoldTerminator() as the underlying SwitchInst can be changed.
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SwitchInstProfUpdateWrapper SI(*I);
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// Check to see if the switch condition is equal to/not equal to the case
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for (auto CI = SI->case_begin(), CE = SI->case_end(); CI != CE;) {
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// value on every incoming edge, equal/not equal being the same each time.
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ConstantInt *Case = CI->getCaseValue();
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LazyValueInfo::Tristate State = LazyValueInfo::Unknown;
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for (pred_iterator PI = PB; PI != PE; ++PI) {
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// Check to see if the switch condition is equal to/not equal to the case
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// Is the switch condition equal to the case value?
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// value on every incoming edge, equal/not equal being the same each time.
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LazyValueInfo::Tristate Value = LVI->getPredicateOnEdge(CmpInst::ICMP_EQ,
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LazyValueInfo::Tristate State = LazyValueInfo::Unknown;
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Cond, Case, *PI,
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for (pred_iterator PI = PB; PI != PE; ++PI) {
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BB, SI);
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// Is the switch condition equal to the case value?
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// Give up on this case if nothing is known.
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LazyValueInfo::Tristate Value = LVI->getPredicateOnEdge(CmpInst::ICMP_EQ,
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if (Value == LazyValueInfo::Unknown) {
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Cond, Case, *PI,
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State = LazyValueInfo::Unknown;
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BB, SI);
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break;
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// Give up on this case if nothing is known.
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if (Value == LazyValueInfo::Unknown) {
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State = LazyValueInfo::Unknown;
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break;
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}
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// If this was the first edge to be visited, record that all other edges
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// need to give the same result.
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if (PI == PB) {
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State = Value;
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continue;
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}
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// If this case is known to fire for some edges and known not to fire for
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// others then there is nothing we can do - give up.
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if (Value != State) {
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State = LazyValueInfo::Unknown;
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break;
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}
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}
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}
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// If this was the first edge to be visited, record that all other edges
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if (State == LazyValueInfo::False) {
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// need to give the same result.
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// This case never fires - remove it.
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if (PI == PB) {
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BasicBlock *Succ = CI->getCaseSuccessor();
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State = Value;
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Succ->removePredecessor(BB);
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CI = SI.removeCase(CI);
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CE = SI->case_end();
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// The condition can be modified by removePredecessor's PHI simplification
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// logic.
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Cond = SI->getCondition();
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++NumDeadCases;
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Changed = true;
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if (--SuccessorsCount[Succ] == 0)
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DTU.applyUpdatesPermissive({{DominatorTree::Delete, BB, Succ}});
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continue;
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continue;
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}
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}
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if (State == LazyValueInfo::True) {
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// If this case is known to fire for some edges and known not to fire for
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// This case always fires. Arrange for the switch to be turned into an
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// others then there is nothing we can do - give up.
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// unconditional branch by replacing the switch condition with the case
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if (Value != State) {
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// value.
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State = LazyValueInfo::Unknown;
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SI->setCondition(Case);
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NumDeadCases += SI->getNumCases();
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Changed = true;
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break;
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break;
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}
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}
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// Increment the case iterator since we didn't delete it.
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++CI;
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}
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}
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if (State == LazyValueInfo::False) {
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// This case never fires - remove it.
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BasicBlock *Succ = CI->getCaseSuccessor();
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Succ->removePredecessor(BB);
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CI = SI->removeCase(CI);
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CE = SI->case_end();
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// The condition can be modified by removePredecessor's PHI simplification
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// logic.
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Cond = SI->getCondition();
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++NumDeadCases;
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Changed = true;
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if (--SuccessorsCount[Succ] == 0)
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DTU.applyUpdatesPermissive({{DominatorTree::Delete, BB, Succ}});
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continue;
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}
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if (State == LazyValueInfo::True) {
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// This case always fires. Arrange for the switch to be turned into an
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// unconditional branch by replacing the switch condition with the case
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// value.
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SI->setCondition(Case);
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NumDeadCases += SI->getNumCases();
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Changed = true;
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break;
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}
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// Increment the case iterator since we didn't delete it.
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++CI;
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}
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}
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if (Changed)
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if (Changed)
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@ -0,0 +1,119 @@
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; RUN: opt < %s -correlated-propagation -S | FileCheck %s
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; Removed several cases from switch.
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define i32 @switch1(i32 %s) {
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; CHECK-LABEL: @switch1(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[S:%.*]], 0
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; CHECK-NEXT: br i1 [[CMP]], label [[NEGATIVE:%.*]], label [[OUT:%.*]]
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;
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entry:
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%cmp = icmp slt i32 %s, 0
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br i1 %cmp, label %negative, label %out
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negative:
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; CHECK: negative:
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; CHECK-NEXT: switch i32 [[S]], label [[OUT]] [
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; CHECK-NEXT: i32 -2, label [[NEXT:%.*]]
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; CHECK-NEXT: i32 -1, label [[NEXT]]
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switch i32 %s, label %out [
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i32 0, label %out
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i32 1, label %out
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i32 -1, label %next
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i32 -2, label %next
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i32 2, label %out
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i32 3, label %out
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; CHECK-NEXT: !prof ![[MD0:[0-9]+]]
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], !prof !{!"branch_weights", i32 99, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6}
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out:
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%p = phi i32 [ 1, %entry ], [ -1, %negative ], [ -1, %negative ], [ -1, %negative ], [ -1, %negative ], [ -1, %negative ]
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ret i32 %p
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next:
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%q = phi i32 [ 0, %negative ], [ 0, %negative ]
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ret i32 %q
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}
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; Removed all cases from switch.
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define i32 @switch2(i32 %s) {
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; CHECK-LABEL: @switch2(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i32 [[S:%.*]], 0
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; CHECK-NEXT: br i1 [[CMP]], label [[POSITIVE:%.*]], label [[OUT:%.*]]
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;
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entry:
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%cmp = icmp sgt i32 %s, 0
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br i1 %cmp, label %positive, label %out
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positive:
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switch i32 %s, label %out [
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i32 0, label %out
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i32 -1, label %next
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i32 -2, label %next
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], !prof !{!"branch_weights", i32 99, i32 1, i32 2, i32 3}
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out:
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%p = phi i32 [ -1, %entry ], [ 1, %positive ], [ 1, %positive ]
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ret i32 %p
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next:
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%q = phi i32 [ 0, %positive ], [ 0, %positive ]
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ret i32 %q
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}
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; Change switch into conditional branch.
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define i32 @switch3(i32 %s) {
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; CHECK-LABEL: @switch3(
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;
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entry:
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%cmp = icmp sgt i32 %s, 0
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br i1 %cmp, label %positive, label %out
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positive:
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; CHECK: positive:
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; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 %s, 1
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; CHECK-NEXT: br i1 [[CMP]], label [[NEXT:%.*]], label [[OUT:%.*]], !prof ![[MD1:[0-9]+]]
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switch i32 %s, label %out [
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i32 1, label %next
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i32 -1, label %next
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i32 -2, label %next
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], !prof !{!"branch_weights", i32 99, i32 1, i32 2, i32 3}
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out:
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%p = phi i32 [ -1, %entry ], [ 1, %positive ]
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ret i32 %p
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next:
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%q = phi i32 [ 0, %positive ], [ 0, %positive ], [ 0, %positive ]
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ret i32 %q
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}
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; Removed all cases from switch.
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define i32 @switch4(i32 %s) {
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; CHECK-LABEL: @switch4(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[S:%.*]], 0
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; CHECK-NEXT: br i1 [[CMP]], label [[NEGATIVE:%.*]], label [[OUT:%.*]]
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;
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entry:
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%cmp = icmp slt i32 %s, 0
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br i1 %cmp, label %negative, label %out
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negative:
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; CHECK: negative:
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; CHECK-NEXT: br label %out
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switch i32 %s, label %out [
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i32 0, label %out
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i32 1, label %out
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i32 2, label %out
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i32 3, label %out
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], !prof !{!"branch_weights", i32 99, i32 1, i32 2, i32 3, i32 4}
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out:
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%p = phi i32 [ 1, %entry ], [ -1, %negative ], [ -1, %negative ], [ -1, %negative ], [ -1, %negative ], [ -1, %negative ]
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ret i32 %p
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}
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; CHECK: ![[MD0]] = !{!"branch_weights", i32 99, i32 4, i32 3}
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; CHECK: ![[MD1]] = !{!"branch_weights", i32 1, i32 99}
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