[llvm] r316721 - Revert "[CGP] Merge empty case blocks if no extra moves are added."
Balaram Makam via llvm-commits
llvm-commits at lists.llvm.org
Thu Oct 26 17:35:18 PDT 2017
Author: bmakam
Date: Thu Oct 26 17:35:18 2017
New Revision: 316721
URL: http://llvm.org/viewvc/llvm-project?rev=316721&view=rev
Log:
Revert "[CGP] Merge empty case blocks if no extra moves are added."
This reverts commit r316711. The domtree isn't getting updated correctly.
Modified:
llvm/trunk/lib/CodeGen/CodeGenPrepare.cpp
llvm/trunk/test/Transforms/CodeGenPrepare/skip-merging-case-block.ll
Modified: llvm/trunk/lib/CodeGen/CodeGenPrepare.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/CodeGenPrepare.cpp?rev=316721&r1=316720&r2=316721&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/CodeGenPrepare.cpp (original)
+++ llvm/trunk/lib/CodeGen/CodeGenPrepare.cpp Thu Oct 26 17:35:18 2017
@@ -212,7 +212,6 @@ class TypePromotionTransaction;
const TargetTransformInfo *TTI = nullptr;
const TargetLibraryInfo *TLInfo;
const LoopInfo *LI;
- DominatorTree *DT;
std::unique_ptr<BlockFrequencyInfo> BFI;
std::unique_ptr<BranchProbabilityInfo> BPI;
@@ -263,7 +262,6 @@ class TypePromotionTransaction;
void getAnalysisUsage(AnalysisUsage &AU) const override {
// FIXME: When we can selectively preserve passes, preserve the domtree.
- AU.addRequired<DominatorTreeWrapperPass>();
AU.addRequired<ProfileSummaryInfoWrapperPass>();
AU.addRequired<TargetLibraryInfoWrapperPass>();
AU.addRequired<TargetTransformInfoWrapperPass>();
@@ -345,8 +343,6 @@ bool CodeGenPrepare::runOnFunction(Funct
TLInfo = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
- DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
-
OptSize = F.optForSize();
if (ProfileGuidedSectionPrefix) {
@@ -759,11 +755,6 @@ bool CodeGenPrepare::isMergingEmptyBlock
return true;
SmallPtrSet<BasicBlock *, 16> SameIncomingValueBBs;
- SmallVector<PHINode *, 16> PNs;
-
- for (auto DestBBI = DestBB->begin();
- auto *DestPN = dyn_cast<PHINode>(&*DestBBI); ++DestBBI)
- PNs.push_back(DestPN);
// Find all other incoming blocks from which incoming values of all PHIs in
// DestBB are the same as the ones from BB.
@@ -773,10 +764,16 @@ bool CodeGenPrepare::isMergingEmptyBlock
if (DestBBPred == BB)
continue;
- if (llvm::all_of(PNs, [&](PHINode *PN) {
- return (PN->getIncomingValueForBlock(BB) ==
- PN->getIncomingValueForBlock(DestBBPred));
- }))
+ bool HasAllSameValue = true;
+ BasicBlock::const_iterator DestBBI = DestBB->begin();
+ while (const PHINode *DestPN = dyn_cast<PHINode>(DestBBI++)) {
+ if (DestPN->getIncomingValueForBlock(BB) !=
+ DestPN->getIncomingValueForBlock(DestBBPred)) {
+ HasAllSameValue = false;
+ break;
+ }
+ }
+ if (HasAllSameValue)
SameIncomingValueBBs.insert(DestBBPred);
}
@@ -786,14 +783,6 @@ bool CodeGenPrepare::isMergingEmptyBlock
if (SameIncomingValueBBs.count(Pred))
return true;
- // Check to see if none of the phis have constant incoming values for BB and
- // Pred dominates DestBB, in such case extra COPYs are likely not added, so
- // there is no reason to skip merging.
- if (DT->dominates(Pred, DestBB) && llvm::none_of(PNs, [BB](PHINode *PN) {
- return isa<Constant>(PN->getIncomingValueForBlock(BB));
- }))
- return true;
-
if (!BFI) {
Function &F = *BB->getParent();
LoopInfo LI{DominatorTree(F)};
@@ -896,7 +885,7 @@ void CodeGenPrepare::eliminateMostlyEmpt
// Remember if SinglePred was the entry block of the function. If so, we
// will need to move BB back to the entry position.
bool isEntry = SinglePred == &SinglePred->getParent()->getEntryBlock();
- MergeBasicBlockIntoOnlyPred(DestBB, DT);
+ MergeBasicBlockIntoOnlyPred(DestBB, nullptr);
if (isEntry && BB != &BB->getParent()->getEntryBlock())
BB->moveBefore(&BB->getParent()->getEntryBlock());
@@ -937,21 +926,7 @@ void CodeGenPrepare::eliminateMostlyEmpt
// The PHIs are now updated, change everything that refers to BB to use
// DestBB and remove BB.
- SmallVector<DominatorTree::UpdateType, 3> Updates;
- for (auto *PredBB : predecessors(BB)) {
- if (PredBB == BB)
- continue;
- DominatorTree::UpdateType UT = {DominatorTree::Delete, PredBB, BB};
- if (!is_contained(Updates, UT)) {
- Updates.push_back(UT);
- if (PredBB != DestBB)
- Updates.push_back({DominatorTree::Insert, PredBB, DestBB});
- }
- }
BB->replaceAllUsesWith(DestBB);
- DT->applyUpdates(Updates);
- BB->getTerminator()->eraseFromParent();
- DT->deleteEdge(BB, DestBB);
BB->eraseFromParent();
++NumBlocksElim;
Modified: llvm/trunk/test/Transforms/CodeGenPrepare/skip-merging-case-block.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/CodeGenPrepare/skip-merging-case-block.ll?rev=316721&r1=316720&r2=316721&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/CodeGenPrepare/skip-merging-case-block.ll (original)
+++ llvm/trunk/test/Transforms/CodeGenPrepare/skip-merging-case-block.ll Thu Oct 26 17:35:18 2017
@@ -143,107 +143,11 @@ declare void @calldefault(...) local_unn
!1 = !{!"branch_weights", i32 1 , i32 5, i32 1,i32 1, i32 1}
!2 = !{!"branch_weights", i32 1 , i32 4, i32 1,i32 1, i32 1}
-; while.cond does not dominate return, expect to skip merging empty block
-; return.loopexit into return.
- at b = external global i32, align 4
- at a = external global i32*, align 8
-
-define void @f_switch4(i32 %i) local_unnamed_addr personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
-; CHECK-LABEL: @f_switch4
-entry:
- %0 = load i32, i32* @b, align 4
- %cond = icmp eq i32 %0, 6
- br i1 %cond, label %return, label %if.end
-
-if.end: ; preds = %entry
- %add = add i32 %i, 2
- %1 = load i32*, i32** @a, align 8
- %magicptr = ptrtoint i32* %1 to i32
- br label %while.cond
-
-; CHECK-LABEL: while.cond:
-; CHECK: i32 0, label %return.loopexit
-; CHECK: i32 47, label %return.loopexit
-while.cond: ; preds = %while.cond.backedge, %if.end
- switch i32 %magicptr, label %while.cond.if.end10_crit_edge [
- i32 0, label %return.loopexit
- i32 47, label %return.loopexit
- ]
-
-while.cond.if.end10_crit_edge: ; preds = %while.cond
- br label %while.cond.backedge
-
-while.cond.backedge: ; preds = %while.cond.if.end10_crit_edge, %if.then9
- br label %while.cond
-
-return.loopexit: ; preds = %while.cond
- br label %return
-
-; CHECK_LABEL: return:
-; CHECK: %{{.*}} = phi i32 [ 0, %entry ], [ %add, %return.loopexit ]
-return: ; preds = %return.loopexit, %entry
- %retval.4 = phi i32 [ 0, %entry ], [ %add, %return.loopexit ]
- ret void
-}
-declare i32 @__gxx_personality_v0(...)
-
-; Expect to merge empty block while.cond2.loopexit into while.cond2
-define i32 @f_switch5(i32 %i) local_unnamed_addr {
-; CHECK-LABEL: @f_switch5
-entry:
- %0 = load i32, i32* @b, align 4
- %cond = icmp eq i32 %0, 6
- br i1 %cond, label %while.cond.preheader, label %sw.epilog
-
-while.cond.preheader: ; preds = %entry
- %1 = load i32*, i32** @a, align 8
- %magicptr = ptrtoint i32* %1 to i64
- %arrayidx = getelementptr inbounds i32, i32* %1, i64 1
- br label %while.cond
-
-; CHECK-LABEL: while.cond:
-; CHECK: i64 32, label %while.cond2
-; CHECK: i64 0, label %while.cond2
-while.cond: ; preds = %land.rhs, %while.cond.preheader
- switch i64 %magicptr, label %land.rhs [
- i64 32, label %while.cond2.loopexit
- i64 0, label %while.cond2.loopexit
- ]
-
-land.rhs: ; preds = %while.cond
- %2 = load i32, i32* %arrayidx, align 4
- %tobool1 = icmp eq i32 %2, 0
- br i1 %tobool1, label %while.cond2thread-pre-split.loopexit, label %while.cond
-
-while.cond2thread-pre-split.loopexit: ; preds = %land.rhs
- br label %while.cond2thread-pre-split
-
-while.cond2thread-pre-split: ; preds = %while.body4, %while.cond2thread-pre-split.loopexit
- %.pr = phi i32* [ %.pr.pre, %while.body4 ], [ %1, %while.cond2thread-pre-split.loopexit ]
- br label %while.cond2
-
-while.cond2.loopexit: ; preds = %while.cond, %while.cond
- br label %while.cond2
-
-; CHECK-LABEL: while.cond2:
-; CHECK: %{{.*}} = phi i32* [ %.pr.pre, %while.body4 ], [ %1, %land.rhs ], [ %1, %while.cond ], [ %1, %while.cond ]
-while.cond2: ; preds = %while.cond2.loopexit, %while.cond2thread-pre-split
- %3 = phi i32* [ %.pr, %while.cond2thread-pre-split ], [ %1, %while.cond2.loopexit ]
- %tobool3 = icmp eq i32* %3, null
- br i1 %tobool3, label %sw.epilog, label %while.body4
-
-while.body4: ; preds = %while.cond2
- tail call void bitcast (void (...)* @fn2 to void ()*)()
- %.pr.pre = load i32*, i32** @a, align 8
- br label %while.cond2thread-pre-split
-
-sw.epilog: ; preds = %while.cond2, %entry
- ret i32 undef
-}
-
; This test that BFI/BPI is created without any assertion in isMergingEmptyBlockProfitable()
; in the case where empty blocks are removed before creating BFI/BPI.
+ at b = common global i32 0, align 4
+ at a = common global i32* null, align 8
define i32 @should_not_assert(i32 %i) local_unnamed_addr {
entry:
%0 = load i32, i32* @b, align 4
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