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[simplifycfg][loop-simplify] Preserve loop metadata in 2 transformations.
insertUniqueBackedgeBlock in lib/Transforms/Utils/LoopSimplify.cpp now propagates existing llvm.loop metadata to newly the added backedge. llvm::TryToSimplifyUncondBranchFromEmptyBlock in lib/Transforms/Utils/Local.cpp now propagates existing llvm.loop metadata to the branch instructions in the predecessor blocks of the empty block that is removed. Differential Revision: https://reviews.llvm.org/D26495 llvm-svn: 287341
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@ -890,6 +890,17 @@ bool llvm::TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB) {
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}
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}
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// If the unconditional branch we replaced contains llvm.loop metadata, we
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// add the metadata to the branch instructions in the predecessors.
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unsigned LoopMDKind = BB->getContext().getMDKindID("llvm.loop");
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Instruction *TI = BB->getTerminator();
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if (TI)
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if (MDNode *LoopMD = TI->getMetadata(LoopMDKind))
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for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
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BasicBlock *Pred = *PI;
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Pred->getTerminator()->setMetadata(LoopMDKind, LoopMD);
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}
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// Everything that jumped to BB now goes to Succ.
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BB->replaceAllUsesWith(Succ);
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if (!Succ->hasName()) Succ->takeName(BB);
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@ -470,13 +470,21 @@ static BasicBlock *insertUniqueBackedgeBlock(Loop *L, BasicBlock *Preheader,
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}
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// Now that all of the PHI nodes have been inserted and adjusted, modify the
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// backedge blocks to just to the BEBlock instead of the header.
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// backedge blocks to jump to the BEBlock instead of the header.
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// If one of the backedges has llvm.loop metadata attached, we remove
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// it from the backedge and add it to BEBlock.
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unsigned LoopMDKind = BEBlock->getContext().getMDKindID("llvm.loop");
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MDNode *LoopMD = nullptr;
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for (unsigned i = 0, e = BackedgeBlocks.size(); i != e; ++i) {
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TerminatorInst *TI = BackedgeBlocks[i]->getTerminator();
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if (!LoopMD)
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LoopMD = TI->getMetadata(LoopMDKind);
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TI->setMetadata(LoopMDKind, nullptr);
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for (unsigned Op = 0, e = TI->getNumSuccessors(); Op != e; ++Op)
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if (TI->getSuccessor(Op) == Header)
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TI->setSuccessor(Op, BEBlock);
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}
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BEBlock->getTerminator()->setMetadata(LoopMDKind, LoopMD);
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//===--- Update all analyses which we must preserve now -----------------===//
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42
test/Transforms/LoopSimplify/preserve-llvm-loop-metadata.ll
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42
test/Transforms/LoopSimplify/preserve-llvm-loop-metadata.ll
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@ -0,0 +1,42 @@
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; RUN: opt -loop-simplify -S < %s | FileCheck %s
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define void @test1(i32 %n) {
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entry:
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br label %while.cond
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while.cond: ; preds = %if.then, %if.else, %entry
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%count.0 = phi i32 [ 0, %entry ], [ %add, %if.then ], [ %add2, %if.else ]
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%cmp = icmp ugt i32 %count.0, %n
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br i1 %cmp, label %while.end, label %while.body
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while.body: ; preds = %while.cond
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%rem = and i32 %count.0, 1
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%cmp1 = icmp eq i32 %rem, 0
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br i1 %cmp1, label %if.then, label %if.else
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if.then: ; preds = %while.body
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%add = add i32 %count.0, 1
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br label %while.cond, !llvm.loop !0
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if.else: ; preds = %while.body
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%add2 = add i32 %count.0, 2
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br label %while.cond, !llvm.loop !0
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while.end: ; preds = %while.cond
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ret void
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}
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; CHECK: if.then
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; CHECK-NOT: br {{.*}}!llvm.loop{{.*}}
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; CHECK: while.cond.backedge:
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; CHECK: br label %while.cond, !llvm.loop !0
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; CHECK: if.else
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; CHECK-NOT: br {{.*}}!llvm.loop{{.*}}
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!0 = distinct !{!0, !1}
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!1 = !{!"llvm.loop.distribute.enable", i1 true}
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; CHECK: !0 = distinct !{!0, !1}
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; CHECK: !1 = !{!"llvm.loop.distribute.enable", i1 true}
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53
test/Transforms/SimplifyCFG/preserve-llvm-loop-metadata.ll
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53
test/Transforms/SimplifyCFG/preserve-llvm-loop-metadata.ll
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@ -0,0 +1,53 @@
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; RUN: opt -simplifycfg -S < %s | FileCheck %s
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define void @test1(i32 %n) #0 {
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entry:
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%n.addr = alloca i32, align 4
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%count = alloca i32, align 4
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store i32 %n, i32* %n.addr, align 4
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%0 = bitcast i32* %count to i8*
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store i32 0, i32* %count, align 4
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br label %while.cond
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while.cond: ; preds = %if.end, %entry
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%1 = load i32, i32* %count, align 4
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%2 = load i32, i32* %n.addr, align 4
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%cmp = icmp ule i32 %1, %2
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br i1 %cmp, label %while.body, label %while.end
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while.body: ; preds = %while.cond
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%3 = load i32, i32* %count, align 4
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%rem = urem i32 %3, 2
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%cmp1 = icmp eq i32 %rem, 0
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br i1 %cmp1, label %if.then, label %if.else
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if.then: ; preds = %while.body
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%4 = load i32, i32* %count, align 4
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%add = add i32 %4, 1
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store i32 %add, i32* %count, align 4
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br label %if.end
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; CHECK: if.then:
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; CHECK: br label %while.cond, !llvm.loop !0
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if.else: ; preds = %while.body
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%5 = load i32, i32* %count, align 4
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%add2 = add i32 %5, 2
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store i32 %add2, i32* %count, align 4
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br label %if.end
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; CHECK: if.else:
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; CHECK: br label %while.cond, !llvm.loop !0
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if.end: ; preds = %if.else, %if.then
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br label %while.cond, !llvm.loop !0
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while.end: ; preds = %while.cond
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%6 = bitcast i32* %count to i8*
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ret void
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}
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!0 = distinct !{!0, !1}
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!1 = !{!"llvm.loop.distribute.enable", i1 true}
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; CHECK: !0 = distinct !{!0, !1}
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; CHECK: !1 = !{!"llvm.loop.distribute.enable", i1 true}
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