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