From 11ee15bafcbfc54c96c3f148437fe028c5cdf22a Mon Sep 17 00:00:00 2001 From: Jun Bum Lim Date: Mon, 22 Aug 2016 18:21:56 +0000 Subject: [PATCH] [InstCombine] Allow sinking from unique predecessor with multiple edges Summary: We can allow sinking if the single user block has only one unique predecessor, regardless of the number of edges. Note that a switch statement with multiple cases can have the same destination. Reviewers: mcrosier, majnemer, spatel, reames Subscribers: reames, mcrosier, llvm-commits Differential Revision: https://reviews.llvm.org/D23722 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279448 91177308-0d34-0410-b5e6-96231b3b80d8 --- .../InstCombine/InstructionCombining.cpp | 2 +- test/Transforms/InstCombine/sink_instruction.ll | 23 ++++++++++++++++++++++ 2 files changed, 24 insertions(+), 1 deletion(-) diff --git a/lib/Transforms/InstCombine/InstructionCombining.cpp b/lib/Transforms/InstCombine/InstructionCombining.cpp index 6424e083bd1..12c42ce6472 100644 --- a/lib/Transforms/InstCombine/InstructionCombining.cpp +++ b/lib/Transforms/InstCombine/InstructionCombining.cpp @@ -2903,7 +2903,7 @@ bool InstCombiner::run() { // If the user is one of our immediate successors, and if that successor // only has us as a predecessors (we'd have to split the critical edge // otherwise), we can keep going. - if (UserIsSuccessor && UserParent->getSinglePredecessor()) { + if (UserIsSuccessor && UserParent->getUniquePredecessor()) { // Okay, the CFG is simple enough, try to sink this instruction. if (TryToSinkInstruction(I, UserParent)) { DEBUG(dbgs() << "IC: Sink: " << *I << '\n'); diff --git a/test/Transforms/InstCombine/sink_instruction.ll b/test/Transforms/InstCombine/sink_instruction.ll index 1bbd6b76384..4c057c66f7f 100644 --- a/test/Transforms/InstCombine/sink_instruction.ll +++ b/test/Transforms/InstCombine/sink_instruction.ll @@ -54,3 +54,26 @@ bb4: ; preds = %bb2 } declare i32 @bar() + +define i32 @test3(i32* nocapture readonly %P, i32 %i) { +entry: + %idxprom = sext i32 %i to i64 + %arrayidx = getelementptr inbounds i32, i32* %P, i64 %idxprom + %0 = load i32, i32* %arrayidx, align 4 + switch i32 %i, label %sw.epilog [ + i32 5, label %sw.bb + i32 2, label %sw.bb + ] + +sw.bb: ; preds = %entry, %entry +; CHECK-LABEL: sw.bb: +; CHECK: %idxprom = sext i32 %i to i64 +; CHECK: %arrayidx = getelementptr inbounds i32, i32* %P, i64 %idxprom +; CHECK: %0 = load i32, i32* %arrayidx, align 4 + %add = add nsw i32 %0, %i + br label %sw.epilog + +sw.epilog: ; preds = %entry, %sw.bb + %sum.0 = phi i32 [ %add, %sw.bb ], [ 0, %entry ] + ret i32 %sum.0 +} -- 2.11.0