diff options
5 files changed, 29 insertions, 13 deletions
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp index c3343ed8ecc..82ef1b91e74 100644 --- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp @@ -5733,9 +5733,12 @@ bool SimplifyCFGOpt::SimplifyUncondBranch(BranchInst *BI, // header. (This is for early invocations before loop simplify and // vectorization to keep canonical loop forms for nested loops. These blocks // can be eliminated when the pass is invoked later in the back-end.) + // Note that if BB has only one predecessor then we do not introduce new + // backedge, so we can eliminate BB. bool NeedCanonicalLoop = Options.NeedCanonicalLoop && - (LoopHeaders && (LoopHeaders->count(BB) || LoopHeaders->count(Succ))); + (LoopHeaders && std::distance(pred_begin(BB), pred_end(BB)) > 1 && + (LoopHeaders->count(BB) || LoopHeaders->count(Succ))); BasicBlock::iterator I = BB->getFirstNonPHIOrDbg()->getIterator(); if (I->isTerminator() && BB != &BB->getParent()->getEntryBlock() && !NeedCanonicalLoop && TryToSimplifyUncondBranchFromEmptyBlock(BB)) diff --git a/llvm/test/Transforms/LoopUnroll/peel-loop.ll b/llvm/test/Transforms/LoopUnroll/peel-loop.ll index 3f7c64d8154..55e818244a7 100644 --- a/llvm/test/Transforms/LoopUnroll/peel-loop.ll +++ b/llvm/test/Transforms/LoopUnroll/peel-loop.ll @@ -19,10 +19,8 @@ ; CHECK: store i32 2, i32* %[[INC2]], align 4 ; CHECK: %[[CMP3:.*]] = icmp eq i32 %k, 3 ; CHECK: br i1 %[[CMP3]], label %for.end, label %[[LOOP_PH:.*]] -; CHECK: [[LOOP_PH]]: -; CHECK: br label %[[LOOP:.*]] -; CHECK: [[LOOP]]: -; CHECK: %[[IV:.*]] = phi i32 [ 3, %[[LOOP_PH]] ], [ {{.*}}, %[[LOOP]] ] +; CHECK: for.end: +; CHECK: ret void define void @basic(i32* %p, i32 %k) #0 { entry: @@ -68,11 +66,8 @@ for.end: ; preds = %for.cond.for.end_cr ; CHECK: store i32 2, i32* %[[INC2]], align 4 ; CHECK: %[[CMP3:.*]] = icmp eq i32 %k, 3 ; CHECK: br i1 %[[CMP3]], label %for.end, label %[[LOOP_PH:.*]] -; CHECK: [[LOOP_PH]]: -; CHECK: br label %[[LOOP:.*]] -; CHECK: [[LOOP]]: -; CHECK: %[[IV:.*]] = phi i32 [ 3, %[[LOOP_PH]] ], [ %[[IV:.*]], %[[LOOP]] ] -; CHECK: %ret = phi i32 [ 0, %entry ], [ 1, %[[NEXT0]] ], [ 2, %[[NEXT1]] ], [ 3, %[[NEXT2]] ], [ %[[IV]], %[[LOOP]] ] +; CHECK: for.end: +; CHECK: %ret = phi i32 [ 0, %entry ], [ 1, %[[NEXT0]] ], [ 2, %[[NEXT1]] ], [ 3, %[[NEXT2]] ], [ %inc, %for.body ] ; CHECK: ret i32 %ret define i32 @output(i32* %p, i32 %k) #0 { entry: diff --git a/llvm/test/Transforms/LoopUnswitch/2015-06-17-Metadata.ll b/llvm/test/Transforms/LoopUnswitch/2015-06-17-Metadata.ll index 8652829bc51..a215be9d487 100644 --- a/llvm/test/Transforms/LoopUnswitch/2015-06-17-Metadata.ll +++ b/llvm/test/Transforms/LoopUnswitch/2015-06-17-Metadata.ll @@ -16,7 +16,7 @@ for.body: ; preds = %for.inc, %for.body. %cmp1 = icmp eq i32 %a, 12345 br i1 %cmp1, label %if.then, label %if.else, !prof !0 ; CHECK: %cmp1 = icmp eq i32 %a, 12345 -; CHECK-NEXT: br i1 %cmp1, label %for.body.preheader.split.us, label %for.body.preheader.split, !prof !0 +; CHECK-NEXT: br i1 %cmp1, label %for.body.us, label %for.body, !prof !0 if.then: ; preds = %for.body ; CHECK: for.body.us: ; CHECK: add nsw i32 %{{.*}}, 123 @@ -53,7 +53,7 @@ entry: br label %for.body ;CHECK: entry: ;CHECK-NEXT: %cmp1 = icmp eq i32 1, 2 -;CHECK-NEXT: br i1 %cmp1, label %entry.split, label %for.cond.cleanup.split, !prof !1 +;CHECK-NEXT: br i1 %cmp1, label %for.body, label %for.cond.cleanup.split, !prof !1 ;CHECK: for.body: for.body: ; preds = %for.inc, %entry %inc.i = phi i32 [ 0, %entry ], [ %inc, %if.then ] diff --git a/llvm/test/Transforms/LoopUnswitch/infinite-loop.ll b/llvm/test/Transforms/LoopUnswitch/infinite-loop.ll index af8725b02a1..013355faf35 100644 --- a/llvm/test/Transforms/LoopUnswitch/infinite-loop.ll +++ b/llvm/test/Transforms/LoopUnswitch/infinite-loop.ll @@ -16,7 +16,7 @@ ; CHECK-NEXT: br i1 %a, label %entry.split, label %abort0.split ; CHECK: entry.split: -; CHECK-NEXT: br i1 %b, label %entry.split.split, label %abort1.split +; CHECK-NEXT: br i1 %b, label %for.body, label %abort1.split ; CHECK: for.body: ; CHECK-NEXT: br label %for.body diff --git a/llvm/test/Transforms/SimplifyCFG/UncondBranchToHeader.ll b/llvm/test/Transforms/SimplifyCFG/UncondBranchToHeader.ll new file mode 100644 index 00000000000..6a265539e75 --- /dev/null +++ b/llvm/test/Transforms/SimplifyCFG/UncondBranchToHeader.ll @@ -0,0 +1,18 @@ +; RUN: opt < %s -simplifycfg -S | FileCheck %s + +; Check that we can get rid of empty block leading to header +; if it does not introduce new edge. +define i32 @test(i32 %c) { +entry: + br label %header +header: + %i = phi i32 [0, %entry], [%i.1, %backedge] + %i.1 = add i32 %i, 1 + %cmp = icmp slt i32 %i.1, %c + br i1 %cmp, label %backedge, label %exit +; CHECK-NOT: backedge: +backedge: + br label %header +exit: + ret i32 %i +} |
