diff options
| -rw-r--r-- | llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp | 12 | ||||
| -rw-r--r-- | llvm/test/Transforms/LoopUnroll/runtime-loop-multiple-exits.ll | 44 |
2 files changed, 54 insertions, 2 deletions
diff --git a/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp b/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp index 59408ffe7a7..2b432426b24 100644 --- a/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp +++ b/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp @@ -470,8 +470,9 @@ bool llvm::UnrollRuntimeLoopRemainder(Loop *L, unsigned Count, bool UseEpilogRemainder, LoopInfo *LI, ScalarEvolution *SE, DominatorTree *DT, bool PreserveLCSSA) { - // for now, only unroll loops that contain a single exit - if (!UnrollRuntimeMultiExit && !L->getExitingBlock()) + bool hasMultipleExitingBlocks = !L->getExitingBlock(); + // Support only single exiting block unless UnrollRuntimeMultiExit is true. + if (!UnrollRuntimeMultiExit && hasMultipleExitingBlocks) return false; // Make sure the loop is in canonical form. @@ -516,6 +517,13 @@ bool llvm::UnrollRuntimeLoopRemainder(Loop *L, unsigned Count, // connectEpilog. if (!LatchExit->getSinglePredecessor()) return false; + // FIXME: We bail out of multi-exit unrolling when epilog loop is generated + // and L is an inner loop. This is because in presence of multiple exits, the + // outer loop is incorrect: we do not add the EpilogPreheader and exit to the + // outer loop. This is automatically handled in the prolog case, so we do not + // have that bug in prolog generation. + if (hasMultipleExitingBlocks && UseEpilogRemainder && L->getParentLoop()) + return false; // Use Scalar Evolution to compute the trip count. This allows more loops to // be unrolled than relying on induction var simplification. if (!SE) diff --git a/llvm/test/Transforms/LoopUnroll/runtime-loop-multiple-exits.ll b/llvm/test/Transforms/LoopUnroll/runtime-loop-multiple-exits.ll index 18548c8af73..73672e14f78 100644 --- a/llvm/test/Transforms/LoopUnroll/runtime-loop-multiple-exits.ll +++ b/llvm/test/Transforms/LoopUnroll/runtime-loop-multiple-exits.ll @@ -434,3 +434,47 @@ loopexit1: ; preds = %header %sext3 = phi i32 [ %shft, %header ] ret i32 %sext3 } + +; Nested loop and inner loop is unrolled +; FIXME: we cannot unroll with epilog remainder currently, because +; the outer loop does not contain the epilog preheader and epilog exit (while +; infact it should). This causes us to choke up on LCSSA form being incorrect in +; outer loop. However, the exit block where LCSSA fails, is infact still within +; the outer loop. For now, we just bail out in presence of outer loop and epilog +; loop is generated. +; The outer loop header is the preheader for the inner loop and the inner header +; branches back to the outer loop. +define void @test8() { +; EPILOG: test8( +; EPILOG-NOT: niter + +; PROLOG: test8( +; PROLOG: outerloop: +; PROLOG-NEXT: phi i64 [ 3, %bb ], [ 0, %outerloop.loopexit ] +; PROLOG: %lcmp.mod = icmp eq i64 +; PROLOG-NEXT: br i1 %lcmp.mod, label %innerH.prol.loopexit, label %innerH.prol.preheader +; PROLOG: latch.6: +; PROLOG-NEXT: %tmp4.7 = add nsw i64 %tmp3, 8 +; PROLOG-NEXT: br i1 false, label %outerloop.loopexit.loopexit, label %latch.7 +; PROLOG: latch.7 +; PROLOG-NEXT: %tmp6.7 = icmp ult i64 %tmp4.7, 100 +; PROLOG-NEXT: br i1 %tmp6.7, label %innerH, label %exit.unr-lcssa +bb: + br label %outerloop + +outerloop: ; preds = %innerH, %bb + %tmp = phi i64 [ 3, %bb ], [ 0, %innerH ] + br label %innerH + +innerH: ; preds = %latch, %outerloop + %tmp3 = phi i64 [ %tmp4, %latch ], [ %tmp, %outerloop ] + %tmp4 = add nuw nsw i64 %tmp3, 1 + br i1 false, label %outerloop, label %latch + +latch: ; preds = %innerH + %tmp6 = icmp ult i64 %tmp4, 100 + br i1 %tmp6, label %innerH, label %exit + +exit: ; preds = %latch + ret void +} |
