diff options
| -rw-r--r-- | llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp | 4 | ||||
| -rw-r--r-- | llvm/test/Transforms/LoopUnroll/PowerPC/a2-high-cost-trip-count-computation.ll | 27 |
2 files changed, 31 insertions, 0 deletions
diff --git a/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp b/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp index 08328d9acac..25d563a7d97 100644 --- a/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp +++ b/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp @@ -187,6 +187,10 @@ void PPCTTIImpl::getUnrollingPreferences(Loop *L, // The A2 is in-order with a deep pipeline, and concatenation unrolling // helps expose latency-hiding opportunities to the instruction scheduler. UP.Partial = UP.Runtime = true; + + // We unroll a lot on the A2 (hundreds of instructions), and the benefits + // often outweigh the cost of a division to compute the trip count. + UP.AllowExpensiveTripCount = true; } BaseT::getUnrollingPreferences(L, UP); diff --git a/llvm/test/Transforms/LoopUnroll/PowerPC/a2-high-cost-trip-count-computation.ll b/llvm/test/Transforms/LoopUnroll/PowerPC/a2-high-cost-trip-count-computation.ll new file mode 100644 index 00000000000..bd5f68f9f20 --- /dev/null +++ b/llvm/test/Transforms/LoopUnroll/PowerPC/a2-high-cost-trip-count-computation.ll @@ -0,0 +1,27 @@ +; RUN: opt < %s -S -mtriple=powerpc64-unknown-linux-gnu -mcpu=a2 -loop-unroll | FileCheck %s + +target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128" + +;; Check that we do emit expensive instructions to compute trip +;; counts when unrolling loops on the a2 (because we unroll a lot). + +define i32 @test(i64 %v12, i8* %array, i64* %loc) { +; CHECK-LABEL: @test( +; CHECK: udiv +entry: + %step = load i64, i64* %loc, !range !0 + br label %loop + +loop: ; preds = %entry, %loop + %k.015 = phi i64 [ %v15, %loop ], [ %v12, %entry ] + %v14 = getelementptr inbounds i8, i8* %array, i64 %k.015 + store i8 0, i8* %v14 + %v15 = add nuw nsw i64 %k.015, %step + %v16 = icmp slt i64 %v15, 8193 + br i1 %v16, label %loop, label %loopexit + +loopexit: ; preds = %loop + ret i32 0 +} + +!0 = !{i64 1, i64 100} |
