diff options
Diffstat (limited to 'llvm/test/Transforms/LoopUnroll/runtime-loop-branchweight.ll')
| -rw-r--r-- | llvm/test/Transforms/LoopUnroll/runtime-loop-branchweight.ll | 58 |
1 files changed, 52 insertions, 6 deletions
diff --git a/llvm/test/Transforms/LoopUnroll/runtime-loop-branchweight.ll b/llvm/test/Transforms/LoopUnroll/runtime-loop-branchweight.ll index 2617199..2f8f98d 100644 --- a/llvm/test/Transforms/LoopUnroll/runtime-loop-branchweight.ll +++ b/llvm/test/Transforms/LoopUnroll/runtime-loop-branchweight.ll @@ -2,12 +2,24 @@ ;; Check that the remainder loop is properly assigned a branch weight for its latch branch. ; CHECK-LABEL: @test( -; CHECK-LABEL: for.body: -; CHECK: br i1 [[COND1:%.*]], label %for.end.loopexit.unr-lcssa, label %for.body, !prof ![[#PROF:]], !llvm.loop ![[#LOOP:]] -; CHECK-LABEL: for.body.epil: -; CHECK: br i1 [[COND2:%.*]], label %for.body.epil, label %for.end.loopexit.epilog-lcssa, !prof ![[#PROF2:]], !llvm.loop ![[#LOOP2:]] -; CHECK: ![[#PROF]] = !{!"branch_weights", i32 1, i32 2499} -; CHECK: ![[#PROF2]] = !{!"branch_weights", i32 1, i32 1} +; CHECK-LABEL: entry: +; CHECK: [[FOR_BODY_PREHEADER:.*]]: +; CHECK: br i1 %{{.*}}, label %[[FOR_BODY_EPIL_PREHEADER:.*]], label %[[FOR_BODY_PREHEADER_NEW:.*]], !prof ![[#PROF_UR_GUARD:]] +; CHECK: [[FOR_BODY_PREHEADER_NEW]]: +; CHECK: br label %for.body +; CHECK: for.body: +; CHECK: %add = add +; CHECK: %add.1 = add +; CHECK: %add.2 = add +; CHECK: %add.3 = add +; CHECK-NOT: %add.4 = add +; CHECK: br i1 %{{.*}}, label %[[FOR_END_LOOPEXIT_UNR_LCSSA:.*]], label %for.body, !prof ![[#PROF_UR_LATCH:]], !llvm.loop ![[#LOOP_UR_LATCH:]] +; CHECK: [[FOR_END_LOOPEXIT_UNR_LCSSA]]: +; CHECK: br i1 %{{.*}}, label %[[FOR_BODY_EPIL_PREHEADER]], label %[[FOR_END_LOOPEXIT:.*]], !prof ![[#PROF_RM_GUARD:]] +; CHECK: [[FOR_BODY_EPIL_PREHEADER]]: +; CHECK: br label %[[FOR_BODY_EPIL:.*]] +; CHECK: [[FOR_BODY_EPIL]]: +; CHECK: br i1 {{.*}}, label %[[FOR_BODY_EPIL]], label %[[FOR_END_LOOPEXIT_EPILOG_LCSSA:.*]], !prof ![[#PROF_RM_LATCH:]], !llvm.loop ![[#LOOP_RM_LATCH:]] define i3 @test(ptr %a, i3 %n) { entry: @@ -31,3 +43,37 @@ for.end: } !0 = !{!"branch_weights", i32 1, i32 9999} + +; Original loop probability: p = 9999/(1+9999) = 0.9999 +; Original estimated trip count: (1+9999)/1 = 10000 +; Unroll count: 4 + +; Probability of >=3 iterations after first: p^3 = 0.9970003 =~ +; 2146839468 / (644180 + 2146839468). +; CHECK: ![[#PROF_UR_GUARD]] = !{!"branch_weights", i32 644180, i32 2146839468} + +; Probability of >=4 more iterations: p^4 = 0.99960006 =~ +; 2146624784 / (858864 + 2146624784). +; CHECK: ![[#PROF_UR_LATCH]] = !{!"branch_weights", i32 858864, i32 2146624784} + +; 10000//4 = 2500 +; CHECK: ![[#LOOP_UR_LATCH]] = distinct !{![[#LOOP_UR_LATCH]], ![[#LOOP_UR_TC:]], ![[#DISABLE:]]} +; CHECK: ![[#LOOP_UR_TC]] = !{!"llvm.loop.estimated_trip_count", i32 2500} +; +; CHECK: ![[#DISABLE]] = !{!"llvm.loop.unroll.disable"} + +; Probability of 1 to 3 more of 3 more remainder iterations: +; (p-p^4)/(1-p^4) = 0.749962497 =~ 1610532724 / (1610532724 + 536950924). +; CHECK: ![[#PROF_RM_GUARD]] = !{!"branch_weights", i32 1610532724, i32 536950924} + +; Frequency of first remainder iter: r1 = 1 +; Frequency of second remainder iter: r2 = r1*(p-p^3)/(1-p^3) = 0.666633331 +; Frequency of third remainder iter: r3 = r2*(p-p^2)/(1-p^2) = 0.333299999 +; Solve for loop probability that produces that frequency: f = 1/(1-p') => +; p' = 1-1/f = 1-1/(r1+r2+r3) = 0.499983332 =~ +; 1073706403 / (1073706403 + 1073777245). +; CHECK: ![[#PROF_RM_LATCH]] = !{!"branch_weights", i32 1073706403, i32 1073777245} + +; 10000%4 = 0 +; CHECK: ![[#LOOP_RM_LATCH]] = distinct !{![[#LOOP_RM_LATCH]], ![[#LOOP_RM_TC:]], ![[#DISABLE:]]} +; CHECK: ![[#LOOP_RM_TC]] = !{!"llvm.loop.estimated_trip_count", i32 0} |