Use profile summary to disable peeling for huge working sets

Summary:
Detect when the working set size of a profiled application is huge,
by comparing the number of counts required to reach the hot percentile
in the profile summary to a large threshold*.

When the working set size is determined to be huge, disable peeling
to avoid bloating the working set further.

*Note that the selected threshold (15K) is significantly larger than the
largest working set value in SPEC cpu2006 (which is gcc at around 11K).

Reviewers: davidxl

Subscribers: mehdi_amini, mzolotukhin, eraman, llvm-commits

Differential Revision: https://reviews.llvm.org/D36288

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310005 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 37 insertions, 18 deletions

diff --git a/test/Transforms/LoopUnroll/peel-loop-pgo.ll b/test/Transforms/LoopUnroll/peel-loop-pgo.ll
index ee5846c6325..361a2ca71c3 100644
--- a/test/Transforms/LoopUnroll/peel-loop-pgo.ll
+++ b/test/Transforms/LoopUnroll/peel-loop-pgo.ll
@@ -1,5 +1,8 @@
 ; RUN: opt < %s -S -debug-only=loop-unroll -loop-unroll 2>&1 | FileCheck %s
-; RUN: opt < %s -S -debug-only=loop-unroll -passes='require<opt-remark-emit>,unroll' 2>&1 | FileCheck %s
+; RUN: opt < %s -S -debug-only=loop-unroll -passes='require<profile-summary>,function(require<opt-remark-emit>,unroll)' 2>&1 | FileCheck %s
+; Confirm that peeling is disabled if the number of counts required to reach
+; the hot percentile is above the threshold.
+; RUN: opt < %s -S -profile-summary-huge-working-set-size-threshold=9 -debug-only=loop-unroll -passes='require<profile-summary>,function(require<opt-remark-emit>,unroll)' 2>&1 | FileCheck %s --check-prefix=NOPEEL
 ; REQUIRES: asserts
 
 ; Make sure we use the profile information correctly to peel-off 3 iterations
@@ -11,19 +14,19 @@
 ; CHECK-NOT: PEELING
 
 ; Confirm that no peeling occurs when we are performing full unrolling.
-; RUN: opt < %s -S -debug-only=loop-unroll -passes='require<opt-remark-emit>,loop(unroll-full)' 2>&1 | FileCheck %s --check-prefix=FULLUNROLL
-; FULLUNROLL-NOT: PEELING
+; RUN: opt < %s -S -debug-only=loop-unroll -passes='require<opt-remark-emit>,loop(unroll-full)' 2>&1 | FileCheck %s --check-prefix=NOPEEL
+; NOPEEL-NOT: PEELING
 
 ; CHECK-LABEL: @basic
-; CHECK: br i1 %{{.*}}, label %[[NEXT0:.*]], label %for.cond.for.end_crit_edge, !prof !1
+; CHECK: br i1 %{{.*}}, label %[[NEXT0:.*]], label %for.cond.for.end_crit_edge, !prof !15
 ; CHECK: [[NEXT0]]:
-; CHECK: br i1 %{{.*}}, label %[[NEXT1:.*]], label %for.cond.for.end_crit_edge, !prof !2
+; CHECK: br i1 %{{.*}}, label %[[NEXT1:.*]], label %for.cond.for.end_crit_edge, !prof !16
 ; CHECK: [[NEXT1]]:
-; CHECK: br i1 %{{.*}}, label %[[NEXT2:.*]], label %for.cond.for.end_crit_edge, !prof !3
+; CHECK: br i1 %{{.*}}, label %[[NEXT2:.*]], label %for.cond.for.end_crit_edge, !prof !17
 ; CHECK: [[NEXT2]]:
-; CHECK: br i1 %{{.*}}, label %for.body, label %{{.*}}, !prof !4
+; CHECK: br i1 %{{.*}}, label %for.body, label %{{.*}}, !prof !18
 
-define void @basic(i32* %p, i32 %k) #0 !prof !0 {
+define void @basic(i32* %p, i32 %k) #0 !prof !15 {
 entry:
   %cmp3 = icmp slt i32 0, %k
   br i1 %cmp3, label %for.body.lr.ph, label %for.end
@@ -38,7 +41,7 @@ for.body:                                         ; preds = %for.body.lr.ph, %fo
   store i32 %i.05, i32* %p.addr.04, align 4
   %inc = add nsw i32 %i.05, 1
   %cmp = icmp slt i32 %inc, %k
-  br i1 %cmp, label %for.body, label %for.cond.for.end_crit_edge, !prof !1
+  br i1 %cmp, label %for.body, label %for.cond.for.end_crit_edge, !prof !16
 
 for.cond.for.end_crit_edge:                       ; preds = %for.body
   br label %for.end
@@ -54,7 +57,7 @@ for.end:                                          ; preds = %for.cond.for.end_cr
 ; CHECK: for.body:
 ; CHECK-NOT: br
 ; CHECK: br i1 %cmp, label %for.body, label %for.cond.for.end_crit_edge
-define void @optsize(i32* %p, i32 %k) #1 !prof !0 {
+define void @optsize(i32* %p, i32 %k) #1 !prof !15 {
 entry:
   %cmp3 = icmp slt i32 0, %k
   br i1 %cmp3, label %for.body.lr.ph, label %for.end
@@ -69,7 +72,7 @@ for.body:                                         ; preds = %for.body.lr.ph, %fo
   store i32 %i.05, i32* %p.addr.04, align 4
   %inc = add nsw i32 %i.05, 1
   %cmp = icmp slt i32 %inc, %k
-  br i1 %cmp, label %for.body, label %for.cond.for.end_crit_edge, !prof !1
+  br i1 %cmp, label %for.body, label %for.cond.for.end_crit_edge, !prof !16
 
 for.cond.for.end_crit_edge:                       ; preds = %for.body
   br label %for.end
@@ -81,11 +84,27 @@ for.end:                                          ; preds = %for.cond.for.end_cr
 attributes #0 = { nounwind }
 attributes #1 = { nounwind optsize }
 
-!0 = !{!"function_entry_count", i64 1}
-!1 = !{!"branch_weights", i32 3001, i32 1001}
-
-;CHECK: !1 = !{!"branch_weights", i32 900, i32 101}
-;CHECK: !2 = !{!"branch_weights", i32 540, i32 360}
-;CHECK: !3 = !{!"branch_weights", i32 162, i32 378}
-;CHECK: !4 = !{!"branch_weights", i32 1399, i32 162}
+!llvm.module.flags = !{!1}
+
+!1 = !{i32 1, !"ProfileSummary", !2}
+!2 = !{!3, !4, !5, !6, !7, !8, !9, !10}
+!3 = !{!"ProfileFormat", !"InstrProf"}
+!4 = !{!"TotalCount", i64 10}
+!5 = !{!"MaxCount", i64 3}
+!6 = !{!"MaxInternalCount", i64 1}
+!7 = !{!"MaxFunctionCount", i64 3}
+!8 = !{!"NumCounts", i64 2}
+!9 = !{!"NumFunctions", i64 2}
+!10 = !{!"DetailedSummary", !11}
+!11 = !{!12, !13, !14}
+!12 = !{i32 10000, i64 3, i32 2}
+!13 = !{i32 999000, i64 1, i32 10}
+!14 = !{i32 999999, i64 1, i32 10}
+!15 = !{!"function_entry_count", i64 1}
+!16 = !{!"branch_weights", i32 3001, i32 1001}
+
+;CHECK: !15 = !{!"branch_weights", i32 900, i32 101}
+;CHECK: !16 = !{!"branch_weights", i32 540, i32 360}
+;CHECK: !17 = !{!"branch_weights", i32 162, i32 378}
+;CHECK: !18 = !{!"branch_weights", i32 1399, i32 162}