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[MemProf] Fix the stack updating handling of pruned contexts (#81322)
Fix a bug in the handling of cases where a callsite's stack ids partially overlap with the pruned context during matching of calls to the graph contructed from the profiled contexts. This fix makes the code match the comments.
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‎llvm/lib/Transforms/IPO/MemProfContextDisambiguation.cpp

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@@ -1381,7 +1381,7 @@ void CallsiteContextGraph<DerivedCCG, FuncTy, CallTy>::updateStackNodes() {
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// not fully matching stack contexts. To do this, subtract any context ids
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// found in caller nodes of the last node found above.
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if (Ids.back() != getLastStackId(Call)) {
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for (const auto &PE : CurNode->CallerEdges) {
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for (const auto &PE : LastNode->CallerEdges) {
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set_subtract(StackSequenceContextIds, PE->getContextIds());
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if (StackSequenceContextIds.empty())
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break;

‎llvm/test/Transforms/MemProfContextDisambiguation/inlined3.ll

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@@ -0,0 +1,193 @@
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;; This test ensures that the logic which assigns calls to stack nodes
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;; correctly handles an inlined callsite with stack ids that partially
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;; overlap with a trimmed context. In particular when it also partially
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;; overlaps with a longer non-trimmed context that doesn't match all of
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;; the inlined callsite stack ids.
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;; The profile data and call stacks were all manually added, but the code
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;; would be structured something like the following (fairly contrived to
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;; result in the type of control flow needed to test):
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;; void A(bool b) {
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;; if (b)
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;; // cold: stack ids 6, 2, 8 (trimmed ids 10)
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;; // not cold: stack ids 6, 7 (trimmed ids 9, 11)
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;; new char[10]; // stack id 6
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;; else
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;; // not cold: stack ids 1, 2, 8, 3, 4
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;; // cold: stack ids 1, 2, 8, 3, 5
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;; new char[10]; // stack id 1
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;; }
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;;
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;; void XZ() {
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;; A(false); // stack ids 2, 8 (e.g. X inlined into Z)
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;; }
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;;
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;; void XZN() {
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;; // This is the tricky one to get right. We want to ensure it gets
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;; // correctly correlated with a stack node for the trimmed 6, 2, 8
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;; // context shown in A. It should *not* be correlated with the longer
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;; // untrimmed 1, 2, 8, 3, 4|5 contexts.
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;; A(true); // stack ids 2, 8, 9 (e.g. X inlined into Z inlined into N)
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;; }
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;;
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;; void Y() {
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;; A(true); // stack id 7
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;; }
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;;
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;; void M() {
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;; XZ(); // stack id 3
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;; }
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;;
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;; int main() {
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;; M(); // stack id 4 (leads to not cold allocation)
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;; M(); // stack id 5 (leads to cold allocation)
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;; XZN(); // stack id 11 (leads to cold allocation)
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;; Y(); // stack id 10 (leads to not cold allocation)
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;; }
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;; -stats requires asserts
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; REQUIRES: asserts
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; RUN: opt -passes=memprof-context-disambiguation -supports-hot-cold-new \
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; RUN: -memprof-verify-ccg -memprof-verify-nodes \
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; RUN: -stats -pass-remarks=memprof-context-disambiguation \
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; RUN: %s -S 2>&1 | FileCheck %s --check-prefix=IR \
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; RUN: --check-prefix=STATS --check-prefix=REMARKS
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; REMARKS: created clone _Z1Ab.memprof.1
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; REMARKS: created clone _Z2XZv.memprof.1
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; REMARKS: created clone _Z1Mv.memprof.1
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;; Make sure the inlined context in _Z3XZNv, which partially overlaps
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;; trimmed cold context, and also partially overlaps completely
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;; unrelated contexts, correctly calls a cloned version of Z1Ab,
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;; which will call the cold annotated allocation.
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; REMARKS: call in clone _Z3XZNv assigned to call function clone _Z1Ab.memprof.1
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; REMARKS: call in clone main assigned to call function clone _Z1Mv.memprof.1
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; REMARKS: call in clone _Z1Mv.memprof.1 assigned to call function clone _Z2XZv.memprof.1
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; REMARKS: call in clone _Z2XZv.memprof.1 assigned to call function clone _Z1Ab
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; REMARKS: call in clone main assigned to call function clone _Z1Mv
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; REMARKS: call in clone _Z1Mv assigned to call function clone _Z2XZv
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; REMARKS: call in clone _Z2XZv assigned to call function clone _Z1Ab.memprof.1
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; REMARKS: call in clone _Z1Ab.memprof.1 marked with memprof allocation attribute cold
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; REMARKS: call in clone _Z1Yv assigned to call function clone _Z1Ab
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; REMARKS: call in clone _Z1Ab marked with memprof allocation attribute notcold
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; REMARKS: call in clone _Z1Ab marked with memprof allocation attribute cold
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; REMARKS: call in clone _Z1Ab.memprof.1 marked with memprof allocation attribute notcold
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target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-linux-gnu"
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define dso_local void @_Z1Ab(i1 noundef zeroext %b) {
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entry:
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br i1 %b, label %if.then, label %if.else
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if.then:
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%call = call noalias noundef nonnull ptr @_Znam(i64 noundef 10) #7, !memprof !5, !callsite !11
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br label %if.end
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if.else:
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%call2 = call noalias noundef nonnull ptr @_Znam(i64 noundef 10) #7, !memprof !0, !callsite !10
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br label %if.end
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if.end:
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ret void
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}
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; Function Attrs: nobuiltin
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declare ptr @_Znam(i64) #0
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define dso_local void @_Z2XZv() local_unnamed_addr #0 {
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entry:
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tail call void @_Z1Ab(i1 noundef zeroext false), !callsite !12
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ret void
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}
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define dso_local void @_Z1Mv() local_unnamed_addr #0 {
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entry:
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tail call void @_Z2XZv(), !callsite !19
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ret void
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}
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define dso_local void @_Z3XZNv() local_unnamed_addr {
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entry:
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tail call void @_Z1Ab(i1 noundef zeroext true), !callsite !15
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ret void
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}
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define dso_local void @_Z1Yv() local_unnamed_addr {
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entry:
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tail call void @_Z1Ab(i1 noundef zeroext true), !callsite !17
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ret void
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}
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define dso_local noundef i32 @main() local_unnamed_addr {
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entry:
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tail call void @_Z1Mv(), !callsite !13 ;; Not cold context
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tail call void @_Z1Mv(), !callsite !14 ;; Cold context
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tail call void @_Z3XZNv(), !callsite !16 ;; Cold context
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tail call void @_Z1Yv(), !callsite !18 ;; Not cold context
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ret i32 0
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}
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attributes #0 = { nobuiltin }
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attributes #7 = { builtin }
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!0 = !{!1, !3}
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;; Not cold context via first call to _Z1Mv in main
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!1 = !{!2, !"notcold"}
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!2 = !{i64 1, i64 2, i64 8, i64 3, i64 4}
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;; Cold context via second call to _Z1Mv in main
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!3 = !{!4, !"cold"}
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!4 = !{i64 1, i64 2, i64 8, i64 3, i64 5}
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!5 = !{!6, !8}
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;; Cold (trimmed) context via call to _Z3XZNv in main
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!6 = !{!7, !"cold"}
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!7 = !{i64 6, i64 2, i64 8}
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;; Not cold (trimmed) context via call to _Z1Yv in main
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!8 = !{!9, !"notcold"}
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!9 = !{i64 6, i64 7}
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!10 = !{i64 1}
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!11 = !{i64 6}
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!12 = !{i64 2, i64 8}
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!13 = !{i64 4}
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!14 = !{i64 5}
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;; Inlined context in _Z3XZNv, which includes part of trimmed cold context
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!15 = !{i64 2, i64 8, i64 9}
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!16 = !{i64 11}
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!17 = !{i64 7}
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!18 = !{i64 10}
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!19 = !{i64 3}
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; IR: define {{.*}} @_Z1Ab(i1 noundef zeroext %b)
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; IR: call {{.*}} @_Znam(i64 noundef 10) #[[NOTCOLD:[0-9]+]]
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; IR: call {{.*}} @_Znam(i64 noundef 10) #[[COLD:[0-9]+]]
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; IR: define {{.*}} @_Z2XZv()
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; IR: call {{.*}} @_Z1Ab.memprof.1(i1 noundef zeroext false)
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; IR: define {{.*}} @_Z1Mv()
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; IR: call {{.*}} @_Z2XZv()
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;; Make sure the inlined context in _Z3XZNv, which partially overlaps
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;; trimmed cold context, and also partially overlaps completely
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;; unrelated contexts, correctly calls the cloned version of Z1Ab
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;; that will call the cold annotated allocation.
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; IR: define {{.*}} @_Z3XZNv()
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; IR: call {{.*}} @_Z1Ab.memprof.1(i1 noundef zeroext true)
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; IR: define {{.*}} @_Z1Yv()
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; IR: call {{.*}} @_Z1Ab(i1 noundef zeroext true)
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; IR: define {{.*}} @main()
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; IR: call {{.*}} @_Z1Mv()
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; IR: call {{.*}} @_Z1Mv.memprof.1()
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; IR: call {{.*}} @_Z3XZNv()
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; IR: call {{.*}} @_Z1Yv()
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; IR: define {{.*}} @_Z1Ab.memprof.1(i1 noundef zeroext %b)
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; IR: call {{.*}} @_Znam(i64 noundef 10) #[[COLD]]
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; IR: call {{.*}} @_Znam(i64 noundef 10) #[[NOTCOLD]]
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; IR: define {{.*}} @_Z2XZv.memprof.1()
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; IR: call {{.*}} @_Z1Ab(i1 noundef zeroext false)
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; IR: define {{.*}} @_Z1Mv.memprof.1()
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; IR: call {{.*}} @_Z2XZv.memprof.1()
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; STATS: 2 memprof-context-disambiguation - Number of cold static allocations (possibly cloned)
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; STATS: 2 memprof-context-disambiguation - Number of not cold static allocations (possibly cloned)
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; STATS: 3 memprof-context-disambiguation - Number of function clones created during whole program analysis

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