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[MemProf] Handle empty stack context during ThinLTO cloning #81008

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Merged
merged 1 commit into from
Feb 7, 2024
Merged

[MemProf] Handle empty stack context during ThinLTO cloning #81008

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6 changes: 5 additions & 1 deletion llvm/lib/Transforms/IPO/MemProfContextDisambiguation.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3475,7 +3475,11 @@ bool MemProfContextDisambiguation::applyImport(Module &M) {
auto ContextIterBegin =
StackContext.beginAfterSharedPrefix(CallsiteContext);
// Skip the checking on the first iteration.
uint64_t LastStackContextId = *ContextIterBegin == 0 ? 1 : 0;
uint64_t LastStackContextId =
(ContextIterBegin != StackContext.end() &&
*ContextIterBegin == 0)
? 1
: 0;
for (auto ContextIter = ContextIterBegin;
ContextIter != StackContext.end(); ++ContextIter) {
// If this is a direct recursion, simply skip the duplicate
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36 changes: 36 additions & 0 deletions llvm/test/ThinLTO/X86/memprof-import-fix.ll
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Original file line number Diff line number Diff line change
@@ -0,0 +1,36 @@
;; Test to ensure that importing of cloning decisions does not assert when
;; the callsite context is longer than the MIB context.
;; FIXME: Presumably this happened as a result of inlining, but in theory the
;; metadata should have been replaced with an attribute in that case. Need to
;; investigate why this is occuring.

; RUN: opt -thinlto-bc %s >%t.o
; RUN: llvm-lto2 run %t.o -enable-memprof-context-disambiguation \
; RUN: -supports-hot-cold-new \
; RUN: -r=%t.o,main,plx \
; RUN: -r=%t.o,_Znam, \
; RUN: -save-temps \
; RUN: -o %t.out

; RUN: llvm-dis %t.out.1.4.opt.bc -o - | FileCheck %s --check-prefix=IR
;; The call to new is not changed in this case.
; IR: call ptr @_Znam(i64 0)

source_filename = "memprof-import-fix.ll"
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

define i32 @main() #0 {
entry:
%call = call ptr @_Znam(i64 0), !memprof !0, !callsite !3
ret i32 0
}

declare ptr @_Znam(i64)

attributes #0 = { noinline optnone }

!0 = !{!1}
!1 = !{!2, !"notcold"}
!2 = !{i64 9086428284934609951}
!3 = !{i64 9086428284934609951, i64 -5964873800580613432}