[MemProf] Fix when CallStackTrie has a single chain to leaf with multi alloc type (#79433)

Fix one corner case when `CallStackTrie` has a single chain to leaf with
multi alloc type. This will cause stackIds in function summary is empty.

Author: lifengxiang1025

llvm/lib/Analysis/MemoryProfileInfo.cpp

@@ -244,12 +244,21 @@ bool CallStackTrie::buildAndAttachMIBMetadata(CallBase *CI) {
   MIBCallStack.push_back(AllocStackId);
   std::vector<Metadata *> MIBNodes;
   assert(!Alloc->Callers.empty() && "addCallStack has not been called yet");
-  buildMIBNodes(Alloc, Ctx, MIBCallStack, MIBNodes,
-                /*CalleeHasAmbiguousCallerContext=*/true);
-  assert(MIBCallStack.size() == 1 &&
-         "Should only be left with Alloc's location in stack");
-  CI->setMetadata(LLVMContext::MD_memprof, MDNode::get(Ctx, MIBNodes));
-  return true;
+  // The last parameter is meant to say whether the callee of the given node
+  // has more than one caller. Here the node being passed in is the alloc
+  // and it has no callees. So it's false.
+  if (buildMIBNodes(Alloc, Ctx, MIBCallStack, MIBNodes, false)) {
+    assert(MIBCallStack.size() == 1 &&
+           "Should only be left with Alloc's location in stack");
+    CI->setMetadata(LLVMContext::MD_memprof, MDNode::get(Ctx, MIBNodes));
+    return true;
+  }
+  // If there exists corner case that CallStackTrie has one chain to leaf
+  // and all node in the chain have multi alloc type, conservatively give
+  // it non-cold allocation type.
+  // FIXME: Avoid this case before memory profile created.
+  addAllocTypeAttribute(Ctx, CI, AllocationType::NotCold);
+  return false;
 }
 
 template <>

llvm/test/Transforms/PGOProfile/Inputs/memprof_loop_unroll.exe

@@ -144,4 +144,33 @@ EOF
 ${CLANG} ${COMMON_FLAGS} -fmemory-profile -funique-internal-linkage-names ${OUTDIR}/memprof_internal_linkage.cc -o ${OUTDIR}/memprof_internal_linkage.exe
 env MEMPROF_OPTIONS=log_path=stdout ${OUTDIR}/memprof_internal_linkage.exe > ${OUTDIR}/memprof_internal_linkage.memprofraw
 
-rm ${OUTDIR}/memprof_internal_linkage.cc
+rm ${OUTDIR}/memprof_internal_linkage.cc
+
+cat > ${OUTDIR}/memprof_loop_unroll_a.cc << EOF
+int* a[2];
+extern void foo();
+int main() {
+    foo();
+    for (int i = 0; i < 1000000; ++i) {
+        *a[0] = 1;
+    }
+    return 0;
+}
+EOF
+cat > ${OUTDIR}/memprof_loop_unroll_b.cc << EOF
+#include <string>
+extern int* a[2];
+void foo() {
+    for (int i = 0; i < 2; ++i) {
+        a[i] = new int[1];
+    }
+}
+EOF
+${CLANG} ${COMMON_FLAGS} -fmemory-profile ${OUTDIR}/memprof_loop_unroll_a.cc -O0 -o ${OUTDIR}/memprof_loop_unroll_a.o -c
+${CLANG} ${COMMON_FLAGS} -fmemory-profile ${OUTDIR}/memprof_loop_unroll_b.cc -O3 -o ${OUTDIR}/memprof_loop_unroll_b.o -c
+${CLANG} ${COMMON_FLAGS} -fmemory-profile ${OUTDIR}/memprof_loop_unroll_a.o ${OUTDIR}/memprof_loop_unroll_b.o -o ${OUTDIR}/memprof_loop_unroll.exe
+env MEMPROF_OPTIONS=log_path=stdout ${OUTDIR}/memprof_loop_unroll.exe > ${OUTDIR}/memprof_loop_unroll.memprofraw
+rm ${OUTDIR}/memprof_loop_unroll_a.cc
+rm ${OUTDIR}/memprof_loop_unroll_a.o
+rm ${OUTDIR}/memprof_loop_unroll_b.cc
+rm ${OUTDIR}/memprof_loop_unroll_b.o

llvm/test/Transforms/PGOProfile/Inputs/memprof_loop_unroll.memprofraw

@@ -0,0 +1,96 @@
+;; Tests memprof when contains loop unroll.
+
+;; Avoid failures on big-endian systems that can't read the profile properly
+; REQUIRES: x86_64-linux
+
+;; TODO: Use text profile inputs once that is available for memprof.
+;; # To update the Inputs below, run Inputs/update_memprof_inputs.sh.
+;; # To generate below LLVM IR for use in matching.
+;; $ clang++ -gmlt -fdebug-info-for-profiling -S %S/Inputs/memprof_loop_unroll_b.cc -emit-llvm
+
+; RUN: llvm-profdata merge %S/Inputs/memprof_loop_unroll.memprofraw --profiled-binary %S/Inputs/memprof_loop_unroll.exe -o %t.memprofdata
+; RUN: opt < %s -passes='memprof-use<profile-filename=%t.memprofdata>' -S | FileCheck %s
+
+; CHECK: call {{.*}} @_Znam{{.*}} #[[ATTR:[0-9]+]]
+; CHECK: attributes #[[ATTR]] = { builtin allocsize(0) "memprof"="notcold" }
+; CHECK-NOT: stackIds: ()
+
+; ModuleID = 'memprof_loop_unroll_b.cc'
+source_filename = "memprof_loop_unroll_b.cc"
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@a = external global [2 x ptr], align 16
+
+; Function Attrs: mustprogress noinline optnone uwtable
+define dso_local void @_Z3foov() #0 !dbg !10 {
+entry:
+  %i = alloca i32, align 4
+  store i32 0, ptr %i, align 4, !dbg !13
+  br label %for.cond, !dbg !14
+
+for.cond:                                         ; preds = %for.inc, %entry
+  %0 = load i32, ptr %i, align 4, !dbg !15
+  %cmp = icmp slt i32 %0, 2, !dbg !17
+  br i1 %cmp, label %for.body, label %for.end, !dbg !18
+
+for.body:                                         ; preds = %for.cond
+  %call = call noalias noundef nonnull ptr @_Znam(i64 noundef 4) #2, !dbg !19
+  %1 = load i32, ptr %i, align 4, !dbg !20
+  %idxprom = sext i32 %1 to i64, !dbg !21
+  %arrayidx = getelementptr inbounds [2 x ptr], ptr @a, i64 0, i64 %idxprom, !dbg !21
+  store ptr %call, ptr %arrayidx, align 8, !dbg !22
+  br label %for.inc, !dbg !23
+
+for.inc:                                          ; preds = %for.body
+  %2 = load i32, ptr %i, align 4, !dbg !24
+  %inc = add nsw i32 %2, 1, !dbg !24
+  store i32 %inc, ptr %i, align 4, !dbg !24
+  br label %for.cond, !dbg !26, !llvm.loop !27
+
+for.end:                                          ; preds = %for.cond
+  ret void, !dbg !30
+}
+
+; Function Attrs: nobuiltin allocsize(0)
+declare noundef nonnull ptr @_Znam(i64 noundef) #1
+
+attributes #0 = { mustprogress noinline optnone uwtable "frame-pointer"="all" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+attributes #1 = { nobuiltin allocsize(0) "frame-pointer"="all" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+attributes #2 = { builtin allocsize(0) }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2, !3, !4, !5, !6, !7, !8}
+!llvm.ident = !{!9}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 18.0.0", isOptimized: false, runtimeVersion: 0, emissionKind: LineTablesOnly, splitDebugInlining: false, debugInfoForProfiling: true, nameTableKind: None)
+!1 = !DIFile(filename: "memprof_loop_unroll_b.cc", directory: "/", checksumkind: CSK_MD5, checksum: "00276e590d606451dc54f3ff5f4bba25")
+!2 = !{i32 7, !"Dwarf Version", i32 5}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!4 = !{i32 1, !"wchar_size", i32 4}
+!5 = !{i32 8, !"PIC Level", i32 2}
+!6 = !{i32 7, !"PIE Level", i32 2}
+!7 = !{i32 7, !"uwtable", i32 2}
+!8 = !{i32 7, !"frame-pointer", i32 2}
+!9 = !{!"clang version 18.0.0"}
+!10 = distinct !DISubprogram(name: "foo", linkageName: "_Z3foov", scope: !1, file: !1, line: 4, type: !11, scopeLine: 4, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0)
+!11 = !DISubroutineType(types: !12)
+!12 = !{}
+!13 = !DILocation(line: 5, column: 14, scope: !10)
+!14 = !DILocation(line: 5, column: 10, scope: !10)
+!15 = !DILocation(line: 5, column: 21, scope: !16)
+!16 = !DILexicalBlockFile(scope: !10, file: !1, discriminator: 2)
+!17 = !DILocation(line: 5, column: 23, scope: !16)
+!18 = !DILocation(line: 5, column: 5, scope: !16)
+!19 = !DILocation(line: 6, column: 16, scope: !10)
+!20 = !DILocation(line: 6, column: 11, scope: !10)
+!21 = !DILocation(line: 6, column: 9, scope: !10)
+!22 = !DILocation(line: 6, column: 14, scope: !10)
+!23 = !DILocation(line: 7, column: 5, scope: !10)
+!24 = !DILocation(line: 5, column: 28, scope: !25)
+!25 = !DILexicalBlockFile(scope: !10, file: !1, discriminator: 4)
+!26 = !DILocation(line: 5, column: 5, scope: !25)
+!27 = distinct !{!27, !28, !23, !29}
+!28 = !DILocation(line: 5, column: 5, scope: !10)
+!29 = !{!"llvm.loop.mustprogress"}
+!30 = !DILocation(line: 8, column: 1, scope: !10)