[llvm] [MemProf] Extend MemProfUse pass to make use of data access profiles to partition data (PR #151238)

[Snehasish Kumar via llvm-commits]

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+; RUN: rm -rf %t && split-file %s %t && cd %t
+
+;; Read a text profile and merge it into indexed profile.
+; RUN: llvm-profdata merge --memprof-version=4 memprof.yaml -o memprof.profdata
+
+;; Run optimizer pass on the IR, and check the section prefix.
+; RUN: opt -passes='memprof-use<profile-filename=memprof.profdata>' -annotate-static-data-prefix \
+; RUN: -S input.ll -o - 2>&1 | FileCheck %s
+
+;; Repeat the command line above and enable -print-static-data-prefix. Test both IR and log.
+; RUN: opt -passes='memprof-use<profile-filename=memprof.profdata>' -annotate-static-data-prefix \
+; RUN: -print-static-data-prefix -S input.ll -o - 2>&1 | FileCheck %s --check-prefixes=LOG,CHECK
+
+; LOG: Global variable .str has no section prefix
+; LOG: Global variable var1 has section prefix: hot
+; LOG: Global variable var2.llvm.125 has section prefix: hot
+; LOG: Global variable foo has section prefix: unlikely
+; LOG: Global variable bar has no section prefix
+
+;; String literals are not annotated.
+; CHECK: @.str = unnamed_addr constant [5 x i8] c"abcde"
+; CHECK-NOT: section_prefix
+; CHECK: @var1 = global i32 123, !section_prefix !0
+
+;; @var.llvm.125 will be canonicalized to @var2 for profile look-up.
+; CHECK-NEXT: @var2.llvm.125 = global i64 0, !section_prefix !0
+; CHECK-NEXT: @foo = global i8 2, !section_prefix !1
+
+;; @bar is not seen in hot symbol or known symbol set, so it doesn't get
+;; a section prefix. It's up to the linker to decide how to map input sections
+;; to output, and one conservative practice is to map unlikely-prefixed ones to
+;; unlikely output section, and map the rest (hot-prefixed or prefix-less) to
+;; the canonical output section.
+; CHECK-NEXT: @bar = global i16 3
+
+; CHECK: !0 = !{!"section_prefix", !"hot"}
+; CHECK-NEXT: !1 = !{!"section_prefix", !"unlikely"}
+
+;--- memprof.yaml
+---
+HeapProfileRecords:
+  - GUID:            0xdeadbeef12345678
+    AllocSites:
+      - Callstack:
+          - { Function: 0x1111111111111111, LineOffset: 11, Column: 10, IsInlineFrame: true }
+          - { Function: 0x2222222222222222, LineOffset: 22, Column: 20, IsInlineFrame: false }
+        MemInfoBlock:
+          AllocCount:      111
+          TotalSize:       222
+          TotalLifetime:   333
+          TotalLifetimeAccessDensity: 444
+    CallSites:
+      - Frames:
+        - { Function: 0x5555555555555555, LineOffset: 55, Column: 50, IsInlineFrame: true }
+        - { Function: 0x6666666666666666, LineOffset: 66, Column: 60, IsInlineFrame: false }
+        CalleeGuids: [ 0x100, 0x200 ]
+DataAccessProfiles:
+  SampledRecords:
+    - Symbol:          var1
+      AccessCount:     1000
+    - Symbol:          var2
+      AccessCount:     5
+    - Hash:            101010
+      AccessCount:     145
+  KnownColdSymbols:
+    - foo
+  KnownColdStrHashes: [ 999, 1001 ]
+...
+;--- input.ll
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snehasish wrote:

Add another test where there are no functions in the module.

https://github.com/llvm/llvm-project/pull/151238