Reland "[utils] Implement the llvm-locstats tool"

The tool reports verbose output for the DWARF debug location coverage. The llvm-locstats for each variable or formal parameter DIE computes what percentage from the code section bytes, where it is in scope, it has location description. The line 0 shows the number (and the percentage) of DIEs with no location information, but the line 100 shows the number (and the percentage) of DIEs where there is location information in all code section bytes (where the variable or parameter is in the scope). The line 50..59 shows the number (and the percentage) of DIEs where the location information is in between 50 and 59 percentage of its scope covered. Differential Revision: https://reviews.llvm.org/D66526 llvm-svn: 373183
rust-lang · Sep 30, 2019 · 0f30960 · 0f30960
1 parent e794c04
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diff --git a/llvm/CMakeLists.txt b/llvm/CMakeLists.txt
@@ -1097,3 +1097,7 @@ if (LLVM_INCLUDE_BENCHMARKS)
   add_subdirectory(utils/benchmark)
   add_subdirectory(benchmarks)
 endif()
+
+if (LLVM_INCLUDE_UTILS AND LLVM_INCLUDE_TOOLS)
+  add_subdirectory(utils/llvm-locstats)
+endif()
diff --git a/llvm/docs/CommandGuide/index.rst b/llvm/docs/CommandGuide/index.rst
@@ -74,3 +74,4 @@ Developer Tools
    llvm-build
    llvm-exegesis
    llvm-pdbutil
+   llvm-locstats
diff --git a/llvm/docs/CommandGuide/llvm-locstats.rst b/llvm/docs/CommandGuide/llvm-locstats.rst
@@ -0,0 +1,79 @@
+llvm-locstats - calculate statistics on DWARF debug location
+============================================================
+
+.. program:: llvm-locstats
+
+SYNOPSIS
+--------
+
+:program:`llvm-locstats` [*options*] [*filename*]
+
+DESCRIPTION
+-----------
+
+:program:`llvm-locstats` works like a wrapper around :program:`llvm-dwarfdump`.
+It parses :program:`llvm-dwarfdump` statistics regarding debug location by
+pretty printing it in a more human readable way.
+
+The line 0% shows the number and the percentage of DIEs with no location
+information, but the line 100% shows the information for DIEs where there is
+location information in all code section bytes (where the variable or parameter
+is in the scope). The line 50-59% shows the number and the percentage of DIEs
+where the location information is between 50 and 59 percentage of its scope
+covered.
+
+OPTIONS
+-------
+
+.. option:: -only-variables
+
+            Calculate the location statistics only for local variables.
+
+.. option:: -only-formal-parameters
+
+            Calculate the location statistics only for formal parameters.
+
+.. option:: -ignore-debug-entry-values
+
+            Ignore the location statistics on locations containing the
+            debug entry values DWARF operation.
+
+EXIT STATUS
+-----------
+
+:program:`llvm-locstats` returns 0 if the input file were parsed
+successfully. Otherwise, it returns 1.
+
+OUTPUT EXAMPLE
+--------------
+
+.. code-block:: none
+
+  =================================================
+            Debug Location Statistics
+  =================================================
+        cov%          samples       percentage(~)
+  -------------------------------------------------
+     0%                    1              16%
+     1-9%                  0               0%
+     10-19%                0               0%
+     20-29%                0               0%
+     30-39%                0               0%
+     40-49%                0               0%
+     50-99%                1              16%
+     60-69%                0               0%
+     70-79%                0               0%
+     80-89%                1              16%
+     90-99%                0               0%
+     100%                  3              50%
+  =================================================
+  -the number of debug variables processed: 6
+  -PC ranges covered: 81%
+  -------------------------------------------------
+  -total availability: 83%
+  =================================================
+
+SEE ALSO
+--------
+
+:manpage:`llvm-dwarfdump(1)`
diff --git a/llvm/test/lit.cfg.py b/llvm/test/lit.cfg.py
@@ -124,6 +124,11 @@ def get_asan_rtlib():
 
 opt_viewer_cmd = '%s %s/tools/opt-viewer/opt-viewer.py' % (sys.executable, config.llvm_src_root)
 
+llvm_locstats_tool = os.path.join(config.llvm_tools_dir, 'llvm-locstats')
+config.substitutions.append(
+    ('%llvm-locstats', "'%s' %s" % (config.python_executable, llvm_locstats_tool)))
+config.llvm_locstats_used = os.path.exists(llvm_locstats_tool)
+
 tools = [
     ToolSubst('%lli', FindTool('lli'), post='.', extra_args=lli_args),
     ToolSubst('%llc_dwarf', FindTool('llc'), extra_args=llc_args),

diff --git a/llvm/test/tools/llvm-locstats/lit.local.cfg b/llvm/test/tools/llvm-locstats/lit.local.cfg
@@ -0,0 +1,2 @@
+if not config.llvm_locstats_used:
+    config.unsupported = True
diff --git a/llvm/test/tools/llvm-locstats/locstats.ll b/llvm/test/tools/llvm-locstats/locstats.ll
@@ -0,0 +1,173 @@
+; RUN: llc %s -o %t0.o -filetype=obj \
+; RUN:   | %llvm-locstats %t0.o | FileCheck %s --check-prefix=LOCSTATS
+;
+; Test the llvm-locstats output.
+; LOCSTATS: 0% 0 0%
+; LOCSTATS: 1-9% 0 0%
+; LOCSTATS: 10-19% 0 0%
+; LOCSTATS: 20-29% 1 11%
+; LOCSTATS: 30-39% 0 0%
+; LOCSTATS: 40-49% 1 11%
+; LOCSTATS: 50-59% 1 11%
+; LOCSTATS: 60-69% 1 11%
+; LOCSTATS: 70-79% 0 0%
+; LOCSTATS: 80-89% 2 22%
+; LOCSTATS: 90-99% 1 11%
+; LOCSTATS: 100% 2 22%
+;
+; The source code of the test case:
+;extern int fn2 (int);
+;
+;__attribute__((noinline))
+;int
+;fn1 (int *x, int *y)
+;{
+;  int a = *x;
+;  int b = *y;
+;  int local = a + b;
+;  if (a > 1) {
+;    local += 2;
+;    ++local;
+;    if (local > 200)
+;      local -= fn2(a);
+;  } else {
+;    local += 3;
+;    ++local;
+;    local += fn2(a);
+; }
+;  if (b > 4)
+;   local += a;
+;  int local2 = 7;
+;  local -= fn2 (local2);
+;  return local;
+;}
+;
+;__attribute__((noinline))
+;int f()
+;{
+;  int l, k;
+;  int res = 0;
+;  res += fn1 (&l, &k);
+;  return res;
+;}
+;
+; ModuleID = 'locstats.c'
+source_filename = "locstats.c"
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Function Attrs: noinline nounwind uwtable
+define dso_local i32 @fn1(i32* nocapture readonly %0, i32* nocapture readonly %1) local_unnamed_addr !dbg !7 {
+  call void @llvm.dbg.value(metadata i32* %0, metadata !13, metadata !DIExpression()), !dbg !19
+  call void @llvm.dbg.value(metadata i32* %1, metadata !14, metadata !DIExpression()), !dbg !19
+  %3 = load i32, i32* %0, align 4, !dbg !20
+  call void @llvm.dbg.value(metadata i32 %3, metadata !15, metadata !DIExpression()), !dbg !19
+  %4 = load i32, i32* %1, align 4, !dbg !20
+  call void @llvm.dbg.value(metadata i32 %4, metadata !16, metadata !DIExpression()), !dbg !19
+  %5 = add nsw i32 %4, %3, !dbg !20
+  call void @llvm.dbg.value(metadata i32 %5, metadata !17, metadata !DIExpression()), !dbg !19
+  %6 = icmp sgt i32 %3, 1, !dbg !20
+  br i1 %6, label %7, label %13, !dbg !22
+
+7:                                                ; preds = %2
+  call void @llvm.dbg.value(metadata i32 %5, metadata !17, metadata !DIExpression(DW_OP_plus_uconst, 2, DW_OP_stack_value)), !dbg !19
+  %8 = add nsw i32 %5, 3, !dbg !23
+  call void @llvm.dbg.value(metadata i32 %8, metadata !17, metadata !DIExpression()), !dbg !19
+  %9 = icmp sgt i32 %8, 200, !dbg !25
+  br i1 %9, label %10, label %17, !dbg !27
+
+10:                                               ; preds = %7
+  %11 = tail call i32 @fn2(i32 %3), !dbg !27
+  %12 = sub nsw i32 %8, %11, !dbg !27
+  call void @llvm.dbg.value(metadata i32 %12, metadata !17, metadata !DIExpression()), !dbg !19
+  br label %17, !dbg !27
+
+13:                                               ; preds = %2
+  call void @llvm.dbg.value(metadata i32 %5, metadata !17, metadata !DIExpression(DW_OP_plus_uconst, 3, DW_OP_stack_value)), !dbg !19
+  %14 = add nsw i32 %5, 4, !dbg !28
+  call void @llvm.dbg.value(metadata i32 %14, metadata !17, metadata !DIExpression()), !dbg !19
+  %15 = tail call i32 @fn2(i32 %3), !dbg !30
+  %16 = add nsw i32 %14, %15, !dbg !30
+  call void @llvm.dbg.value(metadata i32 %16, metadata !17, metadata !DIExpression()), !dbg !19
+  br label %17
+
+17:                                               ; preds = %7, %10, %13
+  %18 = phi i32 [ %12, %10 ], [ %8, %7 ], [ %16, %13 ], !dbg !31
+  call void @llvm.dbg.value(metadata i32 %18, metadata !17, metadata !DIExpression()), !dbg !19
+  %19 = icmp sgt i32 %4, 4, !dbg !32
+  %20 = select i1 %19, i32 %3, i32 0, !dbg !34
+  %21 = add nsw i32 %18, %20, !dbg !34
+  call void @llvm.dbg.value(metadata i32 %21, metadata !17, metadata !DIExpression()), !dbg !19
+  call void @llvm.dbg.value(metadata i32 7, metadata !18, metadata !DIExpression()), !dbg !19
+  %22 = tail call i32 @fn2(i32 7), !dbg !34
+  %23 = sub i32 %21, %22, !dbg !34
+  call void @llvm.dbg.value(metadata i32 %23, metadata !17, metadata !DIExpression()), !dbg !19
+  ret i32 %23, !dbg !34
+}
+
+declare dso_local i32 @fn2(i32) local_unnamed_addr
+
+; Function Attrs: noinline nounwind uwtable
+define dso_local i32 @f() local_unnamed_addr !dbg !35 {
+  %1 = alloca i32, align 4
+  %2 = alloca i32, align 4
+  %3 = bitcast i32* %1 to i8*, !dbg !42
+  %4 = bitcast i32* %2 to i8*, !dbg !42
+  call void @llvm.dbg.value(metadata i32 0, metadata !41, metadata !DIExpression()), !dbg !42
+  call void @llvm.dbg.value(metadata i32* %1, metadata !39, metadata !DIExpression(DW_OP_deref)), !dbg !42
+  call void @llvm.dbg.value(metadata i32* %2, metadata !40, metadata !DIExpression(DW_OP_deref)), !dbg !42
+  %5 = call i32 @fn1(i32* nonnull %1, i32* nonnull %2), !dbg !42
+  call void @llvm.dbg.value(metadata i32 %5, metadata !41, metadata !DIExpression()), !dbg !42
+  ret i32 %5, !dbg !42
+}
+
+; Function Attrs: nounwind readnone speculatable willreturn
+declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
+!1 = !DIFile(filename: "locstats.c", directory: "/dir")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 10.0.0"}
+!7 = distinct !DISubprogram(name: "fn1", scope: !1, file: !1, line: 5, type: !8, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !12)
+!8 = !DISubroutineType(types: !9)
+!9 = !{!10, !11, !11}
+!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!11 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !10, size: 64)
+!12 = !{!13, !14, !15, !16, !17, !18}
+!13 = !DILocalVariable(name: "x", arg: 1, scope: !7, file: !1, line: 5, type: !11)
+!14 = !DILocalVariable(name: "y", arg: 2, scope: !7, file: !1, line: 5, type: !11)
+!15 = !DILocalVariable(name: "a", scope: !7, file: !1, line: 7, type: !10)
+!16 = !DILocalVariable(name: "b", scope: !7, file: !1, line: 8, type: !10)
+!17 = !DILocalVariable(name: "local", scope: !7, file: !1, line: 9, type: !10)
+!18 = !DILocalVariable(name: "local2", scope: !7, file: !1, line: 22, type: !10)
+!19 = !DILocation(line: 0, scope: !7)
+!20 = !DILocation(line: 7, column: 11, scope: !7)
+!21 = distinct !DILexicalBlock(scope: !7, file: !1, line: 10, column: 7)
+!22 = !DILocation(line: 10, column: 7, scope: !7)
+!23 = !DILocation(line: 12, column: 5, scope: !24)
+!24 = distinct !DILexicalBlock(scope: !21, file: !1, line: 10, column: 14)
+!25 = !DILocation(line: 13, column: 15, scope: !26)
+!26 = distinct !DILexicalBlock(scope: !24, file: !1, line: 13, column: 9)
+!27 = !DILocation(line: 13, column: 9, scope: !24)
+!28 = !DILocation(line: 17, column: 5, scope: !26)
+!29 = distinct !DILexicalBlock(scope: !21, file: !1, line: 15, column: 10)
+!30 = !DILocation(line: 18, column: 14, scope: !29)
+!31 = !DILocation(line: 0, scope: !21)
+!32 = !DILocation(line: 20, column: 9, scope: !33)
+!33 = distinct !DILexicalBlock(scope: !7, file: !1, line: 20, column: 7)
+!34 = !DILocation(line: 20, column: 7, scope: !7)
+!35 = distinct !DISubprogram(name: "f", scope: !1, file: !1, line: 28, type: !36, scopeLine: 29, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !38)
+!36 = !DISubroutineType(types: !37)
+!37 = !{!10}
+!38 = !{!39, !40, !41}
+!39 = !DILocalVariable(name: "l", scope: !35, file: !1, line: 30, type: !10)
+!40 = !DILocalVariable(name: "k", scope: !35, file: !1, line: 30, type: !10)
+!41 = !DILocalVariable(name: "res", scope: !35, file: !1, line: 31, type: !10)
+!42 = !DILocation(line: 30, column: 3, scope: !35)
diff --git a/llvm/utils/llvm-locstats/CMakeLists.txt b/llvm/utils/llvm-locstats/CMakeLists.txt
@@ -0,0 +1,7 @@
+if (LLVM_BUILD_UTILS AND LLVM_BUILD_TOOLS)
+  add_custom_target(llvm-locstats ALL
+    COMMAND  ${CMAKE_COMMAND} -E copy ${LLVM_MAIN_SRC_DIR}/utils/llvm-locstats/llvm-locstats.py ${LLVM_TOOLS_BINARY_DIR}/llvm-locstats
+    COMMENT "Copying llvm-locstats into ${LLVM_TOOLS_BINARY_DIR}"
+    )
+  set_target_properties(llvm-locstats PROPERTIES FOLDER "Tools")
+endif()