SamplePGO - Add optimization reports.

This adds a couple of optimization remarks to the SamplePGO
transformation. When it decides to inline a hot function (to mimic the
inline stack and repeat useful inline decisions in the original build).

It will also report branch destinations. For instance, given the code
fragment:

     6      if (i < 1000)
     7        sum -= i;
     8      else
     9        sum += -i * rand();

If the 'else' branch is taken most of the time, building this code with
-Rpass=sample-profile will produce:

a.cc:9:14: remark: most popular destination for conditional branches at small.cc:6:9 [-Rpass=sample-profile]
      sum += -i * rand();
             ^

llvm-svn: 251330

2 files changed, 192 insertions, 0 deletions

diff --git a/llvm/test/Transforms/SampleProfile/Inputs/remarks.prof b/llvm/test/Transforms/SampleProfile/Inputs/remarks.prof
new file mode 100644
index 00000000000..1e905834cf4
--- /dev/null
+++ b/llvm/test/Transforms/SampleProfile/Inputs/remarks.prof
@@ -0,0 +1,7 @@
+main:623868:0
+ 0: 0
+ 0: _Z3foov:623868
+  3: 18346
+  4: 0
+  6: 19475
+  2: 18305
diff --git a/llvm/test/Transforms/SampleProfile/remarks.ll b/llvm/test/Transforms/SampleProfile/remarks.ll
new file mode 100644
index 00000000000..f6e9a4267f4
--- /dev/null
+++ b/llvm/test/Transforms/SampleProfile/remarks.ll
@@ -0,0 +1,185 @@
+; RUN: opt < %s -sample-profile -sample-profile-file=%S/Inputs/remarks.prof -S -pass-remarks=sample-profile 2>&1 | FileCheck %s
+;
+; Original test case.
+;
+;     1    #include <stdlib.h>
+;     2
+;     3    long long foo() {
+;     4      long long int sum = 0;
+;     5      for (int i = 0; i < 500000000; i++)
+;     6        if (i < 1000)
+;     7          sum -= i;
+;     8        else
+;     9          sum += -i * rand();
+;    10      return sum;
+;    11    }
+;    12
+;    13    int main() { return foo() > 0; }
+
+; We are expecting foo() to be inlined in main() (almost all the cycles are
+; spent inside foo).
+; CHECK: remark: remarks.cc:13:21: inlined hot callee '_Z3foov' with 623868 samples into 'main'
+
+; The back edge for the loop is the hottest edge in the loop subgraph.
+; CHECK: remark: remarks.cc:6:9: most popular destination for conditional branches at remarks.cc:5:3
+
+; The predicate almost always chooses the 'else' branch.
+; CHECK: remark: remarks.cc:9:15: most popular destination for conditional branches at remarks.cc:6:9
+
+; Function Attrs: nounwind uwtable
+define i64 @_Z3foov() #0 {
+entry:
+  %sum = alloca i64, align 8
+  %i = alloca i32, align 4
+  %0 = bitcast i64* %sum to i8*, !dbg !19
+  call void @llvm.lifetime.start(i64 8, i8* %0) #4, !dbg !19
+  call void @llvm.dbg.declare(metadata i64* %sum, metadata !9, metadata !20), !dbg !21
+  store i64 0, i64* %sum, align 8, !dbg !21, !tbaa !22
+  %1 = bitcast i32* %i to i8*, !dbg !26
+  call void @llvm.lifetime.start(i64 4, i8* %1) #4, !dbg !26
+  call void @llvm.dbg.declare(metadata i32* %i, metadata !10, metadata !20), !dbg !27
+  store i32 0, i32* %i, align 4, !dbg !27, !tbaa !28
+  br label %for.cond, !dbg !26
+
+for.cond:                                         ; preds = %for.inc, %entry
+  %2 = load i32, i32* %i, align 4, !dbg !30, !tbaa !28
+  %cmp = icmp slt i32 %2, 500000000, !dbg !34
+  br i1 %cmp, label %for.body, label %for.cond.cleanup, !dbg !35
+
+for.cond.cleanup:                                 ; preds = %for.cond
+  %3 = bitcast i32* %i to i8*, !dbg !36
+  call void @llvm.lifetime.end(i64 4, i8* %3) #4, !dbg !36
+  br label %for.end
+
+for.body:                                         ; preds = %for.cond
+  %4 = load i32, i32* %i, align 4, !dbg !38, !tbaa !28
+  %cmp1 = icmp slt i32 %4, 1000, !dbg !40
+  br i1 %cmp1, label %if.then, label %if.else, !dbg !41
+
+if.then:                                          ; preds = %for.body
+  %5 = load i32, i32* %i, align 4, !dbg !42, !tbaa !28
+  %conv = sext i32 %5 to i64, !dbg !42
+  %6 = load i64, i64* %sum, align 8, !dbg !43, !tbaa !22
+  %sub = sub nsw i64 %6, %conv, !dbg !43
+  store i64 %sub, i64* %sum, align 8, !dbg !43, !tbaa !22
+  br label %if.end, !dbg !44
+
+if.else:                                          ; preds = %for.body
+  %7 = load i32, i32* %i, align 4, !dbg !45, !tbaa !28
+  %sub2 = sub nsw i32 0, %7, !dbg !46
+  %call = call i32 @rand() #4, !dbg !47
+  %mul = mul nsw i32 %sub2, %call, !dbg !48
+  %conv3 = sext i32 %mul to i64, !dbg !46
+  %8 = load i64, i64* %sum, align 8, !dbg !49, !tbaa !22
+  %add = add nsw i64 %8, %conv3, !dbg !49
+  store i64 %add, i64* %sum, align 8, !dbg !49, !tbaa !22
+  br label %if.end
+
+if.end:                                           ; preds = %if.else, %if.then
+  br label %for.inc, !dbg !50
+
+for.inc:                                          ; preds = %if.end
+  %9 = load i32, i32* %i, align 4, !dbg !51, !tbaa !28
+  %inc = add nsw i32 %9, 1, !dbg !51
+  store i32 %inc, i32* %i, align 4, !dbg !51, !tbaa !28
+  br label %for.cond, !dbg !52
+
+for.end:                                          ; preds = %for.cond.cleanup
+  %10 = load i64, i64* %sum, align 8, !dbg !53, !tbaa !22
+  %11 = bitcast i64* %sum to i8*, !dbg !54
+  call void @llvm.lifetime.end(i64 8, i8* %11) #4, !dbg !54
+  ret i64 %10, !dbg !55
+}
+
+; Function Attrs: nounwind argmemonly
+declare void @llvm.lifetime.start(i64, i8* nocapture) #1
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #2
+
+; Function Attrs: nounwind
+declare i32 @rand() #3
+
+; Function Attrs: nounwind argmemonly
+declare void @llvm.lifetime.end(i64, i8* nocapture) #1
+
+; Function Attrs: nounwind uwtable
+define i32 @main() #0 {
+entry:
+  %retval = alloca i32, align 4
+  store i32 0, i32* %retval, align 4
+  %call = call i64 @_Z3foov(), !dbg !56
+  %cmp = icmp sgt i64 %call, 0, !dbg !57
+  %conv = zext i1 %cmp to i32, !dbg !56
+  ret i32 %conv, !dbg !58
+}
+
+attributes #0 = { nounwind uwtable "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { nounwind argmemonly }
+attributes #2 = { nounwind readnone }
+attributes #3 = { nounwind "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #4 = { nounwind }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!16, !17}
+!llvm.ident = !{!18}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 3.8.0 (trunk 251041) (llvm/trunk 251053)", isOptimized: true, runtimeVersion: 0, emissionKind: 1, enums: !2, subprograms: !3)
+!1 = !DIFile(filename: "remarks.cc", directory: ".")
+!2 = !{}
+!3 = !{!4, !13}
+!4 = distinct !DISubprogram(name: "foo", linkageName: "_Z3foov", scope: !1, file: !1, line: 3, type: !5, isLocal: false, isDefinition: true, scopeLine: 3, flags: DIFlagPrototyped, isOptimized: true, function: i64 ()* @_Z3foov, variables: !8)
+!5 = !DISubroutineType(types: !6)
+!6 = !{!7}
+!7 = !DIBasicType(name: "long long int", size: 64, align: 64, encoding: DW_ATE_signed)
+!8 = !{!9, !10}
+!9 = !DILocalVariable(name: "sum", scope: !4, file: !1, line: 4, type: !7)
+!10 = !DILocalVariable(name: "i", scope: !11, file: !1, line: 5, type: !12)
+!11 = distinct !DILexicalBlock(scope: !4, file: !1, line: 5, column: 3)
+!12 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
+!13 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 13, type: !14, isLocal: false, isDefinition: true, scopeLine: 13, flags: DIFlagPrototyped, isOptimized: true, function: i32 ()* @main, variables: !2)
+!14 = !DISubroutineType(types: !15)
+!15 = !{!12}
+!16 = !{i32 2, !"Dwarf Version", i32 4}
+!17 = !{i32 2, !"Debug Info Version", i32 3}
+!18 = !{!"clang version 3.8.0 (trunk 251041) (llvm/trunk 251053)"}
+!19 = !DILocation(line: 4, column: 3, scope: !4)
+!20 = !DIExpression()
+!21 = !DILocation(line: 4, column: 17, scope: !4)
+!22 = !{!23, !23, i64 0}
+!23 = !{!"long long", !24, i64 0}
+!24 = !{!"omnipotent char", !25, i64 0}
+!25 = !{!"Simple C/C++ TBAA"}
+!26 = !DILocation(line: 5, column: 8, scope: !11)
+!27 = !DILocation(line: 5, column: 12, scope: !11)
+!28 = !{!29, !29, i64 0}
+!29 = !{!"int", !24, i64 0}
+!30 = !DILocation(line: 5, column: 19, scope: !31)
+!31 = !DILexicalBlockFile(scope: !32, file: !1, discriminator: 3)
+!32 = !DILexicalBlockFile(scope: !33, file: !1, discriminator: 1)
+!33 = distinct !DILexicalBlock(scope: !11, file: !1, line: 5, column: 3)
+!34 = !DILocation(line: 5, column: 21, scope: !33)
+!35 = !DILocation(line: 5, column: 3, scope: !11)
+!36 = !DILocation(line: 5, column: 3, scope: !37)
+!37 = !DILexicalBlockFile(scope: !33, file: !1, discriminator: 2)
+!38 = !DILocation(line: 6, column: 9, scope: !39)
+!39 = distinct !DILexicalBlock(scope: !33, file: !1, line: 6, column: 9)
+!40 = !DILocation(line: 6, column: 11, scope: !39)
+!41 = !DILocation(line: 6, column: 9, scope: !33)
+!42 = !DILocation(line: 7, column: 14, scope: !39)
+!43 = !DILocation(line: 7, column: 11, scope: !39)
+!44 = !DILocation(line: 7, column: 7, scope: !39)
+!45 = !DILocation(line: 9, column: 15, scope: !39)
+!46 = !DILocation(line: 9, column: 14, scope: !39)
+!47 = !DILocation(line: 9, column: 19, scope: !39)
+!48 = !DILocation(line: 9, column: 17, scope: !39)
+!49 = !DILocation(line: 9, column: 11, scope: !39)
+!50 = !DILocation(line: 6, column: 13, scope: !39)
+!51 = !DILocation(line: 5, column: 35, scope: !33)
+!52 = !DILocation(line: 5, column: 3, scope: !33)
+!53 = !DILocation(line: 10, column: 10, scope: !4)
+!54 = !DILocation(line: 11, column: 1, scope: !4)
+!55 = !DILocation(line: 10, column: 3, scope: !4)
+!56 = !DILocation(line: 13, column: 21, scope: !13)
+!57 = !DILocation(line: 13, column: 27, scope: !13)
+!58 = !DILocation(line: 13, column: 14, scope: !13)