Add profile writing capabilities for sampling profiles.

Summary:
This patch finishes up support for handling sampling profiles in both
text and binary formats. The new binary format uses uleb128 encoding to
represent numeric values. This makes profiles files about 25% smaller.

The profile writer class can write profiles in the existing text and the
new binary format. In subsequent patches, I will add the capability to
read (and perhaps write) profiles in the gcov format used by GCC.

Additionally, I will be adding support in llvm-profdata to manipulate
sampling profiles.

There was a bit of refactoring needed to separate some code that was in
the reader files, but is actually common to both the reader and writer.

The new test checks that reading the same profile encoded as text or
raw, produces the same results.

Reviewers: bogner, dexonsmith

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D6000

llvm-svn: 220915

4 files changed, 168 insertions, 1 deletions

diff --git a/llvm/test/Transforms/SampleProfile/Inputs/fnptr.binprof b/llvm/test/Transforms/SampleProfile/Inputs/fnptr.binprof
new file mode 100644
index 00000000000..14d7fd555da
--- /dev/null
+++ b/llvm/test/Transforms/SampleProfile/Inputs/fnptr.binprof
diff --git a/llvm/test/Transforms/SampleProfile/Inputs/fnptr.prof b/llvm/test/Transforms/SampleProfile/Inputs/fnptr.prof
new file mode 100644
index 00000000000..6a3b4e2315b
--- /dev/null
+++ b/llvm/test/Transforms/SampleProfile/Inputs/fnptr.prof
@@ -0,0 +1,12 @@
+_Z3fooi:7711:610
+1: 610
+_Z3bari:20301:1437
+1: 1437
+main:184019:0
+4: 534
+6: 2080
+9: 2064 _Z3bari:1471 _Z3fooi:631
+5.1: 1075
+5: 1075
+7: 534
+4.2: 534
diff --git a/llvm/test/Transforms/SampleProfile/fnptr.ll b/llvm/test/Transforms/SampleProfile/fnptr.ll
new file mode 100644
index 00000000000..f78123c1ab3
--- /dev/null
+++ b/llvm/test/Transforms/SampleProfile/fnptr.ll
@@ -0,0 +1,155 @@
+; The two profiles used in this test are the same but encoded in different
+; formats. This checks that we produce the same profile annotations regardless
+; of the profile format.
+;
+; RUN: opt < %s -sample-profile -sample-profile-file=%S/Inputs/fnptr.prof | opt -analyze -branch-prob | FileCheck %s
+; RUN: opt < %s -sample-profile -sample-profile-file=%S/Inputs/fnptr.binprof | opt -analyze -branch-prob | FileCheck %s
+
+; CHECK:   edge for.body3 -> if.then probability is 534 / 2598 = 20.5543%
+; CHECK:   edge for.body3 -> if.else probability is 2064 / 2598 = 79.4457%
+; CHECK:   edge for.inc -> for.inc12 probability is 1052 / 2598 = 40.4927%
+; CHECK:   edge for.inc -> for.body3 probability is 1546 / 2598 = 59.5073%
+; CHECK:   edge for.inc12 -> for.end14 probability is 518 / 1052 = 49.2395%
+; CHECK:   edge for.inc12 -> for.cond1.preheader probability is 534 / 1052 = 50.7605%
+
+; Original C++ test case.
+;
+; #include <stdlib.h>
+; #include <math.h>
+; #include <stdio.h>
+;
+; #define N 10000
+; #define M 6000
+;
+; double foo(int x) {
+;   return x * sin((double)x);
+; }
+;
+; double bar(int x) {
+;   return x - cos((double)x);
+; }
+;
+; int main() {
+;   double (*fptr)(int);
+;   double S = 0;
+;   for (int i = 0; i < N; i++)
+;     for (int j = 0; j < M; j++) {
+;       fptr = (rand() % 100 < 30) ? foo : bar;
+;       if (rand() % 100 < 10)
+;         S += (*fptr)(i + j * 300);
+;       else
+;         S += (*fptr)(i - j / 840);
+;     }
+;   printf("S = %lf\n", S);
+;   return 0;
+; }
+
+@.str = private unnamed_addr constant [9 x i8] c"S = %lf\0A\00", align 1
+
+define double @_Z3fooi(i32 %x) #0 {
+entry:
+  %conv = sitofp i32 %x to double, !dbg !2
+  %call = tail call double @sin(double %conv) #3, !dbg !8
+  %mul = fmul double %conv, %call, !dbg !8
+  ret double %mul, !dbg !8
+}
+
+declare double @sin(double) #1
+
+define double @_Z3bari(i32 %x) #0 {
+entry:
+  %conv = sitofp i32 %x to double, !dbg !9
+  %call = tail call double @cos(double %conv) #3, !dbg !11
+  %sub = fsub double %conv, %call, !dbg !11
+  ret double %sub, !dbg !11
+}
+
+declare double @cos(double) #1
+
+define i32 @main() #2 {
+entry:
+  br label %for.cond1.preheader, !dbg !12
+
+for.cond1.preheader:                              ; preds = %for.inc12, %entry
+  %i.025 = phi i32 [ 0, %entry ], [ %inc13, %for.inc12 ]
+  %S.024 = phi double [ 0.000000e+00, %entry ], [ %S.2.lcssa, %for.inc12 ]
+  br label %for.body3, !dbg !14
+
+for.body3:                                        ; preds = %for.inc, %for.cond1.preheader
+  %j.023 = phi i32 [ 0, %for.cond1.preheader ], [ %inc, %for.inc ]
+  %S.122 = phi double [ %S.024, %for.cond1.preheader ], [ %S.2, %for.inc ]
+  %call = tail call i32 @rand() #3, !dbg !15
+  %rem = srem i32 %call, 100, !dbg !15
+  %cmp4 = icmp slt i32 %rem, 30, !dbg !15
+  %_Z3fooi._Z3bari = select i1 %cmp4, double (i32)* @_Z3fooi, double (i32)* @_Z3bari, !dbg !15
+  %call5 = tail call i32 @rand() #3, !dbg !16
+  %rem6 = srem i32 %call5, 100, !dbg !16
+  %cmp7 = icmp slt i32 %rem6, 10, !dbg !16
+  br i1 %cmp7, label %if.then, label %if.else, !dbg !16, !prof !17
+
+if.then:                                          ; preds = %for.body3
+  %mul = mul nsw i32 %j.023, 300, !dbg !18
+  %add = add nsw i32 %mul, %i.025, !dbg !18
+  %call8 = tail call double %_Z3fooi._Z3bari(i32 %add), !dbg !18
+  br label %for.inc, !dbg !18
+
+if.else:                                          ; preds = %for.body3
+  %div = sdiv i32 %j.023, 840, !dbg !19
+  %sub = sub nsw i32 %i.025, %div, !dbg !19
+  %call10 = tail call double %_Z3fooi._Z3bari(i32 %sub), !dbg !19
+  br label %for.inc
+
+for.inc:                                          ; preds = %if.then, %if.else
+  %call8.pn = phi double [ %call8, %if.then ], [ %call10, %if.else ]
+  %S.2 = fadd double %S.122, %call8.pn, !dbg !18
+  %inc = add nsw i32 %j.023, 1, !dbg !20
+  %exitcond = icmp eq i32 %j.023, 5999, !dbg !14
+  br i1 %exitcond, label %for.inc12, label %for.body3, !dbg !14, !prof !21
+
+for.inc12:                                        ; preds = %for.inc
+  %S.2.lcssa = phi double [ %S.2, %for.inc ]
+  %inc13 = add nsw i32 %i.025, 1, !dbg !22
+  %exitcond26 = icmp eq i32 %i.025, 9999, !dbg !12
+  br i1 %exitcond26, label %for.end14, label %for.cond1.preheader, !dbg !12, !prof !23
+
+for.end14:                                        ; preds = %for.inc12
+  %S.2.lcssa.lcssa = phi double [ %S.2.lcssa, %for.inc12 ]
+  %call15 = tail call i32 (i8*, ...)* @printf(i8* getelementptr inbounds ([9 x i8]* @.str, i64 0, i64 0), double %S.2.lcssa.lcssa), !dbg !24
+  ret i32 0, !dbg !25
+}
+
+; Function Attrs: nounwind
+declare i32 @rand() #1
+
+; Function Attrs: nounwind
+declare i32 @printf(i8* nocapture readonly, ...) #1
+
+!llvm.module.flags = !{!0}
+!llvm.ident = !{!1}
+
+!0 = metadata !{i32 2, metadata !"Debug Info Version", i32 2}
+!1 = metadata !{metadata !"clang version 3.6.0 "}
+!2 = metadata !{i32 9, i32 3, metadata !3, null}
+!3 = metadata !{metadata !"0x2e\00foo\00foo\00\008\000\001\000\000\00256\001\008", metadata !4, metadata !5, metadata !6, null, double (i32)* @_Z3fooi, null, null, metadata !7} ; [ DW_TAG_subprogram ] [line 8] [def] [foo]
+!4 = metadata !{metadata !"fnptr.cc", metadata !"."}
+!5 = metadata !{metadata !"0x29", metadata !4}    ; [ DW_TAG_file_type ] [./fnptr.cc]
+!6 = metadata !{metadata !"0x15\00\000\000\000\000\000\000", null, null, null, metadata !7, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!7 = metadata !{}
+!8 = metadata !{i32 9, i32 14, metadata !3, null}
+!9 = metadata !{i32 13, i32 3, metadata !10, null}
+!10 = metadata !{metadata !"0x2e\00bar\00bar\00\0012\000\001\000\000\00256\001\0012", metadata !4, metadata !5, metadata !6, null, double (i32)* @_Z3bari, null, null, metadata !7} ; [ DW_TAG_subprogram ] [line 12] [def] [bar]
+!11 = metadata !{i32 13, i32 14, metadata !10, null}
+!12 = metadata !{i32 19, i32 3, metadata !13, null}
+!13 = metadata !{metadata !"0x2e\00main\00main\00\0016\000\001\000\000\00256\001\0016", metadata !4, metadata !5, metadata !6, null, i32 ()* @main, null, null, metadata !7} ; [ DW_TAG_subprogram ] [line 16] [def] [main]
+!14 = metadata !{i32 20, i32 5, metadata !13, null}
+!15 = metadata !{i32 21, i32 15, metadata !13, null}
+!16 = metadata !{i32 22, i32 11, metadata !13, null}
+!17 = metadata !{metadata !"branch_weights", i32 534, i32 2064}
+!18 = metadata !{i32 23, i32 14, metadata !13, null}
+!19 = metadata !{i32 25, i32 14, metadata !13, null}
+!20 = metadata !{i32 20, i32 28, metadata !13, null}
+!21 = metadata !{metadata !"branch_weights", i32 0, i32 1075}
+!22 = metadata !{i32 19, i32 26, metadata !13, null}
+!23 = metadata !{metadata !"branch_weights", i32 0, i32 534}
+!24 = metadata !{i32 27, i32 3, metadata !13, null}
+!25 = metadata !{i32 28, i32 3, metadata !13, null}
diff --git a/llvm/test/Transforms/SampleProfile/syntax.ll b/llvm/test/Transforms/SampleProfile/syntax.ll
index f807db9d524..28742cbdf03 100644
--- a/llvm/test/Transforms/SampleProfile/syntax.ll
+++ b/llvm/test/Transforms/SampleProfile/syntax.ll
@@ -12,7 +12,7 @@ entry:
   ret void
 }
 ; NO-DEBUG: warning: No debug information found in function empty: Function profile not used
-; MISSING-FILE: error: missing.prof:
+; MISSING-FILE: missing.prof: Could not open profile: No such file or directory
 ; BAD-FN-HEADER: error: {{.*}}bad_fn_header.prof:1: Expected 'mangled_name:NUM:NUM', found 3empty:100:BAD
 ; BAD-SAMPLE-LINE: error: {{.*}}bad_sample_line.prof:3: Expected 'NUM[.NUM]: NUM[ mangled_name:NUM]*', found 1: BAD
 ; BAD-LINE-VALUES: error: {{.*}}bad_line_values.prof:2: Expected 'mangled_name:NUM:NUM', found -1: 10