Encode duplication factor from loop vectorization and loop unrolling to discriminator.

Summary:
This patch starts the implementation as discuss in the following RFC: http://lists.llvm.org/pipermail/llvm-dev/2016-October/106532.html

When optimization duplicates code that will scale down the execution count of a basic block, we will record the duplication factor as part of discriminator so that the offline process tool can find the duplication factor and collect the accurate execution frequency of the corresponding source code. Two important optimization that fall into this category is loop vectorization and loop unroll. This patch records the duplication factor for these 2 optimizations.

The recording will be guarded by a flag encode-duplication-in-discriminators, which is off by default.

Reviewers: probinson, aprantl, davidxl, hfinkel, echristo

Reviewed By: hfinkel

Subscribers: mehdi_amini, anemet, mzolotukhin, llvm-commits

Differential Revision: https://reviews.llvm.org/D26420

llvm-svn: 294782

9 files changed, 89 insertions, 19 deletions

diff --git a/llvm/test/Transforms/AddDiscriminators/basic.ll b/llvm/test/Transforms/AddDiscriminators/basic.ll
index 801eda2b066..a781c0d409b 100644
--- a/llvm/test/Transforms/AddDiscriminators/basic.ll
+++ b/llvm/test/Transforms/AddDiscriminators/basic.ll
@@ -58,5 +58,5 @@ attributes #0 = { nounwind uwtable "less-precise-fpmad"="false" "no-frame-pointe
 ; CHECK: ![[FOO:[0-9]+]] = distinct !DISubprogram(name: "foo"
 ; CHECK: ![[BLOCK:[0-9]+]] = distinct !DILexicalBlock(scope: ![[FOO]],{{.*}} line: 3)
 ; CHECK: ![[THEN]] = !DILocation(line: 3, scope: ![[BLOCKFILE:[0-9]+]])
-; CHECK: ![[BLOCKFILE]] = !DILexicalBlockFile(scope: ![[BLOCK]],{{.*}} discriminator: 1)
+; CHECK: ![[BLOCKFILE]] = !DILexicalBlockFile(scope: ![[BLOCK]],{{.*}} discriminator: 2)
 ; CHECK: ![[END]] = !DILocation(line: 4, scope: ![[FOO]])
diff --git a/llvm/test/Transforms/AddDiscriminators/call-nested.ll b/llvm/test/Transforms/AddDiscriminators/call-nested.ll
index 481d6f26004..4d5145abafe 100644
--- a/llvm/test/Transforms/AddDiscriminators/call-nested.ll
+++ b/llvm/test/Transforms/AddDiscriminators/call-nested.ll
@@ -47,4 +47,4 @@ attributes #1 = { "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-
 !14 = !DILocation(line: 4, column: 3, scope: !4)
 
 ; CHECK: ![[CALL2]] = !DILocation(line: 4, column: 10, scope: ![[CALL2BLOCK:[0-9]+]])
-; CHECK: ![[CALL2BLOCK]] = !DILexicalBlockFile({{.*}} discriminator: 1)
+; CHECK: ![[CALL2BLOCK]] = !DILexicalBlockFile({{.*}} discriminator: 2)
diff --git a/llvm/test/Transforms/AddDiscriminators/call.ll b/llvm/test/Transforms/AddDiscriminators/call.ll
index 847a6ad4dc3..5365d68eb09 100644
--- a/llvm/test/Transforms/AddDiscriminators/call.ll
+++ b/llvm/test/Transforms/AddDiscriminators/call.ll
@@ -5,7 +5,7 @@
 ; #1 void bar();
 ; #2
 ; #3 void foo() {
-; #4  bar();bar()/*discriminator 1*/;bar()/*discriminator 2*/;
+; #4  bar();bar()/*discriminator 2*/;bar()/*discriminator 4*/;
 ; #5 }
 
 ; Function Attrs: uwtable
@@ -49,6 +49,6 @@ attributes #1 = { "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-
 !13 = !DILocation(line: 5, column: 1, scope: !4)
 
 ; CHECK: ![[CALL1]] = !DILocation(line: 4, column: 9, scope: ![[CALL1BLOCK:[0-9]+]])
-; CHECK: ![[CALL1BLOCK]] = !DILexicalBlockFile({{.*}} discriminator: 1)
+; CHECK: ![[CALL1BLOCK]] = !DILexicalBlockFile({{.*}} discriminator: 2)
 ; CHECK: ![[CALL2]] = !DILocation(line: 4, column: 15, scope: ![[CALL2BLOCK:[0-9]+]])
-; CHECK: ![[CALL2BLOCK]] = !DILexicalBlockFile({{.*}} discriminator: 2)
+; CHECK: ![[CALL2BLOCK]] = !DILexicalBlockFile({{.*}} discriminator: 4)
diff --git a/llvm/test/Transforms/AddDiscriminators/diamond.ll b/llvm/test/Transforms/AddDiscriminators/diamond.ll
index b3afe728547..307e95f41e1 100644
--- a/llvm/test/Transforms/AddDiscriminators/diamond.ll
+++ b/llvm/test/Transforms/AddDiscriminators/diamond.ll
@@ -10,7 +10,7 @@
 ; #6 }
 
 ; bar(5):     discriminator 0
-; bar(3):     discriminator 1
+; bar(3):     discriminator 2
 
 ; Function Attrs: uwtable
 define void @_Z3fooi(i32 %i) #0 !dbg !4 {
@@ -69,4 +69,4 @@ attributes #2 = { "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-
 !20 = !DILocation(line: 6, column: 1, scope: !4)
 
 ; CHECK: ![[ELSE]] = !DILocation(line: 5, column: 18, scope: ![[ELSEBLOCK:[0-9]+]])
-; CHECK: ![[ELSEBLOCK]] = !DILexicalBlockFile({{.*}} discriminator: 1)
+; CHECK: ![[ELSEBLOCK]] = !DILexicalBlockFile({{.*}} discriminator: 2)
diff --git a/llvm/test/Transforms/AddDiscriminators/first-only.ll b/llvm/test/Transforms/AddDiscriminators/first-only.ll
index 1bd8dae5d05..dd2117a5b18 100644
--- a/llvm/test/Transforms/AddDiscriminators/first-only.ll
+++ b/llvm/test/Transforms/AddDiscriminators/first-only.ll
@@ -69,7 +69,7 @@ attributes #0 = { nounwind uwtable "less-precise-fpmad"="false" "no-frame-pointe
 !12 = !DILocation(line: 3, scope: !13)
 
 !13 = distinct !DILexicalBlock(line: 3, column: 0, file: !1, scope: !11)
-; CHECK: !DILexicalBlockFile(scope: ![[BLOCK2:[0-9]+]],{{.*}} discriminator: 1)
+; CHECK: !DILexicalBlockFile(scope: ![[BLOCK2:[0-9]+]],{{.*}} discriminator: 2)
 
 !14 = !DILocation(line: 4, scope: !13)
 ; CHECK: ![[BLOCK2]] = distinct !DILexicalBlock(scope: ![[BLOCK1]],{{.*}} line: 3)
diff --git a/llvm/test/Transforms/AddDiscriminators/inlined.ll b/llvm/test/Transforms/AddDiscriminators/inlined.ll
index 2e8ea97348d..226e903ee21 100644
--- a/llvm/test/Transforms/AddDiscriminators/inlined.ll
+++ b/llvm/test/Transforms/AddDiscriminators/inlined.ll
@@ -62,8 +62,8 @@ attributes #3 = { nounwind readnone }
 !12 = distinct !DISubprogram(name: "g", scope: !1, file: !1, line: 1, type: !8, isLocal: false, isDefinition: true, scopeLine: 1, isOptimized: true, unit: !0, variables: !2)
 !13 = distinct !DILocation(line: 1, column: 17, scope: !14)
 ; CHECK: ![[BF:.*]] = !DILexicalBlockFile(scope: ![[LB1:[0-9]+]],
-; CHECK-SAME:                             discriminator: 1)
-!14 = !DILexicalBlockFile(scope: !15, file: !1, discriminator: 1)
+; CHECK-SAME:                             discriminator: 2)
+!14 = !DILexicalBlockFile(scope: !15, file: !1, discriminator: 2)
 ; CHECK: ![[LB1]] = distinct !DILexicalBlock(scope: ![[LB2:[0-9]+]],
 ; CHECK-SAME:                                line: 1, column: 16)
 !15 = distinct !DILexicalBlock(scope: !16, file: !1, line: 1, column: 16)
diff --git a/llvm/test/Transforms/AddDiscriminators/multiple.ll b/llvm/test/Transforms/AddDiscriminators/multiple.ll
index 387689caddf..b4c353cf00f 100644
--- a/llvm/test/Transforms/AddDiscriminators/multiple.ll
+++ b/llvm/test/Transforms/AddDiscriminators/multiple.ll
@@ -67,6 +67,6 @@ attributes #0 = { nounwind uwtable "less-precise-fpmad"="false" "no-frame-pointe
 !12 = !DILocation(line: 4, scope: !4)
 
 ; CHECK: ![[THEN]] = !DILocation(line: 3, scope: ![[THENBLOCK:[0-9]+]])
-; CHECK: ![[THENBLOCK]] = !DILexicalBlockFile(scope: ![[SCOPE:[0-9]+]],{{.*}} discriminator: 1)
+; CHECK: ![[THENBLOCK]] = !DILexicalBlockFile(scope: ![[SCOPE:[0-9]+]],{{.*}} discriminator: 2)
 ; CHECK: ![[ELSE]] = !DILocation(line: 3, scope: ![[ELSEBLOCK:[0-9]+]])
-; CHECK: ![[ELSEBLOCK]] = !DILexicalBlockFile(scope: ![[SCOPE]],{{.*}} discriminator: 2)
+; CHECK: ![[ELSEBLOCK]] = !DILexicalBlockFile(scope: ![[SCOPE]],{{.*}} discriminator: 4)
diff --git a/llvm/test/Transforms/AddDiscriminators/oneline.ll b/llvm/test/Transforms/AddDiscriminators/oneline.ll
index aa52ae42ee4..724574a24dd 100644
--- a/llvm/test/Transforms/AddDiscriminators/oneline.ll
+++ b/llvm/test/Transforms/AddDiscriminators/oneline.ll
@@ -7,9 +7,9 @@
 ; #3 }
 
 ; i == 3:     discriminator 0
-; i == 5:     discriminator 1
-; return 100: discriminator 2
-; return 99:  discriminator 3
+; i == 5:     discriminator 2
+; return 100: discriminator 4
+; return 99:  discriminator 6
 
 define i32 @_Z3fooi(i32 %i) #0 !dbg !4 {
   %1 = alloca i32, align 4
@@ -91,11 +91,11 @@ attributes #1 = { nounwind readnone }
 ; CHECK: ![[F:.*]] = distinct !DISubprogram(name: "foo",
 ; CHECK: ![[IF:.*]] = distinct !DILexicalBlock(scope: ![[F]],{{.*}}line: 2, column: 7)
 ; CHECK: ![[THEN1]] = !DILocation(line: 2, column: 17, scope: ![[THENBLOCK:[0-9]+]])
-; CHECK: ![[THENBLOCK]] = !DILexicalBlockFile(scope: ![[IF]],{{.*}} discriminator: 1)
+; CHECK: ![[THENBLOCK]] = !DILexicalBlockFile(scope: ![[IF]],{{.*}} discriminator: 2)
 ; CHECK: ![[THEN2]] = !DILocation(line: 2, column: 19, scope: ![[THENBLOCK]])
 ; CHECK: ![[THEN3]] = !DILocation(line: 2, column: 7, scope: ![[BRBLOCK:[0-9]+]])
-; CHECK: ![[BRBLOCK]] = !DILexicalBlockFile(scope: ![[F]],{{.*}} discriminator: 1)
+; CHECK: ![[BRBLOCK]] = !DILexicalBlockFile(scope: ![[F]],{{.*}} discriminator: 2)
 ; CHECK: ![[ELSE]] = !DILocation(line: 2, column: 25, scope: ![[ELSEBLOCK:[0-9]+]])
-; CHECK: ![[ELSEBLOCK]] = !DILexicalBlockFile(scope: ![[IF]],{{.*}} discriminator: 2)
+; CHECK: ![[ELSEBLOCK]] = !DILexicalBlockFile(scope: ![[IF]],{{.*}} discriminator: 4)
 ; CHECK: ![[COMBINE]] = !DILocation(line: 2, column: 42, scope: ![[COMBINEBLOCK:[0-9]+]])
-; CHECK: ![[COMBINEBLOCK]] = !DILexicalBlockFile(scope: ![[IF]],{{.*}} discriminator: 3)
+; CHECK: ![[COMBINEBLOCK]] = !DILexicalBlockFile(scope: ![[IF]],{{.*}} discriminator: 6)
diff --git a/llvm/test/Transforms/LoopVectorize/discriminator.ll b/llvm/test/Transforms/LoopVectorize/discriminator.ll
new file mode 100644
index 00000000000..b7d34582dbd
--- /dev/null
+++ b/llvm/test/Transforms/LoopVectorize/discriminator.ll
@@ -0,0 +1,70 @@
+; RUN: opt -S -loop-vectorize -force-vector-width=4 -force-vector-interleave=1 < %s | FileCheck --check-prefix=LOOPVEC_4_1 %s
+; RUN: opt -S -loop-vectorize -force-vector-width=2 -force-vector-interleave=3 < %s | FileCheck --check-prefix=LOOPVEC_2_3 %s
+; RUN: opt -S -loop-unroll  -unroll-count=5 < %s | FileCheck --check-prefix=LOOPUNROLL_5 %s
+; RUN: opt -S -loop-vectorize -force-vector-width=4 -force-vector-interleave=4 -loop-unroll -unroll-count=2 < %s | FileCheck --check-prefix=LOOPVEC_UNROLL %s
+
+; Test if vectorization/unroll factor is recorded in discriminator.
+;
+; Original source code:
+;  1 int *a;
+;  2 int *b;
+;  3 
+;  4 void foo() {
+;  5   for (int i = 0; i < 4096; i++)
+;  6     a[i] += b[i];
+;  7 }
+
+@a = local_unnamed_addr global i32* null, align 8
+@b = local_unnamed_addr global i32* null, align 8
+
+define void @_Z3foov() local_unnamed_addr #0 !dbg !6 {
+  %1 = load i32*, i32** @b, align 8, !dbg !8, !tbaa !9
+  %2 = load i32*, i32** @a, align 8, !dbg !13, !tbaa !9
+  br label %3, !dbg !14
+
+; <label>:3:                                      ; preds = %3, %0
+  %indvars.iv = phi i64 [ 0, %0 ], [ %indvars.iv.next, %3 ]
+  %4 = getelementptr inbounds i32, i32* %1, i64 %indvars.iv, !dbg !8
+  %5 = load i32, i32* %4, align 4, !dbg !8, !tbaa !15
+  %6 = getelementptr inbounds i32, i32* %2, i64 %indvars.iv, !dbg !13
+  %7 = load i32, i32* %6, align 4, !dbg !17, !tbaa !15
+  %8 = add nsw i32 %7, %5, !dbg !17
+  store i32 %8, i32* %6, align 4, !dbg !17, !tbaa !15
+  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1, !dbg !18
+  %exitcond = icmp eq i64 %indvars.iv.next, 4096, !dbg !19
+  br i1 %exitcond, label %9, label %3, !dbg !14, !llvm.loop !20
+
+; <label>:9:                                      ; preds = %3
+  ret void, !dbg !21
+}
+
+;LOOPVEC_4_1: discriminator: 17
+;LOOPVEC_2_3: discriminator: 25
+;LOOPUNROLL_5: discriminator: 21
+; When unrolling after loop vectorize, both vec_body and remainder loop
+; are unrolled.
+;LOOPVEC_UNROLL: discriminator: 385
+;LOOPVEC_UNROLL: discriminator: 9
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, debugInfoForProfiling: true)
+!1 = !DIFile(filename: "a.cc", directory: "/")
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!6 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 4, unit: !0)
+!8 = !DILocation(line: 6, column: 13, scope: !6)
+!9 = !{!10, !10, i64 0}
+!10 = !{!"any pointer", !11, i64 0}
+!11 = !{!"omnipotent char", !12, i64 0}
+!12 = !{!"Simple C++ TBAA"}
+!13 = !DILocation(line: 6, column: 5, scope: !6)
+!14 = !DILocation(line: 5, column: 3, scope: !6)
+!15 = !{!16, !16, i64 0}
+!16 = !{!"int", !11, i64 0}
+!17 = !DILocation(line: 6, column: 10, scope: !6)
+!18 = !DILocation(line: 5, column: 30, scope: !6)
+!19 = !DILocation(line: 5, column: 21, scope: !6)
+!20 = distinct !{!20, !14}
+!21 = !DILocation(line: 7, column: 1, scope: !6)