[PGO] Fix select instruction annotation

Summary:
Select instruction annotation in IR PGO uses the edge count to infer the
branch count. It's currently placed in setInstrumentedCounts() where
no all the BB counts have been computed. This leads to wrong branch weights.
Move the annotation after all BB counts are populated.

Reviewers: davidxl

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D25961

llvm-svn: 285128

2 files changed, 48 insertions, 0 deletions

diff --git a/llvm/test/Transforms/PGOProfile/Inputs/select2.proftext b/llvm/test/Transforms/PGOProfile/Inputs/select2.proftext
new file mode 100644
index 00000000000..56d78387ec2
--- /dev/null
+++ b/llvm/test/Transforms/PGOProfile/Inputs/select2.proftext
@@ -0,0 +1,11 @@
+# IR level Instrumentation Flag
+:ir
+foo
+# Func Hash:
+72057628175588252
+# Num Counters:
+3
+# Counter Values:
+800
+3
+300
diff --git a/llvm/test/Transforms/PGOProfile/select2.ll b/llvm/test/Transforms/PGOProfile/select2.ll
new file mode 100644
index 00000000000..b19fa1ff798
--- /dev/null
+++ b/llvm/test/Transforms/PGOProfile/select2.ll
@@ -0,0 +1,37 @@
+; RUN: llvm-profdata merge %S/Inputs/select2.proftext -o %t.profdata
+; RUN: opt < %s -pgo-instr-use -pgo-test-profile-file=%t.profdata -pgo-instr-select=true -S | FileCheck %s --check-prefix=USE
+; RUN: opt < %s -passes=pgo-instr-use -pgo-test-profile-file=%t.profdata -pgo-instr-select=true -S | FileCheck %s --check-prefix=USE
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define i32 @foo(i32 %n) {
+;USE: define i32 @foo(i32 %n) !prof ![[ENTRY_COUNT:[0-9]+]] {
+entry:
+  br label %for.cond
+
+for.cond:
+  %i.0 = phi i32 [ 0, %entry ], [ %inc, %for.inc ]
+  %sum.0 = phi i32 [ 0, %entry ], [ %add, %for.inc ]
+  %cmp = icmp slt i32 %i.0, %n
+  br i1 %cmp, label %for.body, label %for.end
+;USE:  br i1 %cmp, label %for.body, label %for.end, !prof ![[BW_FOR_BR:[0-9]+]]
+
+for.body:
+  %cmp1 = icmp sgt i32 %sum.0, 10
+  %cond = select i1 %cmp1, i32 20, i32 -10
+;USE:  %cond = select i1 %cmp1, i32 20, i32 -10, !prof ![[BW_FOR_SELECT:[0-9]+]]
+  %add = add nsw i32 %sum.0, %cond
+  br label %for.inc
+
+for.inc:
+  %inc = add nsw i32 %i.0, 1
+  br label %for.cond
+
+for.end:
+  ret i32 %sum.0
+}
+
+;USE: ![[ENTRY_COUNT]] = !{!"function_entry_count", i64 3}
+;USE: ![[BW_FOR_BR]] = !{!"branch_weights", i32 800, i32 3}
+;USE: ![[BW_FOR_SELECT]] = !{!"branch_weights", i32 300, i32 500}