[ORE] Add diagnostics hotness threshold

Summary:
Add an option to prevent diagnostics that do not meet a minimum hotness
threshold from being output. When generating optimization remarks for
large codebases with a ton of cold code paths, this option can be used
to limit the optimization remark output at a reasonable size. Discussion of
this change can be read here:
http://lists.llvm.org/pipermail/llvm-dev/2017-June/114377.html

Reviewers: anemet, davidxl, hfinkel

Reviewed By: anemet

Subscribers: qcolombet, javed.absar, fhahn, eraman, llvm-commits

Differential Revision: https://reviews.llvm.org/D34867

llvm-svn: 306912

2 files changed, 44 insertions, 1 deletions

diff --git a/llvm/test/CodeGen/AArch64/arm64-spill-remarks.ll b/llvm/test/CodeGen/AArch64/arm64-spill-remarks.ll
index bc9340352d7..cfebeb496e1 100644
--- a/llvm/test/CodeGen/AArch64/arm64-spill-remarks.ll
+++ b/llvm/test/CodeGen/AArch64/arm64-spill-remarks.ll
@@ -3,6 +3,15 @@
 ; RUN: llc < %s -mtriple=arm64-apple-ios7.0 -aarch64-neon-syntax=apple 2>&1 | FileCheck -check-prefix=NO_REMARK %s
 ; RUN: llc < %s -mtriple=arm64-apple-ios7.0 -aarch64-neon-syntax=apple -pass-remarks-output=%t.yaml -pass-remarks-with-hotness 2>&1 | FileCheck -check-prefix=NO_REMARK %s
 ; RUN: cat %t.yaml | FileCheck -check-prefix=YAML %s
+;
+; Verify that remarks below the hotness threshold are not output.
+; RUN: llc < %s -mtriple=arm64-apple-ios7.0 -aarch64-neon-syntax=apple -pass-remarks-missed=regalloc \
+; RUN:       -pass-remarks-with-hotness -pass-remarks-hotness-threshold=500 \
+; RUN:       2>&1 | FileCheck -check-prefix=THRESHOLD %s
+; RUN: llc < %s -mtriple=arm64-apple-ios7.0 -aarch64-neon-syntax=apple -pass-remarks-output=%t.threshold.yaml \
+; RUN:       -pass-remarks-with-hotness -pass-remarks-hotness-threshold=500 \
+; RUN:       2>&1 | FileCheck -check-prefix=NO_REMARK %s
+; RUN: cat %t.threshold.yaml | FileCheck -check-prefix=THRESHOLD_YAML %s
 
 ; This has two nested loops, each with one value that has to be spilled and
 ; then reloaded.
@@ -23,6 +32,9 @@
 
 ; NO_REMARK-NOT: remark
 
+; THRESHOLD-NOT: (hotness: 300)
+; THRESHOLD: remark: /tmp/kk.c:2:20: 1 spills 1 reloads generated in loop (hotness: 30000)
+
 ; YAML: --- !Missed
 ; YAML: Pass:            regalloc
 ; YAML: Name:            LoopSpillReload
@@ -63,6 +75,21 @@
 ; YAML:   - String:          generated in loop
 ; YAML: ...
 
+; THRESHOLD_YAML-NOT: Hotness:         300{{$}}
+; THRESHOLD_YAML: --- !Missed
+; THRESHOLD_YAML: Pass:            regalloc
+; THRESHOLD_YAML: Name:            LoopSpillReload
+; THRESHOLD_YAML: DebugLoc:        { File: /tmp/kk.c, Line: 2, Column: 20 }
+; THRESHOLD_YAML: Function:        fpr128
+; THRESHOLD_YAML: Hotness:         30000
+; THRESHOLD_YAML: Args:
+; THRESHOLD_YAML:   - NumSpills:       '1'
+; THRESHOLD_YAML:   - String:          ' spills '
+; THRESHOLD_YAML:   - NumReloads:      '1'
+; THRESHOLD_YAML:   - String:          ' reloads '
+; THRESHOLD_YAML:   - String:          generated in loop
+; THRESHOLD_YAML: ...
+
 define void @fpr128(<4 x float>* %p) nounwind ssp !prof !11 {
 entry:
   br label %loop, !dbg !8
diff --git a/llvm/test/Transforms/Inline/optimization-remarks-yaml.ll b/llvm/test/Transforms/Inline/optimization-remarks-yaml.ll
index 532e443e217..16783634484 100644
--- a/llvm/test/Transforms/Inline/optimization-remarks-yaml.ll
+++ b/llvm/test/Transforms/Inline/optimization-remarks-yaml.ll
@@ -1,8 +1,21 @@
-; RUN: opt < %s -S -inline -pass-remarks-missed=inline -pass-remarks-with-hotness \
+; RUN: opt < %s -S -inline -pass-remarks-missed=inline \
+; RUN:     -pass-remarks-with-hotness -pass-remarks-hotness-threshold 15 \
 ; RUN:     -pass-remarks-output=%t 2>&1 | FileCheck %s
 ; RUN: cat %t | FileCheck -check-prefix=YAML %s
 ; RUN: opt < %s -S -inline -pass-remarks-with-hotness -pass-remarks-output=%t
 ; RUN: cat %t | FileCheck -check-prefix=YAML %s
+;
+; Verify that remarks that don't meet the hotness threshold are not output.
+; RUN: opt < %s -S -inline -pass-remarks-missed=inline \
+; RUN:     -pass-remarks-with-hotness -pass-remarks-hotness-threshold 100 \
+; RUN:     -pass-remarks-output=%t.threshold 2>&1 | \
+; RUN:     FileCheck -check-prefix=THRESHOLD %s
+; RUN: test ! -s %t.threshold
+; RUN: opt < %s -S -inline \
+; RUN:     -pass-remarks-with-hotness -pass-remarks-hotness-threshold 100 \
+; RUN:     -pass-remarks-output=%t.threshold
+; The remarks output file should be empty.
+; RUN: test ! -s %t.threshold
 
 ; Check the YAML file generated for inliner remarks for this program:
 ;
@@ -43,6 +56,9 @@
 ; YAML-NEXT:   - String: ' because its definition is unavailable'
 ; YAML-NEXT: ...
 
+; No remarks should be output, since none meet the threshold.
+; THRESHOLD-NOT: remark
+
 ; ModuleID = '/tmp/s.c'
 source_filename = "/tmp/s.c"
 target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"