[llvm] 5b461d5 - [FS-AFDO] Assign discriminators to pseudo probes
Hongtao Yu via llvm-commits
llvm-commits at lists.llvm.org
Tue Apr 4 17:04:49 PDT 2023
Author: Hongtao Yu
Date: 2023-04-04T17:04:37-07:00
New Revision: 5b461d5ec172d21029da492064704fe3da6f8bab
URL: https://github.com/llvm/llvm-project/commit/5b461d5ec172d21029da492064704fe3da6f8bab
DIFF: https://github.com/llvm/llvm-project/commit/5b461d5ec172d21029da492064704fe3da6f8bab.diff
LOG: [FS-AFDO] Assign discriminators to pseudo probes
This is the first change for FS-AFDO integration with CSSPGO. There are more patches coming.
With pseudo probes, we do not assign FS discriminators to any other instructions since we will be using only probes for profile correlation.
Also call instructions are excluded since their dwarf discriminators are used for other purposes, i.e, storing probe ids. Since they are not getting a FS discriminator, they will also be excluded from MIR profile loading. The corresponding changes will be in the subsequent patches.
Reviewed By: wenlei
Differential Revision: https://reviews.llvm.org/D147286
Added:
llvm/test/CodeGen/X86/fsafdo_probe.ll
Modified:
llvm/lib/CodeGen/MIRFSDiscriminator.cpp
Removed:
################################################################################
diff --git a/llvm/lib/CodeGen/MIRFSDiscriminator.cpp b/llvm/lib/CodeGen/MIRFSDiscriminator.cpp
index e2166a4b484ac..6f985df74c4de 100644
--- a/llvm/lib/CodeGen/MIRFSDiscriminator.cpp
+++ b/llvm/lib/CodeGen/MIRFSDiscriminator.cpp
@@ -18,6 +18,8 @@
#include "llvm/CodeGen/Passes.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/IR/Function.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IR/PseudoProbe.h"
#include "llvm/InitializePasses.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
@@ -92,7 +94,11 @@ static uint64_t getCallStackHash(const DILocation *DIL) {
bool MIRAddFSDiscriminators::runOnMachineFunction(MachineFunction &MF) {
if (!EnableFSDiscriminator)
return false;
- if (!MF.getFunction().shouldEmitDebugInfoForProfiling())
+
+ bool HasPseudoProbe = MF.getFunction().getParent()->getNamedMetadata(
+ PseudoProbeDescMetadataName);
+
+ if (!HasPseudoProbe && !MF.getFunction().shouldEmitDebugInfoForProfiling())
return false;
bool Changed = false;
@@ -125,13 +131,22 @@ bool MIRAddFSDiscriminators::runOnMachineFunction(MachineFunction &MF) {
for (MachineBasicBlock &BB : MF) {
for (MachineInstr &I : BB) {
- if (ImprovedFSDiscriminator && I.isMetaInstruction()) {
+ if (HasPseudoProbe) {
+ // Only assign discriminators to pseudo probe instructions. Call
+ // instructions are excluded since their dwarf discriminators are used
+ // for other purposes, i.e, storing probe ids.
+ if (!I.isPseudoProbe())
+ continue;
+ } else if (ImprovedFSDiscriminator && I.isMetaInstruction()) {
continue;
}
const DILocation *DIL = I.getDebugLoc().get();
if (!DIL)
continue;
- unsigned LineNo = DIL->getLine();
+
+ // Use the id of pseudo probe to compute the discriminator.
+ unsigned LineNo =
+ I.isPseudoProbe() ? I.getOperand(1).getImm() : DIL->getLine();
if (LineNo == 0)
continue;
unsigned Discriminator = DIL->getDiscriminator();
diff --git a/llvm/test/CodeGen/X86/fsafdo_probe.ll b/llvm/test/CodeGen/X86/fsafdo_probe.ll
new file mode 100644
index 0000000000000..bc19a297dc428
--- /dev/null
+++ b/llvm/test/CodeGen/X86/fsafdo_probe.ll
@@ -0,0 +1,72 @@
+; REQUIRES: x86_64-linux
+; REQUIRES: asserts
+; RUN: llc -enable-fs-discriminator -improved-fs-discriminator=false --debug-only=mirfs-discriminators < %s -o - 2>&1 | FileCheck %s --check-prefixes=V0
+; RUN: llc -enable-fs-discriminator -improved-fs-discriminator=true --debug-only=mirfs-discriminators < %s -o - 2>&1 | FileCheck %s --check-prefixes=V1
+
+; Check that fs-afdo discriminators are generated.
+; V0: foo.c:7:3: add FS discriminator, from 0 -> 11264
+; V0: foo.c:9:5: add FS discriminator, from 0 -> 11264
+; V0: Num of FS Discriminators: 2
+
+; V1: foo.c:7:3: add FS discriminator, from 0 -> 256
+; V1: foo.c:9:5: add FS discriminator, from 0 -> 256
+; V1: Num of FS Discriminators: 2
+
+target triple = "x86_64-unknown-linux-gnu"
+
+%struct.Node = type { ptr }
+
+define i32 @foo(ptr readonly %node, ptr readnone %root) !dbg !6 {
+entry:
+ call void @llvm.pseudoprobe(i64 6699318081062747564, i64 1, i32 0, i64 -1), !dbg !8
+ %cmp = icmp eq ptr %node, %root, !dbg !8
+ br i1 %cmp, label %while.end4, label %while.cond1.preheader.lr.ph, !dbg !10
+
+while.cond1.preheader.lr.ph:
+ %tobool = icmp eq ptr %node, null
+ call void @llvm.pseudoprobe(i64 6699318081062747564, i64 2, i32 0, i64 -1), !dbg !11
+ br i1 %tobool, label %while.cond1.preheader.us.preheader, label %while.body2.preheader, !dbg !11
+
+while.body2.preheader:
+ call void @llvm.pseudoprobe(i64 6699318081062747564, i64 2, i32 0, i64 -1), !dbg !11
+ br label %while.body2, !dbg !11
+
+while.cond1.preheader.us.preheader:
+ call void @llvm.pseudoprobe(i64 6699318081062747564, i64 3, i32 0, i64 -1), !dbg !10
+ br label %while.cond1.preheader.us, !dbg !10
+
+while.cond1.preheader.us:
+ call void @llvm.pseudoprobe(i64 6699318081062747564, i64 3, i32 0, i64 -1), !dbg !10
+ br label %while.cond1.preheader.us, !dbg !10
+
+while.body2:
+ call void @llvm.pseudoprobe(i64 6699318081062747564, i64 2, i32 0, i64 -1), !dbg !11
+ br label %while.body2, !dbg !11
+
+while.end4:
+ call void @llvm.pseudoprobe(i64 6699318081062747564, i64 4, i32 0, i64 -1), !dbg !12
+ ret i32 0, !dbg !12
+}
+
+declare void @llvm.pseudoprobe(i64, i64, i32, i64) #0
+
+attributes #0 = { inaccessiblememonly nocallback nofree nosync nounwind willreturn }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4}
+!llvm.pseudo_probe_desc = !{!13}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, isOptimized: true, debugInfoForProfiling: true, emissionKind: LineTablesOnly)
+!1 = !DIFile(filename: "foo.c", directory: "b/")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{}
+!6 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 5, type: !7, isLocal: false, isDefinition: true, scopeLine: 5, flags: DIFlagPrototyped, isOptimized: true, unit: !0, retainedNodes: !2)
+!7 = !DISubroutineType(types: !2)
+!8 = !DILocation(line: 7, column: 15, scope: !9)
+!9 = !DILexicalBlockFile(scope: !6, file: !1, discriminator: 0)
+!10 = !DILocation(line: 7, column: 3, scope: !9)
+!11 = !DILocation(line: 9, column: 5, scope: !9)
+!12 = !DILocation(line: 14, column: 3, scope: !6)
+!13 = !{i64 6699318081062747564, i64 138464321060, !"foo"}
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