[llvm] [LTO][Pipelines] Add 0 hot-caller threshold for SamplePGO + FullLTO (PR #135152)

[via llvm-commits]

https://github.com/tianleliu updated https://github.com/llvm/llvm-project/pull/135152

>From 133dd835a915c403d2ff42d984b34f77a56728e3 Mon Sep 17 00:00:00 2001
From: tianleli <tianle.l.liu at intel.com>
Date: Tue, 8 Apr 2025 13:42:16 +0800
Subject: [PATCH 1/2] [LTO][Pipelines] Add a guard of 0 hot-caller threshold
 for SamplePGO + FullLTO.

If a hot callsite function is not inlined in the 1st build,
inlining the hot callsite in pre-link stage of SPGO 2nd build
may lead to Function Sample not found in profile file in link stage.
It will miss some profile info.
ThinLTO has already considered and dealed with it by setting
HotCallSiteThreshold to 0 to stop the inline. This patch just
adds the same processing for FullLTO.
---
 llvm/lib/Passes/PassBuilderPipelines.cpp           | 14 ++++++++------
 ...w-pm-lto-prelink-samplepgo-inline-threshold.ll} |  5 ++++-
 2 files changed, 12 insertions(+), 7 deletions(-)
 rename llvm/test/Other/{new-pm-thinlto-prelink-samplepgo-inline-threshold.ll => new-pm-lto-prelink-samplepgo-inline-threshold.ll} (91%)

diff --git a/llvm/lib/Passes/PassBuilderPipelines.cpp b/llvm/lib/Passes/PassBuilderPipelines.cpp
index 300898bb092b3..ac41cdaf107a0 100644
--- a/llvm/lib/Passes/PassBuilderPipelines.cpp
+++ b/llvm/lib/Passes/PassBuilderPipelines.cpp
@@ -926,13 +926,14 @@ PassBuilder::buildInlinerPipeline(OptimizationLevel Level,
     IP = getInlineParamsFromOptLevel(Level);
   else
     IP = getInlineParams(PTO.InlinerThreshold);
-  // For PreLinkThinLTO + SamplePGO, set hot-caller threshold to 0 to
-  // disable hot callsite inline (as much as possible [1]) because it makes
+  // For PreLinkThinLTO + SamplePGO or PreLinkFullLTO + SamplePGO,
+  // set hot-caller threshold to 0 to disable hot
+  // callsite inline (as much as possible [1]) because it makes
   // profile annotation in the backend inaccurate.
   //
   // [1] Note the cost of a function could be below zero due to erased
   // prologue / epilogue.
-  if (Phase == ThinOrFullLTOPhase::ThinLTOPreLink && PGOOpt &&
+  if (isLTOPreLink(Phase) && PGOOpt &&
       PGOOpt->Action == PGOOptions::SampleUse)
     IP.HotCallSiteThreshold = 0;
 
@@ -1023,13 +1024,14 @@ PassBuilder::buildModuleInlinerPipeline(OptimizationLevel Level,
   ModulePassManager MPM;
 
   InlineParams IP = getInlineParamsFromOptLevel(Level);
-  // For PreLinkThinLTO + SamplePGO, set hot-caller threshold to 0 to
-  // disable hot callsite inline (as much as possible [1]) because it makes
+  // For PreLinkThinLTO + SamplePGO or PreLinkFullLTO + SamplePGO,
+  // set hot-caller threshold to 0 to disable hot
+  // callsite inline (as much as possible [1]) because it makes
   // profile annotation in the backend inaccurate.
   //
   // [1] Note the cost of a function could be below zero due to erased
   // prologue / epilogue.
-  if (Phase == ThinOrFullLTOPhase::ThinLTOPreLink && PGOOpt &&
+  if (isLTOPreLink(Phase) && PGOOpt &&
       PGOOpt->Action == PGOOptions::SampleUse)
     IP.HotCallSiteThreshold = 0;
 
diff --git a/llvm/test/Other/new-pm-thinlto-prelink-samplepgo-inline-threshold.ll b/llvm/test/Other/new-pm-lto-prelink-samplepgo-inline-threshold.ll
similarity index 91%
rename from llvm/test/Other/new-pm-thinlto-prelink-samplepgo-inline-threshold.ll
rename to llvm/test/Other/new-pm-lto-prelink-samplepgo-inline-threshold.ll
index 9baedcb02ca06..67af5f18e0578 100644
--- a/llvm/test/Other/new-pm-thinlto-prelink-samplepgo-inline-threshold.ll
+++ b/llvm/test/Other/new-pm-lto-prelink-samplepgo-inline-threshold.ll
@@ -1,4 +1,4 @@
-; Tests that hot callsite threshold is set to 0 artifically for thinlto-prelink pipeline.
+; Tests that hot callsite threshold is set to 0 artifically for thinlto-prelink and lto-pre-link pipeline.
 ;
 ; Function `sum` is annotated with inline cost -1 and function `sum1` is
 ; annotated with inline cost 0, by function attribute `function-inline-cost`.
@@ -12,6 +12,9 @@
 
 ; RUN: opt < %s -pass-remarks=inline -pass-remarks-missed=inline -passes='thinlto-pre-link<O2>' -pgo-kind=pgo-sample-use-pipeline -sample-profile-file=%S/Inputs/new-pm-thinlto-prelink-samplepgo-inline-threshold.prof -S 2>&1 | FileCheck %s -check-prefix=REMARK
 
+; RUN: opt < %s -pass-remarks=inline -pass-remarks-missed=inline -passes='lto-pre-link<O2>' -pgo-kind=pgo-sample-use-pipeline -sample-profile-file=%S/Inputs/new-pm-thinlto-prelink-samplepgo-inline-threshold.prof -S | FileCheck %s
+
+; RUN: opt < %s -pass-remarks=inline -pass-remarks-missed=inline -passes='lto-pre-link<O2>' -pgo-kind=pgo-sample-use-pipeline -sample-profile-file=%S/Inputs/new-pm-thinlto-prelink-samplepgo-inline-threshold.prof -S 2>&1 | FileCheck %s -check-prefix=REMARK
 ; Original C++ test case
 ;
 ; #include <stdio.h>

>From e66f5166552ad708c6916a8494d26cd176261ee2 Mon Sep 17 00:00:00 2001
From: tianleli <tianle.l.liu at intel.com>
Date: Thu, 10 Apr 2025 19:11:07 +0800
Subject: [PATCH 2/2] Format code.

---
 llvm/lib/Passes/PassBuilderPipelines.cpp | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/llvm/lib/Passes/PassBuilderPipelines.cpp b/llvm/lib/Passes/PassBuilderPipelines.cpp
index ac41cdaf107a0..f172271be09ab 100644
--- a/llvm/lib/Passes/PassBuilderPipelines.cpp
+++ b/llvm/lib/Passes/PassBuilderPipelines.cpp
@@ -933,8 +933,7 @@ PassBuilder::buildInlinerPipeline(OptimizationLevel Level,
   //
   // [1] Note the cost of a function could be below zero due to erased
   // prologue / epilogue.
-  if (isLTOPreLink(Phase) && PGOOpt &&
-      PGOOpt->Action == PGOOptions::SampleUse)
+  if (isLTOPreLink(Phase) && PGOOpt && PGOOpt->Action == PGOOptions::SampleUse)
     IP.HotCallSiteThreshold = 0;
 
   if (PGOOpt)
@@ -1031,8 +1030,7 @@ PassBuilder::buildModuleInlinerPipeline(OptimizationLevel Level,
   //
   // [1] Note the cost of a function could be below zero due to erased
   // prologue / epilogue.
-  if (isLTOPreLink(Phase) && PGOOpt &&
-      PGOOpt->Action == PGOOptions::SampleUse)
+  if (isLTOPreLink(Phase) && PGOOpt && PGOOpt->Action == PGOOptions::SampleUse)
     IP.HotCallSiteThreshold = 0;
 
   if (PGOOpt)