[llvm] e038c54 - [LTO][Pipelines] Add 0 hot-caller threshold for SamplePGO + FullLTO (#135152)

[via llvm-commits]

Author: Tianle Liu
Date: 2025-04-14T11:21:08+08:00
New Revision: e038c5401c99ca1f19a873a5c88ad7db4645a26a

URL: https://github.com/llvm/llvm-project/commit/e038c5401c99ca1f19a873a5c88ad7db4645a26a
DIFF: https://github.com/llvm/llvm-project/commit/e038c5401c99ca1f19a873a5c88ad7db4645a26a.diff

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

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.

Added: 
    llvm/test/Other/new-pm-lto-prelink-samplepgo-inline-threshold.ll

Modified: 
    llvm/lib/Passes/PassBuilderPipelines.cpp

Removed: 
    llvm/test/Other/new-pm-thinlto-prelink-samplepgo-inline-threshold.ll


################################################################################
diff  --git a/llvm/lib/Passes/PassBuilderPipelines.cpp b/llvm/lib/Passes/PassBuilderPipelines.cpp
index 300898bb092b3..f172271be09ab 100644
--- a/llvm/lib/Passes/PassBuilderPipelines.cpp
+++ b/llvm/lib/Passes/PassBuilderPipelines.cpp
@@ -926,14 +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 &&
-      PGOOpt->Action == PGOOptions::SampleUse)
+  if (isLTOPreLink(Phase) && PGOOpt && PGOOpt->Action == PGOOptions::SampleUse)
     IP.HotCallSiteThreshold = 0;
 
   if (PGOOpt)
@@ -1023,14 +1023,14 @@ 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 &&
-      PGOOpt->Action == PGOOptions::SampleUse)
+  if (isLTOPreLink(Phase) && PGOOpt && PGOOpt->Action == PGOOptions::SampleUse)
     IP.HotCallSiteThreshold = 0;
 
   if (PGOOpt)

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>