[PATCH] D109088: [CSSPGO] Honor preinliner decision for ThinLTO importing

[Wenlei He via Phabricator via llvm-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rGa2768b4732a0: [CSSPGO] Honor preinliner decision for ThinLTO importing (authored by wenlei).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D109088/new/

https://reviews.llvm.org/D109088

Files:
  llvm/lib/Transforms/IPO/SampleContextTracker.cpp
  llvm/lib/Transforms/IPO/SampleProfile.cpp
  llvm/test/Transforms/SampleProfile/csspgo-use-preinliner.ll


Index: llvm/test/Transforms/SampleProfile/csspgo-use-preinliner.ll
===================================================================
--- llvm/test/Transforms/SampleProfile/csspgo-use-preinliner.ll
+++ llvm/test/Transforms/SampleProfile/csspgo-use-preinliner.ll
@@ -8,9 +8,12 @@
 ; DEFAULT-NOT: inlined into
 
 ; PREINLINE-NOT: inlined into
+; `[main:3 @ _Z5funcAi]` does not have preinline decision, so it's up for loader inliner to decided.
 ; PREINLINE: '_Z5funcAi' inlined into 'main'
+; `[main:3 @ _Z5funcAi:1 @ _Z8funcLeafi]` is inlined according to preinline decision.
 ; PREINLINE: '_Z8funcLeafi' inlined into 'main'
-; PREINLINE: '_Z8funcLeafi' inlined into '_Z5funcBi'
+; Even though `[main:3.1 @ _Z5funcBi]` context is marked should inline, `_Z5funcBi` is a noinline function, so we honor that and don't inline.
+; When _Z5funcBi is promoted to be top level context-less profile, `[_Z5funcBi:1 @ _Z8funcLeafi]` becomes synthetic context, so preinline decision is ignored and we don't inline `_Z8funcLeafi`.
 ; PREINLINE-NOT: inlined into
 
 @factor = dso_local global i32 3, align 4, !dbg !0
Index: llvm/lib/Transforms/IPO/SampleProfile.cpp
===================================================================
--- llvm/lib/Transforms/IPO/SampleProfile.cpp
+++ llvm/lib/Transforms/IPO/SampleProfile.cpp
@@ -977,7 +977,14 @@
     // For CSSPGO profile, retrieve candidate profile by walking over the
     // trie built for context profile. Note that also take call targets
     // even if callee doesn't have a corresponding context profile.
-    if (!CalleeSample || CalleeSample->getEntrySamples() < Threshold)
+    if (!CalleeSample)
+      continue;
+
+    // If pre-inliner decision is used, honor that for importing as well.
+    bool PreInline =
+        UsePreInlinerDecision &&
+        CalleeSample->getContext().hasAttribute(ContextShouldBeInlined);
+    if (!PreInline && CalleeSample->getEntrySamples() < Threshold)
       continue;
 
     StringRef Name = CalleeSample->getFuncName();
@@ -1299,10 +1306,13 @@
   // we replay that inline decision under `sample-profile-use-preinliner`.
   // Note that we don't need to handle negative decision from preinliner as
   // context profile for not inlined calls are merged by preinliner already.
-  if (UsePreInlinerDecision &&
-      Candidate.CalleeSamples->getContext().hasAttribute(
-          ContextShouldBeInlined))
-    return InlineCost::getAlways("preinliner");
+  SampleContext &Context = Candidate.CalleeSamples->getContext();
+  if (UsePreInlinerDecision && Context.hasAttribute(ContextShouldBeInlined))
+    // Once two node are merged due to promotion, we're losing some context
+    // so the original context-sensitive preinliner decision should be ignored
+    // for SyntheticContext.
+    if (!Context.hasState(SyntheticContext))
+      return InlineCost::getAlways("preinliner");
 
   // For old FDO inliner, we inline the call site as long as cost is not
   // "Never". The cost-benefit check is done earlier.
Index: llvm/lib/Transforms/IPO/SampleContextTracker.cpp
===================================================================
--- llvm/lib/Transforms/IPO/SampleContextTracker.cpp
+++ llvm/lib/Transforms/IPO/SampleContextTracker.cpp
@@ -545,6 +545,8 @@
     ToSamples->merge(*FromSamples);
     ToSamples->getContext().setState(SyntheticContext);
     FromSamples->getContext().setState(MergedContext);
+    if (FromSamples->getContext().hasAttribute(ContextShouldBeInlined))
+      ToSamples->getContext().setAttribute(ContextShouldBeInlined);
   } else if (FromSamples) {
     // Transfer FromSamples from FromNode to ToNode
     ToNode.setFunctionSamples(FromSamples);


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