[PATCH] D23415: [Inliner] Report when inlining fails because callee's def is unavailable

[Adam Nemet via llvm-commits]

anemet created this revision.
anemet added reviewers: eraman, chandlerc, davidxl, hfinkel.
anemet added a subscriber: llvm-commits.

This is obviously an interesting case because it may motivate code
restructuring or LTO.

Reporting this requires instantiation of ORE in the loop where the call
sites are first gathered.  I've checked compile-time
overhead *with* -Rpass-with-hotness and the worst slow-down was 6% in
mcf and quickly tailing off.  As before without -Rpass-with-hotness
there is no overhead.

https://reviews.llvm.org/D23415

Files:
  include/llvm/Analysis/OptimizationDiagnosticInfo.h
  lib/Transforms/IPO/Inliner.cpp
  test/Transforms/Inline/optimization-remarks.ll

Index: test/Transforms/Inline/optimization-remarks.ll
===================================================================
--- test/Transforms/Inline/optimization-remarks.ll
+++ test/Transforms/Inline/optimization-remarks.ll
@@ -1,5 +1,7 @@
 ; RUN: opt < %s -inline -pass-remarks=inline -pass-remarks-missed=inline -pass-remarks-analysis=inline -S 2>&1 | FileCheck %s
 
+; CHECK: definition of fox is not available
+; CHECK: fox will not be inlined into bar
 ; CHECK: foo should always be inlined (cost=always)
 ; CHECK: foo inlined into bar
 ; CHECK: foz should never be inlined (cost=never)
@@ -32,6 +34,8 @@
   ret float %conv
 }
 
+declare i32 @fox()
+
 ; Function Attrs: nounwind uwtable
 define i32 @bar(i32 %j) #2 {
 entry:
@@ -48,7 +52,9 @@
   %call2 = call float @foz(i32 %sub1, i32 %3)
   %mul = fmul float %conv, %call2
   %conv3 = fptosi float %mul to i32
-  ret i32 %conv3
+  %call3 = call i32 @fox()
+  %add = add i32 %conv3, %call 
+  ret i32 %add
 }
 
 attributes #0 = { alwaysinline nounwind uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
Index: lib/Transforms/IPO/Inliner.cpp
===================================================================
--- lib/Transforms/IPO/Inliner.cpp
+++ lib/Transforms/IPO/Inliner.cpp
@@ -435,9 +435,10 @@
 
   for (CallGraphNode *Node : SCC) {
     Function *F = Node->getFunction();
-    if (!F)
+    if (!F || F->isDeclaration())
       continue;
 
+    OptimizationRemarkEmitter ORE(F);
     for (BasicBlock &BB : *F)
       for (Instruction &I : BB) {
         CallSite CS(cast<Value>(&I));
@@ -450,8 +451,15 @@
         // it.  If it is an indirect call, inlining may resolve it to be a
         // direct call, so we keep it.
         if (Function *Callee = CS.getCalledFunction())
-          if (Callee->isDeclaration())
+          if (Callee->isDeclaration()) {
+            ORE.emitOptimizationRemarkMissedAndAnalysis(
+                DEBUG_TYPE, &I,
+                Twine(Callee->getName()) + " will not be inlined into " +
+                    CS.getCaller()->getName(),
+                Twine("definition of ") + Callee->getName() +
+                    " is not available");
             continue;
+          }
 
         CallSites.push_back(std::make_pair(CS, -1));
       }
Index: include/llvm/Analysis/OptimizationDiagnosticInfo.h
===================================================================
--- include/llvm/Analysis/OptimizationDiagnosticInfo.h
+++ include/llvm/Analysis/OptimizationDiagnosticInfo.h
@@ -132,6 +132,24 @@
                                    Inst->getParent(), Msg);
   }
 
+  /// \brief This variant allows specifying what should be emitted for missed
+  /// and analysis remarks in one call.
+  ///
+  /// \p PassName is the name of the pass emitting the message. If
+  /// -Rpass-missed= is given and \p PassName matches the regular expression, \p
+  /// MsgForMissedRemark is emitted.
+  ///
+  /// If -Rpass-analysis= is given and \p PassName matches the regular
+  /// expression, \p MsgForAnalysisRemark is emitted.
+  ///
+  /// The debug location and the code region is derived from \p Inst.
+  void emitOptimizationRemarkMissedAndAnalysis(
+      const char *PassName, Instruction *Inst, const Twine &MsgForMissedRemark,
+      const Twine &MsgForAnalysisRemark) {
+    emitOptimizationRemarkAnalysis(PassName, Inst, MsgForAnalysisRemark);
+    emitOptimizationRemarkMissed(PassName, Inst, MsgForMissedRemark);
+  }
+
   /// \brief Emit an optimization analysis remark related to floating-point
   /// non-commutativity.
   ///


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