[PATCH] D137165: [JumpThreading] Copy profile metadata on select unfolding

[Roman Paukner via Phabricator via llvm-commits]

rp updated this revision to Diff 474018.
rp edited the summary of this revision.
rp added a comment.

Added setEdgeProbability/setBlockFreq


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D137165/new/

https://reviews.llvm.org/D137165

Files:
  llvm/lib/Transforms/Scalar/JumpThreading.cpp
  llvm/test/Transforms/JumpThreading/select.ll


Index: llvm/test/Transforms/JumpThreading/select.ll
===================================================================
--- llvm/test/Transforms/JumpThreading/select.ll
+++ llvm/test/Transforms/JumpThreading/select.ll
@@ -274,7 +274,7 @@
 ; CHECK:       cond.false:
 ; CHECK-NEXT:    [[ADD:%.*]] = fadd double [[X]], [[Y]]
 ; CHECK-NEXT:    [[CMP1:%.*]] = fcmp ogt double [[ADD]], 1.000000e+01
-; CHECK-NEXT:    br i1 [[CMP1]], label [[COND_END4]], label [[IF_THEN:%.*]]
+; CHECK-NEXT:    br i1 [[CMP1]], label [[COND_END4]], label [[IF_THEN:%.*]], !prof !0
 ; CHECK:       cond.end4:
 ; CHECK-NEXT:    [[COND5:%.*]] = phi double [ [[SUB]], [[ENTRY:%.*]] ], [ [[ADD]], [[COND_FALSE]] ]
 ; CHECK-NEXT:    [[CMP6:%.*]] = fcmp oeq double [[COND5]], 0.000000e+00
@@ -293,7 +293,7 @@
 cond.false:                                       ; preds = %entry
   %add = fadd double %x, %y
   %cmp1 = fcmp ogt double %add, 1.000000e+01
-  %add. = select i1 %cmp1, double %add, double 0.000000e+00
+  %add. = select i1 %cmp1, double %add, double 0.000000e+00, !prof !0
   br label %cond.end4
 
 cond.end4:                                        ; preds = %entry, %cond.false
@@ -311,7 +311,7 @@
 }
 
 
-define void @unfold2(i32 %x, i32 %y) nounwind {
+define void @unfold2(i32 %x, i32 %y) nounwind !prof !1 {
 ; CHECK-LABEL: @unfold2(
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    [[SUB:%.*]] = sub nsw i32 [[X:%.*]], [[Y:%.*]]
@@ -320,7 +320,7 @@
 ; CHECK:       cond.false:
 ; CHECK-NEXT:    [[ADD:%.*]] = add nsw i32 [[X]], [[Y]]
 ; CHECK-NEXT:    [[CMP1:%.*]] = icmp sgt i32 [[ADD]], 10
-; CHECK-NEXT:    br i1 [[CMP1]], label [[IF_THEN:%.*]], label [[COND_END4:%.*]]
+; CHECK-NEXT:    br i1 [[CMP1]], label [[IF_THEN:%.*]], label [[COND_END4:%.*]], !prof !0
 ; CHECK:       cond.end4:
 ; CHECK-NEXT:    [[COND5:%.*]] = phi i32 [ [[ADD]], [[COND_FALSE]] ]
 ; CHECK-NEXT:    [[CMP6:%.*]] = icmp eq i32 [[COND5]], 0
@@ -339,7 +339,7 @@
 cond.false:                                       ; preds = %entry
   %add = add nsw i32 %x, %y
   %cmp1 = icmp sgt i32 %add, 10
-  %add. = select i1 %cmp1, i32 0, i32 %add
+  %add. = select i1 %cmp1, i32 0, i32 %add, !prof !0
   br label %cond.end4
 
 cond.end4:                                        ; preds = %entry, %cond.false
@@ -652,3 +652,6 @@
   %v1 = select i1 %v, i32 %s, i32 42
   ret i32 %v1
 }
+
+!0 = !{!"branch_weights", i32 2146410443, i32 1073205}
+!1 = !{!"function_entry_count", i64 1984}
Index: llvm/lib/Transforms/Scalar/JumpThreading.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/JumpThreading.cpp
+++ llvm/lib/Transforms/Scalar/JumpThreading.cpp
@@ -2759,8 +2759,23 @@
   // Create a conditional branch and update PHI nodes.
   auto *BI = BranchInst::Create(NewBB, BB, SI->getCondition(), Pred);
   BI->applyMergedLocation(PredTerm->getDebugLoc(), SI->getDebugLoc());
+  BI->copyMetadata(*SI, {LLVMContext::MD_prof});
   SIUse->setIncomingValue(Idx, SI->getFalseValue());
   SIUse->addIncoming(SI->getTrueValue(), NewBB);
+  // Set the block frequency of NewBB.
+  if (HasProfileData) {
+    uint64_t TrueWeight, FalseWeight;
+    if (extractBranchWeights(*SI, TrueWeight, FalseWeight)) {
+      SmallVector<BranchProbability, 2 > BP;
+      BP.emplace_back(BranchProbability(TrueWeight, TrueWeight + FalseWeight));
+      BP.emplace_back(BranchProbability(FalseWeight, TrueWeight + FalseWeight));
+      BPI->setEdgeProbability(Pred, BP); 
+    }
+
+    auto NewBBFreq =
+        BFI->getBlockFreq(Pred) * BPI->getEdgeProbability(Pred, NewBB);
+    BFI->setBlockFreq(NewBB, NewBBFreq.getFrequency());
+  }
 
   // The select is now dead.
   SI->eraseFromParent();


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