From 0e9956204db3802ac94a7727bf2fe35c753cc8f5 Mon Sep 17 00:00:00 2001 From: Dmitri Gribenko Date: Tue, 10 Jan 2023 11:37:49 +0100 Subject: [PATCH] Revert "[JumpThreading] Preserve profile metadata during select unfolding" This reverts commit 957952dbf2f34ed552e8e1f8c35eed17eee2ea38. Addition in the newly added code can overflow. As a result, the constructor of `BranchProbability()` can trigger an assertion. See the discussion on https://reviews.llvm.org/D138132 for more details. --- llvm/lib/Transforms/Scalar/JumpThreading.cpp | 16 ---------------- llvm/test/Transforms/JumpThreading/select.ll | 25 +++++++------------------ 2 files changed, 7 insertions(+), 34 deletions(-) diff --git a/llvm/lib/Transforms/Scalar/JumpThreading.cpp b/llvm/lib/Transforms/Scalar/JumpThreading.cpp index 19ed7e5..e9bf66c 100644 --- a/llvm/lib/Transforms/Scalar/JumpThreading.cpp +++ b/llvm/lib/Transforms/Scalar/JumpThreading.cpp @@ -2785,24 +2785,8 @@ void JumpThreadingPass::unfoldSelectInstr(BasicBlock *Pred, BasicBlock *BB, // 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) && - (TrueWeight + FalseWeight) != 0) { - SmallVector 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(); diff --git a/llvm/test/Transforms/JumpThreading/select.ll b/llvm/test/Transforms/JumpThreading/select.ll index d85fb45..aedfab8 100644 --- a/llvm/test/Transforms/JumpThreading/select.ll +++ b/llvm/test/Transforms/JumpThreading/select.ll @@ -1,13 +1,5 @@ ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py -; RUN: opt -S -passes=jump-threading -debug-only=branch-prob < %s 2>&1 | FileCheck %s -; REQUIRES: asserts - -; CHECK-LABEL: ---- Branch Probability Info : unfold1 ---- -; CHECK: set edge cond.false -> 0 successor probability to 0x0ccccccd / 0x80000000 = 10.00% -; CHECK: set edge cond.false -> 1 successor probability to 0x73333333 / 0x80000000 = 90.00% -; CHECK-LABEL: ---- Branch Probability Info : unfold2 ---- -; CHECK: set edge cond.false -> 0 successor probability to 0x0ccccccd / 0x80000000 = 10.00% -; CHECK: set edge cond.false -> 1 successor probability to 0x73333333 / 0x80000000 = 90.00% +; RUN: opt -S -passes=jump-threading < %s | FileCheck %s declare void @foo() declare void @bar() @@ -273,7 +265,7 @@ L4: ret void } -define void @unfold1(double %x, double %y) nounwind !prof !1 { +define void @unfold1(double %x, double %y) nounwind { ; CHECK-LABEL: @unfold1( ; CHECK-NEXT: entry: ; CHECK-NEXT: [[SUB:%.*]] = fsub double [[X:%.*]], [[Y:%.*]] @@ -282,7 +274,7 @@ define void @unfold1(double %x, double %y) nounwind !prof !1 { ; 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:%.*]], !prof [[PROF1:![0-9]+]] +; CHECK-NEXT: br i1 [[CMP1]], label [[COND_END4]], label [[IF_THEN:%.*]] ; CHECK: cond.end4: ; CHECK-NEXT: [[COND5:%.*]] = phi double [ [[SUB]], [[ENTRY:%.*]] ], [ [[ADD]], [[COND_FALSE]] ] ; CHECK-NEXT: [[CMP6:%.*]] = fcmp oeq double [[COND5]], 0.000000e+00 @@ -301,7 +293,7 @@ entry: 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, !prof !0 + %add. = select i1 %cmp1, double %add, double 0.000000e+00 br label %cond.end4 cond.end4: ; preds = %entry, %cond.false @@ -319,7 +311,7 @@ if.end: ; preds = %if.then, %cond.end4 } -define void @unfold2(i32 %x, i32 %y) nounwind !prof !1 { +define void @unfold2(i32 %x, i32 %y) nounwind { ; CHECK-LABEL: @unfold2( ; CHECK-NEXT: entry: ; CHECK-NEXT: [[SUB:%.*]] = sub nsw i32 [[X:%.*]], [[Y:%.*]] @@ -328,7 +320,7 @@ define void @unfold2(i32 %x, i32 %y) nounwind !prof !1 { ; 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:%.*]], !prof [[PROF1:![0-9]+]] +; CHECK-NEXT: br i1 [[CMP1]], label [[IF_THEN:%.*]], label [[COND_END4:%.*]] ; CHECK: cond.end4: ; CHECK-NEXT: [[COND5:%.*]] = phi i32 [ [[ADD]], [[COND_FALSE]] ] ; CHECK-NEXT: [[CMP6:%.*]] = icmp eq i32 [[COND5]], 0 @@ -347,7 +339,7 @@ entry: cond.false: ; preds = %entry %add = add nsw i32 %x, %y %cmp1 = icmp sgt i32 %add, 10 - %add. = select i1 %cmp1, i32 0, i32 %add, !prof !0 + %add. = select i1 %cmp1, i32 0, i32 %add br label %cond.end4 cond.end4: ; preds = %entry, %cond.false @@ -660,6 +652,3 @@ if.end: %v1 = select i1 %v, i32 %s, i32 42 ret i32 %v1 } - -!0 = !{!"branch_weights", i32 1, i32 9} -!1 = !{!"function_entry_count", i64 1984} -- 2.7.4