https://github.com/mtrofin created https://github.com/llvm/llvm-project/pull/161739
None >From 1b6920213b57235b62daf431f11cce74f3b5a5c3 Mon Sep 17 00:00:00 2001 From: Mircea Trofin <[email protected]> Date: Wed, 1 Oct 2025 17:08:48 -0700 Subject: [PATCH] [SimplifyCFG][profcheck] Handle branch weights in `simplifySwitchLookup` --- llvm/lib/Transforms/Utils/SimplifyCFG.cpp | 22 +++++++++++++---- .../Transforms/SimplifyCFG/rangereduce.ll | 24 +++++++++++++++---- 2 files changed, 38 insertions(+), 8 deletions(-) diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp index 63f4b2e030b69..fa3ac273b39f9 100644 --- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp @@ -7319,19 +7319,33 @@ static bool simplifySwitchLookup(SwitchInst *SI, IRBuilder<> &Builder, if (DTU) Updates.push_back({DominatorTree::Insert, LookupBB, CommonDest}); + SmallVector<uint32_t> BranchWeights; + const bool HasBranchWeights = RangeCheckBranch && + !ProfcheckDisableMetadataFixes && + extractBranchWeights(*SI, BranchWeights); + uint64_t ToLookupWeight = 0; + uint64_t ToDefaultWeight = 0; + // Remove the switch. SmallPtrSet<BasicBlock *, 8> RemovedSuccessors; - for (unsigned i = 0, e = SI->getNumSuccessors(); i < e; ++i) { - BasicBlock *Succ = SI->getSuccessor(i); + for (unsigned I = 0, E = SI->getNumSuccessors(); I < E; ++I) { + BasicBlock *Succ = SI->getSuccessor(I); - if (Succ == SI->getDefaultDest()) + if (Succ == SI->getDefaultDest()) { + if (HasBranchWeights) + ToDefaultWeight += BranchWeights[I]; continue; + } Succ->removePredecessor(BB); if (DTU && RemovedSuccessors.insert(Succ).second) Updates.push_back({DominatorTree::Delete, BB, Succ}); + if (HasBranchWeights) + ToLookupWeight += BranchWeights[I]; } SI->eraseFromParent(); - + if (HasBranchWeights) + setFittedBranchWeights(*RangeCheckBranch, {ToLookupWeight, ToDefaultWeight}, + /*IsExpected=*/false); if (DTU) DTU->applyUpdates(Updates); diff --git a/llvm/test/Transforms/SimplifyCFG/rangereduce.ll b/llvm/test/Transforms/SimplifyCFG/rangereduce.ll index 17d65a4d4fa5e..d1fba91d1e505 100644 --- a/llvm/test/Transforms/SimplifyCFG/rangereduce.ll +++ b/llvm/test/Transforms/SimplifyCFG/rangereduce.ll @@ -1,15 +1,22 @@ -; NOTE: Assertions have been autogenerated by utils/update_test_checks.py +; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --check-globals ; RUN: opt < %s -passes=simplifycfg -simplifycfg-require-and-preserve-domtree=1 -switch-to-lookup -S | FileCheck %s ; RUN: opt < %s -passes='simplifycfg<switch-to-lookup>' -S | FileCheck %s target datalayout = "e-n32" -define i32 @test1(i32 %a) { +;. +; CHECK: @switch.table.test1 = private unnamed_addr constant [4 x i32] [i32 11984, i32 1143, i32 99783, i32 99783], align 4 +; CHECK: @switch.table.test3 = private unnamed_addr constant [3 x i32] [i32 11984, i32 1143, i32 99783], align 4 +; CHECK: @switch.table.test6 = private unnamed_addr constant [4 x i32] [i32 99783, i32 99783, i32 1143, i32 11984], align 4 +; CHECK: @switch.table.test8 = private unnamed_addr constant [5 x i32] [i32 11984, i32 1143, i32 99783, i32 8867, i32 99783], align 4 +; CHECK: @switch.table.test9 = private unnamed_addr constant [8 x i32] [i32 99783, i32 8867, i32 99783, i32 8867, i32 8867, i32 8867, i32 11984, i32 1143], align 4 +;. +define i32 @test1(i32 %a) !prof !0 { ; CHECK-LABEL: @test1( ; CHECK-NEXT: [[TMP1:%.*]] = sub i32 [[A:%.*]], 97 ; CHECK-NEXT: [[TMP2:%.*]] = call i32 @llvm.fshl.i32(i32 [[TMP1]], i32 [[TMP1]], i32 30) ; CHECK-NEXT: [[TMP3:%.*]] = icmp ult i32 [[TMP2]], 4 -; CHECK-NEXT: br i1 [[TMP3]], label [[SWITCH_LOOKUP:%.*]], label [[COMMON_RET:%.*]] +; CHECK-NEXT: br i1 [[TMP3]], label [[SWITCH_LOOKUP:%.*]], label [[COMMON_RET:%.*]], !prof [[PROF1:![0-9]+]] ; CHECK: switch.lookup: ; CHECK-NEXT: [[TMP4:%.*]] = zext nneg i32 [[TMP2]] to i64 ; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [4 x i32], ptr @switch.table.test1, i64 0, i64 [[TMP4]] @@ -24,7 +31,7 @@ define i32 @test1(i32 %a) { i32 101, label %two i32 105, label %three i32 109, label %three - ] + ], !prof !1 def: ret i32 8867 @@ -310,3 +317,12 @@ three: ret i32 99783 } +!0 = !{!"function_entry_count", i32 100} +!1 = !{!"branch_weights", i32 5, i32 7, i32 11, i32 13, i32 17} +;. +; CHECK: attributes #[[ATTR0:[0-9]+]] = { optsize } +; CHECK: attributes #[[ATTR1:[0-9]+]] = { nocallback nofree nosync nounwind speculatable willreturn memory(none) } +;. +; CHECK: [[META0:![0-9]+]] = !{!"function_entry_count", i32 100} +; CHECK: [[PROF1]] = !{!"branch_weights", i32 48, i32 5} +;. _______________________________________________ llvm-branch-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
