Author: Roman Lebedev Date: 2020-12-30T00:48:12+03:00 New Revision: 39a56f7f1722b1e917a3bd5c829ec1d7effd5a11
URL: https://github.com/llvm/llvm-project/commit/39a56f7f1722b1e917a3bd5c829ec1d7effd5a11 DIFF: https://github.com/llvm/llvm-project/commit/39a56f7f1722b1e917a3bd5c829ec1d7effd5a11.diff LOG: [SimplifyCFG] Teach SimplifyTerminatorOnSelect() to preserve DomTree Added: Modified: llvm/lib/Transforms/Utils/SimplifyCFG.cpp llvm/test/Transforms/SimplifyCFG/switch-on-const-select.ll Removed: ################################################################################ diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp index d1851da69138..24572810be70 100644 --- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp @@ -3805,6 +3805,8 @@ bool SimplifyCFGOpt::SimplifyTerminatorOnSelect(Instruction *OldTerm, BasicBlock *KeepEdge1 = TrueBB; BasicBlock *KeepEdge2 = TrueBB != FalseBB ? FalseBB : nullptr; + SmallVector<DominatorTree::UpdateType, 4> Updates; + // Then remove the rest. for (BasicBlock *Succ : successors(OldTerm)) { // Make sure only to keep exactly one copy of each edge. @@ -3812,9 +3814,11 @@ bool SimplifyCFGOpt::SimplifyTerminatorOnSelect(Instruction *OldTerm, KeepEdge1 = nullptr; else if (Succ == KeepEdge2) KeepEdge2 = nullptr; - else + else { Succ->removePredecessor(OldTerm->getParent(), /*KeepOneInputPHIs=*/true); + Updates.push_back({DominatorTree::Delete, OldTerm->getParent(), Succ}); + } } IRBuilder<> Builder(OldTerm); @@ -3822,14 +3826,17 @@ bool SimplifyCFGOpt::SimplifyTerminatorOnSelect(Instruction *OldTerm, // Insert an appropriate new terminator. if (!KeepEdge1 && !KeepEdge2) { - if (TrueBB == FalseBB) + if (TrueBB == FalseBB) { // We were only looking for one successor, and it was present. // Create an unconditional branch to it. Builder.CreateBr(TrueBB); - else { + Updates.push_back({DominatorTree::Insert, OldTerm->getParent(), TrueBB}); + } else { // We found both of the successors we were looking for. // Create a conditional branch sharing the condition of the select. BranchInst *NewBI = Builder.CreateCondBr(Cond, TrueBB, FalseBB); + Updates.push_back({DominatorTree::Insert, OldTerm->getParent(), TrueBB}); + Updates.push_back({DominatorTree::Insert, OldTerm->getParent(), FalseBB}); if (TrueWeight != FalseWeight) setBranchWeights(NewBI, TrueWeight, FalseWeight); } @@ -3841,15 +3848,20 @@ bool SimplifyCFGOpt::SimplifyTerminatorOnSelect(Instruction *OldTerm, // One of the selected values was a successor, but the other wasn't. // Insert an unconditional branch to the one that was found; // the edge to the one that wasn't must be unreachable. - if (!KeepEdge1) + if (!KeepEdge1) { // Only TrueBB was found. Builder.CreateBr(TrueBB); - else + Updates.push_back({DominatorTree::Insert, OldTerm->getParent(), TrueBB}); + } else { // Only FalseBB was found. Builder.CreateBr(FalseBB); + Updates.push_back({DominatorTree::Insert, OldTerm->getParent(), FalseBB}); + } } EraseTerminatorAndDCECond(OldTerm); + if (DTU) + DTU->applyUpdatesPermissive(Updates); return true; } diff --git a/llvm/test/Transforms/SimplifyCFG/switch-on-const-select.ll b/llvm/test/Transforms/SimplifyCFG/switch-on-const-select.ll index 98c434a5a0ec..013096625b1c 100644 --- a/llvm/test/Transforms/SimplifyCFG/switch-on-const-select.ll +++ b/llvm/test/Transforms/SimplifyCFG/switch-on-const-select.ll @@ -1,5 +1,5 @@ ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py -; RUN: opt < %s -simplifycfg -S | FileCheck -enable-var-scope %s +; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck -enable-var-scope %s ; Test basic folding to a conditional branch. define i32 @foo(i64 %x, i64 %y) nounwind { _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
