From f042f1cd8d78a8b25bddf06657441092554e08db Mon Sep 17 00:00:00 2001 From: Matthias Braun Date: Wed, 26 Aug 2015 20:46:49 +0000 Subject: [PATCH] FastISel: Avoid adding a successor block twice for degenerate IR. This fixes http://llvm.org/PR24581 Differential Revision: http://reviews.llvm.org/D12350 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@246074 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/SelectionDAG/FastISel.cpp | 6 +++++- test/CodeGen/X86/fast-isel-cmp-branch.ll | 17 +++++++++++++++-- 2 files changed, 20 insertions(+), 3 deletions(-) diff --git a/lib/CodeGen/SelectionDAG/FastISel.cpp b/lib/CodeGen/SelectionDAG/FastISel.cpp index d5011d2d62d..13b097cfc60 100644 --- a/lib/CodeGen/SelectionDAG/FastISel.cpp +++ b/lib/CodeGen/SelectionDAG/FastISel.cpp @@ -1415,7 +1415,11 @@ void FastISel::finishCondBranch(const BasicBlock *BranchBB, if (FuncInfo.BPI) BranchWeight = FuncInfo.BPI->getEdgeWeight(BranchBB, TrueMBB->getBasicBlock()); - FuncInfo.MBB->addSuccessor(TrueMBB, BranchWeight); + // Add TrueMBB as successor unless it is equal to the FalseMBB: This can + // happen in degenerate IR and MachineIR forbids to have a block twice in the + // successor/predecessor lists. + if (TrueMBB != FalseMBB) + FuncInfo.MBB->addSuccessor(TrueMBB, BranchWeight); fastEmitBranch(FalseMBB, DbgLoc); } diff --git a/test/CodeGen/X86/fast-isel-cmp-branch.ll b/test/CodeGen/X86/fast-isel-cmp-branch.ll index d7b64ed3a5b..e262448468e 100644 --- a/test/CodeGen/X86/fast-isel-cmp-branch.ll +++ b/test/CodeGen/X86/fast-isel-cmp-branch.ll @@ -1,5 +1,18 @@ -; RUN: llc -O0 -mtriple=x86_64-linux -asm-verbose=false < %s | FileCheck %s -; RUN: llc -O0 -mtriple=x86_64-windows-itanium -asm-verbose=false < %s | FileCheck %s +; RUN: llc -O0 -mtriple=x86_64-linux -asm-verbose=false -verify-machineinstrs < %s | FileCheck %s +; RUN: llc -O0 -mtriple=x86_64-windows-itanium -asm-verbose=false -verify-machineinstrs < %s | FileCheck %s + +; Fast-isel mustn't add a block to the MBB successor/predecessor list twice. +; The machine verifier will catch and complain about this case. +; CHECK-LABEL: baz +; CHECK: retq +define void @baz() { +entry: + br i1 undef, label %exit, label %exit + +exit: + ret void +} + ; rdar://8337108 ; Fast-isel shouldn't try to look through the compare because it's in a -- 2.34.1