[llvm] 6bb2cea - Fix the compilation assertion due to unreachable BB pruning not deleting the associated BB from the jump tables

[Victor Huang via llvm-commits]

Author: Victor Huang
Date: 2020-11-16T10:35:31-06:00
New Revision: 6bb2ceac90875a54d5c28a2441c29b6cc6029c36

URL: https://github.com/llvm/llvm-project/commit/6bb2ceac90875a54d5c28a2441c29b6cc6029c36
DIFF: https://github.com/llvm/llvm-project/commit/6bb2ceac90875a54d5c28a2441c29b6cc6029c36.diff

LOG: Fix the compilation assertion due to unreachable BB pruning not deleting the associated BB from the jump tables

This patch is added to remove the unreachable MBBs reference in the jump table.

Differential Revisien: https://reviews.llvm.org/D90498
Reviewed by: amyk, bsaleil

Added: 
    llvm/test/CodeGen/PowerPC/unreachable-mbb-jtreference-elimination.ll

Modified: 
    llvm/include/llvm/CodeGen/MachineJumpTableInfo.h
    llvm/lib/CodeGen/MachineFunction.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/CodeGen/MachineJumpTableInfo.h b/llvm/include/llvm/CodeGen/MachineJumpTableInfo.h
index 11781145b378..1d082bd03e5b 100644
--- a/llvm/include/llvm/CodeGen/MachineJumpTableInfo.h
+++ b/llvm/include/llvm/CodeGen/MachineJumpTableInfo.h
@@ -106,6 +106,9 @@ class MachineJumpTableInfo {
     JumpTables[Idx].MBBs.clear();
   }
 
+  /// RemoveMBBFromJumpTables - If MBB is present in any jump tables, remove it.
+  bool RemoveMBBFromJumpTables(MachineBasicBlock *MBB);
+
   /// ReplaceMBBInJumpTables - If Old is the target of any jump tables, update
   /// the jump tables to branch to New instead.
   bool ReplaceMBBInJumpTables(MachineBasicBlock *Old, MachineBasicBlock *New);

diff  --git a/llvm/lib/CodeGen/MachineFunction.cpp b/llvm/lib/CodeGen/MachineFunction.cpp
index a7edc274dd23..2a9a88af3ad6 100644
--- a/llvm/lib/CodeGen/MachineFunction.cpp
+++ b/llvm/lib/CodeGen/MachineFunction.cpp
@@ -420,6 +420,9 @@ MachineFunction::CreateMachineBasicBlock(const BasicBlock *bb) {
 void
 MachineFunction::DeleteMachineBasicBlock(MachineBasicBlock *MBB) {
   assert(MBB->getParent() == this && "MBB parent mismatch!");
+  // Clean up any references to MBB in jump tables before deleting it.
+  if (JumpTableInfo)
+    JumpTableInfo->RemoveMBBFromJumpTables(MBB);
   MBB->~MachineBasicBlock();
   BasicBlockRecycler.Deallocate(Allocator, MBB);
 }
@@ -1047,6 +1050,17 @@ bool MachineJumpTableInfo::ReplaceMBBInJumpTables(MachineBasicBlock *Old,
   return MadeChange;
 }
 
+/// If MBB is present in any jump tables, remove it.
+bool MachineJumpTableInfo::RemoveMBBFromJumpTables(MachineBasicBlock *MBB) {
+  bool MadeChange = false;
+  for (MachineJumpTableEntry &JTE : JumpTables) {
+    auto removeBeginItr = std::remove(JTE.MBBs.begin(), JTE.MBBs.end(), MBB);
+    MadeChange |= (removeBeginItr != JTE.MBBs.end());
+    JTE.MBBs.erase(removeBeginItr, JTE.MBBs.end());
+  }
+  return MadeChange;
+}
+
 /// If Old is a target of the jump tables, update the jump table to branch to
 /// New instead.
 bool MachineJumpTableInfo::ReplaceMBBInJumpTable(unsigned Idx,

diff  --git a/llvm/test/CodeGen/PowerPC/unreachable-mbb-jtreference-elimination.ll b/llvm/test/CodeGen/PowerPC/unreachable-mbb-jtreference-elimination.ll
new file mode 100644
index 000000000000..3ed05594ae12
--- /dev/null
+++ b/llvm/test/CodeGen/PowerPC/unreachable-mbb-jtreference-elimination.ll
@@ -0,0 +1,76 @@
+; RUN: llc -O2 --verify-machineinstrs -stop-before=livevars \
+; RUN:   -mtriple=powerpc64le-unknown-unknown < %s | FileCheck %s
+
+define dso_local void @foo() #0 {
+; CHECK-LABEL: fixedStack:
+; CHECK-NEXT:  stack: []
+; CHECK-NEXT:  callSites: []
+; CHECK-NEXT:  debugValueSubstitutions: []
+; CHECK-NEXT:  constants: []
+; CHECK-NEXT:  machineFunctionInfo: {}
+; CHECK-NEXT:  jumpTable:
+; CHECK-NEXT:    kind:            label-
diff erence32
+; CHECK-NEXT:    entries:
+; CHECK-NEXT:      - id:              0
+; CHECK-NEXT:        blocks:          [  ]
+; CHECK-NEXT:  body:             |
+; CHECK-NEXT:    bb.0.entry:
+; CHECK-NEXT:      successors: %bb.1(0x80000000)
+; CHECK:           B %bb.1
+; CHECK:         bb.1.next11:
+; CHECK-NEXT:      successors: %bb.2(0x80000000)
+; CHECK:           B %bb.2
+; CHECK:         bb.2.if.end139:
+entry:
+  br label %next11
+next11:                                           ; preds = %entry
+  br i1 false, label %if.then12, label %if.end139
+if.then12:                                        ; preds = %next11
+  br label %for.cond14
+for.cond14:                                       ; preds = %if.then12
+  switch i32 undef, label %sw.epilog [
+    i32 1, label %sw.bb
+    i32 4, label %sw.bb
+    i32 6, label %sw.bb
+    i32 7, label %sw.bb
+    i32 9, label %sw.bb
+    i32 12, label %sw.bb
+    i32 15, label %sw.bb
+    i32 16, label %sw.bb
+    i32 24, label %sw.bb
+    i32 0, label %sw.bb26
+    i32 2, label %sw.bb26
+    i32 3, label %sw.bb26
+    i32 8, label %sw.bb26
+    i32 10, label %sw.bb26
+    i32 11, label %sw.bb26
+    i32 13, label %sw.bb26
+    i32 17, label %sw.bb26
+    i32 18, label %sw.bb26
+    i32 20, label %sw.bb26
+    i32 19, label %sw.bb26
+    i32 21, label %sw.bb26
+    i32 22, label %sw.bb26
+    i32 23, label %sw.bb26
+    i32 25, label %sw.bb26
+    i32 27, label %sw.bb26
+    i32 28, label %sw.bb26
+    i32 26, label %sw.bb37
+    i32 29, label %sw.bb37
+    i32 30, label %sw.bb53
+  ]
+
+sw.bb:                                            ; preds = %for.cond14
+  unreachable
+sw.bb26:                                          ; preds = %for.cond14
+  unreachable
+sw.bb37:                                          ; preds = %for.cond14
+  unreachable
+sw.bb53:                                          ; preds = %for.cond14
+  unreachable
+sw.epilog:                                        ; preds = %for.cond14
+  unreachable
+if.end139:                                        ; preds = %next11
+  unreachable
+}
+attributes #0 = { noinline optnone }