/// normal form.
bool isLoopSimplifyForm() const;
+ /// isSafeToClone - Return true if the loop body is safe to clone in practice.
+ bool isSafeToClone() const;
+
/// hasDedicatedExits - Return true if no exit block for the loop
/// has a predecessor that is outside the loop.
bool hasDedicatedExits() const;
return getLoopPreheader() && getLoopLatch() && hasDedicatedExits();
}
+/// isSafeToClone - Return true if the loop body is safe to clone in practice.
+/// Routines that reform the loop CFG and split edges often fail on indirectbr.
+bool Loop::isSafeToClone() const {
+ // Return false if any loop blocks contain indirectbrs.
+ for (Loop::block_iterator I = block_begin(), E = block_end(); I != E; ++I) {
+ if (isa<IndirectBrInst>((*I)->getTerminator()))
+ return false;
+ }
+ return true;
+}
+
/// hasDedicatedExits - Return true if no exit block for the loop
/// has a predecessor that is outside the loop.
bool Loop::hasDedicatedExits() const {
loopPreheader = currentLoop->getLoopPreheader();
}
- /// HasIndirectBrsInPreds - Returns true if there are predecessors, that are
- /// terminated with indirect branch instruction.
- bool HasIndirectBrsInPreds(const SmallVectorImpl<BasicBlock *> &ExitBlocks);
-
/// Split all of the edges from inside the loop to their exit blocks.
/// Update the appropriate Phi nodes as we do so.
void SplitExitEdges(Loop *L, const SmallVector<BasicBlock *, 8> &ExitBlocks);
bool UnswitchIfProfitable(Value *LoopCond, Constant *Val);
void UnswitchTrivialCondition(Loop *L, Value *Cond, Constant *Val,
BasicBlock *ExitBlock);
- bool UnswitchNontrivialCondition(Value *LIC, Constant *OnVal, Loop *L);
+ void UnswitchNontrivialCondition(Value *LIC, Constant *OnVal, Loop *L);
void RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC,
Constant *Val, bool isEqual);
if (!loopPreheader)
return false;
+ // Loops with indirectbr cannot be cloned.
+ if (!currentLoop->isSafeToClone())
+ return false;
+
+ // Without dedicated exits, splitting the exit edge may fail.
+ if (!currentLoop->hasDedicatedExits())
+ return false;
+
LLVMContext &Context = loopHeader->getContext();
// Probably we reach the quota of branches for this loop. If so
if (OptimizeForSize || F->hasFnAttr(Attribute::OptimizeForSize))
return false;
- return UnswitchNontrivialCondition(LoopCond, Val, currentLoop);
+ UnswitchNontrivialCondition(LoopCond, Val, currentLoop);
+ return true;
}
/// CloneLoop - Recursively clone the specified loop and all of its children,
++NumTrivial;
}
-/// HasIndirectBrsInPreds - Returns true if there are predecessors, that are
-/// terminated with indirect branch instruction.
-bool LoopUnswitch::HasIndirectBrsInPreds(
- const SmallVectorImpl<BasicBlock *> &ExitBlocks){
-
- for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) {
- const BasicBlock *ExitBlock = ExitBlocks[i];
- for (const_pred_iterator p = pred_begin(ExitBlock), e = pred_end(ExitBlock);
- p != e; ++p) {
- // Cannot split an edge from an IndirectBrInst
- if (isa<IndirectBrInst>((*p)->getTerminator()))
- return true;
-
- }
- }
- return false;
-}
-
/// SplitExitEdges - Split all of the edges from inside the loop to their exit
/// blocks. Update the appropriate Phi nodes as we do so.
void LoopUnswitch::SplitExitEdges(Loop *L,
/// UnswitchNontrivialCondition - We determined that the loop is profitable
/// to unswitch when LIC equal Val. Split it into loop versions and test the
/// condition outside of either loop. Return the loops created as Out1/Out2.
-bool LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val,
+void LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val,
Loop *L) {
Function *F = loopHeader->getParent();
DEBUG(dbgs() << "loop-unswitch: Unswitching loop %"
SmallVector<BasicBlock*, 8> ExitBlocks;
L->getUniqueExitBlocks(ExitBlocks);
- if (HasIndirectBrsInPreds(ExitBlocks))
- return false;
// Split all of the edges from inside the loop to their exit blocks. Update
// the appropriate Phi nodes as we do so.
if (!LoopProcessWorklist.empty() && LoopProcessWorklist.back() == NewLoop &&
LICHandle && !isa<Constant>(LICHandle))
RewriteLoopBodyWithConditionConstant(NewLoop, LICHandle, Val, true);
-
- return true;
}
/// RemoveFromWorklist - Remove all instances of I from the worklist vector
return false;
}
+ // Loops with indirectbr cannot be cloned.
+ if (!L->isSafeToClone()) {
+ DEBUG(dbgs() << " Can't unroll; Loop body cannot be cloned.\n");
+ return false;
+ }
+
BasicBlock *Header = L->getHeader();
BranchInst *BI = dyn_cast<BranchInst>(LatchBlock->getTerminator());
--- /dev/null
+; RUN: opt < %s -S -loop-unroll -simplifycfg | FileCheck %s
+; PR12513: Loop unrolling breaks with indirect branches.
+; If loop unrolling attempts to transform this loop, it replaces the
+; indirectbr successors. SimplifyCFG then considers them to be unreachable.
+declare void @subtract() nounwind uwtable
+
+; CHECK-NOT: unreachable
+define i32 @main(i32 %argc, i8** nocapture %argv) nounwind uwtable {
+entry:
+ %vals19 = alloca [5 x i32], align 16
+ %x20 = alloca i32, align 4
+ store i32 135, i32* %x20, align 4
+ br label %for.body
+
+for.body: ; preds = ; %call2_termjoin, %call3_termjoin
+ %indvars.iv = phi i64 [ 0, %entry ], [ %joinphi15.in.in, %call2_termjoin ]
+ %a6 = call coldcc i8* @funca(i8* blockaddress(@main, %for.body_code), i8*
+blockaddress(@main, %for.body_codeprime)) nounwind
+ indirectbr i8* %a6, [label %for.body_code, label %for.body_codeprime]
+
+for.body_code: ; preds = %for.body
+ call void @subtract()
+ br label %call2_termjoin
+
+call2_termjoin: ; preds = %for.body_codeprime, %for.body_code
+ %joinphi15.in.in = add i64 %indvars.iv, 1
+ %exitcond = icmp eq i64 %joinphi15.in.in, 5
+ br i1 %exitcond, label %for.end, label %for.body
+
+for.end: ; preds = %call2_termjoin
+ ret i32 0
+
+for.body_codeprime: ; preds = %for.body
+ call void @subtract_v2(i64 %indvars.iv)
+ br label %call2_termjoin
+}
+
+declare coldcc i8* @funca(i8*, i8*) readonly
+
+declare void @subtract_v2(i64) nounwind uwtable
-; RUN: opt -loop-unswitch -disable-output -stats -info-output-file - < %s | FileCheck --check-prefix=STATS %s
-; RUN: opt -S -loop-unswitch -verify-loop-info -verify-dom-info %s | FileCheck %s
-
-; STATS: 1 loop-unswitch - Total number of instructions analyzed
+; RUN: opt < %s -S -loop-unswitch -verify-loop-info -verify-dom-info | FileCheck %s
+; PR12343: -loop-unswitch crash on indirect branch
; CHECK: %0 = icmp eq i64 undef, 0
; CHECK-NEXT: br i1 %0, label %"5", label %"4"
; CHECK: "5": ; preds = %entry
-; CHECK-NEXT: br label %"5.split"
-
-; CHECK: "5.split": ; preds = %"5"
; CHECK-NEXT: br label %"16"
-; CHECK: "16": ; preds = %"22", %"5.split"
+; CHECK: "16": ; preds = %"22", %"5"
; CHECK-NEXT: indirectbr i8* undef, [label %"22", label %"33"]
; CHECK: "22": ; preds = %"16"