bool Changed = false;
for (Function::iterator I = F.begin(), E = F.end(); I != E;) {
BasicBlock *BB = I;
+ // Thread all of the branches we can over this block.
while (ProcessBlock(BB))
Changed = true;
LoopHeaders.erase(BB);
DeleteDeadBlock(BB);
Changed = true;
+ } else if (BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator())) {
+ // Can't thread an unconditional jump, but if the block is "almost
+ // empty", we can replace uses of it with uses of the successor and make
+ // this dead.
+ if (BI->isUnconditional() &&
+ BB != &BB->getParent()->getEntryBlock()) {
+ BasicBlock::iterator BBI = BB->getFirstNonPHI();
+ // Ignore dbg intrinsics.
+ while (isa<DbgInfoIntrinsic>(BBI))
+ ++BBI;
+ // If the terminator is the only non-phi instruction, try to nuke it.
+ if (BBI->isTerminator()) {
+ bool Erased = LoopHeaders.erase(BB);
+
+ if (TryToSimplifyUncondBranchFromEmptyBlock(BB))
+ Changed = true;
+ else if (Erased)
+ LoopHeaders.insert(BB);
+ }
+ }
}
}
AnotherIteration = Changed;
T0:
%A = call i1 @test8a()
br i1 %A, label %T1, label %F1
+
+; CHECK: T0:
+; CHECK-NEXT: call
+; CHECK-NEXT: br i1 %A, label %T1, label %Y
+
T1:
%B = call i1 @test8a()
br i1 %B, label %T2, label %F1
+
+; CHECK: T1:
+; CHECK-NEXT: call
+; CHECK-NEXT: br i1 %B, label %T2, label %Y
T2:
%C = call i1 @test8a()
br i1 %cond, label %T3, label %F1
+
+; CHECK: T2:
+; CHECK-NEXT: call
+; CHECK-NEXT: br i1 %cond, label %T3, label %Y
T3:
ret i32 0
F1:
-; TODO: F1 uncond branch block should be removed, T2 should jump directly to Y.
-; CHECK: F1:
-; CHECK-NEXT br label %Y
%D = phi i32 [0, %T0], [0, %T1], [1, %T2]
%E = icmp eq i32 %D, 1
%F = and i1 %E, %cond