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Reenable tail duplication of bb with just an unconditional jump, but

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don't remove blocks that have their address taken.

llvm-svn: 133659
This commit is contained in:
Rafael Espindola 2011-06-22 22:31:57 +00:00
parent 72c8521466
commit e57d6977be
2 changed files with 32 additions and 4 deletions
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8
lib/CodeGen/TailDuplication.cpp
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@ -207,7 +207,7 @@ bool TailDuplicatePass::TailDuplicateBlocks(MachineFunction &MF) {
// TailBB's immediate successors are now successors of those predecessors
// which duplicated TailBB. Add the predecessors as sources to the PHI
// instructions.
bool isDead = MBB->pred_empty();
bool isDead = MBB->pred_empty() && !MBB->hasAddressTaken();
if (PreRegAlloc)
UpdateSuccessorsPHIs(MBB, isDead, TDBBs, Succs);
@ -568,9 +568,9 @@ bool
TailDuplicatePass::isSimpleBB(MachineBasicBlock *TailBB) {
if (TailBB->succ_size() != 1)
return false;
MachineBasicBlock::iterator I = TailBB->getFirstNonPHI();
MachineBasicBlock::iterator I = TailBB->begin();
MachineBasicBlock::iterator E = TailBB->end();
while (I->isDebugValue() && I != E)
while (I != E && I->isDebugValue())
++I;
if (I == E)
return true;
@ -712,7 +712,7 @@ TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF,
DenseSet<unsigned> UsedByPhi;
getRegsUsedByPHIs(*TailBB, &UsedByPhi);
if (0 && isSimpleBB(TailBB))
if (isSimpleBB(TailBB))
return duplicateSimpleBB(TailBB, TDBBs, UsedByPhi, Copies);
// Iterate through all the unique predecessors and tail-duplicate this

28
test/CodeGen/X86/tail-dup-addr.ll Normal file
View File

@ -0,0 +1,28 @@
; RUN: llc < %s -mtriple=x86_64-apple-darwin | FileCheck %s
; Test that we don't drop a block that has its address taken.
; CHECK: Ltmp1: ## Block address taken
; CHECK: Ltmp2: ## Block address taken
@a = common global i32 0, align 4
@p = common global i8* null, align 8
define void @foo() noreturn nounwind uwtable ssp {
entry:
%tmp = load i32* @a, align 4
%foo = icmp eq i32 0, %tmp
br i1 %foo, label %sw.bb, label %sw.default
sw.bb: ; preds = %entry
store i8* blockaddress(@foo, %sw.bb1), i8** @p, align 8
br label %sw.bb1
sw.bb1: ; preds = %sw.default, %sw.bb, %entry
store i8* blockaddress(@foo, %sw.default), i8** @p, align 8
br label %sw.default
sw.default: ; preds = %sw.bb1, %entry
store i8* blockaddress(@foo, %sw.bb1), i8** @p, align 8
br label %sw.bb1
}