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Revert 94937 and move the noreturn check to codegen.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95198 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -4205,8 +4205,13 @@ isInTailCallPosition(CallSite CS, Attributes CalleeRetAttr,
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const ReturnInst *Ret = dyn_cast<ReturnInst>(Term);
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const Function *F = ExitBB->getParent();
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// The block must end in a return statement or an unreachable.
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if (!Ret && !isa<UnreachableInst>(Term)) return false;
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// The block must end in a return statement.
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// FIXME: Disallow tailcall if the block ends in an unreachable for now.
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// The way tailcall optimization is currently implemented means it will
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// add an epilogue followed by a jump. That is not profitable. Also, if
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// the callee is a special function (e.g. longjmp on x86), it can end up
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// causing miscompilation that has not been fully understood.
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if (!Ret) return false;
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// Unless we are explicitly forcing tailcall optimization do not tailcall if
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// the called function is bitcast'ed. The analysis may not be entirely
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@ -184,11 +184,10 @@ bool TailCallElim::runOnFunction(Function &F) {
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if (!FunctionContainsEscapingAllocas)
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for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
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for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
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if (CallInst *CI = dyn_cast<CallInst>(I))
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if (!CI->doesNotReturn()) {
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CI->setTailCall();
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MadeChange = true;
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}
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if (CallInst *CI = dyn_cast<CallInst>(I)) {
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CI->setTailCall();
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MadeChange = true;
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}
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return MadeChange;
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}
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@ -1,4 +1,4 @@
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; RUN: llc < %s -march=x86 -tailcallopt | grep TAILCALL | count 5
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; RUN: llc < %s -march=x86 -tailcallopt | grep TAILCALL | count 4
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declare fastcc i32 @tailcallee(i32 %a1, i32 %a2, i32 %a3, i32 %a4)
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@ -127,3 +127,16 @@ entry:
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%1 = tail call signext i16 %0(i32 0) nounwind
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ret i16 %1
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}
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define void @t10() nounwind ssp {
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entry:
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; 32: t10:
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; 32: call
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; 64: t10:
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; 64: callq
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%0 = tail call i32 @foo4() noreturn nounwind
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unreachable
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}
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declare i32 @foo4()
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@ -1,12 +0,0 @@
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; RUN: opt < %s -tailcallelim -S | FileCheck %s
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define void @t() nounwind ssp {
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entry:
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; CHECK: entry:
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; CHECK: %0 = call i32 @foo()
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; CHECK: ret void
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%0 = call i32 @foo() nounwind noreturn
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ret void
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}
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declare i32 @foo()
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