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Do early taildup of ret in CodeGenPrepare for potential tail calls that have a

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void return type. This fixes PR9487.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128197 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Cameron Zwarich 2011-03-24 04:52:10 +00:00
parent 4bae588c75
commit 6e8ffc1c4d
2 changed files with 74 additions and 17 deletions
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36
lib/Transforms/Scalar/CodeGenPrepare.cpp
View File

@ -594,15 +594,12 @@ bool CodeGenPrepare::DupRetToEnableTailCallOpts(ReturnInst *RI) {
return false;
Value *V = RI->getReturnValue();
if (!V)
return false;
PHINode *PN = dyn_cast<PHINode>(V);
if (!PN)
PHINode *PN = V ? dyn_cast<PHINode>(V) : NULL;
if (V && !PN)
return false;
BasicBlock *BB = RI->getParent();
if (PN->getParent() != BB)
if (PN && PN->getParent() != BB)
return false;
// It's not safe to eliminate the sign / zero extension of the return value.
@ -612,15 +609,22 @@ bool CodeGenPrepare::DupRetToEnableTailCallOpts(ReturnInst *RI) {
if ((CallerRetAttr & Attribute::ZExt) || (CallerRetAttr & Attribute::SExt))
return false;
// Make sure there are no instructions between PHI and return.
BasicBlock::iterator BI = PN;
// Make sure there are no instructions between the PHI and return, or that the
// return is the first instruction in the block.
if (PN) {
BasicBlock::iterator BI = BB->begin();
do { ++BI; } while (isa<DbgInfoIntrinsic>(BI));
if (&*BI != RI)
return false;
} else {
if (&*BB->begin() != RI)
return false;
}
/// Only dup the ReturnInst if the CallInst is likely to be emitted as a tail
/// call.
SmallVector<CallInst*, 4> TailCalls;
if (PN) {
for (unsigned I = 0, E = PN->getNumIncomingValues(); I != E; ++I) {
CallInst *CI = dyn_cast<CallInst>(PN->getIncomingValue(I));
// Make sure the phi value is indeed produced by the tail call.
@ -628,6 +632,22 @@ bool CodeGenPrepare::DupRetToEnableTailCallOpts(ReturnInst *RI) {
TLI->mayBeEmittedAsTailCall(CI))
TailCalls.push_back(CI);
}
} else {
SmallPtrSet<BasicBlock*, 4> VisitedBBs;
for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE; ++PI) {
if (!VisitedBBs.insert(*PI))
continue;
BasicBlock::InstListType &InstList = (*PI)->getInstList();
BasicBlock::InstListType::reverse_iterator RI = InstList.rbegin();
BasicBlock::InstListType::reverse_iterator RE = InstList.rend();
if (++RI == RE)
continue;
CallInst *CI = dyn_cast<CallInst>(&*RI);
if (CI && CI->getType()->isVoidTy() && TLI->mayBeEmittedAsTailCall(CI))
TailCalls.push_back(CI);
}
}
bool Changed = false;
for (unsigned i = 0, e = TailCalls.size(); i != e; ++i) {

37
test/CodeGen/X86/tailcall-returndup-void.ll Normal file
View File

@ -0,0 +1,37 @@
; RUN: llc < %s -march=x86-64 | FileCheck %s
; CHECK: rBM_info
; CHECK-NOT: ret
@sES_closure = external global [0 x i64]
declare cc10 void @sEH_info(i64* noalias nocapture, i64* noalias nocapture, i64* noalias nocapture, i64, i64, i64) align 8
define cc10 void @rBM_info(i64* noalias nocapture %Base_Arg, i64* noalias nocapture %Sp_Arg, i64* noalias nocapture %Hp_Arg, i64 %R1_Arg, i64 %R2_Arg, i64 %R3_Arg) nounwind align 8 {
c263:
%ln265 = getelementptr inbounds i64* %Sp_Arg, i64 -2
%ln266 = ptrtoint i64* %ln265 to i64
%ln268 = icmp ult i64 %ln266, %R3_Arg
br i1 %ln268, label %c26a, label %n26p
n26p: ; preds = %c263
br i1 icmp ne (i64 and (i64 ptrtoint ([0 x i64]* @sES_closure to i64), i64 7), i64 0), label %c1ZP.i, label %n1ZQ.i
n1ZQ.i: ; preds = %n26p
%ln1ZT.i = load i64* getelementptr inbounds ([0 x i64]* @sES_closure, i64 0, i64 0), align 8
%ln1ZU.i = inttoptr i64 %ln1ZT.i to void (i64*, i64*, i64*, i64, i64, i64)*
tail call cc10 void %ln1ZU.i(i64* %Base_Arg, i64* %Sp_Arg, i64* %Hp_Arg, i64 ptrtoint ([0 x i64]* @sES_closure to i64), i64 ptrtoint ([0 x i64]* @sES_closure to i64), i64 %R3_Arg) nounwind
br label %rBL_info.exit
c1ZP.i: ; preds = %n26p
tail call cc10 void @sEH_info(i64* %Base_Arg, i64* %Sp_Arg, i64* %Hp_Arg, i64 ptrtoint ([0 x i64]* @sES_closure to i64), i64 ptrtoint ([0 x i64]* @sES_closure to i64), i64 %R3_Arg) nounwind
br label %rBL_info.exit
rBL_info.exit: ; preds = %c1ZP.i, %n1ZQ.i
ret void
c26a: ; preds = %c263
%ln27h = getelementptr inbounds i64* %Base_Arg, i64 -2
%ln27j = load i64* %ln27h, align 8
%ln27k = inttoptr i64 %ln27j to void (i64*, i64*, i64*, i64, i64, i64)*
tail call cc10 void %ln27k(i64* %Base_Arg, i64* %Sp_Arg, i64* %Hp_Arg, i64 %R1_Arg, i64 %R2_Arg, i64 %R3_Arg) nounwind
ret void
}