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Selecting the address from a very long chain of GEPs can blow the stack.

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The recursive nature of the address selection code can cause the stack to
explode if there is a long chain of GEPs. Convert the recursive bit into a
iterative method to avoid this.

<rdar://problem/12445434>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191252 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bill Wendling 2013-09-24 00:13:08 +00:00
parent 7533165612
commit cb3023ae51
2 changed files with 25619 additions and 3 deletions
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15
lib/Target/X86/X86FastISel.cpp
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@ -347,6 +347,7 @@ bool X86FastISel::X86FastEmitExtend(ISD::NodeType Opc, EVT DstVT,
/// X86SelectAddress - Attempt to fill in an address from the given value.
///
bool X86FastISel::X86SelectAddress(const Value *V, X86AddressMode &AM) {
redo_gep:
const User *U = NULL;
unsigned Opcode = Instruction::UserOp1;
if (const Instruction *I = dyn_cast<Instruction>(V)) {
@ -469,16 +470,24 @@ bool X86FastISel::X86SelectAddress(const Value *V, X86AddressMode &AM) {
goto unsupported_gep;
}
}
// Check for displacement overflow.
if (!isInt<32>(Disp))
break;
// Ok, the GEP indices were covered by constant-offset and scaled-index
// addressing. Update the address state and move on to examining the base.
AM.IndexReg = IndexReg;
AM.Scale = Scale;
AM.Disp = (uint32_t)Disp;
if (X86SelectAddress(U->getOperand(0), AM))
if (const GetElementPtrInst *GEP =
dyn_cast<GetElementPtrInst>(U->getOperand(0))) {
// Ok, the GEP indices were covered by constant-offset and scaled-index
// addressing. Update the address state and move on to examining the base.
V = GEP;
goto redo_gep;
} else if (X86SelectAddress(U->getOperand(0), AM)) {
return true;
}
// If we couldn't merge the gep value into this addr mode, revert back to
// our address and just match the value instead of completely failing.

25607
test/CodeGen/X86/large-gep-chain.ll Normal file
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