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enhance the logic for looking through tailcalls to look through transparent casts

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in multiple-return value scenarios, like what happens on X86-64 when returning
small structs.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157800 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
2012-06-01 05:29:15 +00:00
parent d9567223e8
commit f59e4e3452
2 changed files with 67 additions and 1 deletions
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lib/CodeGen/Analysis.cpp
+21 -1
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@@ -322,7 +322,27 @@ bool llvm::isInTailCallPosition(ImmutableCallSite CS, Attributes CalleeRetAttr,
return false;
// Otherwise, make sure the unmodified return value of I is the return value.
return getNoopInput(Ret->getOperand(0), TLI) == I;
// We handle two cases: multiple return values + scalars.
Value *RetVal = Ret->getOperand(0);
if (!isa<InsertValueInst>(RetVal) || !isa<StructType>(RetVal->getType()))
// Handle scalars first.
return getNoopInput(Ret->getOperand(0), TLI) == I;
// If this is an aggregate return, look through the insert/extract values and
// see if each is transparent.
for (unsigned i = 0, e =cast<StructType>(RetVal->getType())->getNumElements();
i != e; ++i) {
const Value *InScalar = getNoopInput(FindInsertedValue(RetVal, i), TLI);
// If the scalar value being inserted is an extractvalue of the right index
// from the call, then everything is good.
const ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(InScalar);
if (EVI == 0 || EVI->getOperand(0) != I || EVI->getNumIndices() != 1 ||
EVI->getIndices()[0] != i)
return false;
}
return true;
}
bool llvm::isInTailCallPosition(SelectionDAG &DAG, SDNode *Node,