From f59e4e34528a078c2db57ee72b2814b495989124 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Fri, 1 Jun 2012 05:29:15 +0000 Subject: enhance the logic for looking through tailcalls to look through transparent casts 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 --- lib/CodeGen/Analysis.cpp | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-) (limited to 'lib/CodeGen/Analysis.cpp') diff --git a/lib/CodeGen/Analysis.cpp b/lib/CodeGen/Analysis.cpp index dd11d15975..1a8968dd28 100644 --- a/lib/CodeGen/Analysis.cpp +++ b/lib/CodeGen/Analysis.cpp @@ -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(RetVal) || !isa(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(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(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, -- cgit v1.2.3