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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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22
lib/CodeGen/Analysis.cpp
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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,

46
test/CodeGen/X86/tailcall-64.ll
View File

@ -41,3 +41,49 @@ define <4 x i32> @test_vectorbitcast() {
}
; CHECK: test_vectorbitcast:
; CHECK: jmp _testv ## TAILCALL
declare { i64, i64 } @testp()
define {i64, i64} @test_pair_trivial() {
%A = tail call { i64, i64} @testp()
ret { i64, i64} %A
}
; CHECK: test_pair_trivial:
; CHECK: jmp _testp ## TAILCALL
define {i64, i64} @test_pair_trivial_extract() {
%A = tail call { i64, i64} @testp()
%x = extractvalue { i64, i64} %A, 0
%y = extractvalue { i64, i64} %A, 1
%b = insertvalue {i64, i64} undef, i64 %x, 0
%c = insertvalue {i64, i64} %b, i64 %y, 1
ret { i64, i64} %c
}
; CHECK: test_pair_trivial_extract:
; CHECK: jmp _testp ## TAILCALL
define {i8*, i64} @test_pair_conv_extract() {
%A = tail call { i64, i64} @testp()
%x = extractvalue { i64, i64} %A, 0
%y = extractvalue { i64, i64} %A, 1
%x1 = inttoptr i64 %x to i8*
%b = insertvalue {i8*, i64} undef, i8* %x1, 0
%c = insertvalue {i8*, i64} %b, i64 %y, 1
ret { i8*, i64} %c
}
; CHECK: test_pair_conv_extract:
; CHECK: jmp _testp ## TAILCALL