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we don't have to make an explicit copy of a byval argument when

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inlining a function if we know that the function does not write
to *any* memory.  This implements test/Transforms/Inline/byval2.ll


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@45912 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2008-01-12 18:54:29 +00:00
parent 7723ab3a51
commit 92938b7145
2 changed files with 34 additions and 4 deletions
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10
lib/Transforms/Utils/InlineFunction.cpp
View File

@ -241,10 +241,12 @@ bool llvm::InlineFunction(CallSite CS, CallGraph *CG, const TargetData *TD) {
Value *ActualArg = *AI;
// When byval arguments actually inlined, we need to make the copy implied
// by them actually explicit.
// TODO: If we know that the callee never modifies the struct, we can
// remove this copy.
if (CalledFunc->paramHasAttr(ArgNo+1, ParamAttr::ByVal)) {
// by them explicit. However, we don't do this if the callee is readonly
// or readnone, because the copy would be unneeded: the callee doesn't
// modify the struct.
if (CalledFunc->paramHasAttr(ArgNo+1, ParamAttr::ByVal) &&
!CalledFunc->paramHasAttr(0, ParamAttr::ReadOnly) &&
!CalledFunc->paramHasAttr(0, ParamAttr::ReadNone)) {
const Type *AggTy = cast<PointerType>(I->getType())->getElementType();
const Type *VoidPtrTy = PointerType::getUnqual(Type::Int8Ty);

28
test/Transforms/Inline/byval2.ll Normal file
View File

@ -0,0 +1,28 @@
; RUN: llvm-as < %s | opt -inline | llvm-dis | not grep {llvm.memcpy}
; Inlining a byval struct should NOT cause an explicit copy
; into an alloca if the function is readonly
%struct.ss = type { i32, i64 }
@.str = internal constant [10 x i8] c"%d, %lld\0A\00" ; <[10 x i8]*> [#uses=1]
define internal i32 @f(%struct.ss* byval %b) nounwind readonly {
entry:
%tmp = getelementptr %struct.ss* %b, i32 0, i32 0 ; <i32*> [#uses=2]
%tmp1 = load i32* %tmp, align 4 ; <i32> [#uses=1]
%tmp2 = add i32 %tmp1, 1 ; <i32> [#uses=1]
ret i32 %tmp2
}
declare i32 @printf(i8*, ...) nounwind
define i32 @main() nounwind {
entry:
%S = alloca %struct.ss ; <%struct.ss*> [#uses=4]
%tmp1 = getelementptr %struct.ss* %S, i32 0, i32 0 ; <i32*> [#uses=1]
store i32 1, i32* %tmp1, align 8
%tmp4 = getelementptr %struct.ss* %S, i32 0, i32 1 ; <i64*> [#uses=1]
store i64 2, i64* %tmp4, align 4
%X = call i32 @f( %struct.ss* byval %S ) nounwind
ret i32 %X
}