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Teach alias analysis about readnone/readonly functions.

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Based on a patch by Török Edwin.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@44279 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Duncan Sands 2007-11-22 21:43:27 +00:00
parent 5ef7be79e0
commit 920653d41e
2 changed files with 39 additions and 0 deletions
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6
lib/Analysis/BasicAliasAnalysis.cpp
View File

@ -952,6 +952,12 @@ BasicAliasAnalysis::getModRefBehavior(Function *F, CallSite CS,
if (Ptr != OnlyReadsMemoryTable->end() && strcmp(*Ptr, NamePtr) == 0)
return OnlyReadsMemory;
const ParamAttrsList *Attrs = F->getFunctionType()->getParamAttrs();
if (Attrs && Attrs->paramHasAttr(0, ParamAttr::ReadNone))
return DoesNotAccessMemory;
if (Attrs && Attrs->paramHasAttr(0, ParamAttr::ReadOnly))
return OnlyReadsMemory;
return UnknownModRefBehavior;
}

33
test/Analysis/BasicAA/pure-const-dce.ll Normal file
View File

@ -0,0 +1,33 @@
; RUN: llvm-as < %s | opt -basicaa -gvn | llvm-dis | grep TestConst | count 2
; RUN: llvm-as < %s | opt -basicaa -gvn | llvm-dis | grep TestPure | not count 2
; RUN: llvm-as < %s | opt -basicaa -gvn | llvm-dis | grep TestNone | count 4
@g = global i32 0 ; <i32*> [#uses=1]
define i32 @test() {
entry:
%tmp0 = call i32 @TestConst( i32 5 ) readnone ; <i32> [#uses=1]
%tmp1 = call i32 @TestPure( i32 6 ) readonly ; <i32> [#uses=1]
%tmp2 = call i32 @TestNone( i32 7 ) ; <i32> [#uses=1]
store i32 1, i32* @g
%tmp3 = call i32 @TestConst( i32 5 ) readnone ; <i32> [#uses=1]
%tmp4 = call i32 @TestConst( i32 5 ) readnone ; <i32> [#uses=1]
%tmp5 = call i32 @TestPure( i32 6 ) readonly ; <i32> [#uses=1]
%tmp6 = call i32 @TestPure( i32 6 ) readonly ; <i32> [#uses=1]
%tmp7 = call i32 @TestNone( i32 7 ) ; <i32> [#uses=1]
%tmp8 = call i32 @TestNone( i32 7 ) ; <i32> [#uses=1]
%sum0 = add i32 %tmp0, %tmp1 ; <i32> [#uses=1]
%sum1 = add i32 %sum0, %tmp2 ; <i32> [#uses=1]
%sum2 = add i32 %sum1, %tmp3 ; <i32> [#uses=1]
%sum3 = add i32 %sum2, %tmp4 ; <i32> [#uses=1]
%sum4 = add i32 %sum3, %tmp5 ; <i32> [#uses=1]
%sum5 = add i32 %sum4, %tmp6 ; <i32> [#uses=1]
%sum6 = add i32 %sum5, %tmp7 ; <i32> [#uses=1]
%sum7 = add i32 %sum6, %tmp8 ; <i32> [#uses=1]
ret i32 %sum7
}
declare i32 @TestConst(i32) readnone
declare i32 @TestPure(i32) readonly
declare i32 @TestNone(i32)