Teach alias analysis about readnone/readonly functions.
Based on a patch by Török Edwin.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@44279 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp
index cbbc530..c6e34da 100644
--- a/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/lib/Analysis/BasicAliasAnalysis.cpp
@@ -952,6 +952,12 @@
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;
}
diff --git a/test/Analysis/BasicAA/pure-const-dce.ll b/test/Analysis/BasicAA/pure-const-dce.ll
new file mode 100644
index 0000000..6abc7da
--- /dev/null
+++ b/test/Analysis/BasicAA/pure-const-dce.ll
@@ -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)