parent
9dc8bd327f
commit
71fc19e991
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@ -4,7 +4,7 @@
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@y = common global [256 x i32] zeroinitializer, align 4
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;; for (i = 0; i < 256; i++)
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;; x[i] = x[256 - i] + y[i]
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;; x[i] = x[255 - i] + y[i]
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define void @f1(...) nounwind {
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entry:
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@ -12,8 +12,8 @@ entry:
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for.body:
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%i = phi i64 [ 0, %entry ], [ %i.next, %for.body ]
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%i.256 = sub i64 256, %i
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%y.ld.addr = getelementptr [256 x i32]* @y, i64 0, i64 %i.256
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%i.255 = sub i64 255, %i
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%y.ld.addr = getelementptr [256 x i32]* @y, i64 0, i64 %i.255
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%x.ld.addr = getelementptr [256 x i32]* @x, i64 0, i64 %i
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%x.st.addr = getelementptr [256 x i32]* @x, i64 0, i64 %i
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%x = load i32* %x.ld.addr ; 0
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@ -30,9 +30,8 @@ for.end:
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ret void
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}
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;; // the same example, using more realistic IR
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;; for (i = 0; i < 256; i++)
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;; x[i] = x[256 - i] + y[i]
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;; for (i = 0; i < 100; i++)
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;; x[i] = x[255 - i] + y[i]
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define void @f2(...) nounwind {
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entry:
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@ -40,9 +39,9 @@ entry:
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for.body:
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%i = phi i64 [ 0, %entry ], [ %i.next, %for.body ]
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%i.256 = sub i64 0, %i
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%i.255 = sub i64 0, %i
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%y.ld.addr = getelementptr [256 x i32]* @y, i64 0, i64 %i
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%x.ld.addr = getelementptr [256 x i32]* @x, i64 1, i64 %i.256
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%x.ld.addr = getelementptr [256 x i32]* @x, i64 1, i64 %i.255
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%x.st.addr = getelementptr [256 x i32]* @x, i64 0, i64 %i
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%x = load i32* %x.ld.addr ; 0
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%y = load i32* %y.ld.addr ; 1
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@ -51,14 +50,16 @@ for.body:
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; CHECK: 0,2: dep
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; CHECK: 1,2: ind
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%i.next = add i64 %i, 1
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%exitcond = icmp eq i64 %i.next, 256
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%exitcond = icmp eq i64 %i.next, 100
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br i1 %exitcond, label %for.end, label %for.body
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for.end:
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ret void
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}
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;; for (i = 0; i < 100; i++)
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;; // the first iteration (i=0) leads to an out-of-bounds access of x. as the
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;; // result of this access is undefined, _any_ dependence result is safe.
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;; for (i = 0; i < 256; i++)
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;; x[i] = x[256 - i] + y[i]
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define void @f3(...) nounwind {
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@ -76,9 +77,40 @@ for.body:
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%r = add i32 %y, %x
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store i32 %r, i32* %x.st.addr ; 2
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; CHECK: 0,2: dep
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; CHECK: 1,2: ind
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; CHECK: 1,2:
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%i.next = add i64 %i, 1
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%exitcond = icmp eq i64 %i.next, 100
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%exitcond = icmp eq i64 %i.next, 256
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br i1 %exitcond, label %for.end, label %for.body
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for.end:
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ret void
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}
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;; // slightly contrived but valid IR for the following loop, where all
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;; // accesses in all iterations are within bounds. while this example's first
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;; // (ZIV-)subscript is (0, 1), accesses are dependent.
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;; for (i = 1; i < 256; i++)
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;; x[i] = x[256 - i] + y[i]
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define void @f4(...) nounwind {
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entry:
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br label %for.body
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for.body:
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%i = phi i64 [ 0, %entry ], [ %i.next, %for.body ]
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%i.1 = add i64 1, %i
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%i.256 = sub i64 -1, %i
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%y.ld.addr = getelementptr [256 x i32]* @y, i64 0, i64 %i.1
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%x.ld.addr = getelementptr [256 x i32]* @x, i64 1, i64 %i.256
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%x.st.addr = getelementptr [256 x i32]* @x, i64 0, i64 %i.1
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%x = load i32* %x.ld.addr ; 0
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%y = load i32* %y.ld.addr ; 1
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%r = add i32 %y, %x
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store i32 %r, i32* %x.st.addr ; 2
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; CHECK: 0,2: dep
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; CHECK: 1,2: ind
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%i.next = add i64 %i, 1
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%exitcond = icmp eq i64 %i.next, 256
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br i1 %exitcond, label %for.end, label %for.body
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for.end:
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@ -42,3 +42,22 @@ for.body:
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for.end:
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ret void
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}
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;; x[6] = x[6]
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define void @f3(...) nounwind {
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entry:
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br label %for.body
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for.body:
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%i = phi i64 [ 0, %entry ], [ %i.next, %for.body ]
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%x = load i32* getelementptr ([256 x i32]* @x, i32 0, i64 6)
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store i32 %x, i32* getelementptr ([256 x i32]* @x, i32 0, i64 6)
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; CHECK: 0,1: dep
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%i.next = add i64 %i, 1
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%exitcond = icmp eq i64 %i.next, 256
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br i1 %exitcond, label %for.end, label %for.body
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for.end:
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ret void
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}
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