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57004ae3ac
This index record the position for each metadata record in the bitcode, so that the reader will be able to lazy-load on demand each individual record. We also make sure that every abbrev is emitted upfront so that the block can be skipped while reading. I don't plan to commit this before having the reader counterpart, but I figured this can be reviewed mostly independently. Recommit r290684 (was reverted in r290686 because a test was broken) after adding a threshold to avoid emitting the index when unnecessary (little amount of metadata). This optimization "hides" a limitation of the ability to backpatch in the bitstream: we can only backpatch safely when the position has been flushed. So if we emit an index for one metadata, it is possible that (part of) the offset placeholder hasn't been flushed and the backpatch will fail. Differential Revision: https://reviews.llvm.org/D28083 llvm-svn: 290690
42 lines
1.5 KiB
LLVM
42 lines
1.5 KiB
LLVM
; RUN: llvm-as <%s -bitcode-mdindex-threshold=0 | llvm-bcanalyzer -dump | FileCheck %s
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; Check that nodes are emitted in post-order to minimize the need for temporary
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; nodes. The graph structure is designed to foil naive implementations of
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; iteratitive post-order traersals: the leaves, !3 and !4, are reachable from
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; the entry node, !6, as well as from !5. There is one leaf on either side to
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; be sure it tickles bugs whether operands are visited forward or reverse.
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; Nodes in this testcase are numbered to match how they are referenced in
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; bitcode. !3 is referenced as opN=3.
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; We don't care about the order of the strings (or of !3 and !4). Let's just
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; make sure the strings are first and make it clear that there are two of them.
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; CHECK: <STRINGS {{.*}} num-strings = 2 {
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; CHECK-NEXT: 'leaf
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; CHECK-NEXT: 'leaf
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; CHECK-NEXT: }
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; Before the records we emit an offset to the index for the block
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; CHECK-NEXT: <INDEX_OFFSET
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; The leafs should come first (in either order).
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; CHECK-NEXT: <NODE op0=1/>
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; CHECK-NEXT: <NODE op0=2/>
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!3 = !{!"leaf3"}
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!4 = !{!"leaf4"}
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; CHECK-NEXT: <NODE op0=3 op1=4/>
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!5 = !{!3, !4}
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; CHECK-NEXT: <NODE op0=3 op1=5 op2=4/>
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!6 = !{!3, !5, !4}
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; Before the named records we emit the index containing the position of the
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; previously emitted records
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; CHECK-NEXT: <INDEX {{.*}} (offset match)
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; Note: named metadata nodes are not cannot reference null so their operands
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; are numbered off-by-one.
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; CHECK-NEXT: <NAME
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; CHECK-NEXT: <NAMED_NODE op0=5/>
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!named = !{!6}
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