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Diffstat (limited to 'compiler/optimizing/ssa_builder.h')
| -rw-r--r-- | compiler/optimizing/ssa_builder.h | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/compiler/optimizing/ssa_builder.h b/compiler/optimizing/ssa_builder.h index f50da46040..b414fb2945 100644 --- a/compiler/optimizing/ssa_builder.h +++ b/compiler/optimizing/ssa_builder.h @@ -24,6 +24,26 @@ namespace art { static constexpr int kDefaultNumberOfLoops = 2; +/** + * Transforms a graph into SSA form. The liveness guarantees of + * this transformation are listed below. A DEX register + * being killed means its value at a given position in the code + * will not be available to its environment uses. A merge in the + * following text is materialized as a `HPhi`. + * + * (a) Dex registers that do not require merging (that is, they do not + * have different values at a join block) are available to all their + * environment uses. + * + * (b) Dex registers that require merging, and the merging gives + * incompatible types, will be killed for environment uses of that merge. + * + * (c) When the `debuggable` flag is passed to the compiler, Dex registers + * that require merging and have a proper type after the merge, are + * available to all their environment uses. If the `debuggable` flag + * is not set, values of Dex registers only used by environments + * are killed. + */ class SsaBuilder : public HGraphVisitor { public: explicit SsaBuilder(HGraph* graph) |