| commit | 3f6c87d5aceeada27b16001a63f56defac2f1361 | [log] [tgz] |
|---|---|---|
| author | Vyacheslav Egorov <vegorov@google.com> | Tue May 22 18:05:14 2018 +0000 |
| committer | commit-bot@chromium.org <commit-bot@chromium.org> | Tue May 22 18:05:14 2018 +0000 |
| tree | 4997ddb7ef38e113accf9f99756af3eddbbd3699 | |
| parent | a75624806550b804b5fe6c342716d64451e7f6ec [diff] |
[vm/compiler] Do not use Constant(#null) to reserve space on the expression stack. Given IL like this: t3 <- Constant(#null) <--\ // ... do something ... | StoreLocal(:temp, t4) ---/ // Do something else StoreIndexed(t1, t2, t3) Graph builder would use Constant(#null) as an input definition for StoreIndexed - which leads to wrong generated code in unoptimized mode on X64 where StoreIndexed has specialization for constant values. In optimized code SSA renaming would actually replace t3 with a correct reaching definition. This CL introduces a new IL instruction MakeTemp(...) which has exactly the same effect as Constant(#null) on the expression stack, but is not treated as a constant value by the backend. The bug was unnoticed because of the loose assertions in the SSA renaming which permitted replacing Constant-s with non-Constant reaching definitions. This CL also tightens those assertions to catch this issue. Also cleanup the code in SSA renaming a bit to make it a bit easier to understand. Fixes https://github.com/dart-lang/sdk/issues/33195 Bug: 33195 Change-Id: I7c914c836d4af7a50e8a8e1a02d03e9413f87779 Reviewed-on: https://dart-review.googlesource.com/56112 Commit-Queue: Vyacheslav Egorov <vegorov@google.com> Reviewed-by: Martin Kustermann <kustermann@google.com>
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