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| author | Ian Lance Taylor <ian@gcc.gnu.org> | 2017-06-23 16:03:49 +0000 |
|---|---|---|
| committer | Ian Lance Taylor <ian@gcc.gnu.org> | 2017-06-23 16:03:49 +0000 |
| commit | 5f0b897b2ee47bf3845d924dd5bc3beb949bc78b (patch) | |
| tree | 3f8b464d9ac9de6affa319ea9639ee19ef983302 /gcc/go/gofrontend/lex.h | |
| parent | ef2361cbd8462374b28e9e8becf8710a9b30d125 (diff) | |
| download | gcc-5f0b897b2ee47bf3845d924dd5bc3beb949bc78b.zip gcc-5f0b897b2ee47bf3845d924dd5bc3beb949bc78b.tar.gz gcc-5f0b897b2ee47bf3845d924dd5bc3beb949bc78b.tar.bz2 | |
compiler: add go:notinheap magic comment
Implement go:notinheap as the gc compiler does. A type marked as
go:notinheap may not live in the heap, and does not require a write
barrier. Struct and array types that incorporate notinheap types are
themselves notinheap. Allocating a value of a notinheap type on the
heap is an error.
This is not just an optimization. There is code where a write barrier
may not occur that was getting a write barrier with gccgo but not gc,
because the types in question were notinheap. The case I found was
setting the mcache field in exitsyscallfast.
Reviewed-on: https://go-review.googlesource.com/46490
From-SVN: r249594
Diffstat (limited to 'gcc/go/gofrontend/lex.h')
| -rw-r--r-- | gcc/go/gofrontend/lex.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/gcc/go/gofrontend/lex.h b/gcc/go/gofrontend/lex.h index 0a7a842..a8b7091 100644 --- a/gcc/go/gofrontend/lex.h +++ b/gcc/go/gofrontend/lex.h @@ -64,7 +64,8 @@ enum GoPragma GOPRAGMA_NOWRITEBARRIER = 1 << 6, // No write barriers. GOPRAGMA_NOWRITEBARRIERREC = 1 << 7, // No write barriers here or callees. GOPRAGMA_CGOUNSAFEARGS = 1 << 8, // Pointer to arg is pointer to all. - GOPRAGMA_UINTPTRESCAPES = 1 << 9 // uintptr(p) escapes. + GOPRAGMA_UINTPTRESCAPES = 1 << 9, // uintptr(p) escapes. + GOPRAGMA_NOTINHEAP = 1 << 10 // type is not in heap. }; // A token returned from the lexer. |