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DRAFT: VM: Add a 'tag' argument to the 'static-patch!' instruction.

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This commit is contained in:
Mark H Weaver 2019-06-08 01:06:55 -04:00
parent 90275c1c18
commit 92a7168fbe
3 changed files with 25 additions and 12 deletions
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15
libguile/vm-engine.c
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@ -2192,23 +2192,26 @@ VM_NAME (scm_thread *thread)
NEXT (2);
}
/* static-patch! _:24 dst-offset:32 src-offset:32
/* static-patch! tag:24 dst-offset:32 src-offset:32
*
* Patch a pointer at DST-OFFSET to point to SRC-OFFSET. Both offsets
* are signed 32-bit values, indicating a memory address as a number
* of 32-bit words away from the current instruction pointer.
* Patch a pointer at DST-OFFSET to point to SRC-OFFSET, with TAG
* added in the low bits. Both offsets are signed 32-bit values,
* indicating a memory address as a number of 32-bit words away from
* the current instruction pointer.
*/
VM_DEFINE_OP (86, static_patch, "static-patch!", OP3 (X32, LO32, L32))
VM_DEFINE_OP (86, static_patch, "static-patch!", OP3 (X8_S24, LO32, L32))
{
int32_t dst_offset, src_offset;
void *src;
void** dst_loc;
uint32_t tag;
UNPACK_24 (op, tag);
dst_offset = ip[1];
src_offset = ip[2];
dst_loc = (void **) (ip + dst_offset);
src = ip + src_offset;
src = (char *) (ip + src_offset) + tag;
VM_ASSERT (ALIGNED_P (dst_loc, void*), abort());
*dst_loc = src;