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JIT: improve transition from 32-bit to 64-bit jumps

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Use a recursive call to try again, instead of trying to reset local
state. The reset-local-state variant is definitely broken in
some caes, though I could not provoke the JIT buffer overflow
that I was hoping to fix with this change.
This commit is contained in:
Matthew Flatt 2014-05-31 13:21:59 +01:00
parent d2fb1acb46
commit 1558e1243a
1 changed files with 14 additions and 6 deletions
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20
racket/src/racket/src/jitstate.c
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@ -181,6 +181,16 @@ void *scheme_generate_one(mz_jit_state *old_jitter,
int gcable, int gcable,
void *save_ptr, void *save_ptr,
Scheme_Native_Closure_Data *ndata) Scheme_Native_Closure_Data *ndata)
/* The given generate() function is called at least twice: once to gather
the size of the generated code (at a temporary location), and again
to generate the final code at its final location. The size of the
generated code must not depend on the deistation address. The
`retain_start' field of hte jitter record passed to generate() will
be NULL for a sizing run and non-NULL for a generation run.
In the unlikely event that a 64-bit build switches from 32-bit
branches to 64-bit branches, generate() might be called an extra
time in either mode. */
{ {
mz_jit_state _jitter; mz_jit_state _jitter;
mz_jit_state *jitter = &_jitter; mz_jit_state *jitter = &_jitter;
@ -289,9 +299,8 @@ void *scheme_generate_one(mz_jit_state *old_jitter,
then switch over to long-jump mode. */ then switch over to long-jump mode. */
if (check_long_mode((uintptr_t)buffer, size)) { if (check_long_mode((uintptr_t)buffer, size)) {
/* start over */ /* start over */
known_size = 0; return scheme_generate_one(old_jitter, generate, data, gcable,
use_long_jumps = 1; save_ptr, ndata);
continue;
} }
} }
#endif #endif
@ -342,9 +351,8 @@ void *scheme_generate_one(mz_jit_state *old_jitter,
if (!use_long_jumps) { if (!use_long_jumps) {
if (check_long_mode((uintptr_t)buffer, size)) { if (check_long_mode((uintptr_t)buffer, size)) {
/* start over */ /* start over */
known_size = 0; return scheme_generate_one(old_jitter, generate, data, gcable,
use_long_jumps = 1; save_ptr, ndata);
continue;
} }
} }
#endif #endif