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| author | Luc Van Oostenryck <luc.vanoostenryck@gmail.com> | 2017-06-01 03:38:26 +0200 |
|---|---|---|
| committer | Luc Van Oostenryck <luc.vanoostenryck@gmail.com> | 2018-07-23 01:40:10 +0200 |
| commit | bfe532a4f10f480085aac3a5785de3cca90e7ee5 (patch) | |
| tree | 53619edf41f73e5cc5d26b90e0e85f57cc96dc71 /validation | |
| parent | 6915fbc000970323afb2e7757226f3ad0f17be09 (diff) | |
| download | sparse-dev-bfe532a4f10f480085aac3a5785de3cca90e7ee5.tar.gz | |
big-shift: do not simplify over-sized OP_ASR to zero
Currently, arithmetic right shifts with a shift count bigger
than the operand size are simplified to zero.
While this makes a lot of sense for LSR and SHL, for ASR it's
much less so.
Remove the simplification and let the back-end generate the code
for a non-immediate count (which is what GCC do).
Note: Some other options would be:
- reduce the shift count modulo the operand size, like it was
done previously at expansion time and which correspond to the
run-time behaviour of several CPUs families (x86[-64], arm64,
mips, ...) but not all of them (arm, ppc, ...).
- truncate the count to N-1
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Diffstat (limited to 'validation')
| -rw-r--r-- | validation/shift-undef.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/validation/shift-undef.c b/validation/shift-undef.c index e15847a8..df1ac89e 100644 --- a/validation/shift-undef.c +++ b/validation/shift-undef.c @@ -98,6 +98,7 @@ shift-undef.c:18:30: warning: shift too big (4294967289) for type int shift-undef.c:19:30: warning: shift too big (4294967288) for type unsigned int shift-undef.c:20:30: warning: shift too big (4294967287) for type unsigned int shift-undef.c:21:29: warning: right shift by bigger than source value +shift-undef.c:24:29: warning: right shift by bigger than source value shift-undef.c:32:11: warning: shift too big (100) for type int shift-undef.c:33:11: warning: shift too big (101) for type unsigned int shift-undef.c:34:11: warning: shift too big (102) for type unsigned int @@ -117,5 +118,6 @@ shift-undef.c:47:30: warning: shift too big (4294967289) for type int shift-undef.c:48:30: warning: shift too big (4294967288) for type unsigned int shift-undef.c:49:30: warning: shift too big (4294967287) for type unsigned int shift-undef.c:50:26: warning: right shift by bigger than source value +shift-undef.c:53:26: warning: right shift by bigger than source value * check-error-end */ |